Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties of Bi3+ Doped Manganese Spinel Ferrite Nanoparticles for Photonic Applications

*V. Jagadeesha Angadi, H.R. Lakshmiprasanna and K. Manjunatha*

## **Abstract**

The structural, microstructural, and magnetic properties of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles prepared by solution combustion method were investigated. Rietveld-refined X-ray diffraction patterns confirm the single-phase formation with space group Fd3m having spinel cubic structure. The porous nature of the samples was confirmed by scanning electron microscopy (SEM). Composition values of the theoretical stoichiometry and energy-dispersive spectroscopy (EDS) composition values are well matched for all samples. The dielectric parameters such as real part of dielectric constant, imaginary part of dielectric constant, and dielectric loss tangent decrease with the increase in frequency. The AC conductivity increases with increase in the Bi3+ concentration. The real part of complex impedance decreases with the increase in frequency. Cole-Cole plots reveal that one semicircle was obtained for each of the samples. The real and imaginary parts of electric modulus vary with frequency. The magnetic hysteresis curves of all samples reveal the soft magnetic material nature. We observed S esteems began uniquely from the higher superparamagnetic, we would have watched the monotonic decrease in S with increase in Bi3+ concentration. Furthermore, the magnetic parameters were estimated.

**Keywords:** Maxwell-Wagner interfacial type of polarization, Cole-Cole plots, soft magnetic material, solution combustion method

## **1. Introduction**

Nowadays, manganese (Mn) ferrite nanoparticles have been used for great potential applications such as absorbing electromagnetic waves, storage media, and water treatment catalysts [1–4]. Many researchers focused on the fabrication of spinel ferrite nanoparticles due to their exceptional electrical and magnetic properties [5–9]. To a progressively essential degree, the expanded scaling down and data storage devices of new devices require the utilization of nanosized magnetic attractive particles [10, 11]. Manganese spinel ferrite nanoparticles have gotten expanding consideration for their surprising magnetic properties, such as moderate saturation magnetization (Ms) and low coercivity with a mechanical hardness, high permeability, and good chemical stability [12, 13]. The significance of thick manganese (Mn) spinel ferrites additionally lies in their potential application, for example, transformers, core materials for coils, information and communication devices, and so forth. The MnFe2O4 nanoparticles have a spinel cubic structure having the general formula AB2O4, where the A sites are occupied by the Mn2+ ions and B sites by the Fe3+ ions. In a unit cell of manganese ferrites, there are 8 divalent Mn2+ ions, 16 trivalent Fe3+ ions, and 32 oxygen ions [14].

The spinel MnFe2O4 nanoparticles were prepared by synthesis methods such as sonochemical technique, co-precipitation, sol-gel method, and solution combustion method [15–17]. In the current work, the solution combustion method is often chosen because it is safe, cheap, and easy and it requires less time and energy for the preparation of nanoparticles. It also produces a high-purity product. In this method, the crystallite size, particle size, purity, surface area, degree of nature, and porosity can be influenced by the fuel (F) type [18]. However, for the preparation of nanoparticles, there is no requirement for complex tools, high-temperature furnaces, and reaction chambers in the synthesis process.

In the present work, the Bi3+-substituted MnFe2O4 spinel nanoparticles were prepared by a solution combustion method using a mixture of fuels such as glucose and urea. The structural, microstructural, dielectrical, and magnetic properties of Bi-doped manganese spinel ferrite nanoparticles were synthesized and investigated through XRD, SEM, EDS, and dielectric and vibrating sample magnetometer (VSM) for photonic applications.

## **2. Experimental details**

## **2.1 Materials**

For the preparation of Mn1-xBixFe2O4 (x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles, Mn(NO3)2.4H2O (manganese nitrate) (Sigma-Aldrich; molecular weight 251.01 g/mol, purity 99.0%), Bi(NO3)3·5H2O (bismuth nitrate) (Leica, Sigma-Aldrich; purity 98 + %, molecular weight 485.07 g/mol), and Fe(NO3)2.9H2O (ferric nitrate) (Merck; purity 99.0%, molecular weight 404 g/mol) are used as oxidizers (O) and NH2CONH2 (carbamide) (Fisher Scientific; purity 99.0%, molecular weight 60.06 g/mol) and C6H12O6 (glucose) (Glucomin-D; purity 99.4%, molecular weight 180.156 g/mol) as fuels. Further based on the oxidizer's and fuel's valences of the compounds, the oxidizer-andfuel ratio is maintained to unity.

### **2.2 Synthesis method**

The Mn1-xBixFe2O4 (x = 0.0, 0.05, 0.1, 0.15, and 0.2) spinel nanoparticles were prepared by the solution combustion method using a stoichiometric amount of O and a mixture of F proportions taken as one. Stoichiometric

**133**

**Figure 1.**

*nanoparticles.*

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties...*

amounts of manganese nitrate (Mn(NO3)2·4H2O), bismuth nitrate

(Bi(NO3)3·5H2O), ferric nitrate (Fe(NO3)3·9H2O), carbamide (NH2CONH2), and glucose (C6H12O6) are carried and put in a 500-ml Borosil glass beaker, which is then diluted with a double distilled water. The mixture solution was kept on magnetic stirrer about 60 min to get a homogeneous solution. This homogeneous solution was kept in a pre-warmed suppress heater at 450°C. Within 20 min, the burning process was finished. Then, the obtained powder was grained about 30 min using agate mortar and pestle. The flow chart of the Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) solution combustion is

The XRD patterns were gotten by using CuKα radiation having a wavelength (λ) = 1.5406 Å, and the 2θ values run from 10° to 80° under the step size of 0.02°. The crystalline nature and phase structure can be understood from the XRD patterns. The SEM and EDS micrographs were collected by using JEOL (model JSM-840) to obtain the surface morphology and elemental composition of the samples. To study the electrical properties, the samples are made into pellets using a hydraulic press under the 5-ton pressure using an 11-mm die set. The prepared pellets are sintered at 650°C for 3 h. The sintered pellets are silver coated for a good electrical contact. The electrical properties of all samples are tested at room temperature in the frequency up to 20 MHz using the Wayne Kerr 6500B Series Impedance Analyzer. The magnetic properties were measured at room temperature using a physical properties measurement system (PPMS; Quantum Design, Inc.) up

*The flow chart of the solution combustion method for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2)* 

*DOI: http://dx.doi.org/10.5772/intechopen.92430*

shown in **Figure 1**.

to a field of 20 kOe.

**2.3 Characterizations**

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

amounts of manganese nitrate (Mn(NO3)2·4H2O), bismuth nitrate (Bi(NO3)3·5H2O), ferric nitrate (Fe(NO3)3·9H2O), carbamide (NH2CONH2), and glucose (C6H12O6) are carried and put in a 500-ml Borosil glass beaker, which is then diluted with a double distilled water. The mixture solution was kept on magnetic stirrer about 60 min to get a homogeneous solution. This homogeneous solution was kept in a pre-warmed suppress heater at 450°C. Within 20 min, the burning process was finished. Then, the obtained powder was grained about 30 min using agate mortar and pestle. The flow chart of the Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) solution combustion is shown in **Figure 1**.

## **2.3 Characterizations**

*Bismuth - Fundamentals and Optoelectronic Applications*

oxygen ions [14].

and water treatment catalysts [1–4]. Many researchers focused on the fabrication of spinel ferrite nanoparticles due to their exceptional electrical and magnetic properties [5–9]. To a progressively essential degree, the expanded scaling down and data storage devices of new devices require the utilization of nanosized magnetic attractive particles [10, 11]. Manganese spinel ferrite nanoparticles have gotten expanding consideration for their surprising magnetic properties, such as moderate saturation magnetization (Ms) and low coercivity with a mechanical hardness, high permeability, and good chemical stability [12, 13]. The significance of thick manganese (Mn) spinel ferrites additionally lies in their potential application, for example, transformers, core materials for coils, information and communication devices, and so forth. The MnFe2O4 nanoparticles have a spinel cubic structure having the general formula AB2O4, where the A sites are occupied by the Mn2+ ions and B sites by the Fe3+ ions. In a unit cell of manganese ferrites, there are 8 divalent Mn2+ ions, 16 trivalent Fe3+ ions, and 32

The spinel MnFe2O4 nanoparticles were prepared by synthesis methods such as sonochemical technique, co-precipitation, sol-gel method, and solution combustion method [15–17]. In the current work, the solution combustion method is often chosen because it is safe, cheap, and easy and it requires less time and energy for the preparation of nanoparticles. It also produces a high-purity product. In this method, the crystallite size, particle size, purity, surface area, degree of nature, and porosity can be influenced by the fuel (F) type [18]. However, for the preparation of nanoparticles, there is no requirement for complex tools, high-temperature

In the present work, the Bi3+-substituted MnFe2O4 spinel nanoparticles were prepared by a solution combustion method using a mixture of fuels such as glucose and urea. The structural, microstructural, dielectrical, and magnetic properties of Bi-doped manganese spinel ferrite nanoparticles were synthesized and investigated through XRD, SEM, EDS, and dielectric and vibrating sample magnetometer

For the preparation of Mn1-xBixFe2O4 (x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles, Mn(NO3)2.4H2O (manganese nitrate) (Sigma-Aldrich; molecular weight 251.01 g/mol, purity 99.0%), Bi(NO3)3·5H2O (bismuth nitrate) (Leica, Sigma-Aldrich; purity 98 + %, molecular weight 485.07 g/mol), and Fe(NO3)2.9H2O (ferric nitrate) (Merck; purity 99.0%, molecular weight 404 g/mol) are used as oxidizers (O) and NH2CONH2 (carbamide) (Fisher Scientific; purity 99.0%, molecular weight 60.06 g/mol) and C6H12O6 (glucose) (Glucomin-D; purity 99.4%, molecular weight 180.156 g/mol) as fuels. Further based on the oxidizer's and fuel's valences of the compounds, the oxidizer-and-

The Mn1-xBixFe2O4 (x = 0.0, 0.05, 0.1, 0.15, and 0.2) spinel nanoparticles

were prepared by the solution combustion method using a stoichiometric amount of O and a mixture of F proportions taken as one. Stoichiometric

furnaces, and reaction chambers in the synthesis process.

(VSM) for photonic applications.

fuel ratio is maintained to unity.

**2.2 Synthesis method**

**2. Experimental details**

**2.1 Materials**

**132**

The XRD patterns were gotten by using CuKα radiation having a wavelength (λ) = 1.5406 Å, and the 2θ values run from 10° to 80° under the step size of 0.02°. The crystalline nature and phase structure can be understood from the XRD patterns. The SEM and EDS micrographs were collected by using JEOL (model JSM-840) to obtain the surface morphology and elemental composition of the samples. To study the electrical properties, the samples are made into pellets using a hydraulic press under the 5-ton pressure using an 11-mm die set. The prepared pellets are sintered at 650°C for 3 h. The sintered pellets are silver coated for a good electrical contact. The electrical properties of all samples are tested at room temperature in the frequency up to 20 MHz using the Wayne Kerr 6500B Series Impedance Analyzer. The magnetic properties were measured at room temperature using a physical properties measurement system (PPMS; Quantum Design, Inc.) up to a field of 20 kOe.

**Figure 1.**

*The flow chart of the solution combustion method for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

## **3. Results and discussions**

## **3.1 Phase, crystallinity, and structural elucidation**

**Figure 2** depicts the refined XRD patterns of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) as synthesized ferrite samples were plotted using a WinPLOTR program. The Bragg diffraction peaks corresponding to angular positions were indexed as (220) (311) (222) (400) (331) (422) (511) (440). Rietveld refinement was employed using a FullProf program for structural refinements. The parameters obtained from refinement, such as weighted (Rp) and unweighted (Rwp)

**Figure 2.** *Rietveld-refined XRD patterns of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

**135**

**Figure 3.**

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties...*

crystallite size was calculated by using the equation below [19]:

**Crystallite size D in (nm)**

profile factor ratio (Rwp/Rp), which is less than one, and goodness-of-fit factor

), which is low, are given in **Table 1**. The refined XRD patterns confirm the single phase with a spinel cubic structure having a space further without any additional impurity peaks. The indexed (hkl) values are well matched with the Joint Committee of Powder Diffraction Standards (JCPDS) card number 74-2400. **Figure 3** clearly shows that the lattice parameters increase with the increase of Bi3+ concentration due to the difference in ionic radius of Mn2+ and Bi3+ ions. The ionic radius of Mn2+ (0.83 Å) is less than the ionic radius of Bi3+ (1.03 Å). The average

> D= \_*k cos*

where k is the Scherrer constant (k = 0.9), λ is the wavelength of Cu-kα radiation, β is the full width half maximum, and θ is the angle of diffraction. The estimated crystallite size decreases with the increase of Bi3+ concentration (**Figure 3**). Further internal strain, X-ray density, and hopping length were increased with Bi3+ concentration increasing (**Figure 4**). The lattice parameters, average crystallite size, internal strain, X-ray density, and hopping lengths were tabulated in **Table 1**.

> **Volume (Å3 )**

0.0 8.3612 13.7 584.52 88 5.2406 3.6025 2.9561 0.05 8.3658 11.9 585.49 95 5.4068 3.6225 2.9577 0.10 8.3845 10.8 589.42 96 5.5443 3.6306 2.9643 0.15 8.3874 10.6 590.04 105 5.7117 3.6319 2.9654 0.20 8.3932 9.2 591.26 131 5.8731 3.6343 2.9674

*Crystallite size, lattice constant, strain, X-ray density, magnetic hoping length data of Mn1-xBixFe2O4 (where* 

*Variation of crystallite size (nm) and lattice parameter (a°) with Bi3+ doping concentration of Mn1-xBixFe2O4*

**Internal strain** Є **10<sup>−</sup><sup>2</sup> (%)**

nm (1)

**X-ray density (Δ) g/ cm3**

**Hoping length (Å) LA LB**

*DOI: http://dx.doi.org/10.5772/intechopen.92430*

(χ2

**Bi3+ content**

**Table 1.**

**Lattice parameters (Å)**

*x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

*(where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

profile factor ratio (Rwp/Rp), which is less than one, and goodness-of-fit factor (χ2 ), which is low, are given in **Table 1**. The refined XRD patterns confirm the single phase with a spinel cubic structure having a space further without any additional impurity peaks. The indexed (hkl) values are well matched with the Joint Committee of Powder Diffraction Standards (JCPDS) card number 74-2400. **Figure 3** clearly shows that the lattice parameters increase with the increase of Bi3+ concentration due to the difference in ionic radius of Mn2+ and Bi3+ ions. The ionic radius of Mn2+ (0.83 Å) is less than the ionic radius of Bi3+ (1.03 Å). The average crystallite size was calculated by using the equation below [19]:

$$\text{ng the equation below [19]:}$$

$$\mathbf{D} = \frac{k\,\lambda}{\beta \cos \theta} \,\text{nm} \tag{1}$$

where k is the Scherrer constant (k = 0.9), λ is the wavelength of Cu-kα radiation, β is the full width half maximum, and θ is the angle of diffraction. The estimated crystallite size decreases with the increase of Bi3+ concentration (**Figure 3**). Further internal strain, X-ray density, and hopping length were increased with Bi3+ concentration increasing (**Figure 4**). The lattice parameters, average crystallite size, internal strain, X-ray density, and hopping lengths were tabulated in **Table 1**.


**Table 1.**

*Bismuth - Fundamentals and Optoelectronic Applications*

**3.1 Phase, crystallinity, and structural elucidation**

**Figure 2** depicts the refined XRD patterns of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) as synthesized ferrite samples were plotted using a WinPLOTR program. The Bragg diffraction peaks corresponding to angular positions were indexed as (220) (311) (222) (400) (331) (422) (511) (440). Rietveld refinement was employed using a FullProf program for structural refinements. The parameters obtained from refinement, such as weighted (Rp) and unweighted (Rwp)

*Rietveld-refined XRD patterns of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

**3. Results and discussions**

**134**

**Figure 2.**

*Crystallite size, lattice constant, strain, X-ray density, magnetic hoping length data of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

#### **Figure 3.**

*Variation of crystallite size (nm) and lattice parameter (a°) with Bi3+ doping concentration of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

#### **Figure 4.**

*Variation of internal strain (%) and density (gm/cm3 ) of (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles with Bi3+ doping concentration.*

### **3.2 SEM and EDS**

**Figures 5** and **6** show the SEM and EDS of Bi3+-doped MnFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) ferrite samples synthesized, respectively. All SEM micrographs reveal the highly porous nature of the samples [20]. All the samples show the dry foamy powder due to the combustion. The average grain size cannot be observed due to the high porous nature of the sample. The density of samples increases with Bi3+ concentration. The EDS images clearly reveal that Mn, Fe, and O peaks are clearly visible in all samples. The Bi3+ peak is visible in all samples except at 0 mol % Bi3+ sample. The stoichiometry of constituent elements present in the Mn1-xBixFe2O4 with x = 0.0, 0.05, 0.1, 0.15, and 0.2 ferrite nanoparticles estimated from EDS spectrum is shown in **Table 2**. The estimated stoichiometry as listed in **Table 3** is very near to the composition of theoretical values.

### **3.3 Dielectric studies**

### *3.3.1 Real (ε*′*) and imaginary (ε*′′*) parts of dielectric constant*

The real (ε′) and imaginary (ε′′) parts of the dielectric constant as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles are depicted in **Figure 7(a)** and **Figure 7(b)**, respectively. At low frequency, the real and imaginary parts of dielectric constants show the dispersion for all samples. The dielectric constant values sharply decrease with increasing in frequency, and it is due to Maxwell-Wagner interfacial-type polarization according to Koop's phenomenological theory [21]. At the lower-frequency region, the interfacial polarization contributes to the dispersion. A systematic variation is observed due to the dispersion of dielectric constant with substitution. At the higher-frequency region, it cannot follow the alternating electric field, so real and imaginary parts of dielectric constants are independent of frequency at that region. In ferrites, the maximum dielectric constant is observed in samples having higher Fe2+ content. At the lower-frequency region, the hopping (exchange

**137**

**Figure 5.**

dielectric constant.

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties...*

of electron) between Fe2+ and Fe3+ at octahedral sites follows the alternating electric field. Many literatures on AB2O4 ferrites indicate that high-temperature sintering leads to the exchange of the Fe3+ ions to Fe2+ ions at octahedral sites to some degree [22]. However, the hopping process, involving between the Fe3+ and Fe2+ ions, is attributed to the dielectric properties of the samples. Thus, the increase of Bi3+ concentration results in the increase of dielectric constant. The grain size also influences the dielectric properties, since, in ferrite samples, the dielectric constant of the poorly conducting grain boundary is less than the dielectric constant of highly conducting grains. Thus, size reduction introduces more grain boundaries and hence increases changes in electron polarization at the grain boundaries. Since the size decreases with bismuth substitution increasing, it also increases the

*SEM micrograph images of Mn1-xBixFe2O4 ferrite nanoparticles with x = 0.0 (MnFe2O4), x = 0.05 (Mn0.95Bi0.05Fe2O4), x = 0.1 (Mn0.9Bi0.1Fe2O4), x = 0.15 (Mn0.85Bi0.15Fe2O4), and x = 0.2 (Mn0.8Bi0.2Fe2O4).*

*DOI: http://dx.doi.org/10.5772/intechopen.92430*

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

#### **Figure 5.**

*Bismuth - Fundamentals and Optoelectronic Applications*

**Figures 5** and **6** show the SEM and EDS of Bi3+-doped MnFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) ferrite samples synthesized, respectively. All SEM micrographs reveal the highly porous nature of the samples [20]. All the samples show the dry foamy powder due to the combustion. The average grain size cannot be observed due to the high porous nature of the sample. The density of samples increases with Bi3+ concentration. The EDS images clearly reveal that Mn, Fe, and O peaks are clearly visible in all samples. The Bi3+ peak is visible in all samples except at 0 mol % Bi3+ sample. The stoichiometry of constituent elements present in the Mn1-xBixFe2O4 with x = 0.0, 0.05, 0.1, 0.15, and 0.2 ferrite nanoparticles estimated from EDS spectrum is shown in **Table 2**. The estimated stoichiometry as listed in

*) of (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles* 

The real (ε′) and imaginary (ε′′) parts of the dielectric constant as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles are depicted in **Figure 7(a)** and **Figure 7(b)**, respectively. At low frequency, the real and imaginary parts of dielectric constants show the dispersion for all samples. The dielectric constant values sharply decrease with increasing in frequency, and it is due to Maxwell-Wagner interfacial-type polarization according to Koop's phenomenological theory [21]. At the lower-frequency region, the interfacial polarization contributes to the dispersion. A systematic variation is observed due to the dispersion of dielectric constant with substitution. At the higher-frequency region, it cannot follow the alternating electric field, so real and imaginary parts of dielectric constants are independent of frequency at that region. In ferrites, the maximum dielectric constant is observed in samples having higher Fe2+ content. At the lower-frequency region, the hopping (exchange

**Table 3** is very near to the composition of theoretical values.

*3.3.1 Real (ε*′*) and imaginary (ε*′′*) parts of dielectric constant*

**136**

**3.2 SEM and EDS**

*with Bi3+ doping concentration.*

*Variation of internal strain (%) and density (gm/cm3*

**Figure 4.**

**3.3 Dielectric studies**

*SEM micrograph images of Mn1-xBixFe2O4 ferrite nanoparticles with x = 0.0 (MnFe2O4), x = 0.05 (Mn0.95Bi0.05Fe2O4), x = 0.1 (Mn0.9Bi0.1Fe2O4), x = 0.15 (Mn0.85Bi0.15Fe2O4), and x = 0.2 (Mn0.8Bi0.2Fe2O4).*

of electron) between Fe2+ and Fe3+ at octahedral sites follows the alternating electric field. Many literatures on AB2O4 ferrites indicate that high-temperature sintering leads to the exchange of the Fe3+ ions to Fe2+ ions at octahedral sites to some degree [22]. However, the hopping process, involving between the Fe3+ and Fe2+ ions, is attributed to the dielectric properties of the samples. Thus, the increase of Bi3+ concentration results in the increase of dielectric constant. The grain size also influences the dielectric properties, since, in ferrite samples, the dielectric constant of the poorly conducting grain boundary is less than the dielectric constant of highly conducting grains. Thus, size reduction introduces more grain boundaries and hence increases changes in electron polarization at the grain boundaries. Since the size decreases with bismuth substitution increasing, it also increases the dielectric constant.

*EDS patterns of Mn1-xBixFe2O4 ferrite nanoparticles with x = 0.0 (MnFe2O4), x = 0.05 (Mn0.95Bi0.05Fe2O4), x = 0.1 (Mn0.9Bi0.1Fe2O4), 0.15 (Mn0.85Bi0.15Fe2O4), and x = 0.2 (Mn0.8Bi0.2Fe2O4).*

**139**

**Table 3.**

*3.3.2 Dielectric loss tangent (tan δ)*

The dielectric loss tangent as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles is shown in **Figure 8**. The figure shows the dielectric loss tangent decreases with the increase of the frequency. The dielectric loss tangent is a result of the string in polarization in accordance with the applied external electric field. The materials with high dielectric loss tangent are engaged for manufacturing high-frequency heating devices. The tan δ was calculated using the relation tan δ = ε′/ε″, where ε′ and ε″ are the real

The tan δ decreases with the increase of the frequency, and then it becomes constant at higher frequencies for all samples. The dielectric loss tangent depends on a number of factors, such as homogeneity, stoichiometry, synthesis method,

and imaginary parts of the dielectric constant, respectively [23].

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties...*

**Mn Bi Fe O Total**

0.0 17.92 0.0 32.13 49.96 100 0.05 20.45 0.96 29.07 49.52 100 0.1 18.59 1.75 30.53 49.12 100 0.15 19.37 3.11 29.08 48.44 100 0.2 20.02 4.30 27.83 47.85 100

*The stoichiometry of constituent elements present in the Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2)* 

**Element Composition of theoretical** 

0 Bi 0 0

0.05 Bi 0.05 0.045

0.1 Bi 0.1 0.086

0.15 Bi 0.15 0.138

0.2 Bi 0.2 0.177

*Summary of EDS analysis of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

**values**

Mn 1 0.99

Fe 1 1 Mn 0.95 0.955

Fe 1 1 Mn 0.9 0.914

Fe 1 1 Mn 0.85 0.862

Fe 1 1 Mn 0.8 0.823

Fe 1 1

**Composition from EDX analysis**

**x Atomic abundance of elements (%)**

*DOI: http://dx.doi.org/10.5772/intechopen.92430*

*nanoparticles estimated from EDS spectrum.*

**Bi3+ concentration** 

**Table 2.**

**(x)**

**x Atomic abundance of elements (%) Mn Bi Fe O Total** 0.0 17.92 0.0 32.13 49.96 100 0.05 20.45 0.96 29.07 49.52 100 0.1 18.59 1.75 30.53 49.12 100 0.15 19.37 3.11 29.08 48.44 100 0.2 20.02 4.30 27.83 47.85 100

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

**Table 2.**

*Bismuth - Fundamentals and Optoelectronic Applications*

**138**

**Figure 6.**

*EDS patterns of Mn1-xBixFe2O4 ferrite nanoparticles with x = 0.0 (MnFe2O4), x = 0.05 (Mn0.95Bi0.05Fe2O4),* 

*x = 0.1 (Mn0.9Bi0.1Fe2O4), 0.15 (Mn0.85Bi0.15Fe2O4), and x = 0.2 (Mn0.8Bi0.2Fe2O4).*

*The stoichiometry of constituent elements present in the Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles estimated from EDS spectrum.*


**Table 3.**

*Summary of EDS analysis of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

## *3.3.2 Dielectric loss tangent (tan δ)*

The dielectric loss tangent as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles is shown in **Figure 8**. The figure shows the dielectric loss tangent decreases with the increase of the frequency. The dielectric loss tangent is a result of the string in polarization in accordance with the applied external electric field. The materials with high dielectric loss tangent are engaged for manufacturing high-frequency heating devices. The tan δ was calculated using the relation tan δ = ε′/ε″, where ε′ and ε″ are the real and imaginary parts of the dielectric constant, respectively [23].

The tan δ decreases with the increase of the frequency, and then it becomes constant at higher frequencies for all samples. The dielectric loss tangent depends on a number of factors, such as homogeneity, stoichiometry, synthesis method,

#### **Figure 7.**

*(a) The real (ε*′*) and (b) imaginary (ε*′′*) parts of the dielectric constant as a function of frequency at room temperature, respectively, for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

ferric content, and composition. The frequency increases with the decrease of the dielectric loss tangent; it may be characterized by the Maxwell-Wagner polarization and conduction mechanism in ferrites.

## *3.3.3 AC conductivity (σac)*

The variation of σac as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles is shown in **Figure 9**. From the figure, it may well be seen that at first the conductivity stays steady in the low frequencies, bit by bit increments in the middle of the road frequencies, and afterward shows scattering for high frequencies in consistence with the Jonscher power law. The AC conductivity was calculated by using the equation

**141**

**Figure 9.**

*0.1, 0.15, and 0.2) nanoparticles.*

**Figure 8.**

*0.05, 0.1, 0.15, and 0.2) nanoparticles.*

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties...*

σ*ac* = 2πf ɛ<sup>0</sup> × tanδ, where ɛ0 is the permittivity of free space, f is the frequency, and tan δ is the dielectric loss tangent. Here, the figure shows that σac increases with the increase of the frequency according to the hopping model [24]. In the lower frequencies, grain limits are increasingly adequate; thus the recurrence-free conducts are accomplished. Be that as it may, at high-frequency system, the increase in σac is credited to the increased hopping of charge bearers between the Fe2+ and Fe3+ particles and Mn2+ and Mn3+ particles at the octahedral site and further as a

*The AC conductivity as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05,* 

*The dielectric loss tangent as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0,* 

*DOI: http://dx.doi.org/10.5772/intechopen.92430*

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

#### **Figure 8.**

*Bismuth - Fundamentals and Optoelectronic Applications*

ferric content, and composition. The frequency increases with the decrease of the dielectric loss tangent; it may be characterized by the Maxwell-Wagner polarization

*(a) The real (ε*′*) and (b) imaginary (ε*′′*) parts of the dielectric constant as a function of frequency at room temperature, respectively, for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

The variation of σac as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles is shown in **Figure 9**. From the figure, it may well be seen that at first the conductivity stays steady in the low frequencies, bit by bit increments in the middle of the road frequencies, and afterward shows scattering for high frequencies in consistence with the Jonscher power law. The AC conductivity was calculated by using the equation

and conduction mechanism in ferrites.

*3.3.3 AC conductivity (σac)*

**140**

**Figure 7.**

*The dielectric loss tangent as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

σ*ac* = 2πf ɛ<sup>0</sup> × tanδ, where ɛ0 is the permittivity of free space, f is the frequency, and tan δ is the dielectric loss tangent. Here, the figure shows that σac increases with the increase of the frequency according to the hopping model [24]. In the lower frequencies, grain limits are increasingly adequate; thus the recurrence-free conducts are accomplished. Be that as it may, at high-frequency system, the increase in σac is credited to the increased hopping of charge bearers between the Fe2+ and Fe3+ particles and Mn2+ and Mn3+ particles at the octahedral site and further as a

#### **Figure 9.**

*The AC conductivity as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

### *Bismuth - Fundamentals and Optoelectronic Applications*

result of grain impact. With increasing substitution of Bi3+ by Mn2+ particles, it very well may be seen that at first conductivity diminishes because of the decrease in the quantity of Mn2+-Mn3+ particles which confines the portability of charge transporters at the octahedral destinations.

## *3.3.4 Real and imaginary parts of complex impedance*

**Figure 10(a)** and **(b)** shows the real and imaginary parts of complex impedance as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles, respectively. These types of frequency dependence complex impedance have been used for the study of the contribution of grains and grain boundaries on the electrical properties of nanoferrites. The obtained results showed the complex impedance versus frequency for the cobalt

#### **Figure 10.**

*(a) and (b) The real and imaginary parts of complex impedance as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

**143**

**Figure 11.**

*temperature.*

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties...*

Z′′ demonstrated the existence of space charge relaxation.

*3.3.6 The real (M*′*) and imaginary (M*′′*) parts of electric modulus*

ferrites. **Figure 10(a)** indicates that the magnitude of the real part of dielectric constant Z′ decreased with the increase of frequency. The real part of dielectric constant curves tended to merge in the high-frequency region. Such behavior is related to the effect of space charge polarization in the material [25]. **Figure 10(b)** indicates that the imaginary part of dielectric constant Z′′ reached a maximum value at the low-frequency region and then decreased with further increasing of the frequency, approaching a small value at high-frequency region. Further, it was observed that the height of the peak curve decreased with the concentration increasing, indicating a decrease in the relaxation time. The observed relaxation peak in the magnitude of

**Figure 11** shows the Cole-Cole plots of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles at room temperature. Cole-Cole plot shows the real part complex impedance (Z′) and the imaginary part of complex impedance (Z′′) along x-axis and y-axis, respectively. **Figure 11** clearly shows one semicircle was obtained for each of the samples, due to the grain boundary effect. The effects of grain boundary of the material are contributed by the parallel combination of grain boundary resistance and capacitance. However, the radius of curvature of each semicircular arc is reasonably shifted from the magnitude of Z′ when the concentration increased, which is attributed to the presence of a non-Debye type of relaxation phenomenon [26]. Further, the radius of curvature of each semicircular arc is indirectly proportional to the electrical conductance of the material and directly proportional to the electrical resistance. The position of the semicircular

**Figure 12(a)** and **(b)** shows the real (M′) and imaginary (M′′) parts of electric modulus as a function of frequency at room temperature for Mn1-xBixFe2O4 (where

*The Cole-Cole plots of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles at room* 

*DOI: http://dx.doi.org/10.5772/intechopen.92430*

*3.3.5 Cole-Cole plot*

arc depends on its relaxation times.

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

ferrites. **Figure 10(a)** indicates that the magnitude of the real part of dielectric constant Z′ decreased with the increase of frequency. The real part of dielectric constant curves tended to merge in the high-frequency region. Such behavior is related to the effect of space charge polarization in the material [25]. **Figure 10(b)** indicates that the imaginary part of dielectric constant Z′′ reached a maximum value at the low-frequency region and then decreased with further increasing of the frequency, approaching a small value at high-frequency region. Further, it was observed that the height of the peak curve decreased with the concentration increasing, indicating a decrease in the relaxation time. The observed relaxation peak in the magnitude of Z′′ demonstrated the existence of space charge relaxation.

## *3.3.5 Cole-Cole plot*

*Bismuth - Fundamentals and Optoelectronic Applications*

*3.3.4 Real and imaginary parts of complex impedance*

ers at the octahedral destinations.

result of grain impact. With increasing substitution of Bi3+ by Mn2+ particles, it very well may be seen that at first conductivity diminishes because of the decrease in the quantity of Mn2+-Mn3+ particles which confines the portability of charge transport-

**Figure 10(a)** and **(b)** shows the real and imaginary parts of complex impedance as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles, respectively. These types of frequency dependence complex impedance have been used for the study of the contribution of grains and grain boundaries on the electrical properties of nanoferrites. The obtained results showed the complex impedance versus frequency for the cobalt

*(a) and (b) The real and imaginary parts of complex impedance as a function of frequency at room* 

*temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

**142**

**Figure 10.**

**Figure 11** shows the Cole-Cole plots of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles at room temperature. Cole-Cole plot shows the real part complex impedance (Z′) and the imaginary part of complex impedance (Z′′) along x-axis and y-axis, respectively. **Figure 11** clearly shows one semicircle was obtained for each of the samples, due to the grain boundary effect. The effects of grain boundary of the material are contributed by the parallel combination of grain boundary resistance and capacitance. However, the radius of curvature of each semicircular arc is reasonably shifted from the magnitude of Z′ when the concentration increased, which is attributed to the presence of a non-Debye type of relaxation phenomenon [26]. Further, the radius of curvature of each semicircular arc is indirectly proportional to the electrical conductance of the material and directly proportional to the electrical resistance. The position of the semicircular arc depends on its relaxation times.

## *3.3.6 The real (M*′*) and imaginary (M*′′*) parts of electric modulus*

**Figure 12(a)** and **(b)** shows the real (M′) and imaginary (M′′) parts of electric modulus as a function of frequency at room temperature for Mn1-xBixFe2O4 (where

#### **Figure 11.**

*The Cole-Cole plots of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles at room temperature.*

#### **Figure 12.**

*(a) and (b) The real (M*′*) and imaginary (M*′′*) parts of electric modulus as a function of frequency at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles, respectively. M′ approaches zero in lower-frequency district and shows constant scattering moving in midfrequency area, while it displays a level sort conduct in higher frequency. This sort of conduct is emerged from the unimportant electrode polarization in lower frequencies and short-range and long-range versatility of charge transporters contributing for the conduction wonders in midfrequencies and recurrence-free electrical conduction in higher frequencies, individually [27]. Also, the focus increment M′′ shows the unwinding tops from lower-frequency area to higher-frequency area. The relaxation tops moving plainly demonstrate the spread of relaxation time of the material. The presence of relaxation tops at lower-, center-, and higher-frequency areas is ascribed to the commitment of capacitance to the grain limit, structural, and grain stage attributes, separately, which is very much concurred with the revealed writing.

**145**

ηB = \_ *M*.*W X Ms*

**Figure 13.**

**3.4 Magnetic properties**

applied field of 2 T at room temperature.

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties...*

**Figure 13** gives out the variation of complex electric modulus spectrum (Nyquist plot) (M′ vs. M′′) at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles, and it shows the single semicircular segment for all samples, which is beginning from the grain limit commitments of the material. The Nyquist plot reveals the presence of a non-Debye type of relaxation phenomenon, which is further validated from the electrical modulus analysis [28]. Also, each crescent bend is almost overlapped with each other and no variety is observed, which calls attention to the nearness of electrical unwinding process in the material.

At room temperature, magnetic hysteresis (M-H) curves of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles show very narrow hysteresis loops, which confirms the soft magnetic material nature as depicted in **Figure 14**. The magnetization measurement was done by using VSM mounted with maximum

*Nyquist plot of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles at room temperature.*

The remanent magnetization (Mr) and Ms was estimated by the M-H loop of the y-axis (magnetization axis). The coercivity field (Hc) was estimated by the M-H loop of the x-axis (field axis). The remanence ratio (S) was calculated by using equation S = *Mr*⁄*Ms*. The magneton number (ηB) was calculated by using equation

<sup>5585</sup>. The cubic anisotropy (Kc) was calculated by using the equation *Kc* = \_

[8, 29]. At room temperature, the magnetic parameters such as Mr, Ms, Hc, S, ηB, Kc, and Ku decrease with the increase of Bi3+ concentration (**Figures 15**–**17**). In ferrites, the coercive force is gotten by inversion of the direction of the divider development and that of domain turning around the bearing of the applied field. Generally, the successful sticking for domain wall causes the coercivity; it is understood that the greater grain size reduces HC [30]. In the present examination, the coercive values

The uniaxial anisotropy (Ku) was calculated by using the equation *Ku* = \_

*HcX Ms* 0.64 .

*HcX Ms* 0.985

*DOI: http://dx.doi.org/10.5772/intechopen.92430*

*3.3.7 Nyquist plot*

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

## *3.3.7 Nyquist plot*

*Bismuth - Fundamentals and Optoelectronic Applications*

x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles, respectively. M′ approaches zero in lower-frequency district and shows constant scattering moving in midfrequency area, while it displays a level sort conduct in higher frequency. This sort of conduct is emerged from the unimportant electrode polarization in lower frequencies and short-range and long-range versatility of charge transporters contributing for the conduction wonders in midfrequencies and recurrence-free electrical conduction in higher frequencies, individually [27]. Also, the focus increment M′′ shows the unwinding tops from lower-frequency area to higher-frequency area. The relaxation tops moving plainly demonstrate the spread of relaxation time of the material. The presence of relaxation tops at lower-, center-, and higher-frequency areas is ascribed to the commitment of capacitance to the grain limit, structural, and grain stage attributes, separately, which is very much concurred with the revealed writing.

*(a) and (b) The real (M*′*) and imaginary (M*′′*) parts of electric modulus as a function of frequency at room* 

*temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles.*

**144**

**Figure 12.**

**Figure 13** gives out the variation of complex electric modulus spectrum (Nyquist plot) (M′ vs. M′′) at room temperature for Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles, and it shows the single semicircular segment for all samples, which is beginning from the grain limit commitments of the material. The Nyquist plot reveals the presence of a non-Debye type of relaxation phenomenon, which is further validated from the electrical modulus analysis [28]. Also, each crescent bend is almost overlapped with each other and no variety is observed, which calls attention to the nearness of electrical unwinding process in the material.

**Figure 13.** *Nyquist plot of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles at room temperature.*

## **3.4 Magnetic properties**

At room temperature, magnetic hysteresis (M-H) curves of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles show very narrow hysteresis loops, which confirms the soft magnetic material nature as depicted in **Figure 14**. The magnetization measurement was done by using VSM mounted with maximum applied field of 2 T at room temperature.

The remanent magnetization (Mr) and Ms was estimated by the M-H loop of the y-axis (magnetization axis). The coercivity field (Hc) was estimated by the M-H loop of the x-axis (field axis). The remanence ratio (S) was calculated by using equation S = *Mr*⁄*Ms*. The magneton number (ηB) was calculated by using equation ηB = \_ *M*.*W X Ms* <sup>5585</sup>. The cubic anisotropy (Kc) was calculated by using the equation *Kc* = \_ *HcX Ms* 0.64 . The uniaxial anisotropy (Ku) was calculated by using the equation *Ku* = \_ *HcX Ms* 0.985 [8, 29]. At room temperature, the magnetic parameters such as Mr, Ms, Hc, S, ηB, Kc, and Ku decrease with the increase of Bi3+ concentration (**Figures 15**–**17**). In ferrites, the coercive force is gotten by inversion of the direction of the divider development and that of domain turning around the bearing of the applied field. Generally, the successful sticking for domain wall causes the coercivity; it is understood that the greater grain size reduces HC [30]. In the present examination, the coercive values

**Figure 14.**

*M-H loops measured at room temperature for Mn1-xBixFe2O4 (MBF) ferrite nanoparticles with x = 0.0, 0.05, 0.1, 0.15, and 0.2 nanoparticles.*

#### **Figure 15.**

*Variation of MS and Mr of Mn1-xBixFe2O4 with x = 0.0, 0.05, 0.1, 0.15, and 0.2 ferrite nanoparticles with Bi3+ doping concentration.*

are low; thus, the likelihood of domain rotation is lower. The materials with bigger grain size have been used to accomplish lower core loss. Strikingly, as anticipated, the estimation of the reduced remanence value was found to be the lowest for x = 0.20 concentration sample (**Table 4**). We observed S esteems began interestingly from the higher super paramagnetic and the monotonic decrease in S with

**147**

**Table 4.**

**Figure 16.**

**Figure 17.**

**Bi3+**

**(x)**

*doping concentration.*

**concentration** 

**MS (emu/g)**

*reduced S, (Hc), Ku, cubic anisotropy constant (Kc), and ηB.*

*doping concentration.*

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties...*

*Variation of HC and ηB of Mn1-xBixFe2O4 with x = 0.0, 0.05, 0.1, 0.15, and 0.2 ferrite nanoparticles with Bi3+*

*Variation of KC and Ku of Mn1-xBixFe2O4 with x = 0.0, 0.05, 0.1, 0.15, and 0.2 ferrite nanoparticles with Bi3+*

**Hc (Oe)**

0.00 33.42 2.994 14.14 0.0896 472.55 738.37 1.4259 0.05 24.11 1.705 12.15 0.0707 297.93 457.71 1.0123 0.10 22.98 0.947 7.52 0.0412 172.80 270.02 0.9959 0.15 21.38 0.548 7.18 0.0256 155.84 239.86 0.9713 0.20 17.89 0.337 6.10 0.0189 110.79 170.49 0.8373

*Room temperature magnetic parameters of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2), i.e., MS, Mr,* 

**S =Mr/MS Ku**

**(erg/ cm3 )**

**Kc (erg/ cm3 )**

**η<sup>B</sup> (μB)**

**Mr (emu/g)**

*DOI: http://dx.doi.org/10.5772/intechopen.92430*

*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

#### **Figure 16.**

*Bismuth - Fundamentals and Optoelectronic Applications*

**146**

**Figure 15.**

*doping concentration.*

**Figure 14.**

*0.1, 0.15, and 0.2 nanoparticles.*

are low; thus, the likelihood of domain rotation is lower. The materials with bigger grain size have been used to accomplish lower core loss. Strikingly, as anticipated, the estimation of the reduced remanence value was found to be the lowest for x = 0.20 concentration sample (**Table 4**). We observed S esteems began interestingly from the higher super paramagnetic and the monotonic decrease in S with

*Variation of MS and Mr of Mn1-xBixFe2O4 with x = 0.0, 0.05, 0.1, 0.15, and 0.2 ferrite nanoparticles with Bi3+*

*M-H loops measured at room temperature for Mn1-xBixFe2O4 (MBF) ferrite nanoparticles with x = 0.0, 0.05,* 

*Variation of HC and ηB of Mn1-xBixFe2O4 with x = 0.0, 0.05, 0.1, 0.15, and 0.2 ferrite nanoparticles with Bi3+ doping concentration.*

#### **Figure 17.**

*Variation of KC and Ku of Mn1-xBixFe2O4 with x = 0.0, 0.05, 0.1, 0.15, and 0.2 ferrite nanoparticles with Bi3+ doping concentration.*


#### **Table 4.**

*Room temperature magnetic parameters of Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2), i.e., MS, Mr, reduced S, (Hc), Ku, cubic anisotropy constant (Kc), and ηB.*

increase in Bi3+ concentration. Thus, it is expected that the observed impact is overwhelmed by the surface pinning and the change in intrinsic magnetic anisotropy of the particles because of Bi doping.

## **4. Conclusion**

The Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles are synthesized by the solution combustion method using a mixture of fuels as carbamide and glucose. The crystallite sizes were found in nanometer, and the crystallite size decreases with the increase of Bi3+ concentration. The lattice parameter increases with the increase of Bi3+ concentration due to the difference in ionic radius of Mn2+ and Bi3+ ions. The porous nature of the samples was confirmed by scanning electron microscopy. The elemental composition was analyzed by EDS composition. The dielectric parameters such as real part and imaginary parts of dielectric constant and dielectric loss tangent decrease with the increase of frequency, and this behavior could be explained by a Maxwell-Wagner interfacial-type polarization. All dielectric parameters increase with the increase of Bi3+ concentration. The AC conductivity increases with the increase of frequency according to the hopping model. The real part of complex impedance decreases with the increase of frequency. The observed relaxation peak in the magnitude of imaginary part of complex impedance Z′′ demonstrated the existence of space charge relaxation. The Cole-Cole plot reveals one semicircle was obtained for each of the samples, due to the grain boundary effect. It is attributed to the presence of a non-Debye type of relaxation phenomenon. The real and imaginary parts of electric modulus vary with frequency. The Nyquist plot reveals the presence of a non-Debye type of relaxation phenomenon, which is further validated from the electrical modulus analysis. The magnetic hysteresis curves of all samples reveal the soft magnetic material nature. The magnetic parameters such as remanent magnetization, saturation magnetization, and coercivity field were decreased with the increase of Bi3+ concentration. Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles have great potential for photonic applications.

## **Author details**

V. Jagadeesha Angadi1 \*, H.R. Lakshmiprasanna2 and K. Manjunatha2

1 Department of Physics, P.C. Jabin Science College, Hubballi, India

2 Department of Physics, School of Engineering, Presidency University, Bengaluru, India

\*Address all correspondence to: jagadeeshbub@gmail.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**149**

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*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

## **References**

*Bismuth - Fundamentals and Optoelectronic Applications*

the particles because of Bi doping.

**4. Conclusion**

increase in Bi3+ concentration. Thus, it is expected that the observed impact is overwhelmed by the surface pinning and the change in intrinsic magnetic anisotropy of

The Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles are synthesized by the solution combustion method using a mixture of fuels as carbamide and glucose. The crystallite sizes were found in nanometer, and the crystallite size decreases with the increase of Bi3+ concentration. The lattice parameter increases with the increase of Bi3+ concentration due to the difference in ionic radius of Mn2+ and Bi3+ ions. The porous nature of the samples was confirmed by scanning electron microscopy. The elemental composition was analyzed by EDS composition. The dielectric parameters such as real part and imaginary parts of dielectric constant and dielectric loss tangent decrease with the increase of frequency, and this behavior could be explained by a Maxwell-Wagner interfacial-type polarization. All dielectric parameters increase with the increase of Bi3+ concentration. The AC conductivity increases with the increase of frequency according to the hopping model. The real part of complex impedance decreases with the increase of frequency. The observed relaxation peak in the magnitude of imaginary part of complex impedance Z′′ demonstrated the existence of space charge relaxation. The Cole-Cole plot reveals one semicircle was obtained for each of the samples, due to the grain boundary effect. It is attributed to the presence of a non-Debye type of relaxation phenomenon. The real and imaginary parts of electric modulus vary with frequency. The Nyquist plot reveals the presence of a non-Debye type of relaxation phenomenon, which is further validated from the electrical modulus analysis. The magnetic hysteresis curves of all samples reveal the soft magnetic material nature. The magnetic parameters such as remanent magnetization, saturation magnetization, and coercivity field were decreased with the increase of Bi3+ concentration. Mn1-xBixFe2O4 (where x = 0.0, 0.05, 0.1, 0.15, and 0.2) nanoparticles have great

**148**

India

**Author details**

V. Jagadeesha Angadi1

potential for photonic applications.

\*, H.R. Lakshmiprasanna2

1 Department of Physics, P.C. Jabin Science College, Hubballi, India

\*Address all correspondence to: jagadeeshbub@gmail.com

provided the original work is properly cited.

2 Department of Physics, School of Engineering, Presidency University, Bengaluru,

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

and K. Manjunatha2

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*Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties...*

*DOI: http://dx.doi.org/10.5772/intechopen.92430*

of erbium doping on the electrical behaviour of CaCu3Ti4O12 ceramics probed by impedance spectroscopy analysis. Jose M. Materials Research

Bulletin. 2018;**106**:81-92

[29] Manjunatha K, Jagadeesha Angadi V, Ribeiro RAP,

Materials. 2020;**502**:166595

[30] JagadeeshaAngadi V,

2016;**409**:111-115

Longo E, Oliveira MC, Bomio MRD, et al. Structural, electronic, vibrational and magnetic properties of Zn2+ substituted MnCr2O4 nanoparticles. Journal of Magnetism and Magnetic

Rudraswamy B, Sadhana K, Praveena K. Structural and magnetic properties of manganese zinc ferrite nanoparticles prepared by solution combustion method using mixture of fuels. Journal of Magnetism and Magnetic Materials.

[28] Sakthisabarimoorthi A, Dhas SAMB, Robert R, Influence *Investigation of Structural, Microstructural, Dielectrical and Magnetic Properties... DOI: http://dx.doi.org/10.5772/intechopen.92430*

of erbium doping on the electrical behaviour of CaCu3Ti4O12 ceramics probed by impedance spectroscopy analysis. Jose M. Materials Research Bulletin. 2018;**106**:81-92

*Bismuth - Fundamentals and Optoelectronic Applications*

frequencies. Physical Review.

Materials. 2017;**424**:1-11

[23] Jagadeesha Angadi V,

[24] Kakade SG, Kambale RC, Kolekar YD, Ramana CV. Dielectric, electrical transport and magnetic properties of Er3+ substituted

nanocrystalline cobalt ferrite. Journal of Physics and Chemistry of Solids.

[25] Mangalaraja RV, Ananthakumar S, Manohar P, Gnanam FD. Magnetic, electrical and dielectric behaviour of Ni0.8Zn0.2Fe2O4 prepared through flash combustion technique. Journal of Magnetism and Magnetic Materials.

[26] Tsay C-Y, Lin Y-H, Wang Y-M, Chang H-Y, Lei C-M, Jen S-U. Electrical transport properties of CoMn0.2−xGaxFe1.8O4 ferrites using complex impedance spectroscopy.

[27] Badapanda T, Sarangi S, Parida S, Behera B, Ojha B, Anwar S. Frequency and temperature dependence dielectric study of strontium modified barium zirconium titanate ceramics obtained by mechanochemical synthesis. Journal of Materials Science: Materials in

AIP Advances. 2016;**6**:055909

Electronics. 2015;**26**:3069

[28] Sakthisabarimoorthi A, Dhas SAMB, Robert R, Influence

2016;**656**:5-12

2016;**98**:20-27

2002;**253**:56

[22] Jagdeesha Angadi V, Choudhury L, Sadhana K, Liu H-L, Sandhya R, Matteppanavar S, et al. Structural, electrical and magnetic properties of Sc3+ doped Mn-Zn ferrite nanoparticles. Journal of Magnetism and Magnetic

Rudraswamy B, Sadhana K, Ramana Murthy S, Praveena K. Effect of Sm3+ - Gd3+ on structural, electrical and magnetic properties of MneZn ferrites synthesized via combustion route. Journal of Alloys and Compounds.

1951;**83**:121-124

[15] Dutta DP, Manjanna J, Tyagi AK. Magnetic properties of sonochemically synthesized CoCr2O4 nanoparticles.

[16] Durgesh K, Nemkovski K, Su Y, Rath C. Enhancement of Curie- and spin-spiral temperatures with doping Fe in multiferroic CoCr2O4 nanoparticles. Journal of Magnetism and Magnetic

Journal of Applied Physics.

Materials. 2019;**488**:165378

2018;**44**:10229-10235

[18] Manjunatha K, Srininivasamurthy KM, Naveen CS, Ravikiran YT,

[17] Younis M, Saleem M, Atiq S, Naseem S. Magnetic phase transition and magneto-dielectric analysis of spinel chromites: MCr2O4 (M = Fe, Co and Ni). Ceramics International.

Sitalo EI, Kubrin SP, et al. Observation

performance and structure, dielectric, optical and DC conductivity studies of scandium doped cobalt chromate. Journal of Materials Science: Materials in Electronics. 2019;**30**:17202-17217

[19] Manjunatha K, Jagadeesha Angadi V, Srinivasamurthy KM, Matteppanavar S, Pattar VK, Pasha UM. Exploring the structural, dielectric and magnetic properties of 5 Mol% Bi3+-substituted CoCr2O4 nanoparticles. Journal of Superconductivity and Novel Magnetism. 2020;**71**:1-12

[20] Sathisha IC, Manjunatha K, Jagadeesha Angadi V, Chethan B, Ravikiran YT, Vinayaka K. et al.

10.5772/intechopen.90880.

[21] Koops CG. On the dispersion of resistivity and dielectric constant of some semiconductors at audio

Enhanced humidity sensing response in Eu3+-doped iron-rich Fe2O4: A detailed study of structural, microstructural, sensing, and dielectric properties. IntechOpen [Online First]; 2020. DOI:

of enhanced humidity sensing

2009;**106**:043915

**150**

[29] Manjunatha K, Jagadeesha Angadi V, Ribeiro RAP, Longo E, Oliveira MC, Bomio MRD, et al. Structural, electronic, vibrational and magnetic properties of Zn2+ substituted MnCr2O4 nanoparticles. Journal of Magnetism and Magnetic Materials. 2020;**502**:166595

[30] JagadeeshaAngadi V, Rudraswamy B, Sadhana K, Praveena K. Structural and magnetic properties of manganese zinc ferrite nanoparticles prepared by solution combustion method using mixture of fuels. Journal of Magnetism and Magnetic Materials. 2016;**409**:111-115

## *Edited by Yanhua Luo, Jianxiang Wen and Jianzhong Zhang*

Bismuth—a wonder metal with unique features—plays an important role in the bismuth-related optoelectronic materials. The innovative development of bismuth optoelectronic materials will undoubtedly drive the social development and economic growth in the world towards a glorious future.

Published in London, UK © 2020 IntechOpen © fill / pixabay

Bismuth - Fundamentals and Optoelectronic Applications

Bismuth

Fundamentals and Optoelectronic Applications

*Edited by Yanhua Luo,* 

*Jianxiang Wen and Jianzhong Zhang*