**2. Synthesis of PZT-PZN-PMnN ceramics by the B-site oxide mixing technique**

Lead-based mixed B-site cation perovskites of (B′, B″)O3-type exhibit diffuse phase transition (DPT) behaviors of broad dielectric constant spectra in contrast to the sharp phase transitions of Pb(Zr,Ti)O3 and PbTiO3 [25]. The complex perovskite compounds are difficult to synthesize by conventional solid-state

### *The Investigation on the Fabrication and Characterization of the Multicomponent Ceramics… DOI: http://dx.doi.org/10.5772/intechopen.93534*

reaction method owing to the formation of pyrochlore phases and reduction of desirable properties, such as the electromechanical coupling factor and dielectric constant, which originate from the perovskite structure [25]. The B-site oxide mixing technique (BO) [26, 27] (formation of a B-site precursor of (B′, B″)O2-type, followed by a reaction with PbO) has been applied to several complex perovskite compositions and the results are quite successful [22, 28, 29]. In the conventional method (MO), oxide powders of PbO, ZrO2, TiO2, ZnO, MnO2, and Nb2O5 were weighed and milled for 8 h. To identify the temperature for calcining PZT-PZN-PMnN, we investigated the data of thermal gravimetric (TG) and thermal analysis (DTA) of PZT-PZN-PMnN powder (**Figure 1**). As per the above results, the TG curve exhibits a linear decrease in the total mass of the studied powder. However, the DTA curve shows an endothermic peak from 739 to 840°C, corresponding to the ion evaporation. To ensure the phase creation in the sample, the mixture powder was calcined at temperatures a little higher than 850°C after being milled for 8 h and pressed into pellets [30]. Afterward, the calcined PZT-PZN-PMnN pellets were continued to be milled for 16 h and pressed into disk 12 mm in diameter and 1.5 mm in thick under 100 Tan/cm<sup>2</sup> .

In the B-site oxide mixing technique, in order to identify the temperature for calcining of (Zn,Mn)Nb2(Zr,Ti)O6 (BO), we investigated the data for thermal gravimetric (TG) and thermal analysis (DTA) of (Zn,Mn)Nb2(Zr,Ti)O6 powders, as shown in **Figure 2**. As per results, the TG curve of the mixture powder shows that the total mass of the studied powder decreases linearly. However, the DTA curve shows the endothermic peak at 978°C, corresponding to the temperature of powder evaporation. In order to ensure that the temperature is at least above 978°C for each powder grain, the mixture powder was calcined at little higher temperature of 1100°C [6, 11, 21, 22] after the powders of BO and PbO were weighed and milled for 8 h.

The powders were calcined at a temperature of 850°C for 2 h, producing the PZT-PZN-PMnN compound. The samples were sintered at 950°C for 2 h. **Figure 3** shows the X-ray diffraction (XRD) patterns of the PZT-PZN-PMnN ceramics prepared by different methods. From X-ray diagrams, we can see that the BO sample has only pure perovskite phase with rhombohedral structure, and this was determined by the (*200*) diffraction peak observed near 44° with no splitting. As seen in **Figure 4**, the BO sample was almost fully dense, and the average grain size of the

**Figure 1.** *TG/DTA curves for the powder mixture compositions.*

**Figure 2.** *TG and DTA curves of (Zn,Mn)Nb2(Zr,Ti)O6 power at 10°C/min heating rate.*

**Figure 3.** *X-ray diffraction diagram of the BO and MO samples.*

### **Figure 4.** *Microstructures of BO and MO samples.*

sample was large. However, in the MO sample, besides the perovskite phase with rhombohedral structure (**Figure 3**), there is a small pyrochlore phase. This is in good accordance with the microstructure (**Figure 4**). It is said that formation of the *The Investigation on the Fabrication and Characterization of the Multicomponent Ceramics… DOI: http://dx.doi.org/10.5772/intechopen.93534*

pyrochlore phase may be due to the steric and electrostatic interaction between the high polarization of the Pb2+ cation and the B-sites cation (Zn+2, Nb+5) [24, 27, 31].
