**1. Introduction**

Liquefied petroleum gas (LPG) is the composition of hydrocarbons mainly propane and butane. The lower explosive limit (LEL) as specified by National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) standards for chemical hazards is 21,000 ppm (2.1% by volume in air) for propane and 19,000 ppm (1.9% by volume in air) for butane. The permissible exposure limit (PEL) for LPG as specified by NIOSH and OSHA standards is 1000 ppm [1]. LPG is mostly used as fuel for vehicles and as cooking gas for household applications. Exact observing of leakages of LPG even at low concentrations can be useful to avoid accidental explosions [2, 3]. Sensors have turned into an indispensable piece of the cutting-edge human progress attributable to its significance, where metal oxides have played a major role as reliable sensor materials. Nanoparticle do research presents broad scope for the growth of novel solutions in the field of healthcare, cosmetics, optics and electronics. Varying their sub-atomic and nuclear states results in surprising results, which may not be conceivable by utilizing the materials in their unique states. A few metal oxides

such as TiO2, SnO2, ZnO, WO3 and Cr2O3, etc., are shown in semiconducting nature of materials. The electrical properties of these oxides are sensitive to the oxygen partial pressure since it changes in the concentration of electrons or electron holes in the oxides. This article manages the properties and utilizations of titanium oxide nanoparticles. Titanium oxide (TiO2) is accessible as nanocrystals or nanodots having a high surface area.

Titanium oxide (TiO2) nanoparticle is a non-broke down material which does not break up itself when degrades organic contaminant and kills germs. It has a lasting effect on killing germs and degrading organic contaminants. TiO2 nanoparticle is broadly used as ultra violet-resistant nanomaterials and in the field of produce chemical fiber, plastics, printing ink, coating, self-cleaning glass, self-cleaning ceramic objects, antibacterial material, air purification, cosmetics, sunscreen cream, natural white moisture protection cream, moistening refresher, vanishing cream, skin protecting cream, foods packing material, coating for paper-making industry: used for civilizing the pliability and opacity of the paper and used for producing titanium, ferrotitanium alloy, carbide alloy, etc., in the metallurgical industry, astronautics industry, conducting material, gas sensor, and moisture sensor. TiO2 also famous such as titania is the obviously occurring oxide of titanium. Titania is an inventive material used broadly in industry, research and environmental cleaning. Titania occurs in several crystalline forms; the most significant of which are anatase and rutile. Uncontaminated TiO2 does not occur in nature but is derived from ilmenite or leucoxene ores. It is additionally eagerly mined in one of the most perfect structures, rutile shoreline sand. These minerals are the real crude materials utilized in the generation of titanium dioxide pigment. The initial step is to filter the mineral and is for the most part a refinement step. Either the sulfate process, which uses sulfuric acid as a removal agent or the chloride process, which uses chlorine, may achieve this. After filtration the powders may be treated to enhance their performance as pigments.

Therefore, metal oxide nanomaterials play imperative role in the recent development of science due to its small size and large surface area [4]. In this chapter several synthesis methods to prepare ceramic nanoparticles, characterization techniques and different properties of gas/humidity sensors are described. The role of water vapor has been studied in the environment with respect to human life. For the measurement of humidity, conventional approaches and modern methods using solid state devices are described. Nanomaterials can be metals, stoneware, polymeric materials, or composite materials. Their significant characteristic is a very small feature size in the range of 1–100 nm. At the nanomaterial level, some material properties are influenced by the laws of nuclear material science, instead of carrying on as conventional mass materials do.

### **1.1 Lattice structure of TiO2**

The three forms of titanium dioxide structure materials can exist: rutile, anatase and brookite shown in **Figure 1**.

The basic structural features of anatase and rutile materials have been assessed, as the brookite structure is not used regularly for exploratory examinations. Together, the crystal structures of rutile and anatase are found in the widespread octahedron. In rutile, the bending is slightly orthorhombic in which the unit cell extends beyond a cubic form. In anatase, the distortion of the cubic lattice is more significant and, therefore, the resulting symmetry is smaller than the orthorhombic one. **Figure 2** shows a structural drawing of rutile and anatase bulk materials. The lengths of the connections and the angles between the atoms are shown, showing the elongated cubic form [5].

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**Figure 2.**

*The structure of rutile and anatase titanium dioxide.*

**Figure 1.**

*Design and Growth of Metal Oxide Film as Liquefied Petroleum Gas Sensors*

The crystal structure of TiO2 nanoparticles depend great extent on the arrange-

ment technique. The tiny TiO2 nanoparticle (<50 nm) anatase appeared to be steadier and more changed in to rutile phase at >973K. The change arrangement

*(a) Unit cell of the crystalline structure of TiO2 and crystal structure of (b) rutile (tetragonal) TiO2,* 

*(c) anatase (tetragonal) TiO2, and (d) brookite (orthorhombic) TiO2.*

*DOI: http://dx.doi.org/10.5772/intechopen.82082*

*Design and Growth of Metal Oxide Film as Liquefied Petroleum Gas Sensors DOI: http://dx.doi.org/10.5772/intechopen.82082*

*Gas Sensors*

ing a high surface area.

enhance their performance as pigments.

of carrying on as conventional mass materials do.

**1.1 Lattice structure of TiO2**

and brookite shown in **Figure 1**.

the elongated cubic form [5].

such as TiO2, SnO2, ZnO, WO3 and Cr2O3, etc., are shown in semiconducting nature of materials. The electrical properties of these oxides are sensitive to the oxygen partial pressure since it changes in the concentration of electrons or electron holes in the oxides. This article manages the properties and utilizations of titanium oxide nanoparticles. Titanium oxide (TiO2) is accessible as nanocrystals or nanodots hav-

Titanium oxide (TiO2) nanoparticle is a non-broke down material which does not break up itself when degrades organic contaminant and kills germs. It has a lasting effect on killing germs and degrading organic contaminants. TiO2 nanoparticle is broadly used as ultra violet-resistant nanomaterials and in the field of produce chemical fiber, plastics, printing ink, coating, self-cleaning glass, self-cleaning ceramic objects, antibacterial material, air purification, cosmetics, sunscreen cream, natural white moisture protection cream, moistening refresher, vanishing cream, skin protecting cream, foods packing material, coating for paper-making industry: used for civilizing the pliability and opacity of the paper and used for producing titanium, ferrotitanium alloy, carbide alloy, etc., in the metallurgical industry, astronautics industry, conducting material, gas sensor, and moisture sensor. TiO2 also famous such as titania is the obviously occurring oxide of titanium. Titania is an inventive material used broadly in industry, research and environmental cleaning. Titania occurs in several crystalline forms; the most significant of which are anatase and rutile. Uncontaminated TiO2 does not occur in nature but is derived from ilmenite or leucoxene ores. It is additionally eagerly mined in one of the most perfect structures, rutile shoreline sand. These minerals are the real crude materials utilized in the generation of titanium dioxide pigment. The initial step is to filter the mineral and is for the most part a refinement step. Either the sulfate process, which uses sulfuric acid as a removal agent or the chloride process, which uses chlorine, may achieve this. After filtration the powders may be treated to

Therefore, metal oxide nanomaterials play imperative role in the recent development of science due to its small size and large surface area [4]. In this chapter several synthesis methods to prepare ceramic nanoparticles, characterization techniques and different properties of gas/humidity sensors are described. The role of water vapor has been studied in the environment with respect to human life. For the measurement of humidity, conventional approaches and modern methods using solid state devices are described. Nanomaterials can be metals, stoneware, polymeric materials, or composite materials. Their significant characteristic is a very small feature size in the range of 1–100 nm. At the nanomaterial level, some material properties are influenced by the laws of nuclear material science, instead

The three forms of titanium dioxide structure materials can exist: rutile, anatase

The basic structural features of anatase and rutile materials have been assessed,

as the brookite structure is not used regularly for exploratory examinations. Together, the crystal structures of rutile and anatase are found in the widespread octahedron. In rutile, the bending is slightly orthorhombic in which the unit cell extends beyond a cubic form. In anatase, the distortion of the cubic lattice is more significant and, therefore, the resulting symmetry is smaller than the orthorhombic one. **Figure 2** shows a structural drawing of rutile and anatase bulk materials. The lengths of the connections and the angles between the atoms are shown, showing

**82**

*(a) Unit cell of the crystalline structure of TiO2 and crystal structure of (b) rutile (tetragonal) TiO2, (c) anatase (tetragonal) TiO2, and (d) brookite (orthorhombic) TiO2.*

#### **Figure 2.**

*The structure of rutile and anatase titanium dioxide.*

The crystal structure of TiO2 nanoparticles depend great extent on the arrangement technique. The tiny TiO2 nanoparticle (<50 nm) anatase appeared to be steadier and more changed in to rutile phase at >973K. The change arrangement

#### **Figure 3.**

*The schematic diagram of growth of nanoparticles.*

and thermodynamic stage steadiness relied upon the underlying molecule sizes of anatase appeared in **Figure 3**. In the temperature range 973–1073 K only one phase change from anatase to rutile occurred. Both sizes of anatase and rutile particles increased with increasing temperature, but the growth rate was different. Rutile had a much higher growth rate than anatase. The rate of development of the anatase has been stabilized at 800°C. The rutile particles, after nucleation, have grown rapidly, where the size of the anatase particles has remained virtually unchanged with the decrease of the initial particle size, the temperature of start the diminished transition [6]. The diminished warm steadiness in better nanoparticles was fundamentally because of the lessened enactment vitality as a size related surface enthalpy and stress vitality expanded.
