In the present paper, the influence of precursor concentration on the structural, optical, and humidity sensing properties of spray-deposited titanium dioxide (TiO2) films are investigated. The TiO2 thin films were successfully deposited by spraying different precursor concentrations such as 0.075 M, 0.1 M, and 0.125 M of titanium trichloride solution onto glass substrates. X-ray diffractometry (XRD) studies confirmed the polycrystalline anatase phase of TiO2 with dominant (101) plane. The crystallite size was found to increase with the increase in precursor concentration. The micro-strain and dislocation density in the film was observed to decrease as the crystallite size increased. The UV–vis spectra confirmed the optical absorbance edge of the samples shifted toward lower wavelengths with increased precursor concentration. The humidity sensing properties of the synthesized material were measured by monitoring the change in resistance of the sample with the change in relative humidity. The material synthesized with 0.1 M precursor concentration, by using the spray pyrolysis method, shows good sensitivity and has a response time of 77.5 s and fast recovery time of 3 s.

Measurement of density and viscosity has been used for evaluating derived parameters for binary system of o-dichlorobenzene and o-chlorophenol with diethyl ether, tetrahydrofuran, cyclohexane and anisole at the different temperatures and at atmospheric pressure. From these, excess parameters have been calculated over entire range of composition. The variation of derived parameters as well as the sign and magnitude of corresponding excess functions has been used to investigate the type and extent of interaction between the component molecules of the binary mixture.

Nanocrystalline SnO 2 thin films were successfully prepared using Physical Vapour Deposition technique and were annealed at 400 o C. Structural, morphological, elemental, compositional, optical, and IntroductionSince last few decades there has been an increasing interest to prepare inexpensive SnO 2 thin films. Tin oxide is the most widely used metal oxide semiconductor in gas sensing because of its capability to detect combustible and hazardous gases such as methane, LPG, CNG, CO, CO 2 , Cl 2 , H 2 S etc [1][2][3][4]. It is an n-type semiconductor of tetragonal structure with band gap energy about 3.6 eV at room temperature. It is cheap, nontoxic and has strong oxidizing power, high photochemical corrosive resistance, good electrical, optical and piezoelectric behavior. In recent years, semiconductor metal oxide films have received considerable attention because of their potential applications [5] such as photochemical and photoconductive devices in LCD, lithium-ion batteries,[6-8] a transport conductive electrode for solar cells [9,10] a gas sensing material for gas sensor devices [11], transport conducting electrodes [12] etc. The majority of the applications adopted SnO 2 as the sensing material due to its high sensitivity and stability at lower operational temperatures, in spite of its poor selectivity [13].Out of many thin film preparation techniques such as chemical vapour deposition [14], spray pyrolysis [15], sputtering [16], activated reactive evaporation [17], etc. Physical Vapour Deposition method is straight forward and simple one. Because of deposition in high vacuum and at room temperature, this technique produces contamination free uniform thin films. In the present study, we used Hind Hivac vacuum depositing unit for depositing pure tin onto the cleaned glass substrates at room temperature. The films were then heated in muffle furnace at 200 o C for 24 hrs to allow oxidation. The so formed pure SnO 2 thin films were then annealed at 300, 400 and 500 o C each for 2 hrs. Structural, morphological, electrical, optical and gas sensing characterizations of the samples were studied.

Thin films of AI Sb of varying compositions and thickness have been formed on glass substrates employing three-temperature method. Electrical resistivity (p) and activation energy (AE) have been studied as a function of composition, thickness (d) and temperature of the film. Films of A1 Sb system with aluminium < 50 at.%, ~ 50 at.% and > 50 at.% exhibit metallic, semiconducting and metallic to semiconducting behaviours respectively. Activation energy (AE) of semiconducting films found to vary inversely with thickness, is attributed to combined effects of change in barrier height due to the size of grains and stoichiometry in the films.

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