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A compact Photoacoustic spectrometer (PAS) was fabricated, for the determination of phase transitions in liquid crystals (LCs). Photoacoustic (PA) technique is a powerful tool for the determination of phase transitions in solids, liquids and gasses compared to other techniques like Raman spectroscopy, Newton scattering, NMR & ultrasound studies and DSC. PA signal information is used to investigate the variations in the optical and thermal properties of the materials during phase transitions. The advantage of PA technique is its simplicity in the sample preparation, and its accuracy in the phase transition studies. The instrumentation details and results of phase transition studies on p-pentyloxy benzoic acid (5OBA), N(4-n-hexadcyloxysalicylidene)-2-methylbutyl-4'-amino-cinnamate, 16O(OH)2MBC and N-(4-n-butyloxysalicylidene)-4'-n-Ketylaniline, 4O(OH)5 are presented. The advantages of PA technique are elaborated. [ABSTRACT FROM AUTHOR]

Abstract: Cadmium indate films were deposited by dc reactive magnetron sputtering onto glass substrates in an oxygen partial pressure of 5×10−4 mbar and at various substrate temperatures in the range 373–673 K. The influence of substrate temperature on the structural, electrical and optical properties of the films was systematically studied. The films formed at substrate temperatures <423 K were amorphous while those deposited at ≥423 K were polycrystalline with cubic spinel structure. The decrease of electrical resistivity and increase of Hall mobility with the increase of substrate temperature were due to the improvement in the crystallinity of the films. The temperature dependence of Hall mobility measurements indicated that the grain boundary scattering of charge carriers was predominant in the films. The films formed at a substrate temperature of 673 K exhibited an electrical resistivity of 3.5×10−4 Ω cm, Hall mobility of 29 cm2 V−1 s−1, optical transmittance of 88%, optical band gap of 3.28 eV and figure of merit of 5×10−2 Ω−1. [Copyright &y& Elsevier]

Abstract: Thin films of cuprous oxide (Cu2O) were deposited on glass substrates at various bias voltages using DC reactive magnetron sputtering technique. The effects of substrate bias voltage on structural, electrical and optical properties were systematically analyzed. The crystallographic structure and orientation of the crystallites were strongly influenced by the bias voltage. [Copyright &y& Elsevier]

An attempt has been made to study the continuous drive friction welding characteristics of AISI 430 ferritic stainless steel. All the welds exhibited fine equiaxed ferritic grains. Parameters that result in marginally coarse grain size in the bond zone led to low hardness and high toughness. Welds having a fine grain size exhibited higher hardness and superior notch tensile strength. An inverse relationship was observed between impact toughness and notch tensile strength. Regression analysis of the data revealed a high degree of correlation. It was concluded that the selection of parameters would depend on the property of interest. [ABSTRACT FROM AUTHOR]

Optical absorption studies on vacuum flash evaporated polycrystalline Cu0.5Ag0.5InSe2 thin films are reported. The absorption humps observed in the spectra are attributed to transitions from the valence sub-bands to the conduction band. From the optical transmittance data, the optical band gap energies, spin–orbit and crystal-field parameters are determined. [Copyright &y& Elsevier]