Lead Telluride (PbTe) films of different thickness were prepared onto precleaned glass substrates under the pressure of 2×10 −5 Torr by thermal evaporation. X-ray diffraction technique, scanning electron microscopy, and current-voltage characteristics were used to characterize the films. The structural analysis of the films was carried using X-ray diffractometer. The surface morphology was analyzed by using scanning electron microscope. The dc electrical conduction mechanism in vacuum-evaporated Al/PbTe/Al thin film sandwich system in the thickness range 500-5,000 Å at different temperature (303-483 K) was found to be a modified Poole-Frenkel type. The results of variation of activation energy with applied voltage and thickness are discussed.

Thin films of Sb 2 Te 3 and (Sb 2 Te 3 ) 70 (Bi 2 Te 3 ) 30 alloy and have been deposited on precleaned glass substrate by thermal evaporation technique in a vacuum of 2× 10 −6 Torr. The structural study was carried out by X-ray diffractometer, which shows that the films are polycrystalline in nature. The grain size, microstrain and dislocation density were determined. The Seebeck coefficient was determined as the ratio of the potential difference across the films to the temperature difference. The power factor for the (Sb 2 Te 3 ) 70 (Bi 2 Te 3 ) 30 and (Sb 2 Te 3 ) is found to be 19.602 and 1.066 of the film of thickness 1,500 Å, respectively. The Van der-Pauw technique was used to measure the Hall coefficient at room temperature. The carrier concentration was calculated and the results were discussed.

Purpose: To develop a simple, rapid, accurate and cost-effective reversed phase high performance liquid chromatography (RP-HPLC) method for letrozole in bulk and in tablets. Methods: Development of a method for the determination of letrozole, an anti-cancer drug, by RP-HPLC was undertaken using a new mobile phase of acetonitrile:water (50:50, v/v). The eluent was monitored at 265 nm. Results: The optimized conditions developed showed a linear response from 160 to 240 µg/mL, with a correlation coefficient (R 2 ) of 0.999. The limit of detection (LOD) and limit of quantification ( LOQ) were 136 and 160 µg/mL, respectively. The assay values for the two branded letrozole tablets tested were 99.2 and 100.2 %, respectively with % relative standard deviation (RSD) of 0.781 and 0.568, respectively. The bench top stability data of the drug in the mobile phase indicate that the drug was stable in the mobile phase for 24 h. Recovery data were good. Placebo study for specificity and interference of common excipients showed that the method was specific and free from interfering substances. Conclusion: Therefore, the fully validated method developed was sensitive enough to carry out routine analysis of letrozole in tablet formulations with regard to its run time, simplicity of sample preparation and accuracy.

Antimony telluride thin films were prepared on the well-cleaned glass substrates under a pressure of l0 -5 torr by thermal evaporation method. The thicknesses of the films were measured using Multiple Beam Interferometer (MBI) technique. The structure of the sample was analyzed by Xray diffraction technique. The film attains crystalline structure as the temperature of the substrate is increased to 373 K. The d spacing and the lattice parameters of the sample were calculated. Optical behavior of the film samples with the various thicknesses was analyzed by obtaining their transmittance spectra in the wavelength range of 400 -800 nm. The transmittance is found to decrease with increase in film thickness and also it falls steeply with decreasing wavelength. The optical constants were estimated and the results are discussed. The optical band gap energy decreases with increase in the film thickness. The optical transition in these films is found to be indirect and allowed.

No abstract