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Effects of gamma irradiation at different doses up to 135 kGy on polyethylene terephthalate (PET) polymer films have been investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and ultraviolet-visible (UV-VIS) spectroscopy. From XRD analysis, it was found that even at a high dose of gamma irradiation of 135 kGy, crystallinity of the PET samples remain unchanged. However, the FTIR peak at 871 cm −1 (depicting C-H bending mode of out-of-plane vibration) and another at 1303 cm −1 (representing C-H bending mode of in-plane vibration) disappear for gamma-irradiated PET. In this study, it has also been found that γ-irradiation in air enhances the optical absorption in the wavelength region 320-370 nm. This has been attributed to free radicals being produced in the polymer by the γ-radiation. Further, the free radicals react with oxygen of air to form carbonyl group and hydroxyls. With increasing γ-dose, there is a red shift of the UV-near visible cutoff for PET. XRD and FTIR observations on γ-damage have been correlated.

Tin oxide (SnOx) films have been deposited using a RF magnetron sputtering technique from a hot pressed SnO2 target in an ambient mixture of argon and oxygen. Depending on the deposition parameters the structure of the films may be varied from amorphous to crystalline along with a consequent decrease in resistivity. An attempt has been made to understand the causes of formation of insulating and conducting films. By optimizing the oxygen partial pressure and substrate temperature, SnOx films of resistivity 6.1*10-3 Omega cm with a corresponding optical transmission approximately 95% and direct optical gap of 4.13 eV can be prepared. For films having a relatively high conductivity, a long exposure to the atmosphere changed their electronic properties which could be partially recovered by annealing. The effect of annealing SnOx films in different ambients was studied.

The meta-stable orthorhombic phase of lead meta-niobate (PbNb 2 O 6 ), as obtained by quenching, is piezoelectric, but difficult to prepare in pure state as a few competing phases like the non-piezoelectric rhombohedral PbNb 2 O 6 tend to form during the preparation. However, it can have an attractively high Curie temperature above 570 • C. High Curie temperature piezoelectric sensors are desirable for imaging and other applications in certain industrial and research sectors. Presently, both phases have been synthesized as single phase samples as shown here from structural Rietveld analysis of their XRD. Characterization of both compounds by FTIR and XRD have been carried out and presented.

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