Thin films of BaTiO3 were prepared by radio-frequency magnetron sputtering at substrate temperatures from 450 to 750 °C and analysed by x-ray diffraction, optical transmittance and Raman spectroscopy. The packing density of the films relative to the crystalline density increases from 0.75 at 450 °C to about 1 at 750 °C. At a substrate temperature of 450 °C, the film is nano-crystalline (5 to 20 nm) with big lattice expansion, large band gap and pronounced hexagonal Raman lines. This film is homogeneous in the thickness direction. Films prepared at higher temperatures exhibit perovskite peaks in the Raman spectrum and an optical band gap of 3.38 eV. At 600 °C, the film exhibits a pronounced two-phase growth with a porous nucleation layer of initial packing density of 0.78, a preferred (100)-orientation of the grains and minimum micro-strain. At 750 °C, the films are again homogeneous in the thickness direction, have nearly crystalline packing density and preferably (110)-oriented grains.

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High crystalline quality (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 (BSTZ) thin films were epitaxially grown by pulsed laser deposition on (001) SrTiO3 single crystal substrates. Their epitaxial nature was revealed by x-ray and electron diffraction. Thinnest film (∼9 nm) has largest out-of-plane lattice constant (4.135 Å) and tetragonality (1.06). Films are under compressive strain. Film thicknesses above ∼9 nm were started to relax as revealed from reciprocal space mapping. Thicknesses deduced from x-ray diffraction and transmission electron microscopy methods are in good agreement. Critical thickness to relieve strain of the BSTZ film is about 7.6±0.4 nm.

The objective of the present research work is to develop a gradient, reversed-phase liquid chromatographic (RP-UPLC) method for the determination of Finasteride in pharmaceutical bulk drugs for assay and its related impurities. The chromatographic separation was achieved on a Waters ACQUITY TM UPLC BEH Phenyl Column (150 mm × 2.1 mm, 1.7 µm), The gradient LC method employs solutions A and B as mobile phase. The solution A Contains 2.5 mM ortho phosphoric acid (Buffer) and solution B contains a mixture of acetonitrile and water in the ratio of (90:10 v/v). The flow rate was 0.22 ml/min and the detection wavelength was 210 nm. In the developed UPLC method, the resolution between Finasteride and its potential impurities, namely Imp-1, Imp-2, Imp-3 and Imp-4 was found to be greater than 2.0. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in alkaline medium and oxidative stress conditions. Degradation product formed during oxidative hydrolysis was found to be Imp-1. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.5%. The developed RP-UPLC method was validated with respect to linearity, accuracy, precision and robustness. The limit of quantification of Imp-1, Imp-2, Imp-3 and Imp-4 were 0.06, 0.06, 0.05 and 0.036% (of analyte concentration, i.e. 0.5 mg/ml) with 1 µl injection volume. The developed method was found to be linear in the range of 2.5 -15 µg/mL with correlation coefficient of 0.999 for assay procedures and found to be linear in the range of 0.05 -3 µg/mL with correlation coefficient of 0.999 for related impurities.

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