Ellipsometric study of {Pb(Mg_1/3Nb_2/3)O₃}_1-x {PbTiO₃}_x: Evaluation of refractive index, extinction coefficient and optical band gap

This investigation delves into the analysis of the structural, microstructural, and optical characteristics of {Pb(Mg_1/3Nb_2/3) O₃}_1-x {PbTiO₃}_x (x = 0.1, 0.2, 0.3, 0.4) prepared through the spin coating technique. The synthesized ceramics showed monoclinic structure which was verified by X-ray diffraction, showcasing distinct reflections that suggest a homogeneous composition. Examination of crystallite size and strain unveiled a pattern of initial growth, followed by reduction and subsequent increment, revealing intricate interactions between PbTiO₃ (PT) and Pb(Mg_1/3Nb_2/3)O₃ (PMN) lattice. Field emission scanning electron microscopic observations displayed fluctuations in particle dimensions, where a moderate PT content facilitated grain enlargement while higher concentrations impeded it. Through spectroscopic ellipsometry, it was illustrated that the refractive index and extinction coefficient underwent changes based on PT content, thereby influencing the optical characteristics. Initially, the band gap energy experienced an increase, with a subsequent slight decrease at higher PT concentrations. These results underscore the notable impact of PT content on the properties of the material, indicating its potential for customized optoelectronic applications.