The effect of structural defects on the optical and dielectric properties of Pby(ZrxTi1-x)O3 piezoelectric compounds prepared by hydrothermal-autoclave method

In this paper, the Pb y (Zr 1-x Ti x ) O 3 piezoelectric compounds prepared by the hydrothermal- autoclave and the effect of calcination in thermal furnace and microwave furnace on optical and dielectric properties has been studied. The research was targeted for study on effect of varying the concentration of lead (Pb), zirconium (Zr), and titanium (Ti) on the structural, optical, and dielectric properties under different thermal condition. The concentration of compound was changed for Pb by y = 0.5, y = 1, and for Zr and Ti by x = 0.50, x = 0.55 and x = 0.6 The Pby(Zr 1−x Ti x )O 3 (PZT) nanopowders were synthesized using a hydrothermal–autoclave method to investigate how Pb stoichiometry, Zr/Ti ratio, and post-annealing treatments influence structural evolution and optical behavior. Compositions with Pb-deficient (y = 0.5) and Pb-stoichiometric (y = 1) ratios and Zr/Ti contents of x = 0.5–0.6 were prepared and subsequently treated by conventional furnace annealing (500–900°C) and microwave irradiation (900–1200 W). Phase formation, microstructure, and compositional trends were examined using XRD, FESEM, and EDX analyses, while optical and dielectric properties were evaluated by UV–Vis spectroscopy. The results show that both composition and thermal pathway strongly affect phase development, crystallite size, and microstructural features. Distinct optical responses were observed depending on the post-annealing route, with noticeable variations in absorption behavior, optical bandgap, and related optical constants. The extracted optical bandgap values span a wide range (≈1.8–4.6 eV), indicating a high degree of tunability. Urbach energy analysis reveals moderate band-tail broadening, suggesting that localized states associated with structural disorder contribute to the optical response. Pronounced differences in morphology and porosity were also observed, reflecting different densification and grain-growth mechanisms. In addition, the obtained results are directly compared with the authors’ previous study conducted on PZT materials with the same stoichiometric compositions synthesized via a sol–gel route, enabling a clear assessment of the role of the synthesis pathway on phase stability, microstructure, and optical behavior. These findings demonstrate that hydrothermal synthesis combined with tailored post-annealing provides an effective approach for adjusting the optical and microstructural characteristics of PZT nanopowders.