A comprehensive analysis of the structural, microstructural, optical, and piezocatalytic activity of Ba_0.92Ca_0.08Zr_0.09Ti_0.91O3 and Ba_0.98Ca_0.02Zr_0.07Ti_0.93O3 lead-free ceramics

Through this study, we aim to comprehensively explore the piezocatalytic efficiency of Ca2+ and Zr4+ cosubstituted BaTiO3 (BT) based ceramics Ba0.92Ca0.08Zr0.09Ti0.91O3 (BCZT-92) and Ba0.98Ca0.02Zr0.07Ti0.93O3 (BCZT-98), synthesized through the solid-state reaction method. Furthermore, the study delves into the interplay between the structural, microstructural, optical, and piezocatalytic properties of these ceramics. The coexistence of tetragonal (T, P4mm) and orthorhombic (O, Amm2) phases in both ceramics was verified through the Rietveld refinement of the X-ray diffraction patterns along with the analysis of the Raman spectra. The optical properties, investigated using the Tauc's model, revealed an indirect bandgap in both compounds. Other optical parameters such as the Urbach energy (Eu), extinction coefficient (k), and refractive index (n) were also calculated from the absorbance data. The dispersion parameters (E0 and Ed) were estimated using the Wemple and Di-Domenico model. In contrast to BCZT-92 compound, BCZT-98 demonstrated improved piezocatalytic degradation efficiency presumably due to its lower bandgap energy, more oxygen defects, and increased surface charges. It is shown that kinetic factors such as initial dye concentration, catalytic dosage, and stirring speed influence the degradation performance of the BCZT-98 compound. The degradation efficiency as high as 82.7% with a rate constant of 0.03163 min-1 was achieved on Rhodamine B dye. The implications of these findings are significant in advancing the development of lead-free piezocatalysts with meticulously tailored dopants concentrations, fostering real-world applications in environmental remediation.