Annealing effects on the structural and optical properties of undoped and Zr-doped Ba titanate prepared by self-propagating high-temperature synthesis

Undoped and Zr-doped BaTiO powders have been prepared by self-propagating combustion synthesis from suitable precursors. The obtained powders have been subjected to thermal annealing in air at temperatures between 400 and 1200 °C. Experimental findings indicate that annealing affects compositional, structural and optical properties. XRD analysis reveals the presence of a metastable hexagonal phase in powders obtained by SHS. Its relative amount drastically decreases during high-temperature annealing. As-synthesized powders have broad photoluminescence due to the degree of structural order in the powders. This can be also seen from the absorbance spectra, which exhibit a band at 650 nm. F color centers form as a consequence of electron trapping in oxygen vacancies.