Influence of vacancy defect on the structural and optical properties of hexagonal barium titanate ceramics: Experimental and theoretical analysis

This study aims to investigate the properties of the metastable hexagonal barium titanate and its corresponding phase evolution with annealing treatment. Specifically, the metastable hexagonal (h) phase, its defect structure, and the tetragonal (t) one were investigated from both the first-principles computational and the experimental perspectives. The powders prepared using self-propagating high-temperature synthesis were consolidated by spark plasma sintering (SPS) under vacuum conditions. The ceramics were subjected to an annealing treatment at 800 and 1200 degrees C to restore the oxygen stoichiometry and initiate phase transformation. The unannealed sample had about 80 wt% of the h-BaTiO3 phase and 8.4% oxygen defect concentration. Our first-principles calculations showed that oxygen vacancy induced spin-polarized solution with half-metallic behavior.

Automated summary

The study investigates the properties and phase evolution of metastable hexagonal barium titanate with annealing treatment, combining computational and experimental approaches. Powder consolidation using spark plasma sintering under vacuum conditions, followed by annealing at 800 and 1200 degrees C, revealed the presence of different phases in the ceramics.