Bandgap engineering and antiferroelectric stability of tantalum doped silver niobate ceramics from first-principles.

Extensive research has been conducted on silver niobite (AgNbO 3)-based antiferroelectric ceramics for their promising applications in energy storage applications, with various compositional modifications explored to improve their energy storage capabilities. In this theoretical study, we have systematically investigated the electronic, structural, and chemical bonding properties of AgNb 1- x Ta x O 3 (x = 0.00, 0.125, 0.25, 0.375, 0.50, abbreviated as ANT100 x) solid solutions based on first-principles calculation. Our results reveal that the bandgap increases from 1.82 eV to 1.89 eV, due to the higher energy level of Ta 5 d orbitals compared to Nb 4 d orbitals. The enlarged bandgap, accompanied with oxygen vacancy formation energy (Δ E f , v a c ), contributes to the enhancement of E b. The Ta substitution of Nb site suppresses the cation displacement, oxygen octahedral distortion, and bond length and angles, indicating an improved stability of antiferroelectric phase. In addition, the electron localization function (ELF) and Bader charge values show weakened covalent bonding of Ta−O bonds compared to Nb−O bonds. These theoretical findings have the potential to aid in the advancement and creation of novel energy storage applications using lead-free AFE perovskites, as well as facilitate the manipulation of their breakdown electric field through bandgap engineering. [ABSTRACT FROM AUTHOR]