Tantalates

Tantalates are a class of inorganic compounds that contain tantalum in the +5 oxidation state coordinated to oxygen. The simplest anion is orthotantalate, TaO4^3−, but many tantalates form extended solids in which TaO6 octahedra share corners and edges to create three-dimensional oxide networks. This leads to a variety of structural motifs, including perovskite-like frameworks. The most familiar member of the family is potassium tantalate, KTaO3, a wide-bandgap, n-type ceramic oxide that adopts a perovskite-related structure.

Because of their robust Ta–O coordination, tantalates are chemically stable and occur as both simple salts with alkali or alkaline earth cations and as complex oxide materials. They are of interest for dielectric and nonlinear optical applications, and several tantalates exhibit photocatalytic activity under ultraviolet light, making them candidates for water splitting and environmental remediation. Their electronic structure can be tuned by cation substitution, oxygen vacancies, and doping, which alters bandgap, conductivity, and catalytic properties.

Synthesis typically involves high-temperature solid-state reactions of tantalum oxide Ta2O5 with alkali or alkaline earth carbonates or hydroxides, followed by calcination, or via hydrothermal, sol-gel, or precipitation routes from tantalum precursors. In oxide ceramics, processing conditions determine phase purity and crystallinity, while dopants can tailor optical and electronic behavior for specific applications.