KTaO3

KTaO3, or potassium tantalate, is a chemically simple oxide that adopts the perovskite structure with the formula ABX3 (A = K, B = Ta, X = O). At room temperature it crystallizes in a high-symmetry cubic perovskite structure (space group Pm3m) with a lattice parameter around 3.97 Å. It is a wide-bandgap oxide, with an optical gap in the ultraviolet region.

Dielectric and electronic properties are notable. KTaO3 exhibits a very large dielectric constant at low temperatures and is widely described as a quantum paraelectric or incipient ferroelectric, meaning it does not undergo a spontaneous ferroelectric transition in zero field because of quantum fluctuations. As an insulator, it has a wide bandgap, and when aliovalent dopants such as niobium are introduced, Nb-doped KTaO3 becomes n-type conducting, enabling applications in oxide electronics.

Synthesis and materials engineering involve producing high-quality polycrystalline ceramics and single crystals. Common growth methods for substrates include crystal growth techniques such as floating-zone or other crystal-growing approaches, alongside solid-state routes for ceramics. Doped variants and epitaxial thin films are used to explore functional properties and to serve as transparent conducting or active oxide layers.

Applications include use as a substrate for epitaxial growth of oxide thin films and heterostructures in research on oxide electronics and related phenomena. Doped KTaO3 is also studied for optoelectronic and photocatalytic applications, where its wide bandgap and tunable conductivity can be advantageous. Related perovskite oxides and substitutions provide a broader context for comparing dielectric, electronic, and optical behaviors.