Preparation and properties of alkali-alkaline earth niobates with structure of tetragonal potassium-tungsten bronze

Using the method of solid phase synthesis crystal samples of compounds AΛ21AΛ42NbΛ1Λ0OΛ3Λ0 with the structure of tetragonal potassium - tungsten bronze, the temperatures of their ferroelectric phase transitions and certain parameters of band structure are determi ned. Electric conductivity of compounds AΛ21AΛ42NbΛ1Λ0OΛ3Λ0 below 900 K is of impurity electron type. Possibilities directed change in properties of alkali-alkaline earth niobates in the process of cation heterovalency substitution are limited. It has been established for the first time, that for temperature dependences rho of the compounds AΛ21AΛ42NbΛ1Λ0OΛ3Λ0 the presence of a region with a positive temperature coefficient of resistance in the range 300-410 K is characteristic