Alkali-rare earth niobates with the tungsten bronze-type structure

A new series of alkali-rare earth niobates of the type A2+RE3+Nb5O15 is described. These materials are solid solutions with a tetragonal bronze-like structure, and exhibit dielectric anomalies from -120°C to +300°C. The dielectric properties of these phases are examined in terms of the crystal chemistry of the tetragonal bronze-type structure. © 1968.