Communicating with wireless perovskites: cation order and zinc volatilization

The synthesis of new families of perovskites with a 1:2 ordered Ba(Zn1/3Ta2/3)O3-type structure was investigated. The compound La(Li1/3Ti2/3)O3 was prepared with a 1:2 ordered arrangement of Li and Ti and is the first reported titanate with this type of structure. A new family of ordered perovskites, (Sr2/3La1/3)(Li1/3Ta2/3)O3 and (Sr2/3La1/3)(Li1/3Nb2/3)O3, were also prepared with a 1:2 layered order of Li+ and B5+ cations. All three compounds exhibit dielectric constants >25 and Q.f values >20,000. Studies were also made on the phase stability of Zn-deficient compositions of BZT. The hexagonal perovskite, Ba8ZnTa6O24, was isolated in single-phase form and was found to be the stable phase formed as a result of the loss of ZnO from BZT. Ba8ZnTa6O24 can be sintered to high density at temperatures considerably lower than pure BZT and exhibits very good microwave properties. In particular at GHz frequencies ε=30.5, Q.f=62,000, and τf=+36 ppm/°C.