Abstract:
Cation-deficient perovskites with the general formula A(6)B(5)O(18) (A=Ba, Sr, La; B=Nb, Ta, Ti, Zr, Mg, and Zn) have been synthesized and their microwave dielectric properties have been investigated. X-ray diffraction studies indicate the formation of monophase materials. The structures of Ba6Ta4TiO18 and Ba5SrTa4TiO18 are different from that of Sr6Ta4TiO18. The A(6)B(5)O(18) have Q x f in the range 5600-51 000 GHz, dielectric constants 26-48, and the temperature coefficient of resonant frequency varies from -39 to +83 ppm/degrees C, depending on the composition. Scanning electron microscopy studies show that the grain size decreases with an increase in the Sr content.
