MICROWAVE DIELECTRIC PROPERTIES OF BanLa4Ti3+nO12+3n HOMOLOGOUS SERIES

Authors investigated the phase structure and microwave dielectric properties of the BanLa4Ti3+nO12+3n homologous series. In BaLa4Ti4O15 with n=1 composition, authors obtained high Q characteristics at the dielectric constant er=46, the temperature coefficient of the resonant frequency tf=-11 ppm/C and Q*f=46000 GHz. In the BaO-La2O3-TiO2 system, BanLa4Ti3+nO12+3n compounds exist on the tie line BaTiO3-La4Ti3O12 near the tungsten bronze-type like Ba6-3xR8+2xTi18O54 (R=rare earth) solid solutions. There are three kinds of compounds: n=1, BaLa4Ti4O15; n=2, Ba2La4Ti5O18; and n=4, Ba4La4Ti7O24. These compounds have a layered hexagonal perovskite-like structure, which has a common substructure in the crystal structure. Authors have investigated the phase compositions and microwave dielectric properties of BanLa4Ti3+nO12+3n. With an increase of n, the dielectric constant increases and the quality factor decreases. 18 refs.