MICROWAVE DIELECTRIC-PROPERTIES OF HEXAGONAL, PEROVSKITES

The dielectric properties of the hexagonal perovskite oxides, La4BaTi4 O15, La4Ba2Ti5O18 and Ba5Nb4O15 have been characterized at microwave f requencies. These systems combine a relatively high permittivity (39 < epsilon(T) < 46) with a low dielectric loss (11,583 < Q.f < 31,839) a nd small temperature coefficient of resonant frequency (-36 < tau(f) < 79) and may be suitable for application as dielectric resonators. The dielectric polarizability of each compound was compared to values pre dicted from the sum of tabulated empirical ion dielectric polarizabili ties. From these analyses it was concluded that published values for t he ion polarizability of La are high; self consistent results for thes e and other La-containing oxides can be obtained with alpha(La) = 4.82 (Angstrom(3)).