DEPENDENCE OF MICROWAVE DIELECTRIC PROPERTIES ON STRUCTURAL CHARACTERISTICS OF ILMENITE, TRI-RUTILE AND WOLFRAMITE CERAMICS

Abstract

Effects of crystal structures on dielectric properties of ATiO 3 (trigonal ilmenite), ATa 2 O 6 (tetragonal tri-rutile) and AWO 4 (monoclinic wolframite) (A = Ni, Mg, Co) ceramics with A- and B-site oxygen octahedra were investigated at microwave frequencies. The dielectric constant (K) of the specimens was affected by the dielectric polarizabilities of composition and cation bond valence between octahedral cation and oxygen ion per molar volume (V m ). The quality factor (Qf) of ATiO 3 was appreciably larger than those of ATa 2 O 6 and AWO 4 due to the different sharing types of oxygen octahedra. The temperature coefficient of resonant frequency (TCF) of the specimens was dependent on the octahedral distortion per V m .