MICROWAVE DIELECTRIC CHARACTERISTICS OF ILMENITE-TYPE TITANATES WITH HIGH Q-VALUES

The microwave dielectric characteristics of ilmenite titanates, M(2+)TiO(3) (where M(2+)=Ni, Mg and Mn) and (Mg(0.95)M(0.05)(2+)TiO(3) (where, M(2)=Ni, Mg, Co and Mn) series, have been investigated as a function of ionic radius of M(2+) and (Mg(0.95)M(0.05)(2+))(2+) ions, respectively. The ilmenite titanates have high Q value and low dielectric constant due to the isolation of TiO6 octahedra by the MO(6) octahedron layer and cation vacancy layer in comparison with the perovskite titanates. The existence of localized 3d electrons in N2+(3d(8)) and Mn2+(3d(5)) is concerned with the microwave dielectric properties of the M(2+)TiO(3) series. The dielectric constant, epsilon(r) at 10 GHz of the (Mg(0.9)5M(0.05)(2+)) TiO3 series shows the minimum value around the average ionic radius of 0.721 Angstrom A while the Q value shows a maximum, probably due to a local lattice distortion. The Mg(0.9)5Co(0.05))TiO3 compound shows a maximum Q value of 23,000 at 10 GHz, dielectric constant of 16.8, and tau(f) of -54 ppm/K.