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

The microwave dielectric characteristics of ilmenite titanates, M(2+)T iO(3) (where M(2+)=Ni, Mg and Mn) and (Mg(0.95)M(0.05)(2+)TiO(3) (wher e, M(2)=Ni, Mg, Co and Mn) series, have been investigated as a functio n of ionic radius of M(2+) and (Mg(0.95)M(0.05)(2+))(2+) ions, respect ively. The ilmenite titanates have high Q value and low dielectric con stant due to the isolation of TiO6 octahedra by the MO(6) octahedron l ayer and cation vacancy layer in comparison with the perovskite titana tes. 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 av erage ionic radius of 0.721 Angstrom A while the Q value shows a maxim um, probably due to a local lattice distortion. The Mg(0.9)5Co(0.05))T iO3 compound shows a maximum Q value of 23,000 at 10 GHz, dielectric c onstant of 16.8, and tau(f) of -54 ppm/K.