Low-loss microwave dielectrics using SrTiO3-modified (Mg0.95Co0.05)2TiO4 ceramics

The microstructure and microwave dielectric properties of the (1-x)(Mg0.95Co0.05)(2)TiO4-XSrTiO3 (x = 0.05-0.1) ceramic system have been investigated in this paper. The X-ray diffraction (XRD) results indicate that all samples exhibit a two-phase system, which has a spinel-structured primary phase (Mg0.95Co0.05)(2)TiO4 associated with a perovskite-structured SrTiO3 minor phase. in addition to these two phases, a (Mg0.95Co0.05)TiO3 second phase is also detected throughout the entire compositional range. The microwave dielectric properties are strongly related to the density and the surface morphology of the specimens. However, the presence of second phase would not deteriorate the dielectric properties of the specimen, since the second phase properties are very similar to the primary phase. The r(f) value is strongly correlated to the compositions and can be controlled through the compositional ratio. A new microwave dielectric material 0.93(Mg0.95Co0.05)(2)TiO4-0.07SrTiO(3), possessing an excellent combination of microwave dielectric properties with an E, of 18.44, a Q x f of 102,200 GHz (at 9.5 GHz) and a rf of 1.1 ppm/degrees C, is proposed as a very promising candidate material for today's 3G applications. (C) 2009 Elsevier B.V All rights reserved.