Improved high Q value of (1-x)Ca(Mg1/3Ta2/3)O3-xCa0.8Sm0.4/3TiO3 solid solution with zero temperature coefficient of resonant frequency

High-relative-permittivity and low-loss ceramics in the (1 - x)Ca(Mg1/3Ta2/3)O-3-xCa(0.8)Sm(0.4/3)TiO(3) system have been prepared by the conventional solid state route and their microwave dielectric properties have been investigated. (1 - x)Ca(Mg1/3Ta2/3)O-3-xCa(0.8)Sm(0.4/3)TiO(3) solid solution exhibited orthorhombic crystal structures for all compositions. A rapid grain growth is observed at temperatures higher than 1450 degrees C, which would lead to a decrease in the density and the Q x f of the ceramics. A near-zero temperature coefficient of resonant frequency can be achieved for Ca(Mg1/3Ta2/3)O-3 with the addition of Ca0.8Sm0.4/3TiO3. The temperature coefficient of resonant frequency increases with increasing Ca0.8Sm0.4/3TiO3 content and tunes through zero at x=0.45. Specimen using 0.55Ca(Mg1/3Ta2/3)O-3-0.45Ca(0.8)Sm(0.4/3)TiO(3) possesses an excellent combination of microwave dielectric properties: epsilon(r) similar to 44.96, Q x f similar to 41,700 GHz (where f=6.6 GHz, is the resonant frequency) and tau(f) value of 0 ppm/degrees C. It is proposed as a suitable candidate material for today's 3G passive components and small-sized GPS patch antennas. (c) 2009 Elsevier B.V. All rights reserved.