Improved high Q value of (1 − x)Ca(Mg 1/3Ta 2/3)O 3– xCa 0.8Sm 0.4/3TiO 3 solid solution with zero temperature coefficient of resonant frequency

Abstract

High-relative-permittivity and low-loss ceramics in the (1 − x)Ca(Mg 1/3Ta 2/3)O 3– xCa 0.8Sm 0.4/3TiO 3 system have been prepared by the conventional solid state route and their microwave dielectric properties have been investigated. (1 − x)Ca(Mg 1/3Ta 2/3)O 3– xCa 0.8Sm 0.4/3TiO 3 solid solution exhibited orthorhombic crystal structures for all compositions. A rapid grain growth is observed at temperatures higher than 1450 °C, which would lead to a decrease in the density and the Q × f of the ceramics. A near-zero temperature coefficient of resonant frequency can be achieved for Ca(Mg 1/3Ta 2/3)O 3 with the addition of Ca 0.8Sm 0.4/3TiO 3. The temperature coefficient of resonant frequency increases with increasing Ca 0.8Sm 0.4/3TiO 3 content and tunes through zero at x = 0.45. Specimen using 0.55Ca(Mg 1/3Ta 2/3)O 3–0.45Ca 0.8Sm 0.4/3TiO 3 possesses an excellent combination of microwave dielectric properties: ɛ r ∼ 44.96, Q × f ∼ 41,700 GHz (where f = 6.6 GHz, is the resonant frequency) and τ f value of 0 ppm/°C. It is proposed as a suitable candidate material for today's 3G passive components and small-sized GPS patch antennas.