Improved high Q value of (1 -x)Ca(Mg_(1/3)Ta_(2/3))O_3-xCa_(0.8)Sm_(0.4/3)TiO_3 solid solution with zero temperature coefficient of resonant frequency

摘要

High-relative-permittivity and low-loss ceramics in the (1 -x)Ca(Mg_(1/3)Ta_(2/3))O_3-xCa_(0.8)Sm_(0.4/3)TiO_3system have been prepared by the conventional solid state route and their microwave dielectric properties have been investigated. (1 -x)Ca(Mg_(1/3)Ta_(2/3))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 °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_(1/3)Ta_(2/3) )O_3 with the addition of Ca_(0.8)Sm_(0.4/3)TiO_3. The temperature coefficient of resonant frequency increases with increasing Ca_(0.8)Sm_(0.4/3)TiO_3 content and tunes through zero at x = 0.45. Specimen using 0.55Ca(Mg_(1/3)Ta_(2/3))O_3-0.45Ca_(0.8)Sm_(0.4/3)TiO_3 possesses an excellent combination of microwave dielectric properties: ε_r~44.96, Q × f approx 41,700GHz (where/= 6.6GHz, is the resonant frequency) and T_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.