Structure and microwave dielectric characteristics of lithium-excess Ca0.6Nd0.8/3TiO3/(Li0.5Nd0.5)TiO3 ceramics

Compositions based on (1−x)Ca0.6Nd8/3TiO3−x(Li1/2Nd1/2)TiO3 + yLi (CNLNTx + yLi, x = 0.30–0.60, y = 0–0.05), suitable for microwave applications have been developed by systematically adding excess lithium in order to tune the microwave dielectric properties and lower sintering temperature. Addition of 0.03 excess-Li simultaneously reduced the sintering temperature and improved the relative density of sintered CNLNTx ceramics. The excess Li addition can compensate the evaporation of Li during sintering process and decrease the secondary phase content. The CNLNTx (x = 0.45) ceramics with 0.03 Li excess sintered at 1190 °C have single phase orthorhombic perovskite structure, together with the optimum combination of microwave dielectric properties of ɛr = 129, Q × f = 3600 GHz, τf = 38 ppm/°C. Obviously, excess-Li addition can efficiently decrease the sintering temperature and improve the microwave dielectric properties. The high permittivity and relatively low sintering temperatures of lithium-excess Ca0.6Nd0.8/3TiO3/(Li0.5Nd0.5)TiO3 ceramics are ideal for the development of low cost ultra-small dielectric loaded antenna.