Improved microwave dielectric properties of CaMgSi2O6 ceramics through CuO doping

High-performance dielectric materials for microwave communication requires low dielectric constants (epsilon(r) < 10), high quality factor (Qf) and near-zero temperature coefficient of resonance frequency (tau(f)). However, CaMgSi2O6 ceramics typically exhibit low Qf and largely negative tau(f), despite its low epsilon(r). In this study, nominal composition CaMg1-xCuxSi2O6 (0 <= x <= 0.16) ceramics were synthesized via a solid-state reaction. Enhanced microwave dielectric properties were achieved in the x = 0.04 ceramic sintered at 1250 degrees C with epsilon(r) = 7.41, Qf = 160 100 GHz (two times better than the previously reported values), and tau(f) = - 42 ppm/degrees C. Benefited from the optimal CuO doping, this enhancement in microwave dielectric property was realized by the contribution of order structure and the densification. Excess CuO doping, which can lead to a phase transition (from C2/c to P2(1)/c), could degenerate the microwave dielectric properties of the CaMgSi2O6 ceramics. Considering the excellent microwave dielectric properties, the CuO-doped CaMgSi2O6 ceramic is a promising candidate material for microwave communication applications. (C) 2018 Elsevier B.V. All rights reserved.