Improvements on sintering behavior and microwave dielectric properties of Li4WO5 ceramics through MgO modification

In this work, compositional modification was proposed to improve the sintering behavior of Li4WO5 via MgO additive. A series of (1-x)Li4WO5-xMgO ceramics were prepared by a simple solid-state reaction route. Solid solutions between Li4WO5 and MgO were formed due to their same crystal structure and the similar ionic sizes. MgO modification improved the microstructure and densification, which in turn increased the dielectric performances of Li4WO5. A composition with x = 0.075 possessed a combination of optimum dielectric properties with a relative permittivity (εr) of 10.8, a quality factor (Q×f) of 26,270 GHz, and a temperature coefficient of resonance frequency (τf) of −8 ppm/°C. The evolutions in dielectric properties with composition were studied from internal effects (ionic polarizability, and packing fraction) and external contributions (density variation). Competing effects from extrinsic and intrinsic contributions give rise to improvements in dielectric properties.