Effects of Zn2+ substitution on the sintering behaviour and dielectric properties of Li2Mg1−xZnxSiO4 ceramics

Abstract

Silicates, the basis on which low-temperature-fired dielectric materials widely studied for applications in the fields of microwave integrated circuits, have been developing vigorously owing to their low dielectric constants and tangent loss values. In this work, Zn2+ was gradually substituted to Mg2+ to make the sintering temperature decreased and enhance the microwave dielectric properties of Li2MgSiO4. Li2Mg1−xZnxSiO4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) powders were prepared through solid-state reaction. Aiming to decrease the sintering temperature to approximately 900 °C, 3 wt% Li2O–B2O3–SiO2–CaO–Al2O3 glass was used as a sintering aid. The XRD patterns made it clear that the major crystalline phase of the materials was Li2(Mg,Zn)SiO4. A new unexpected crystalline phase of ZnxSiO4 appeared when the amount of Zn2+ substituted increased to more than 0.4. SEM micrographs demonstrated that when x = 0.4, the most homogeneous microstructure appeared. Meanwhile, the Q × f value and the relative density also reached to their peaks when x = 0.4, respectively. Moreover, 3 wt% LBSCA-doped Li2Mg0.6Zn0.4SiO4 ceramics exhibited excellent dielectric properties of er = 5.89, Q × f = 44,787 GHz and τf = − 71.65 ppm/°C when sintered at 900 °C. The material exhibited low relative permittivity and low dielectric loss and could thus be a potential candidate for LTCC device applications.