Lowered sintering temperature and modulated microwave dielectric properties in Mg2SiO4 forsterite via Ge substitution

In this work, a strategy was demonstrated to reduce the sintering temperature of Mg 2 SiO 4 ceramics while keeping the macrostructure unchanged, through an appropriate amount of low melting point Ge substitution for B-site Si. A series of Mg 2 Si 1 − x Ge x O 4 ( x  = 0.1–0.4) ceramics were prepared by a solid-state reaction method. Influences of Ge substitution on the sintering behavior, crystal structure, and microwave dielectric properties were studied. By comparison, the Ge-substituted samples could be effectively sintered at relatively lower sintering temperatures (~ 1370 °C), which is more than 100 °C lower than the nominal Mg 2 SiO 4 . In addition, the optimum microwave dielectric performance was achieved in the sample with x  = 0.4, with the relative density ~ 97%, the relative dielectric constant ( ε r ) of 7.2, the quality factor ( Q  ×  f ) of 75,794 GHz, and the temperature coefficient of the resonance frequency ( τ f ) of − 41.2 ppm/°C. This compositional regulation provides a paradigm for improving the sintering characteristics of silicate.