Reaction-sintered highly transparent MgGa2O4 ceramics with enhanced dielectric properties

Reaction sintering of MgO and Ga2O3 powders was first used to prepare MgGa2O4 transparent ceramics. The microstructural evolution suggested that the negligible volume change resulting from the solid-phase reaction of MgO and Ga2O3, as well as the close and homogeneous arrangement of both fine particles, are the key factors in obtaining pre-sintered ceramics with an ideal microstructure at lower temperature. After a hot isostatic pressing (HIP) treatment, the fully dense ceramic exhibited improved in-transmittance (74.7 %@600 nm, and 85.4 % @4401 nm) and quality factor (Q x f = 168,000 GHz). Due to the combination of high transparency, wide transmission range (6.22 mu m at the 60 % transmittance), ultra-low dielectric loss, and near-zero temperature coefficient of resonance frequency (- 3.9 ppm/degrees C), transparent MgGa2O4 ceramic is suggested to be an ideal optical-dielectric integration material.