Novel transparent ZnO·3Al2O3 ceramics prepared by reactive hot isostatic pressing

Abstract Transparent ZnO·3Al2O3 ceramics were produced, for the first time, by the reactive hot isostatic pressing of air-sintered ZnAl2O4–2Al2O3 composites. Before the evident reaction of ZnAl2O4 and Al2O3 occurred, the composite system had already been highly densified and maintained a uniform distribution of both phases, which is the key to suppressing the volatilization of zinc, and thus obtaining a single-phase, pore-free structure by hot isostatic pressing. The new material is competitive for optical-dielectric applications, with the maximum in-line transmittance of 86.0 % (4.0-mm-thick), the transmission window (in-line transmittance > 60 %) of 0.33 ∼ 5.0 μm and the quality factor of 1.70 × 105 GHz at 8.84 GHz.