Preparation of CaF2 transparent ceramics by cold sintering

High transparent CaF2 ceramics were prepared by a cold sintering process, and their microstructure and transmittance were studied. The results show that the sample with a relative density of 97.65% can be successfully sintered by the cold sintering process at 350 °C and 470 MPa. Micrographs show that the ceramics have high relative density and the average grain size is about 0.3 μm. When the thickness of the prepared sample is 1 mm, the average transmittance in the visible region (380 nm–780 nm) is 81.99%, and the transmittance at 1100 nm is 89.00%. CaF2 ceramics microwave dielectric property is Qf = 10,499 GHz, εr = 3.858 at 350 °C.