Effect of powder calcination temperature on the microstructure and laser performance of Yb:CaF ₂ transparent ceramics

Abstract The 5 at.% Yb:CaF ₂ transparent ceramics were fabricated by hot pressing and hot isostatic pressing (HIP) using nano‐powders synthesized by the co‐precipitation method. Before hot pressing, the co‐precipitated powders were vacuum calcined at different temperatures. To understand the relationship between the calcination temperature and the resulting material properties, a series of in‐depth studies were conducted on the microstructure and optical properties of Yb:CaF ₂ ceramics. Following HIP post‐treatment at 600°C, residual porosity within the hot‐pressed ceramics was effectively eliminated, leading to enhancements in optical quality. The ceramic samples hot pressed at 625°C from powders vacuum calcined at 600°C and then HIP post‐treated at 600°C exhibited the highest in‐line transmittance of 91.0% at 1200 nm as well as the best laser performance. The maximum output power of 1.51 W and the maximum slope efficiency of 22.9% were obtained, surpassing those of other Yb:CaF ₂ ceramics fabricated via the HP method reported in the literature.