Effect of Cr3+ doping concentration on the microstructure, mechanical properties and optical properties of Cr3+: SrF2 transparent ceramics

Cr³⁺: SrF₂ nanopowders were synthesized using a chemical co-precipitation method. The nanoparticles exhibited a structure consistent with the pure SrF₂ phase. Cr³⁺: SrF₂ transparent ceramics were fabricated by hot-pressed (HP) sintering technique. The transmittance of 1 at% Cr³⁺: SrF₂ transparent ceramics reached up to 83 % at 1054 nm, which is superior to other SrF₂ transparent ceramics with different Cr³⁺ doping concentration. Furthermore, the mechanical properties of Cr³⁺: SrF₂ transparent ceramics improved with increasing Cr³⁺ doping levels. The 1 at% Cr³⁺: SrF₂ transparent ceramics exhibited the best mechanical properties, with a microhardness of 2.573 GPa, fracture toughness of 0.70 MPa·m^1/2, and compressive strength of 38.1 MPa. The luminescence spectra and fluorescence lifetimes of the SrF₂ transparent ceramics as a function of Cr³⁺ doping concentration were also analyzed and discussed.