Fabrication of Er:SrF2 transparent ceramics by air pre-sintering and hot isostatic pressing

Using the 1 at.% Er:SrF2 nano-powders synthesized by the co-precipitation method as starting powders, 1 at.% Er:SrF2 transparent ceramics were successfully prepared by air pre-sintering at different temperatures for 2 h combined with hot isostatic pressing (HIP) post-treatment at 600 degrees C for 2 h under 100 MPa Ar. The influences of the pre-sintering temperature on optical quality, microstructure, phase composition and EPR spectrum of ceramics were investigated. Among all the HIP post-treated 1 at.% Er:SrF2 ceramics in the thickness of 2.5 mm, the sample pre-sintered at 650 degrees C shows the best optical quality, whose transmittance at 2500 nm and 1500 nm reaches 83.4% and 73.6%, respectively. Furthermore, the spectral characteristics of this ceramic sample were systematically analyzed. The fluorescence lifetime for the 1 at.% Er:SrF2 ceramics at 1530 nm is 49.62 ms. The strongest absorption and emission cross section for the peaks at around 1530 nm are 6.20 x 10-21 and 3.47 x 10-21 cm2, respectively. In brief, the above findings indicate that the Er:SrF2 ceramics is a promising candidate as middle infra-red laser gain media.