Defects in U³⁺:CaF₂ single crystals grown under different conditions by the temperature gradient technique

Abstract

Defects in as‐grown U3+:CaF2 crystals grown with or without PbF2 as an oxygen scavenger were studied using Raman spectra, thermoluminescence glow curves, and additional absorption (AA) spectra induced by heating and γ‐irradiation. The effects of heating and irradiation on as‐grown U3+:CaF2 crystals are similar, accompanied by the elimination of H‐type centers and production of F‐type centers. U3+ is demonstrated to act as an electron donor in the CaF2 lattice, which is oxidized to the tetravalent form by thermal activation or γ‐irradiation. In the absence of PbF2 as an oxygen scavenger, the as‐grown U3+:CaF2 crystals contain many more lattice defects in terms of both quantity and type, due to the presence of O2– impurities. Some of these defects can recombine with each other in the process of heating and γ‐irradiation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Color centers in Yb:YAG crystals grown by temperature‐gradient techniques

“…Color centers or impurity defects in Yb:YAG crystals have a significant effect on laser performance or scintillation parameters. It has been shown that color centers produced in crystals are closely related to the growth atmosphere [7]. However, there is a lack of studies analyzing the color centers in Yb:YAG crystals grown in different atmospheres, and it is very interesting to carry out such an experiment which should suggest opportunities to enhance the laser or scintillation efficiency.…”