Thermal Expansions of Pure and Al-doped CsLiB₆O₁₀ Crystals for Nonlinear Optical Applications

Abstract

Changes in X-ray powder diffraction patterns of pure and Al-doped CsLiB 6 O 10 (CLBO) crystals for nonlinear optics upon heating are observed between room temperature and 500°C. The crystals undergo linear elongation by about 2×10 -5 deg -1 along the a -axis, and contraction by about -2×10 -5 deg -5 is observed along the c -axis. Such extraordinary behavior on heating is a reflection of the structure of CLBO which costists mainly of a combination of hexagonal B 3 O 4 rings, and a marked difference in linkage of the rings appears between the a - and c -axes. No significant changes in the thermal expansion coefficients are observed on Al-doping, though considerable expansions along the a - and c -axis are observed.