Phase Equilibria in LiYF4-LiLuF4 System and Heat Conductivity of LiY1-x Lu (x) F-4 Single Crystals

Single crystals of LiY1-x Lu (x) F-4 (x = 0, 0.25, 0.5, 0.65, 0.9) solid solution were grown by Bridgman-Stockbarger technique. Melting points determined by DSC monotonically varied with composition from 831 to 841 K when x increased. Interval between liquidus and solidus curves is not larger 1A degrees C. This feature extremely favors to the growth of homogeneous single crystals from melt. Heat conductivity (kappa) of solid solution is lower than that of LiYF4 and LiLuF4 components. In the region 0.25 0.65 at 300 K, kappa = 4 +/- 0.1 W/(m K).