Hydrothermal growth of LiLuF4 crystals and new lithium lutetium fluorides LiKLuF5 and LiNaLu2F8

The hydrothermal synthesis and crystal growth of LiLuF 4 were investigated. Small crystals of LiLuF 4 were produced but while investigating various alkali fluoride mineralizers, a new series of alkali lithium lutetium fluorides, including, LiKLuF 5 and LiNaLu 2 F 8 , were synthesized under hydrothermal conditions (570 °C at 12.5 kpsi). The mineralizer KF leads to formation of a new compound LiKLuF 5 crystallized in the space group C 2/ m with the lattice parameters a = 6.2328(12), b = 11.709(2), c = 6.3986(13), β = 113.87(3). Tm and Yb analogs were also synthesized using the same conditions. Use of NaF as mineralizer leads to a new compound LiNaLu 2 F 8 , crystallized in space group Cmcm , a = 10.3181(21), b = 8.2393(16), c = 6.9565(14). Several doped compounds were also isolated and electronic spectra were obtained.