Preparation and properties of disordered NaBi(XO4)(2), X = W or Mo, crystals doped with rare earths

NaBi1-xREx(XO4)(2), X = W or Mo and RE = Pr, Nd, Ho, Er and Yb single cryst als have been grown by the Czochralski technique. Rare earth concentrations about 3.5 X 10(20) cm(-3) have been achieved in crystals with good optical quality. Melt stability is obtained by synthesising NaBi(XO4)(2) from the precursor Na2X4O13 phase and minimising Mo volatility. The strength of W an d Mo compounds to chemical attack and thermal annealing in several atmosphe res is reported. Mo compound is etched by inorganic acids and becomes colou red after vacuum annealing. The optical absorption, photoluminescence and r efractive indices of the hosts are characterised and show a dichroic charac ter. The lattice disorder induces broadening of the 10 K optical absorption of the rare earth impurities. (C) 2001 Elsevier Science Ltd. All rights re served.