NaBi1−xREx(XO4)2, X=W or Mo and RE=Pr, Nd, Ho, Er and Yb single crystals have been grown by the Czochralski technique. Rare earth concentrations about 3.5×1020 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 and Mo compounds to chemical attack and thermal annealing in several atmospheres is reported. Mo compound is etched by inorganic acids and becomes coloured after vacuum annealing. The optical absorption, photoluminescence and refractive indices of the hosts are characterised and show a dichroic character. The lattice disorder induces broadening of the 10 K optical absorption of the rare earth impurities.

This work is supported by CICyT under project numbers 2FD97-0912-C02 and MAT99-1077-C02. V. Volkov is supported by a sabbatical grant from the Spanish Education Ministry. A. Mendez-Blas acknowledges a CONACYT (Mexico) grant.

Peer reviewed