Journal of Crystal Growth, Vol.254, No.1-2, 107-114, 2003
Crystal growth of pure and Cr3+-doped NaAl(WO4)(2)
The growth conditions of single crystals of the recently synthesized new double tungstate of sodium and aluminum, NaAl(WO4)(2) (J. Alloys Compounds 351 (2003) 202), have been investigated. Data have been obtained on the concentration and temperature regions of crystallization of this compound in the system Na2O-Al2O3-WO3 and its thermal stability. Nonsoichiometric high-temperature solutions of the binary oxides with very low crystallization temperatures, low viscosity and absence of volatility have been found and used for growing pure and differently Cr3+-doped single crystals of NaAl(WO4)(2) by the top seeded solution growth technique with slow cooling. The main defects of the crystals obtained have been established, the reasons for their appearance analysed and some possible ways of avoiding their formation are proposed. The absorption and luminescence spectra of Cr3+ :NaAl(WO4)(2) at room temperature are obtained. The results show that this material is an appropriate candidate for laser medium combining a broad luminescence spectrum with technological convenience of single crystal growth. (C) 2003 Elsevier Science B.V. All rights reserved.