Al 2-X MeX (WO 4 ) 3 single crystal, Me=Sc, Y, Ga and In, as a new tunable laser media

Abstract

The crystallization conditions of Al₂(WO₄)₃ from Li₂O-WO₃ solvents (molar ratio 30.0:70.0, 32.5:67.5, 35.0:65.0, 45.0:55.0 and 55.0:45.0) as well as from Na₂O-WO₃ solvents (molar ratio 25.0:75.0, 27.5:72.5, 30.0:70.0 and 32.5:67.5) have been investigated. The concentration and temperature regions of crystallization of Al₂(WO₄)₃and the density, viscosity as well as the solution losses due to evaporation have been established. On the basis of the data obtained it has been concluded that the most suitable solvent for growing Al₂(WO₄)₃ single crystals is Na₂O-WO₃ with a molar ratio of 27.5:72.5. The temperature and concentration regions of crystallization of Al_2-xMe_x(WO₄)₃ solid solutions obtained by replacement of Al2O3 in the Na₂O-Al₂O₃-WO₃ system by Ga₂O₃, In₂O₃, Sc₂O₃ or Y₂O₃ have been investigated. The crystallization regions and concentration boundaries of existence of the solutions are found to depend strongly on the nature of the replacing element. Solid solutions containing Sc and In crystallize from high-temperature solutions with a lower concentration as compared to that of pure Al₂(WO₄)₃, this being accompanied by a high distribution coefficient of the substituting ion. On the contrary, Ga and Y containing solid solutions crystallize from high-temperature solutions with much higher concentrations, the distribution coefficient of the substituting ions being relatively low. The experimental obtained data are the basis for growing bulk single crystals with preset compositions from the Al_2-X Me_X (WO₄)₃, Me=Sc, Y, Ga or In, solid solutions.