LuYAG [(Lu,Y)(3)Al5O12] single crystals have been grown by means of the Czochralski method. The solidification points of LuYAG ranged from 2010degreesC for Lu3Al5O12 to 1930degreesC for Y3Al5O12. Lattice parameters of LuYAG changed linearly with variations in composition from 11.9164(4) Angstrom for Y3Al5O12 to 12.0075(3) Angstrom for Y3Al5O12. The effective segregation coefficients k(eff), experimentally determined from the lattice parameters, show that compositional segregation of Y atoms proceeds with increasing Lu content. The heat capacity, heat diffusivity, and thermal conductivity Of Y3Al5O12, Lu2YAl5O12, Lu1.5Y1.5Al5O12, LuY2Al5O12 and Y3Al5O12 were also measured. The two latter properties exhibit minima near the equimolar solid solution composition. Refractive indices, determined by the minimum deviation method, vary smoothly between 0.40 and 1.97 mum wavelengths and permit derivation of the Sellmeier constants. (C) 2003 Elsevier B.V. All rights reserved.