Transparent and nearly colorless CaxBa1-x,Nb2O6 (CBN) single crystals with five different compositions in the range 0.22 <= x(Ca) <= 0.35 have been grown by the Czochralski method. An improved crystalline quality could be achieved by adjusting optimized thermal conditions and by using an accurately oriented [00 1] seed. The congruent melting composition was calculated to be located at about 28.1 Ca mol fraction by correlating the initial melt compositions and the crystal compositions. The analysis showed that the distribution coefficients on both sides of the congruent melting composition were close to unity. The density of CBN, measured by the buoyancy method, is a linear function of the composition. On the other side, only lattice parameter c(0) is markedly influenced by the variation of the Ca content, whereas a(0) shows only minor changes. (c) 2007 Elsevier B.V. All rights reserved.