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We present a new approach for scaling-up the growth of β-Ga2O3 single crystals grown from the melt by the Czochralski method, which has also a direct application to other melt-growth techniques involving a noble metal crucible. Experimental and theoretical results point to melt thermodynamics as the crucial factor in increasing the volume of a growing crystal. In particular, the formation of metallic gallium in the liquid phase in large melt volumes causes problems with crystal growth and eutectic or intermetallic phase formation with the noble metal crucible. The larger crystals to be grown the higher oxygen concentration is required. The minimum oxygen concentration ranges from about 8 to 100 vol.% for 2 to 4 inch diameter cylindrical crystals, challenging the use of iridium crucibles in a combination with such high oxygen concentrations. A specific way of oxygen delivery to a growth furnace with the iridium crucible allows to minimize the formation of metallic gallium in the melt and thus obtaining large crystal volumes while decreasing the probability of the eutectic formation.

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The lattice parameters of three perovskite-related oxides have been measured with high precision at room temperature. An accuracy of the order of 10(-5) has been achieved by applying a sophisticated high-resolution X-ray diffraction technique which is based on the modified Bond method. The results on cubic SrTiO(3) [a = 3.905268 (98) Å], orthorhombic DyScO(3) [a = 5.442417 (54), b = 5.719357 (52) and c = 7.904326 (98) Å], and orthorhombic NdGaO(3) [a = 5.428410 (54), b = 5.498407 (55) and c = 7.708878 (95) Å] are discussed in view of possible systematic errors as well as non-stoichiometry in the crystals.