A mixture of poly-and single crystals of zinc and ytterbium (2 at.%) oxides have been grown from the melt at 3.8 GPa in a toroid-type high-pressure apparatus . The details of the growth method are described elsewhere . Microcrystalline powders of ZnO (Alfa Aesar, 99,9995%) and Yb 2 O 3 (Alfa Aesar, 99,99%) were thoroughly mixed and ground in a mortar, then pressed into a pellet and placed into a special gold capsule. The ZnO:Yb 2 O 3 molar ratio was equal to 50:1. The samples were gradually compressed up to 3.8 GPa and heated up to 1430C with an average rate 500C/min, annealed at this temperature for 2 min and cooled down to 1100C with an average rate 90C/min. Crystallization of the melt was observed in the temperature range from 1290 to 1250C, as evidenced by an increase of electrical resistance of the high-pressure cell. Finally, the sample was quenched down to room temperature and slowly decompressed. The recovered pellet comprised of a mixture of transparent greenish-yellow crystals with diameters from 0.005 to 0.2 mm.