Growth of big single crystals of Sr₂YRu_1-xCu _xO₆ from high temperature solutions

Single crystals of Sr₂YRu_1-xCu_xO ₆ (x = 0 - 0.4) have been grown from PbO-PbF₂ based solutions in the temperature range 1150 - 1350°C. A silicon carbide heating element furnace (with a recrystallized alumina tube lining) in a vertical configuration was used to grow the crystals in platinum crucibles. Conditions for the stable growth of big crystals have been investigated. The morphology of the crystals containing Cu was found to change from octahedral to cube octahedral as the growth temperature is increased from 1150 to 1350°C. Crystals measuring up to 4.5 mm across and 2.5 mm thick have been grown from 1250°C. The incorporation of Cu into the crystals was ascertained by EDS and x-ray diffraction analysis. A diamagnetic transition which increased in magnitude and temperature with x was observed.