Single-crystal growth of sulphospinel CuIr2S4 from Bi solution

Single crystals of a sulphospinel CuIr2S4 have been grown From bismuth solution by a slow cooling method for the first time. The grown crystals have a maximum edge of about 1 mm in size and a mirror-like shilling surface. Optimum growth conditions are fairly strict. The specific weight of stal tine materials for the crystal growth is found to be 0.30 g of CuIr2S4 and 10.0 g of Bi in order to obtain good quality crystals. The starting and finishing temperatures for the slow cooling step in the temperature control are 1000 and 500 degrees C. The pertinent cooling rate is similar to 2 degrees C/h. Since the volume of bismuth itself expands in the transition From liquid phase to solid phase. a simple method of separation of the grown crystals from the liquid solution will be proposed for avoiding the mechanical damages to the grown crystals. The single crystals have the normal-spinel structure of the lattice constant a = 9.849 Angstrom at room temperature. A step-like anomaly in the susceptibility of the single crystals, corresponding to the metal-insulator transition in the resistivity, occurs much sharply than in the powder specimen. (C) 2000 Elsevier Science B.V. All rights reserved.