Growth of Single Crystals of ZrW sub 2 O sub 8

The compound, ZrW sub 2 O sub 8, exhibits an unusual negative coefficient of thermal expansion of approximately -10 ppm/C over ambient temperatures. The incongruent melting point and narrow thermal stability limits of ZrW sub 2 O sub 8 from 1105 to 1257C severely restrict crystal growth conditions. However, single crystals of ZrW sub 2 O sub 8 having masses on the order of a gram were grown from a WO sub 3-rich flux under non-equilibrium conditions. Crystals were characterized by X-ray diffraction, inductively coupled plasma emission spectroscopy (ICP-ES), dilatometry, and etching behavior. Details of the crystal growth technique and possible growth mechanisms are discussed.