Zirconium hydride an ore, usually a zirconium silicate, such as zircon. Zirconium is extracted from zirconium ore by removing the oxygen and silica. This process, known as the Kroll process, was first applied to titanium. The Kroll process results in an alloy containing hafnium. The hafnium and other impurities are removed in a subsequent step. Zirconium hydride is created by combining refined zirconium with hydrogen. Like titanium, solid zirconium dissolves hydrogen quite readily. The density of zirconium hydride varies based the hydrogen and ranges between 5.56 and 6.52 g cm. Even in the narrow range of concentrations which make up zirconium hydride,
Cubic zirconia exceeded that of earlier synthetics, such as synthetic strontium titanate, synthetic rutile, YAG (yttrium aluminium garnet) and GGG (gadolinium gallium garnet). Some of the earliest research into controlled single-crystal growth of cubic zirconia occurred in 1960s France, much work being done by Y. Roulin and R. Collongues. This technique involved molten zirconia being contained within a thin shell of still-solid zirconia, with crystal growth from the melt. The process was named "cold crucible", an allusion to the system of water cooling used. Though promising, these attempts yielded only small crystals. Later, Soviet scientists under V. V. Osiko at the Lebedev