Growth of barium chlorapatite crystals from a sodium chloride flux

Large and well-formed crystals of barium chlorapatite [Ba5Cl(PO4)(3)] were grown for the first time from a sodium chloride flux. The solubility of Ba5Cl(PO4)(3) in NaCl increased with increasing temperature, reaching about 1.9 mol% solubility at 1100 degrees C. The crystal growth of Ba5Cl(PO4)(3) was conducted by heating a mixture of solute and flux at 1100 degrees C for 10 h, and then cooling to 500 degrees C at a rate of 5 degrees C h(-1). Colorless and transparent prismatic crystals with lengths of up to 12 mm and widths of 3 mm were grown from high-temperature solutions containing 0.4-2.2 mol% solute. The most suitable solute content for the growth of prismatic crystals was 1.2 mol%. The prismatic crystals were bounded by the {10(1) over bar 0} and {10(1) over bar 1} faces. The aspect ratios were in the region of 1.1 to 4.8. Needle crystals with lengths of up to 4 mm and widths of 60 mu m were obtained during every growth run. The needle crystals were elongated in the [0001] directions, with aspect ratios ranging from 43 to 56. The major constituents were almost homogeneously distributed in the prismatic and needle crystals.