Growth of gallium orthophosphate single crystals in acidic hydrothermal solutions

The hydrothermal growth of GaPO₄ single crystals has been studied in several solutions. Among many solutions, H₃PO₄, HCl and H₂SO₄ solutions were found to be effective solvents for the growth of GaPO₄ single crystals. Single crystals have been hydrothermally grown at temperatures over the range 210 to 290 °C in these solutions with seed crystals. HCl solution was found to be the most effective solvent in which to grow large single crystals.Morphologies of crystals grown at temperatures below 200 °C tended to be bounded by small major rhombohedral (1 0 ¯1 1) faces. In the temperature range from 210 to 430°C, the crystals have morphologies bounded by prism (1 0 ¯1 0), small major rhombohedral (1 0 ¯1 1) and minor rhombohedral (0 1 ¯1 1) faces, and grew with well developed basal (0 0 0 1) faces with increase in the growth temperature. Single crystals of GaPO₄ with lower dislocation density have been hydrothermally grown at 210 to 290°C in 3 m H₃PO₄ solution.