Abstract
The solubility of quartz from ammonium fluoride solution was measured using a small autoclave. Based on the solubility data, a single crystal of quartz was grown from ammonium fluoride solutions at 230-280°C and 4-101MPa. The growth rate depended on the growth temperature, temperature gradient and concentration of the ammonium fluoride solution. The maximum growth rate of the Z face attained was 0.88mm/day which was comparable to that in alkaline solutions. However, the growth rate of the X face was very low, the growth rate of -X face was less than one fifth of that for +X face. Fine pyramidal growth hills were observed on Z face, and the size increased with increasing pressure and concentration of ammonium fluoride solution. The linear defect density in Z growth zone was about 103-105pcs/cm2, higher than that in alkaline solutions. Strong absorption at about 3500cm-1 by -OH stretching vibration was observed in FTIR spectra. The defects originating from -OH depended on the temperature gradient.
