Abstract
The growth of emerald (Be_3Al_2Si_6O_<18>: Cr) crystals by slow cooling in the PbO-V_2O_5 flux is reported. The crystal growth was conducted by heating mixtures at 1200℃ for 10h, followed by cooling to 600℃ at a rate of 5℃/h. The emerald crystals exhibited the typical emerald-green color, were up to 2.2 mm in size and transparent. Their form was a regular hexagonal rod bounded by the well-developed {0001} and {101^^-0} faces. The aspect ratio (L/W) of emerald crystals grown at the respective runs was approximately 1. Batch containing the oxide dopant (Cr_2O_3) added as 1.0 or 1.5 wt% of the beryl mixture produced the emerald crystals of good quality. The most suitable com-position of flux was found to be PbO (50 mol%)-V_2O_5(50 mol%). The larger volume batches produced emerald crystals of smaller size and also unwanted crystal phases such as SiO_2 and Be_2SiO_4.
