Flux-Growth of Emerald Single Crystais

Abstract

Emerald single crystals have been grown by a molten V₂O₂ flux technique. V₂O₂ and natural beryl crystal mixture at the ratio 4 : 1 (wt %), containing 5.0 wt. % Cr₂O₃, were charged in platinum crucible. Soaking temperature was about 1050°C and natural beryl was used for seed.
Synthetic emeralds were examined by the microscopic observation, Laue photograph, infrared spectrometry, etc.
It is found that the condition with the nutrient temperature being higher than that of natural beryl seed and an use of buffle plate proved an excellent for the emerald growth. Without an use of buffle plate, a large number of small emerald single crystals, having hexagonalcolumnar habits, were grown near liquid surface.
A solubility curve of the synthetic emerald in V₂O₂ flux were examined and found that about 6.3 g of synthetic emerald was melt in V₂O₂ at 1050°C. Laue photographs of both c and m planes of synthetic emeralds were identical with that of natural beryl, and showed good crystallinities.
Infrared spectra of synthetic emeralds were recorded from 400 to 4000 cm^-1 on powder samples using a KBr wafer technique. Band with maxima at 490, 520, 590, 648, 679, 738, 802, 955, 1015, 1200±5cm^-1 were observed and were in essential agreement with the literature values for beryl.
The 3, 500 cm-' broad band might be attributed to water molecules picked up by the KBr during sample preparat ion.
During crystal growth of emerald, card-like hexagonal tabular steps were observed on c-plane, the thickness being about several ten microns.