Growth of emerald crystals from PbO · V2O5 flux

Abstract

The flux growth of emerald crystals by slow cooling in the PbO-V205 flux is reported. The crystals exhibited the typical emerald-green colour, were up to 1.8 mm in size and transparent. Their form was a regular hexagonal rod bounded by the well-developed {0001} and {1 010} faces. The solubility of emerald in PbO" V205 was also investigated; about 9.0 g emerald was dissolved in 1 O0 g PbO 9 V205 at 1200 ~ The solubility decreased gradually with decreasing temperature. Taking the solubility data into account, the presence of undissolved particles in the solution was found to be a necessary condition for the growth of large emerald crystals. Unsaturated solution at a soak temperature produced good and relatively small emerald crystals in a subsequent cooling experiment. Advantages of the PbO'V205 flux are also mentioned. Emerald crystals showing various kinds of imperfections, and even good crystals, were also present.

A venture into the interior of natural diamond: genetic information and implications for the gem industry

“…B10 -12: Thermally altered inclusions. Pictures 1 by M. Glas,[2][3][4][5][6][7][8][9][10][11][12] nb: I = immersion Two sapphires with unusual properties deserve separate description: l The first stone ( Figure 20a) was diffusiontreated by J. Emmett and shows a weak colour zoning after proper orientation in the immersion microscope ( Figure 20b). The coloration of the sapphire consists of somewhat lighter and more intense yellowish-orange zones parallel to rhombohedral growth planes.…”

“…C10 -12: Thermally altered inclusions. Pictures 1 by M. Glas,[2][3][4][5][6][7][8][9][10][11][12] nb: I = immersion Figure C11: 50 x Figure C12: 50 x ( Figure D6). No characteristic inclusion feature that would easily allow a distinction between simply heat-treated and diffusion-treated Sri Lankan sapphires was found.…”

“…I12: Thermally altered 'boehmite needle'. [3][4][5][6][7][8][9][10][11][12] nb: I = immersion, # pol. = crossed polarisers Figure I1: I, 0.34 to 0.53 ct Figure I2: I, 0.38 to 0.57 ct Figure I3: I, 0.38 ct Figure I4: I, 40 x Figure I5: I, 40 x # pol.…”

“…In the case of fluxevaporation, molybdate system fluxes are much less dangerous than lead compounds and are, therefore, good candidates as alternatives. Recent work in growth of gem crystals using systems of molybdate fluxes [12][13][14][15] has led to a recent conclusion that hexagonal bipyramidal ruby crystals can be synthesized from molybdenum trioxide flux. In this paper, we report on the growth of hexagonal ruby crystals from a MoO 3 flux at a growth temperature much less than the melting point of ruby.…”

Effect of Holding Temperature on Growth of Ruby Crystal Films via Molybdenum Trioxide Flux Evaporation–Solubility of Aluminum Oxide, Growth Rate, and Material Balance

“…However, the solubility could not be measured because the MoO 3 flux was volatile, and its mass decreased upon heating; it was thus difficult to measure the solubility of Al 2 O 3 in the MoO 3 flux. In general, in the case of a nonevaporable flux, both the solute crystal and the flux are held at a target temperature, and the solubility is measured based on the mass of flux and reduced solute. − It is necessary to hold these at the target temperature for several hours to achieve equilibrium. However, this method cannot be applied to evaporative MoO 3 flux; therefore, we developed a new method to measure the solubility of Al 2 O 3 in MoO 3 flux at 1100 °C .…”