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Growth of Cr-containing topaz single crystals on a seed and their characterization

Vladimir S. Balitskiy 1Liudmila V. Balitskaya 1Denis V. Balitski 2Viktor A. Rassulov 3Tatiana V. Setkova 1

1. Institute of Experimental Mineralogy RAS (IEMRAS), Acad. Osipiana St, Chernogolovka 142432, Russian Federation
2. Cristal Laser SA, 32 rue Robert Schuman, Messein 54850, France
3. Federal state unitary enterprise "All-russian scientific-research institute of mineral resources named after N.M.Fedorovsky", Moscow 119017, Russian Federation

We report the first successful growth of Cr-containing topaz single crystals on seeds by hydrothermal method. Crystal growth was based on received earlier results of study of silica/alumina transport phenomena in supercritical water solutions. This study concerns investigation of growth conditions of Cr-topaz crystals: compositions of solution, TP parameters and nutrient materials. So, the principal condition of topaz crystal growth is neutral and acid fluoride solutions of density from 0.05 to 0.5 g/cm3 at temperatures from 450 to 720°С. The nutrient consisted from mixture of both quartz and topaz places in the upper (colder) zone of autoclave. The topaz seeds best position is in lower (hotter) zone of autoclave. Some quantity of chrome ions were injected into solution by dissolution of chromium salts. Duration of the crystal growth runs was from 1 to 2 months.
 As a result, topaz single crystals of bluish-green to yellowish green colour were grown (Fig. 1). The external morphology of the as grown crystals is determined by crystallographic orientation of seeds, their form and sizes. The crystals are characterized by a clear zoning and sectorial structure (see Fig. 1).
The described feature of colour change of natural Cr-topaz under different wavelength light was observed as well on synthesised Cr-topaz single crystals. At normal incandescent lamp illumination the Cr-topaz get a pink coloring, and at ultra-violet radiation (337 nm) as grown crystals demonstrate an intensive fluorescence of purple-red colour (see Fig. 1). The primary colouring of as grown crystals and also intensive fluorescence are connected with isomorphic occurrence of Cr+3/Al+3 and confirmed by optical and fluorescent spectres. The content of Cr3+ in the crystals doesn't exceed 0.2-0.5 mass. %.

Thus, for the first time Cr-containing topaz single crystals with intensive fluorescence was grown in supercritical fluids and their structure characteristics and main properties were studied.

 Fig. 1 The top line: Cr-containing topaz crystals for the first time grown in supercritical fluids; the bottom line: a,b - cross-section cuts of the grown crystals; Gr-containing topaz at daylight (c), electric (d) and ultra-violet (e) illumination.


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Related papers

Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 2, by Vladimir S. Balitskiy
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-03-29 14:01
Revised:   2013-07-16 13:34