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Crystallization of AgGaS2 melts enriched with Ag2S and Ga2S3

Konstantin A. Kokh 1Elena F. Sinyakova 1Anatoly A. Politov 2

1. Institute of Geology and Mineralogy SB RAS (IGM), Koptyuga ave., 3, Novosibirsk 630090, Russian Federation
2. Institute for Solid State and Mechanical Chemistry of RAS, Novosibirsk 630090, Russian Federation

Abstract

Silver thiogallate (AgGaS2) crystals have unique nonlinear optical properties. The crystals are usually grown from melts with starting composition lying on Ag2S-Ga2S3 section since it is this part of Ag-Ga-S system which provides growth of high quality crystals [1]. It is accepted that there is a solid solution on the basis of AgGaS2 with existence region ~1-2 mol.% of Ga2S3. In this work we consider experiments with directed crystallization of melts with slight deviation from stoichiometric composition of AgGaS2 (in moles: 48%Ag2S+52% Ga2S3 and 52%Ag2S+48% Ga2S3). Two-zone synthesis procedure from Ag, Ga and S with nominal purity of 99.999% was the same as described in [2]. Synthesis and growth ampoules were sealed under 10-4 torr. Vertical Bridgman-Stockbarger technique was used for directed crystallization of the melts. Translation rate and axial temperature gradient at crystallization front was 2 mm/day and ~3.5 deg C/mm, respectively. The change of melt composition was calculated for both experiments using measured chemical composition of the solid phase. Also the difference in unit cell parameters and luminescence spectra for AgGaS2 grown from above described melts was found. We suppose these phenomena are due to different concentration of vacancies in grown crystals. Both monocrystal samples and samples synthesized from elementary Ag, Ga and S were used for thermal analyses. Obtained data suggests that different ways of preparing the samples are responsible for defects concentration and thus for so wide range (70°C) of melting temperatures reported in scientific literature.

References:

1. Feigelson R. S., Route R. K., Recent developments in the growth of chalcopyrite crystals for nonlinear infrared applications, Opt. Eng., 1987, v.26, N2, 113-119.

2. Zhao B., Zhu S., Li Z., Yu F., Zhu X., Gao D., Growth of AgGaS2 single crystal by descending crucible with rotation method and observation of properties. - Chi. Sci. Bull, Vol. 46, No. 23, 2

 

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Related papers

Presentation: Poster at Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth, by Konstantin A. Kokh
See On-line Journal of Joint Fith International Conference on Solid State Crystals & Eighth Polish Conference on Crystal Growth

Submitted: 2007-01-13 11:50
Revised:   2009-06-07 00:44