Growth and morphology of ruby crystals with unusual chromium concentration

Single crystals of ruby have been obtained from fluxed melts based on the systems Li2O-MoO3, Li2O-WO3, Na2O-WO3, 2PbO-3V2O5, PbO-V2O5-WO3, PbF2-Bi2O3 and Na3AlF6 by both the TSSG method and spontaneous crystallization at the temperatures 1330-900 °C. Al2O3 solubility has been measured for the flux composition of 2Bi2O3-5PbF2 in the temperature range 1200-1000 °C and dissolution enthalpy has been defined as 29.4 KJ/Mol. The composition of grown crystals was studied by electron microprobe analysis. The synthetic ruby contains from 0.51 to 6.38 at% of chromium admixture depending on the crystal growth conditions. Experimental results on growth conditions, composition and morphology of grown crystals are presented for each flux and temperature interval.