Local compressibilities of Cr3+ octahedral clusters in the natural and synthetic emerald crystals

摘要

The local linear compressibilities of Cr3+ octahedral clusters in the natural and synthetic emerald (Be3Al2Si6O18:Cr3+) crystals are investigated by analyzing their pressure-induced R-line shifts. The results show that the local compressibility of Cr3+ cluster in the synthetic emerald is slightly smaller than that in the natural emerald, suggesting that the atom arrangement of Cr3+ impurity clusters in the synthetic emerald is slightly tighter than that in the natural one. The point is supported by the observed cubic field parameters Dq in the two emerald crystals. The local compressibilities of Cr3+ dusters in both the natural and synthetic emeralds are also slightly different from that of the whole host beryl (Be3Al2Si6O18) crystal. The causes are discussed. (C) 2016 Elsevier GmbH. All rights reserved.