Effects of Cr3+ impurity concentration on the crystallography of synthetic emerald crystals

✍ Scribed by Pei-Lun Lee; Eugene Huang; Jan-Shing Lee; Shu-Cheng Yu

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 969 KB
• Volume: 324
• Category: Article
• ISSN: 0022-0248
• DOI: 10.1016/j.jcrysgro.2011.03.042

✦ Synopsis

Flux method has been adopted for the synthesis of emerald crystals using PbO-V 2 O 5 as a flux in order to study the crystallography of the synthetic crystals. In general, the hue of green color of emerald deepens with the addition of Cr 3 þ . The molar volume of the synthesized crystals was found to increase with the incorporation of Cr 2 O 3 dopant. The substitution of Cr 3 þ for Al 3 þ in the octahedral sites of beryl results in the expansion of a-axis, while c-axis remains nearly unchanged. The maximum Cr 2 O 3 -content allowed in the crystal lattice of emerald has been found to be about 3.5 wt%. When the doping Cr 2 O 3 -content exceeds 3.5 wt%, a significant anomaly in lattice parameters starts to take place, accompanying the precipitation of an unknown phase in the emerald matrix.