Hydroxyl groups in nonmetamict chevkinite-（Ce）: a crystal chemical discussion
来源期刊：Journal of Rare Earths2008年第4期
论文作者：杨主明 Franz Pertlik Michel Fleck
文章页码：609 - 613
摘 要：The minerals of chevkinite group were commonly considered to be anhydrous minerals. The infrared absorption spectrum of natural nonmetamict chevkinite-（Ce） from the aegirine-alkali granite, Mianning, Sichuan Province, China, exhibited two broad peaks in the 3600–2800 cm–1 region owing to the OH stretching. The corresponding H2O content required for the charge balance in formula was 1.27%. The O-H ··· O bond lengths maight cover from 0.2658 to 0.2794 nm by the correlated OH stretching energies. An electrostatic charge bal- ance for chevkinite-（Ce） based on the assigned site-population from chemical data was calculated without the hydrogen contribution. The resulting empirical bond-valence sum on O6, O8, O2, O3, O5, and O4 ranged from 1.73 to 1.95 vu. The partial substitution of O by OH may occur in four atom sites: O6, O2, O4, and O5. The small differences in the bond-valence sums between the supposed donors and acceptors may mean a mixed donor/acceptor role of the involved oxygen atoms. The IR spectral features between 3394 and 3035 cm–1 consisted of various hydrous species at different structural sites and orientations. The OH groups in the chevkinite-（Ce） appeared to be involved in local charge imbalance in the structure and to be present when the mineral crystallized hydrothermally.
杨主明，Franz Pertlik，Michel Fleck
摘 要：The minerals of chevkinite group were commonly considered to be anhydrous minerals. The infrared absorption spectrum of natural nonmetamict chevkinite-（Ce） from the aegirine-alkali granite, Mianning, Sichuan Province, China, exhibited two broad peaks in the 3600–2800 cm–1 region owing to the OH stretching. The corresponding H2O content required for the charge balance in formula was 1.27%. The O-H ··· O bond lengths maight cover from 0.2658 to 0.2794 nm by the correlated OH stretching energies. An electrostatic charge bal- ance for chevkinite-（Ce） based on the assigned site-population from chemical data was calculated without the hydrogen contribution. The resulting empirical bond-valence sum on O6, O8, O2, O3, O5, and O4 ranged from 1.73 to 1.95 vu. The partial substitution of O by OH may occur in four atom sites: O6, O2, O4, and O5. The small differences in the bond-valence sums between the supposed donors and acceptors may mean a mixed donor/acceptor role of the involved oxygen atoms. The IR spectral features between 3394 and 3035 cm–1 consisted of various hydrous species at different structural sites and orientations. The OH groups in the chevkinite-（Ce） appeared to be involved in local charge imbalance in the structure and to be present when the mineral crystallized hydrothermally.
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