Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Pb 8 K 1.68 Na 0.32 [(Ge 0.65 Si 0.35 ) 2 O 7 ] 3 —a Silicogermanate Analogue of the Mineral Nasonite

Pb 8 K 1.68 Na 0.32 [(Ge 0.65 Si 0.35 ) 2 O 7 ] 3 —a Silicogermanate Analogue of the Mineral... Abstract Crystals of new silicogermanate Pb8K1.68Na0.32[(Ge0.65Si0.35)2O7]3 were synthesized under hydrothermal conditions in the PbO–SiO2–GeO2 system. The new compound is a synthetic variety of the diorthosilicate mineral nasonite Pb6Ca4[Si2O7]3Cl2 related to apatite. The hexagonal unit cell parameters are a = 10.1822(3) Å, c = 13.4088(5) Å, sp. gr. P63/m. The crystal structure was determined by direct methods using the SHELX program package and refined to R = 0.0647 based on 975 reflections with I ≥ 1.96σ(I). The new compound is characterized by wide isomorphism. The Ge and Si atoms occupy a tetrahedral site, and the K and Na atoms share a large-cation site. The main difference between the new compound and nasonite is that all Ca sites in the new compound are occupied by Pb, K, and (K,Na) atoms, and the tetrahedral site is mainly occupied by Ge. In nasonite the channels are filled by Cl anions that compensate the positive charge, whereas these channels are empty in the new synthetic variety. The presence of a large lead cation at the site occupied by Ca in nasonite causes structure distortion and changes in the coordination polyhedra. The umbrella-like coordination of the lead atom at the Pb1 site provides additional space for the lone pair of the Pb atom in the empty channel of the crystal structure; however, the crystals are centrosymmetric and, consequently, exhibit no nonlinear-optical properties. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Crystallography Reports Springer Journals

Pb 8 K 1.68 Na 0.32 [(Ge 0.65 Si 0.35 ) 2 O 7 ] 3 —a Silicogermanate Analogue of the Mineral Nasonite

Download PDF
4 pages

Loading next page...
 
/lp/springer-journals/pb-8-k-1-68-na-0-32-ge-0-65-si-0-35-2-o-7-3-a-silicogermanate-analogue-6cuU3Y9aqt

References (8)

Publisher
Springer Journals
Copyright
2018 Pleiades Publishing, Inc.
ISSN
1063-7745
eISSN
1562-689X
DOI
10.1134/s1063774518060044
Publisher site
See Article on Publisher Site

Abstract

Abstract Crystals of new silicogermanate Pb8K1.68Na0.32[(Ge0.65Si0.35)2O7]3 were synthesized under hydrothermal conditions in the PbO–SiO2–GeO2 system. The new compound is a synthetic variety of the diorthosilicate mineral nasonite Pb6Ca4[Si2O7]3Cl2 related to apatite. The hexagonal unit cell parameters are a = 10.1822(3) Å, c = 13.4088(5) Å, sp. gr. P63/m. The crystal structure was determined by direct methods using the SHELX program package and refined to R = 0.0647 based on 975 reflections with I ≥ 1.96σ(I). The new compound is characterized by wide isomorphism. The Ge and Si atoms occupy a tetrahedral site, and the K and Na atoms share a large-cation site. The main difference between the new compound and nasonite is that all Ca sites in the new compound are occupied by Pb, K, and (K,Na) atoms, and the tetrahedral site is mainly occupied by Ge. In nasonite the channels are filled by Cl anions that compensate the positive charge, whereas these channels are empty in the new synthetic variety. The presence of a large lead cation at the site occupied by Ca in nasonite causes structure distortion and changes in the coordination polyhedra. The umbrella-like coordination of the lead atom at the Pb1 site provides additional space for the lone pair of the Pb atom in the empty channel of the crystal structure; however, the crystals are centrosymmetric and, consequently, exhibit no nonlinear-optical properties.

Journal

Crystallography Reports – Springer Journals

Published: Nov 1, 2018

Keywords: Crystallography and Scattering Methods

There are no references for this article.