Affiliation:
1. Crystallography , Lomonosov Moscow State University, Faculty of Geology , Leninskie Gory 1 , Moscow 119991 , Russian Federation
Abstract
Abstract
New silicate-germanates (K2.9Cs0.1)(Sc0.7In0.3)[(Si2.95Ge0.05)O9]·H2O and (K2.16Cs0.84)Bi[(Si0.5Ge0.5)3O9]·H2O have been synthesized in multi-component systems under mild hydrothermal conditions. The new compounds are classified as new representatives of close related K3ScSi3O9·H2O parent structure, sp. gr. Pmn21. Their structural and isomorphic peculiarities are compared with it as well as with earlier investigated K1.46Pb1.54Сa[(Ge0.23Si0.77)3O9](ОН)0.54·0.46Н2О. Together with other known compounds, silicate-germanates form the extensive family A3M[T3O9]·H2O, A = K, Cs, Ca, Pb; M = Ho, Sc, Lu, Tb, Er, Y, Bi, Pb, In; T = Si, Ge, with a mixed microporous framework combined of M-octahedra and T-tetrahedra. Large alkali metal or/and Ca, Pb cations fill broad framework channels with cross-section up to 7.3 Å. Because of wide isomorphic substitution in the channels, and in tetrahedra and octahedra, ion exchange properties in the family are expected. Due to polar symmetry, all the crystals possess second-order nonlinearity which was confirmed with positive SHG tests for four compositions. Powder SHG experiments demonstrated moderate second harmonic intensities of order of α-quartz standard signals.
Subject
Inorganic Chemistry,Condensed Matter Physics,General Materials Science
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