New framework hydrous silicate K{sub 3}Sc[Si{sub 3}O{sub 9}] {center_dot} H{sub 2}O related to the high-temperature anhydrous silicate K{sub 3}Ho[Si{sub 3}O{sub 9}] and symmetry analysis of a phase transition with prediction of structures
- Moscow State University, Faculty of Geology (Russian Federation)
Crystals of a new framework silicate K{sub 3}Sc[Si{sub 3}O{sub 9}] {center_dot} H{sub 2}O, space group Pm2{sub 1}n (nonstandard setting of space group Pmn2{sub 1} = C{sub 2v}{sup 7}), are obtained under hydrothermal conditions. The structure is determined without preliminary knowledge of the chemical formula. The absolute configuration is determined. The structure is close to that of the high-temperature K{sub 3}Ho[Si{sub 3}O{sub 9}] phase, which was obtained upon the heating of K{sub 3}HoSi{sub 3}O{sub 8}(OH){sub 2}. This structural similarity is due to the specific conditions of synthesis and an analogous formula, where holmium is replaced by scandium. A symmetry analysis shows that the high local symmetry of a block (rod) is responsible for the first-order phase transition of both the order-disorder (OD) and displacement type. The number of structures in which the simplest and high-symmetry layers are multiplied by different symmetry elements are predicted.
- OSTI ID:
- 22121691
- Journal Information:
- Crystallography Reports, Vol. 58, Issue 4; Other Information: Copyright (c) 2013 Pleiades Publishing, Ltd.; http://www.springer-ny.com; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7745
- Country of Publication:
- United States
- Language:
- English
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