Crystal-Chemical Properties of Synthetic Almandine-Pyrope Solid Solution by X-Ray Single-Crystal Diffraction and Raman Spectroscopy
| Autor: | Shijie Huang, Wenge Zhou, Maining Ma, Bo Li, Jingui Xu, Yunqian Kuang, Dongzhou Zhang, Zhilin Ye, Wei Chen |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Diffraction
Materials science 010504 meteorology & atmospheric sciences General Chemical Engineering Analytical chemistry 010502 geochemistry & geophysics crystal-chemical property 01 natural sciences Inorganic Chemistry Crystal Dodecahedron symbols.namesake lcsh:QD901-999 General Materials Science 0105 earth and related environmental sciences Ionic radius Condensed Matter Physics Bond length Pyrope X-ray single-crystal diffraction Raman spectroscopy symbols lcsh:Crystallography synthetic almandine-pyrope solid solution Solid solution |
| Zdroj: | Crystals Volume 9 Issue 10 Crystals, Vol 9, Iss 10, p 541 (2019) |
| ISSN: | 2073-4352 |
| DOI: | 10.3390/cryst9100541 |
| Popis: | Crystal-chemical properties of synthetic Almandine-Pyrope (Alm-Pyr) solid solutions were investigated by X-ray single-crystal diffraction and Raman spectroscopy. Garnet solid solution with different compositions were synthesized from powder at 4.0 GPa and annealed at 1200 ° C for 48 h by a multi-anvil pressure apparatus. Garnet crystals with different sizes (about 60-1000 &mu m) were obtained from synthesis. The results of X-ray single-crystal diffraction show that the unit cell constants decrease with increasing Pyr contents in the synthetic Alm-Pyr crystals due to the smaller ionic radius of Mg2+ in eightfold coordination than that of Fe2+. The data exhibit obviously positive deviations from ideal mixing volumes across the Alm-Pyr join which may be caused by the distortion of the SiO4 tetrahedron. Moreover, the significant decrease in the average M-O bond length and volume of the [MgO8]/[FeO8] dodecahedron with increasing Pyr contents are the most important factors to the decrease in the Alm-Pyr crystal unit cell constant and volume. On the other hand, selected bond distances (average < M-O> < Al-O> and < D-O> distances) have a linear correlation with the unit-cell parameter, but the < Si-O> distance has nonlinear correlation. With increasing the unit-cell parameter, the average < distance increases significantly, followed by the average < distances. While the < distance changes negligibly further confirming the conclusion that the significant decrease of the average M-O bond length of the [MgO8]/[FeO8] dodecahedron with increasing Pyr contents are the most important factors to the decrease in the Alm-Pyr crystal unit cell volume. In the Raman spectra collected for the Alm-Pyr solid solutions, Raman vibration mode assignments indicate that the Raman vibrational spectra change along the Alm-Pyr binary solution. The mode frequencies of Si-O stretching, Si-O bending, and the rotation of the SiO4-tetrahedron (R(SiO4)) decrease linearly, while the translational modes of the SiO4-tetrahedron (T(SiO4)) increase with increasing Alm contents. |
| Databáze: | OpenAIRE |
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