Raman investigation on the behavior of parasibirskite CaHBO3 at high pressure
| Autor: | W. Sun, J.-X. Mi, Y. Pan, Mikhail B. Smirnov, S.V. Goryainov |
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| Rok vydání: | 2017 |
| Předmět: |
Phase transition
Analytical chemistry chemistry.chemical_element 02 engineering and technology 010502 geochemistry & geophysics 021001 nanoscience & nanotechnology 01 natural sciences Atomic and Molecular Physics and Optics Analytical Chemistry Crystallography symbols.namesake chemistry Phase (matter) High pressure symbols Wavenumber 0210 nano-technology Raman spectroscopy Boron Instrumentation Spectroscopy 0105 earth and related environmental sciences Ambient pressure Monoclinic crystal system |
| Zdroj: | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 173:46-52 |
| ISSN: | 1386-1425 |
| DOI: | 10.1016/j.saa.2016.08.040 |
| Popis: | Knowledge about the stability of hydrous borates and borosilicates at high pressures are of critical importance to our understanding on the boron geochemical cycle. Raman spectroscopic measurements of parasibirskite CaHBO3, containing the [BO2(OH)] groups, have been made to pressures up to 5.4GPa. The Raman data show that a progressive structural evolution from ambient pressure to 5.4GPa can be accounted for by the same monoclinic phase P21/m, where the splitting of several Raman bands observed at some pressures is interpreted as the effect of the complex disordering in the H-bond network that has bifurcated H-bonds and ½-occupied H sites. There is no unambiguous evidence for phase transition to the ordered P21 monoclinic phase predicted by first-principles calculations at T=0K (W. Sun et al., Can. Miner., 2011). On the contrary, the disordering of parasibirskite, evidenced by the widening and attenuating Raman spectra, increases markedly at high pressures above 4.5GPa that results in incipient amorphization. Comparison of theoretical (lattice-dynamical) and experimental Raman spectra allows the reliable interpretation of almost all observed bands. The strongest symmetric B-O stretching band v1 at the wavenumber 908cm-1, which is split into a doublet at high pressures, exhibits a shift rate of 4.22cm-1/GPa for the main component. |
| Databáze: | OpenAIRE |
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