Pressure-induced phase transitions in CuGeO3 from Raman spectroscopic studies

Jayaraman, A. ; Shieh, S. R. ; Sharma, S. K. ; Ming, L. C. ; Wang, S. Y. (2001) Pressure-induced phase transitions in CuGeO3 from Raman spectroscopic studies Journal of Raman Spectroscopy, 32 (3). pp. 167-175. ISSN 0377-0486

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/jrs.676...

Related URL: http://dx.doi.org/10.1002/jrs.676

Abstract

Pressure-induced phase transitions in the normal phase (I) and metastably retained phase III of CuGeO3 were investigated up to 30 and 36 GPa, respectively, by Raman spectroscopy, using single-crystal samples in helium and methanol-ethanol mixture (M/E) as pressure medium. Phase I undergoes two pressure-induced phase transitions; the previously reported I-II near 7 GPa and another near 18 GPa to a phase designated VI. With phase III as the starting material three reversible pressure-induced phase transitions occur: IV, IV', V at 8, 12.5 and 18 GPa. The above sequence of phase transitions is observed in helium and in M/E. A highly disordered phase occurs only when phase II is pressurized in M/E but not in helium. The Raman data are discussed in terms of plausible structure models for the high-pressure phases of CuGeO3, indicated by the x-ray diffraction data, as well as the high-pressure crystal chemistry of other divalent metagermanates. The need for further detailed x-ray diffraction studies is stressed, to gain a deeper understanding of the two different pathways that the pressure-induced transitions follow, depending on the nature of the pressure medium.

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ID Code:13266
Deposited On:11 Nov 2010 08:16
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