Dera, Przemyslaw ; Jayaraman, Aiyasami ; Prewitt, Charles T. ; Gramsch, Stephen A. (2002) Structural basis for high-pressure polymorphism in CuGeO3 Physical Review B, 65 (13). 134105_1-134105_10. ISSN 0163-1829
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Official URL: http://prb.aps.org/abstract/PRB/v65/i13/e134105
Related URL: http://dx.doi.org/10.1103/PhysRevB.65.134105
Abstract
Two unusual pressure-induced structural transformations in the inorganic spin-Peierls compound CuGeO3 have been studied using single-crystal x-ray diffraction and diamond-anvil cell techniques. CuGeO3-III was formed after nonhydrostatic compression of the ambient pressure phase CuGeO3-I and the structure determined after quenching back to ambient pressure from 7.0 GPa. CuGeO3-III is orthorhombic, with space group Pbam. The mechanism of the I-III transformation, which occurs exclusively under nonhydrostatic conditions, involves a shift of half of the Ge atoms to tetrahedral sites adjacent to those occupied in the ambient pressure modification. Hydrostatic compression of CuGeO3-III from ambient conditions to near 7.0 GPa results in the formation of monoclinic CuGeO3-IV, with space group P21/c. Upon compression, the Ge atoms in CuGeO3-IV adopt an approximately trigonal bipyramidal coordination environment, formed by the condensation of two tetrahedral sites. Our findings provide a basis for the formulation of a general mechanism explaining the pressure-induced transformations in CuGeO3 and their sensitivity to deviatoric stress.
Item Type: | Article |
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Source: | Copyright of this article belongs to American Physical Society. |
ID Code: | 13216 |
Deposited On: | 11 Nov 2010 06:44 |
Last Modified: | 17 Feb 2011 09:15 |
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