Pressure-induced structural transitions in M(O)O(3).xH(2)O (x = 1/2, 2) molybdenum trioxide hydrates: a Raman study

• Published in: The journal of physical chemistry. B Vol. 113; no. 52; pp. 16479 - 16482
• Main Authors: Liu, Dan, Lei, Weiwei, Chen, Xiaohui, Hao, Jian, Jin, Yunxia, Cui, Qiliang, Zou, Guangtian
• Format: Journal Article
• Language: English
• Published: United States 31.12.2009
• ISSN: 1520-5207
• DOI: 10.1021/jp906423w

The high-pressure behaviors of M(O)O(3).1/2H(2)O and M(O)O(3).2H(2)O have been investigated by Raman spectroscopy in a diamond anvil cell up to 31.3 and 30.3 GPa, respectively. In the pressure range up to around 30 GPa, both M(O)O(3).1/2H(2)O and M(O)O(3).2H(2)O undergo two reversible structural phase transitions. We observed a subtle structural transition due to O-H...O hydrogen bond in M(O)O(3).1/2H(2)O at 3.3 GPa. We found a soft mode phase transition in M(O)O(3).2H(2)O at 6.6 GPa. At higher pressures, a frequency discontinuity shift and appearance of new peaks occurred in both M(O)O(3).1/2H(2)O and M(O)O(3).2H(2)O, indicating that the second phase transition is a first-order transition. The frequency redshift of the O-H stretching bands of M(O)O(3).1/2H(2)O and M(O)O(3).2H(2)O are believed to be related to the enhancement of the O-H...O weak hydrogen bonds under high pressures.