title: Pressure-induced structural transitions in M(O)O(3).xH(2)O (x = 1/2, 2) molybdenum trioxide hydrates: a Raman study.
abstract: 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.
authors: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China.
authors: Dan
authors: D
authors: Liu
authors: Weiwei
authors: W
authors: Lei
authors: Xiaohui
authors: X
authors: Chen
authors: Jian
authors: J
authors: Hao
authors: Yunxia
authors: Y
authors: Jin
authors: Qiliang
authors: Q
authors: Cui
authors: Guangtian
authors: G
authors: Zou