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