An Investigation of the Pressure-Induced Structural Phase Transition of Nanocrystalline α-CuMoO4

The structural behavior of nanocrystalline alpha-CuMoO4 was studied at ambient temperature up to 2 GPa using in situ synchrotron X-ray powder diffraction. We found that nanocrystalline alpha-CuMoO4 undergoes a structural phase transition into gamma-CuMoO4 at 0.5 GPa. The structural sequence is analogous to the behavior of its bulk counterpart, but the transition pressure is doubled. A coexistence of both phases was observed till 1.2 GPa. The phase transition gives rise to a change in the copper coordination from square-pyramidal to octahedral coordination. The transition involves a volume reduction of 13% indicating a first-order nature of the phase transition. This transformation was observed to be irreversible in nature. The pressure dependence of the unit-cell parameters was obtained and is discussed, and the compressibility analyzed.

Automated summary

The structural behavior of nanocrystalline alpha-CuMoO4 was studied using synchrotron X-ray powder diffraction up to 2 GPa at ambient temperature. It was found that the nanocrystalline alpha-CuMoO4 undergoes a structural phase transition to gamma-CuMoO4 at a pressure of 0.5 GPa. Both phases coexist until 1.2 GPa. The phase transition involves a change in copper coordination, with a 13% reduction in volume, indicating a first-order nature of the transition.