Anharmonic behavior and structural phase transition in Yb2O3

The investigation of structural phase transition and anharmonic behavior of Yb2O3 has been carried out by high-pressure and temperature dependent Raman scattering studies respectively. In situ Raman studies under high pressure were carried out in a diamond anvil cell at room temperature which indicate a structural transition from cubic to hexagonal phase at and above 20.6 GPa. In the decompression cycle, Yb2O3 retained its high pressure phase. We have observed a Stark line in the Raman spectra at 337.5 cm(-1) which arises from the electronic transition between F-2(5/2) and F-2(7/2) multiplates of Yb3+ (4f(13)) levels. These were followed by temperature dependent Raman studies in the range of 80-440 K, which show an unusual mode hardening with increasing temperature. The hardening of the most dominant mode (T-g + A(g)) was analyzed in light of the theory of anharmonic phonon-phonon interaction and thermal expansion of the lattice. Using the mode Gruneisen parameter obtained from high pressure Raman measurements; we have calculated total anharmonicity of the T-g + A(g) mode from the temperature dependent Raman data. (C) 2013 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.