Anharmonic behavior and structural phase transition in Yb2O3

Sugandha Dogra Pandey,Jasveer Singh,K Samanta,A K Bandyopadhyay,Nita Dilawar Sharma

doi:10.1063/1.4858421

Sugandha Dogra Pandey, Jasveer Singh + Show 3 more

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https://doi.org/10.1063/1.4858421

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Journal: AIP Advances	Publication Date: Dec 1, 2013
Citations: 33	License type: cc-by

Affiliation: CSIR National Physical Laboratory of India

Abstract

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 2F5/2 and 2F7/2 multiplates of Yb3+ (4f13) 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 (Tg + Ag) was analyzed in light of the theory of anharmonic phonon-phonon interaction and thermal expansion of the lattice. Using the mode Grüneisen parameter obtained from high pressure Raman measurements; we have calculated total anharmonicity of the Tg + Ag mode from the temperature dependent Raman data.

Highlights

The rare earth (RE) sesquioxides [Re2O3] attract an enormous research interest from both technological as well as fundamental point of view.[1]
Using the mode Gruneisen parameter obtained from high pressure Raman measurements; we have calculated total anharmonicity of the Tg + Ag mode from the temperature dependent Raman data
The RE oxides exist in three polymorphic phases: for large cationic radius (La to Nd), the hexagonal phase designated as the A-type with a space group P3 ̄m1 is the most stable; for the medium cations (Sm to Gd), the monoclinic phase designated as B-type with space group C2/m is preferred; and for the small cations (Tb to Lu), the cubic-phase designated as C-type with space group I a3 ̄ is the most stable.[6,7]

Summary

INTRODUCTION

The rare earth (RE) sesquioxides [Re2O3] attract an enormous research interest from both technological as well as fundamental point of view.[1]. The high pressure studies of RE sesquioxides are a subject of fundamental research; to address the problems of stability and structural transformation, metal-insulator transition, enhancement or collapse of magnetic ordering, and amorphization, etc. Under such conditions the bonding patterns established for the systems near ambient conditions change dramatically, causing profound effects on numerous physical and chemical properties and leading to the formation of new classes of materials. To the best of our knowledge, there are no reports on combined studies on high pressure Raman scattering to investigate the phase transition as well as the anharmonic behavior of optical phonons as a function of temperature. We are reporting a detailed Raman scattering investigation of Yb2O3 as a function of pressure as well as temperature

EXPERIMENTAL

RESULTS AND DISCUSSION

CONCLUSIONS