Pressure‐induced anomalous phase transformation in nano‐crystalline dysprosium sesquioxide

Abstract

The phase transformation in nano-crystalline dysprosium sesquioxide (Dy 2 O 3 ) under high pressures is investigated using in situ Raman spectroscopy. The material at ambient was found to be cubic in structure using X-ray diffraction (XRD) and Raman spectroscopy, while atomic force microscope (AFM) showed the nano-crystalline nature of the material which was further confirmed using XRD. Under ambient conditions the Raman spectrum showed a predominant cubic phase peak at 374 cm −1 , identified as F g mode. With increase in the applied pressure this band steadily shifts to higher wavenumbers. However, around a pressure of about 14.6 GPa, another broad band is seen to be developing around 530 cm −1 which splits into two distinct peaks as the pressure is further increased. In addition, the cubic phase peak also starts losing intensity significantly, and above a pressure of 17.81 GPa this peak almost completely disappears and is replaced by two strong peaks at about 517 and 553 cm −1 . These peaks have been identified as occurring due to the development of hexagonal phase at the expense of cubic phase. Further increase in pressure up to about 25.5 GPa does not lead to any new peaks apart from slight shifting of the hexagonal phase peaks to higher wavenumbers. With release of the applied pressure, these peaks shift to lower wavenumbers and lose their doublet nature. However, the starting cubic phase is not recovered at total release but rather ends up in monoclinic structure. The factors contributing to this anomalous phase evolution would be discussed in detail.

Structural properties and the pressure-induced C → A phase transition of lanthanide sesquioxides from DFT and DFT + U calculations

“…As a matter of example, different measurements for B over the Ln 2 O 3 series gave values that ranges from 113 GPa (for A-La 2 O 3 [13]) to 231 GPa (for A-Dy 2 O 3 [14]). Recently, this kind of studies has also included nanosized sesquioxides [15][16][17].…”

“…In some cases, evidence of a direct C→A transition was recently observed for the first time [13,18,19]. In this respect, XRD and also Raman scattering experiments allowed the study of the C to A transition induced by high pressure under static load [15][16][17][18][19][20][21][22][23][24] or shock compression [25].…”

Preparation of Mesoporous Dysprosium Oxide for Dynamic Hydrogen Peroxide Detection without Enzymes

“…High‐resolution transmission electron microscopy (HRTEM) inspection in Figure D reveals the facet (222) lattice spacing was 0.307 nm in the Dy 2 O 3 cubic crystalline form, with the inset showing nano‐sized pores in the nanosheets. The X‐ray diffraction (XRD) results in Figure A are in fine accordance with the JCPDS 22–0612 pattern of cubic Dy 2 O 3 for both Dy 2 O 3 ‐ms and bulk Dy 2 O 3 , representing their crystal planes. The X‐ray photoelectron spectroscopy (XPS) spectrum (in Figure B) shows a Dy 3+ 3d core‐level splitting into 3d 3/2 and 3d 5/2 at 1335 and 1297 eV, respectively.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part VI

“…Sharma et al . studied pressure‐induced anomalous phase transformation in nanocrystalline dysprosium sesquioxide …”