skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: X-ray diffraction and spectroscopy study of nano-Eu 2O 3 structural transformation under high pressure

Abstract

Nanoscale materials exhibit properties that are quite distinct from those of bulk materials because of their size restricted nature. Here, we investigated the high-pressure structural stability of cubic (C-type) nano-Eu2O3 using in situ synchrotron X-ray diffraction (XRD), Raman and luminescence spectroscopy, and impedance spectra techniques. Our high-pressure XRD experimental results revealed a pressure-induced structural phase transition in nano-Eu2O3 from the C-type phase (space group: Ia-3) to a hexagonal phase (A-type, space group: P-3m1). Our reported transition pressure (9.3 GPa) in nano-Eu2O3 is higher than that of the corresponding bulk-Eu2O3 (5.0 GPa), which is contrary to the preceding reported experimental result. After pressure release, the A-type phase of Eu2O3 transforms into a new monoclinic phase (B-type, space group: C2/m). Compared with bulk-Eu2O3, C-type and A-type nano-Eu2O3 exhibits a larger bulk modulus. Our Raman and luminescence findings and XRD data provide consistent evidence of a pressure-induced structural phase transition in nano-Eu2O3. To our knowledge, we have performed the first high-pressure impedance spectra investigation on nano-Eu2O3 to examine the effect of the structural phase transition on its transport properties. We propose that the resistance inflection exhibited at ~12 GPa results from the phase boundary between the C-type and A-type phases. Besides, we summarizedmore » and discussed the structural evolution process by the phase diagram of lanthanide sesquioxides (Ln2O3) under high pressure.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1342247
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Alloys and Compounds; Journal Volume: 701; Journal Issue: C
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; Rare earth sesquioxides; Nanocrystalline materials; High pressure; Structural phase transition

Citation Formats

Yu, Zhenhai, Wang, Qinglin, Ma, Yanzhang, and Wang, Lin. X-ray diffraction and spectroscopy study of nano-Eu2O3 structural transformation under high pressure. United States: N. p., 2017. Web. doi:10.1016/j.jallcom.2017.01.143.
Yu, Zhenhai, Wang, Qinglin, Ma, Yanzhang, & Wang, Lin. X-ray diffraction and spectroscopy study of nano-Eu2O3 structural transformation under high pressure. United States. doi:10.1016/j.jallcom.2017.01.143.
Yu, Zhenhai, Wang, Qinglin, Ma, Yanzhang, and Wang, Lin. Tue . "X-ray diffraction and spectroscopy study of nano-Eu2O3 structural transformation under high pressure". United States. doi:10.1016/j.jallcom.2017.01.143.
@article{osti_1342247,
title = {X-ray diffraction and spectroscopy study of nano-Eu2O3 structural transformation under high pressure},
author = {Yu, Zhenhai and Wang, Qinglin and Ma, Yanzhang and Wang, Lin},
abstractNote = {Nanoscale materials exhibit properties that are quite distinct from those of bulk materials because of their size restricted nature. Here, we investigated the high-pressure structural stability of cubic (C-type) nano-Eu2O3 using in situ synchrotron X-ray diffraction (XRD), Raman and luminescence spectroscopy, and impedance spectra techniques. Our high-pressure XRD experimental results revealed a pressure-induced structural phase transition in nano-Eu2O3 from the C-type phase (space group: Ia-3) to a hexagonal phase (A-type, space group: P-3m1). Our reported transition pressure (9.3 GPa) in nano-Eu2O3 is higher than that of the corresponding bulk-Eu2O3 (5.0 GPa), which is contrary to the preceding reported experimental result. After pressure release, the A-type phase of Eu2O3 transforms into a new monoclinic phase (B-type, space group: C2/m). Compared with bulk-Eu2O3, C-type and A-type nano-Eu2O3 exhibits a larger bulk modulus. Our Raman and luminescence findings and XRD data provide consistent evidence of a pressure-induced structural phase transition in nano-Eu2O3. To our knowledge, we have performed the first high-pressure impedance spectra investigation on nano-Eu2O3 to examine the effect of the structural phase transition on its transport properties. We propose that the resistance inflection exhibited at ~12 GPa results from the phase boundary between the C-type and A-type phases. Besides, we summarized and discussed the structural evolution process by the phase diagram of lanthanide sesquioxides (Ln2O3) under high pressure.},
doi = {10.1016/j.jallcom.2017.01.143},
journal = {Journal of Alloys and Compounds},
number = C,
volume = 701,
place = {United States},
year = {Tue Jan 17 00:00:00 EST 2017},
month = {Tue Jan 17 00:00:00 EST 2017}
}
  • The phase behavior of monoclinic (B-type) Eu{sub 2}O{sub 3} under pressure in a diamond anvil cell was studied at room temperature by energy-dispersive X-ray diffraction at the Cornell High Energy Synchrotron Source. The bulk modulus (B{sub 0}) of B-type Eu{sub 2}O{sub 3}, derived from the compression curve obtained, was 140 GPa. A pressure-induced phase transition from the monoclinic to the hexagonal (A-type) crystal structure was observed at about 4.7 GPa. The fractional volume change, {Delta}V/V, under this transition pressure was approximately -2%.
  • Cubic (x = 0.3) and rhombohedral (x = 0.2) phases have been prepared in the solid solution (Bi{sub 2}O{sub 3}){sub 1-x} (Eu{sub 2}O{sub 3}){sub x}. The cubic material transformed to the rhombohedral form when subjected to a pressure of 4 GPa at a temperature of 873 K; at 4 GPa and 1073 K the transformation was to a phase of apparently monoclinic symmetry. {sup 151}Eu Moessbauer spectroscopy has been used to study all three forms of (Bi{sub 2}O{sub 3}){sub 0.7}(Eu{sub 2}O{sub 3}){sub 0.3} in order to estimate the extent of anion-vacancy ordering in the solid solution. The Moessbauer linewidth frommore » all samples is lower than that measured for C-Eu{sub 2}O{sub 3}, suggesting that the Eu atoms in these compounds have a single, well-defined, local environment.« less
  • The structural stability of {beta}-Ti{sub 3}O{sub 5} (C2/m) has been investigated by X-ray diffraction and Raman spectroscopy with diamond anvil cells. {beta}-Ti{sub 3}O{sub 5} is stable up to about 26 GPa at room temperature. Isothermal pressure-volume relationship of {beta}-Ti{sub 3}O{sub 5} is well presented by the third-order Birch-Murnaghan equation of state with V{sub 0}=348.6(8) A{sup 3} and B{sub 0}=216(9) GPa. Axial compressibility presents obvious anisotropy. The a-axis and c-axis are more compressible than b-axis due to the different crystal structure arrangement of {beta}-Ti{sub 3}O{sub 5} along b-axis and perpendicular to b-axis direction. The Grueneisen parameters of thirteen observed Raman modesmore » are 0.79-1.74, whose mean is 1.32. - Graphical abstract: The crystal structure of {beta}-Ti{sub 3}O{sub 5}: the projection of {beta}-Ti{sub 3}O{sub 5} along b-axis (Left) and the projection of {beta}-Ti{sub 3}O{sub 5} along c-axis (Right). Highlights: Black-Right-Pointing-Pointer High pressure structural stability of {beta}-Ti{sub 3}O{sub 5} was investigated. Black-Right-Pointing-Pointer {beta}-Ti{sub 3}O{sub 5} is stable up to about 26 GPa. Black-Right-Pointing-Pointer Axial compressibility presents obvious anisotropy. Black-Right-Pointing-Pointer Pressure-volume relationship is well presented by Birch-Murnaghan equation of state. Black-Right-Pointing-Pointer The Grueneisen parameters are 0.79-1.74.« less
  • Sm{sub 2}O{sub 3} was compressed at room temperature up to 44.0 GPa and then decompressed back to ambient pressure. In situ X-ray diffraction was used to monitor the structural changes in the sample. A cubic to hexagonal phase transformation was observed in Sm{sub 2}O{sub 3} for the first time. After decompression back to ambient pressure, the hexagonal phase was not quenchable and transformed to a monoclinic phase. Ab initio Density-Functional-Theory (DFT) calculations were performed to obtain theoretical data for comparison with the experimental results and elucidation of the transformation mechanism. A possible phase transformation mechanism that is consistent with themore » experimental results and theoretical calculations is proposed.« less