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Title: In situ Raman spectroscopy of pressure-induced phase transformations in polycrystalline TbPO 4, DyPO 4, and Gd xDy (1–x)PO 4 [ In situ Raman spectroscopy of pressure-induced phase transformations in DyPO 4 and Gd xDy (1–x)PO 4]

Xenotime DyPO 4 and Gd xDy (1–x)PO 4 (x = 0.4, 0.5, 0.6) (tetragonal I41amd zircon structure) have been studied at ambient temperature under high pressures inside a diamond anvil cell with in situ Raman spectroscopy. The typical Raman–active modes of the xenotime structure were observed at low pressures and the appearance of new Raman peaks at higher pressures indicated a phase transformation to a lower symmetry structure—likely monoclinic. Raman mode softening was observed, resulting in a line crossing at approximately 7–8 GPa for each material and preceding the phase transformation. The onset of phase transformation for DyPO 4 occurred at a pressure of 15.3 GPa. DyPO 4 underwent a reversible phase transformation and returned to the xenotime phase after decompression. The transformation pressures of the solid solutions (Gd xDy (1–x)PO 4) were in the range 10–12 GPa. The GdxDy(1–x)PO 4 solid solutions yielded partially reversible phase transformations, retaining some of the high–pressure phase spectrum while reforming xenotime peaks during decompression. The substitution of Gd into DyPO 4 decreased the transformation pressure relative to pure DyPO 4. In conclusion, the ability to modify the phase transformation pressures of xenotime rare–earth orthophosphates by chemical variations of solid solutions may provide additionalmore » methods to improve the performance of ceramic matrix composites.« less
Authors:
ORCiD logo [1] ;  [1] ; ORCiD logo [2] ;  [1]
  1. Colorado School of Mines, Golden, CO (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of the American Ceramic Society
Additional Journal Information:
Journal Volume: 101; Journal Issue: 6; Journal ID: ISSN 0002-7820
Publisher:
American Ceramic Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; phase transformations; phosphates; Raman spectroscopy; rare earths
OSTI Identifier:
1464024
Alternate Identifier(s):
OSTI ID: 1416390