Abstract
In situ synchrotron X-ray diffraction was conducted on polycrystalline DyPO4 to elucidate the details of the pressure-induced transition from the xenotime polymorph to the monazite polymorph. We used three different pressure-transmitting media (neon, a 16:3:1 methanol-ethanol-water mixture, and potassium chloride) to investigate the effect of hydrostaticity on the phase behavior. Specifically, our data clearly show a hydrostatic onset pressure of the xenotime-monazite transition of 9.1 GPa, considerably lower than the 15.3 GPa previously determined by Raman spectroscopy. Based on (quasi)hydrostatic data taken in a neon environment, third-order Birch-Murnaghan equation-of-state fits give a xenotime bulk modulus of 144 GPa and a monazite bulk modulus of 180 GPa (both with pressure derivatives of 4.0). Structural data and axial compressibilities show that DyPO4 is sensitive to shear and has an anisotropic response to pressure. More highly deviatoric conditions cause the onset of the transition to shift to pressures at least as low as 7.0 GPa. We attribute early transition to shear-induced distortion of the PO4 tetrahedra. Our characterization of the high-pressure behavior of DyPO4 under variable hydrostaticity is critical for advancing rare earth orthophosphate fiber coating applications in ceramic matrix composites and may inform future tailoring of phase composition for controlled shear and pressure applications.
| Original language | English |
|---|---|
| Article number | 184105 |
| Journal | Physical Review B |
| Volume | 103 |
| Issue number | 18 |
| DOIs | |
| State | Published - May 12 2021 |
Funding
The authors thank Dr. Jesse Smith and Dr. Ross Hrubiak for performing initial alignments at the beamline, Dr. Sergey Tkachev for assisting with gas-loading samples, as well as Sarah Boardman and Dr. Yachao Chen for helping perform the beamline experiments. The authors also thank Dr. Nitin Kumar and Dr. Sina Soltanmohammed, who assisted in developing the batch-processing and batch-fitting procedures for the synchrotron data. J.S. was supported by the Department of Defense through the National Defense Science & Engineering Graduate Fellowship Program. B.H. was supported by resources at the Spallation Neutron Source and the High Flux Isotope Reactor, Department of Energy (DOE) Office of Science User Facilities operated by the Oak Ridge National Laboratory. This work was performed at HPCAT (Sector 16), Advanced Photon Source, Argonne National Laboratory. HPCAT operations are supported by DOE National Nuclear Security Administration under Award No. DE-NA0001974 and DOE Office of Basic Energy Sciences (BES) under Award No. DE-FG02-99ER45775, with partial instrumentation funding by the National Science Foundation (NSF). Use of the COMPRES-GSECARS gas-loading system was supported by COMPRES under NSF Cooperative Agreement No. EAR 11–57758 and by GSECARS through NSF Grant No. EAR-1128799 and DOE Grant No. DE- FG02-94ER14466. A.P.S. is supported by DOE-BES, under Contract No. DE-AC02-06CH11357. This research was funded by the NSF under Award No. DMR-1352499.