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Title: Pressure-induced structural modifications of rare-earth hafnate pyrochlore

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
DOE - BASIC ENERGY SCIENCES
OSTI Identifier:
1368276
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physics. Condensed Matter; Journal Volume: 29; Journal Issue: 25
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Turner, Katlyn M., Rittman, Dylan R., Heymach, Rachel A., Tracy, Cameron L., Turner, Madison L., Fuentes, Antonio F., Mao, Wendy L., and Ewing, Rodney C.. Pressure-induced structural modifications of rare-earth hafnate pyrochlore. United States: N. p., 2017. Web. doi:10.1088/1361-648X/aa7148.
Turner, Katlyn M., Rittman, Dylan R., Heymach, Rachel A., Tracy, Cameron L., Turner, Madison L., Fuentes, Antonio F., Mao, Wendy L., & Ewing, Rodney C.. Pressure-induced structural modifications of rare-earth hafnate pyrochlore. United States. doi:10.1088/1361-648X/aa7148.
Turner, Katlyn M., Rittman, Dylan R., Heymach, Rachel A., Tracy, Cameron L., Turner, Madison L., Fuentes, Antonio F., Mao, Wendy L., and Ewing, Rodney C.. Thu . "Pressure-induced structural modifications of rare-earth hafnate pyrochlore". United States. doi:10.1088/1361-648X/aa7148.
@article{osti_1368276,
title = {Pressure-induced structural modifications of rare-earth hafnate pyrochlore},
author = {Turner, Katlyn M. and Rittman, Dylan R. and Heymach, Rachel A. and Tracy, Cameron L. and Turner, Madison L. and Fuentes, Antonio F. and Mao, Wendy L. and Ewing, Rodney C.},
abstractNote = {},
doi = {10.1088/1361-648X/aa7148},
journal = {Journal of Physics. Condensed Matter},
number = 25,
volume = 29,
place = {United States},
year = {Thu May 25 00:00:00 EDT 2017},
month = {Thu May 25 00:00:00 EDT 2017}
}
  • The structural transitions of the pyrochlore, Cd{sub 2}Nb{sub 2}O{sub 7}, at pressures up to 32.5 GPa have been investigated by in situ Raman scattering and angle-dispersive x-ray diffraction (ADXRD) methods. The x-ray diffraction results reveal that small amounts ({approx}7%) of metallic cadmium form by chemical decomposition at pressures greater than 4 GPa. Both Raman and XRD results indicate that a pressure-induced structural distortion from pyrochlore to defect fluorite occurs in pyrochlore Cd{sub 2}Nb{sub 2}O{sub 7} at pressures of 12-14 GPa. Subsequently, a new high-pressure phase formed and the phase transition was complete at {approx}27 GPa. The high-pressure phase is eithermore » monoclinic or orthorhombic and transforms to either the pyrochlore (or defect fluorite) structure or the amorphous state when quenched to ambient conditions. Energy dispersive spectroscopy (EDS) analysis and high-resolution transmission electron microscopy (HRTEM) observation of the quenched sample confirmed the Cd loss and resulting mixture of ordered pyrochlore, defect fluorite, high-pressure phase, as well as amorphous domains.« less
  • The structural transitions of the pyrochlore, Cd{sub 2}Nb{sub 2}O{sub 7}, at pressures up to 32.5 GPa have been investigated by in situ Raman scattering and angle-dispersive x-ray diffraction (ADXRD) methods. The x-ray diffraction results reveal that small amounts ({approx}7%) of metallic cadmium form by chemical decomposition at pressures greater than 4 GPa. Both Raman and XRD results indicate that a pressure-induced structural distortion from pyrochlore to defect fluorite occurs in pyrochlore Cd{sub 2}Nb{sub 2}O{sub 7} at pressures of 12-14 GPa. Subsequently, a new high-pressure phase formed and the phase transition was complete at {approx}27 GPa. The high-pressure phase is eithermore » monoclinic or orthorhombic and transforms to either the pyrochlore (or defect fluorite) structure or the amorphous state when quenched to ambient conditions. Energy dispersive spectroscopy (EDS) analysis and high-resolution transmission electron microscopy (HRTEM) observation of the quenched sample confirmed the Cd loss and resulting mixture of ordered pyrochlore, defect fluorite, high-pressure phase, as well as amorphous domains.« less
  • Ground-state electronic and structural properties of Lu under pressure are investigated with use of the self-consistent all-electron total-energy linear muffin-tin orbital band-structure method within a local-density-functional approximation. Pressure-induced structural transitions are found to occur in the following sequence: hcp--(Sm-type)--dhcp--fcc, which is the same as that observed in the crystal structures of the trivalent rare-earth metals with decreasing atomic number. This structural transition is correlated with the increase in the number of d-italic electrons under pressure.