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Title: Mechanical behavior of rare‐earth orthophosphates near the monazite/xenotime boundary characterized by nanoindentation

Authors:
; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1414783
Grant/Contract Number:
U2015B0008; AC52-06NA25396
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing
Additional Journal Information:
Journal Volume: 691; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-12-23 15:46:10; Journal ID: ISSN 0921-5093
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Wilkinson, Taylor M., Wu, Dong, Musselman, Matthew A., Li, Nan, Mara, Nathan, and Packard, Corinne E.. Mechanical behavior of rare‐earth orthophosphates near the monazite/xenotime boundary characterized by nanoindentation. Netherlands: N. p., 2017. Web. doi:10.1016/j.msea.2017.03.041.
Wilkinson, Taylor M., Wu, Dong, Musselman, Matthew A., Li, Nan, Mara, Nathan, & Packard, Corinne E.. Mechanical behavior of rare‐earth orthophosphates near the monazite/xenotime boundary characterized by nanoindentation. Netherlands. doi:10.1016/j.msea.2017.03.041.
Wilkinson, Taylor M., Wu, Dong, Musselman, Matthew A., Li, Nan, Mara, Nathan, and Packard, Corinne E.. Sat . "Mechanical behavior of rare‐earth orthophosphates near the monazite/xenotime boundary characterized by nanoindentation". Netherlands. doi:10.1016/j.msea.2017.03.041.
@article{osti_1414783,
title = {Mechanical behavior of rare‐earth orthophosphates near the monazite/xenotime boundary characterized by nanoindentation},
author = {Wilkinson, Taylor M. and Wu, Dong and Musselman, Matthew A. and Li, Nan and Mara, Nathan and Packard, Corinne E.},
abstractNote = {},
doi = {10.1016/j.msea.2017.03.041},
journal = {Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing},
number = C,
volume = 691,
place = {Netherlands},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.msea.2017.03.041

Citation Metrics:
Cited by: 1work
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  • We present 31P magic angle spinning nuclear magnetic resonance (MAS-NMR) spectra of flux-grown solid solutions of La1-xCexPO4 ( x between 0.027 and 0.32) having the monoclinic monazite structure, and of Y1-xMxPO4 (M = Vn+, Ce3+, Nd3+, x between 0.001 and 0.014) having the tetragonal zircon structure. Paramagnetically shifted NMR resonances are observed in all samples due to the presence of paramagnetic Vn+, Ce3+, and Nd3+ in the diamagnetic LaPO4 or YPO4. As a first-order observation, the number and relative intensity of these peaks is related to the symmetry and structure of the diamagnetic host phase. The presence of paramagnetic shiftsmore » allows for increased resolution between NMR resonances for distinct atomic species which leads to the observation of low intensity peaks related to PO4 species having more than one paramagnetic neighbor two or four atomic bonds away. Through careful analysis of peak areas and comparison with predictions for simple models, it was determined that solid solutions in the systems examined here are characterized by complete disorder (random distribution) of diamagnetic La3+ or Y3+ with the paramagnetic substitutional species Ce3+ and Nd3+. The increased resolution given by the paramagnetic interactions also leads to the observation of splitting of specific resonances in the 31P NMR spectra that may be caused by local, small-scale distortions from the substitution of ions having dissimilar ionic radii.« less
  • The mineral monazite, a mixed lanthanide orthophosphate LnPO/sub 4/, is considered as a perfect host for geologic disposal of actinides, rare earths, and possibly other elements formed during nuclear-reactor operation. Synthetic monazite-type orthophosphates of all the elements of the first half of the lanthanide series (except Pm) have been prepared: single crystals were grown using a flux technique, and powders were precipitated in molten urea. The electron paramagnetic resonance (EPR) spectra of intentionally added Gd impurities show that the Gd/sup 3 +/ ions occupy predominantly substitutional rare-earth sites in both the flux-grown single crystals and the precipitated powders. Though thesemore » sites have a very low (triclinic C/sub 1/) symmetry, the spectra were successfully interpreted using an orthorhombic spin Hamiltonian. It has been found that, while the main spin-Hamiltonian parameter b/sup 0//sub 2/ is almost constant when going from the LaPO/sub 4/ to the EuPO/sub 4/ host (b/sup 0//sub 2/approx. =+830 x 10/sup -4/ cm/sup -1/), the parameter b/sup 2//sub 2/ decreases monotonically from +373 x 10/sup -4/ to +283 x 10/sup -4/ cm/sup -1/, respectively. The complete analysis (i.e., angular variations of the EPR lines and position of the principal electric-field axes relative to the crystallographic axes) of the EPR single-crystal spectra has been done for the two diamagnetic hosts LaPO/sub 4/ and EuPO/sub 4/, where the observed EPR lines are the sharpest. It is shown, in particular, that the two magnetically inequivalent EPR spectra (i.e., 14 lines) observed for the monazite-type single crystals are in fact equivalent when the magnetic field is applied parallel or perpendicular to the b axis of the monoclinic structure (i.e., for these directions, only seven degenerate lines are observed). These results are in perfect agreement with the description of the monazite structure.« less
  • A method is given for the quantithtive separation and determination of individual rare earth elements in minerals. The method utilizes ion-exchange chromatography (0.5 M ammonium lactate in pH = 3.50, 4.30, 87 deg C) and pile- neutron (lO/sup 1//sup 1/ n/cm/sup 2//sec) activation. The rare earths are extracted by the 5,7-dichloro-8-quinolinol method from each fraction and determined photometrically by the Neothorin method after destroying the organic reagent. Analyses of gadolinite, xenotime, fergusonite, euxenite, and yttrialite were carried out with precision. (auth)
  • The proposed process approaches the problem of solubilizing rare-earth phosphates (monazite and zenotime) found at the Pea Ridge iron mine in Sullivan, MO, from both a pyrometallurgical and hydrometallurgical point of view. It utilizes a roasting operation that converts the rare-earth phosphates to rare-earth oxides (REOs), which eliminates some costly and hazardous processing steps currently in practice. Different combinations of roasting temperatures and acid concentrations have been investigated to selectively extract the rare-earth values. Cerium is selectively solubilized by roasting at 427{degrees}C and leaching with a sulfuric acid concentration of 265 g/L. After the cerium is removed, the neodymium andmore » lanthanum can be solubilized at a roasting temperature of 500{degrees}C and a sulfuric acid concentration of 88 g/L. Finally, neodymium, praseodymium, and yttrium are solubilized at a roasting temperature of 871{degrees}C and a sulfuric acid concentration of 265 g/L. Alternative leaching media, such as thiourea, sulfuric acid-doped thiourea mixtures, ammonium thiosulfate, nitric acid, and hydrochloric acid have also been investigated along with the addition of ultrasonic agitation. Using ultrasonics in addition to mechanical agitation, hydrochloric acid proved to be the best leaching medium. The best roasting temperatures for selective solubilization remained the same, but all of the leaching steps were conducted at 64 g/L hydrochloric acid.« less
  • A method for the quantitative separation and determination of the individual rare-earth elements in the rare-earth minerals which utilizes ion- exchange chromatography (0.5M ammonium lactate in pH = 3.60, 4.60) and pile neutron (JRR-1, 10/sup 11/ neutrons/cm/sup 2//sec) activation is presented. After separation by the ion-exchange method using ammonium lactate at 87 deg C and destruction of the organic reagent, the rare earths were determined by the photometric method (Neothorin). Analyses of three monazites and an allanite were carried out with precision. (auth)