Abstract
La1−xNdxPO4 monazite-type ceramics were synthesized by precipitation and sintering. The obtained crystalline powders and pellets were structurally characterized by X-ray diffraction, electron microscopy, and infrared and Raman spectroscopy. The determined unit cell constants agree with published values for the pure end-members ranging from LaPO4 to DyPO4, as well as with values for known mixed monazite-type lanthanide orthophosphates, indicating a homogeneous solid solution. However, Raman spectroscopy shows a change in short-range order and the results of high temperature oxide melt solution calorimetry suggest a subregular solid solution, which requires two Margules parameters to calculate the observed enthalpy of mixing ΔHmix for La1−xNdxPO4, which is positive and asymmetric and shows a maximum at x = 0.299 (ΔHmix=7.53±0.01kJmol−1) at 298 K.
Original language | English (US) |
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Pages (from-to) | 470-478 |
Number of pages | 9 |
Journal | Journal of Solid State Chemistry |
Volume | 270 |
DOIs | |
State | Published - Feb 2019 |
Externally published | Yes |
Keywords
- Actinides
- Crystal structure
- Enthalpy of mixing
- Monazite
- Nuclear waste
- Solid solution
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry