In this work, incorporation of hexavalent molybdenum and selected trivalent lanthanides using divalent calcium as charge compensator into the monazite structure were studied. Rare earth substituted phosphomolybdates of the formula REE0.9Ca0.1P0.9Mo0.1O4 (REE&nbsp;=&nbsp;Ce, Nd, Sm, Gd) and the wasteform La0.4Nd0.1Y0.1Gd0.1Sm0.1Ce0.1Ca0.1P0.9Mo0.1O4 were synthesized by simple solution route. The prepared compounds were characterized by powder X-ray diffraction, Fourier transformed infrared spectra, thermogravimetric analysis, energy dispersive X-ray analysis and scanning electron microscopic techniques. Chemical durability of the wasteform was studied by dynamic MCC-5 test for a period of one month. Normalized elemental mass loss and leach rate of molybdenum was found to be in the order of 103&nbsp;g/m2 and 103–101&nbsp;g/m2/d respectively. Polymer-monazite composite wasteform was prepared to control the leaching of molybdenum. The composite approach reduced molybdenum leach rate order from 101 to 10−4&nbsp;g/m2/d.

Buvaneswari G

Department of Chemistry

School of Advanced Sciences

Vellore Campus

Pratheep Kumar S

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Journal of Nuclear Materials

In contrast to the existing cubic langbeinite phosphates and sulphates, orthorhombic langbeinite phosphosilicates of the chemical formula KBaYMP2SiO12 (M: Zr, Sn), KBaREEZrP2SiO12 (REE: La, Nd, Sm, Eu, Gd, Dy) and the wasteform KBaY0.6La0.1Nd0.1Sm0.1Eu0.1ZrP2SiO12 have been synthesized by solution method. <a href="https://www.sciencedirect.com/topics/materials-science/powder-x-ray-diffraction">Powder X-ray diffraction</a> analysis affirmed that the compounds were phase pure and crystallized in an orthorhombic structure with P212121 space group. Spectral analysis of the wasteform revealed the phase stability, thermal stability and chemical durability of the langbeinite structure. Chemical durability of the powder wasteform has been studied by a dynamic Soxhlet test. <a href="https://www.sciencedirect.com/topics/materials-science/elemental-analysis">Elemental analysis</a> of the leachates showed that the normalized mass losses of <a href="https://www.sciencedirect.com/topics/materials-science/barium">barium</a>, <a href="https://www.sciencedirect.com/topics/materials-science/zirconium">zirconium</a> and silicon were in the order of 10−3–10−2&nbsp;g/m2, 10−5–10−4&nbsp;g/m2 and 10−2–10−1&nbsp;g/m2 respectively. Normalized mass losses of <a href="https://www.sciencedirect.com/topics/materials-science/lanthanide-series">lanthanides</a>, potassium and phosphorous were found to be below the instrumental detection limits.

Journal of Alloys and Compounds

New rare earth langbeinite phosphosilicates KBaREEZrP 2 SiO 12 (REE: La, Nd, Sm, Eu, Gd, Dy) for lanthanide comprising nuclear waste storage

Materials Research Bulletin

Synthesis of apatite phosphates containing Cs+, Sr2+ and RE3+ ions and chemical durability studies

Progress in Nuclear Energy

Studies on thermal and mechanical properties of monazite-type ceramics for the conditioning of minor actinides

Raman and infrared spectroscopy of monazite-type ceramics used for nuclear waste conditioning

Nuclear Engineering and Design

Garnet nuclear waste forms – Solubility at repository conditions

Iron phosphate glass for immobilization of 99Tc

Simulated monazite crystalline wasteform La0.4Nd0.1Y0.1Gd0.1Sm0.1Ce0.1Ca0.1(P0.9Mo0.1O4): Synthesis, phase stability and chemical durability study

Journal	Data powered by TypesetJournal of Nuclear Materials
Publisher	Data powered by TypesetElsevier BV
ISSN	0022-3115
Open Access	0