Thermodynamic studies on charge-coupled substituted synthetic monazite

New insights into phosphate based materials for the immobilisation of actinides

“…The majority of thermochemical investigations were performed on pure LnPO 4 endmembers [47,49,[208][209][210][211], monazite-type solid solutions [52,54,160] and to a lesser extent on monazite-cheralite-type solid solutions [212][213][214]. Ushakov et al [49] reported a roughly linear trend of the enthalpies of formation of LnPO 4 endmembers consistent with the lanthanides contraction and the decrease of ionic binding energy in these materials which has been confirmed by ab initio calculations [172,176].…”

“…Drop solution calorimetry measurements of the CaTh(PO 4 ) 2 endmember as well as the Ln 1−2x Ca x Th x PO 4 (Ln = La, Ce) solid solution series were performed by Popa et al [220] and Konings et al [213] showing typical excess properties of regular solid solutions with a slight influence of the smaller Th 4+ ions compared to the lanthanide ions. Recently, results of the heat capacity and standard molar enthalpies of formation of La 1−2x Ca x Th x PO 4 solid solutions were reported by Rawat et al [214], indicating a stabilisation of the solid solution by the incorporation of 12.5 mol% of Th 4+ which is an appropriate waste load for the disposal of tetravalent actinides.…”

Structural and thermodynamic mixing properties of La1−xNdxPO4Schlenz1, Dellen2, Kegler3 et al. 2019Journal of Solid State Chemistry9000View full textAdd to dashboardCite

“…This linear trend supports the accuracy of H Δ ds,973 values used in our calculations of the two end members LaPO 4 and NdPO 4 . Recently Rawat et al [33] published new high temperature calorimetric data for LaPO 4 . They determined sig- ).…”

“…Kowalski et al [34] and references therein). The data of [33] were not taken into account for our own calculations. ).…”