Download or read book Computational Study of the Energetics and Defect Clustering Tendencies for Y- and La-doped UO2 written by and published by . This book was released on 2014 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The energetics and defect-ordering tendencies in solid solutions of uoritestructured UO2 with trivalent rare earth cations (M3+=Y, La) are investigated computationally using a combination of ionic-pair-potential and densityfunctional- theory (DFT) based methods. Calculated enthalpies of formation with respect to constituent oxides show higher energetic stability for La solid solutions relative to Y, consistent with the di erences in experimentally measured solubility limits for the two systems. Additionally, calculations performed for di erent atomic con gurations show a preference for reduced (increased) oxygen vacancy coordination around La (Y) dopants. The current results are shown to be qualitatively consistent with related calculations and calorimetry measurements in other trivalent-doped uorite-structured oxides, which show a tendency for increasing stability and increasing preference for higher oxygen coordination with increasing size of the trivalent impurity. The implications of these results are discussed in the context of the e ect of trivalent impurities on oxygen-ion mobilities in UO2, which are relevant to the understanding of experimental observations concerning the e ect of trivalent ssion products on oxidative corrosion rates of spent nuclear fuel.