High temperature heat capacities of (U0.91 M0.09)O2 (where M is Pr, Ce, Zr) from 290 to 1410 K

Thermophysical properties of uranium–europium mixed oxides

“…Such anomalous increase in the heat capacity is usually observed when UO 2 is doped with an aliovalent cation (in this case Eu +3 , Eu +2 ). This phenomenon was reported earlier [11][12][13][19][20][21][22][23][24][25] and has been ascribed to the formation of oxygen Frenkel defect pairs. An estimate of the temperature dependence of the heat capacity pertaining to the solid solutions (U 1y Eu y )O 2x (y = 0.2, 0.4, 0.6) over the temperature range 298-1800 K was obtained by extrapolating the expression derived through the least squares regression analysis of these data in the temperature range 298-900 K. This would hence forth be termed as baseline heat capacity.…”

Heat capacity measurements and XPS studies on uranium–lanthanum mixed oxides

“…500-600 K. This phenomenon was attributed to the formation of Frenkel-pair like defects of oxygen [4][5][6][8][9][10]. This is because the formation of large number of Frenkel-pair defects of oxygen is enabled, when UO 2 is doped with aliovalent cations (La 3+ in this case).…”

“…Heat capacity of uranium-rare earth mixed oxides has been determined by various authors [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Anomalous increase in the heat capacity with temperature was reported by various authors [3][4][5][6][7][8][9][10][11] whereas certain authors [12][13][14][15][16] reported no anomalous increase in the heat capacity. Earlier [11], we have measured the heat capacity of (U 1−y Gd y )O 2±x (y = 0.1, 0.2, and 0.5) by DSC in the temperature range 298-800 K. Considerable anomalous increase in the heat capacity was observed for (U 1−y Gd y )O 2±x with y = 0.1-0.5.…”

Computational study of the energetics of charge and cation mixing in U1−xCexO2Hanken1, Stanek2, Grønbech‐Jensen3 et al. 2011Phys. Rev. B370251View full textAdd to dashboardCite

“…The thermophysical properties of urania-ceria mixtures have been investigated for more than three decades [1][2][3][4][5][6][7][8][9][10][11][12][13] , due to the relevance of these materials to the understanding of nuclear fuel behavior. Cerium is a fission product that is highly soluble in urania (UO 2 ) 1 , and its effects on phase stability, thermal conductivity and ionic diffusion are thus relevant to the performance of oxide fuels, particularly at high burnup.…”

“…In addition to the extensive studies of phase equilibria, a variety of thermophysical properties have been measured for urania-ceria mixtures. These properties include oxygen partial molar free energies and enthalpies 4 , lattice parameters 5 , bond lengths 6 , heat capacities 7,8 , magnetic properties [9][10][11] , and electronic structure 12,13 . While many of the properties of urania-ceria are relatively well characterized, there are at present no published values of the mixing thermodynamic properties (enthalpy, entropy and free energy) that the authors are aware of.…”