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Uranium–europium mixed oxides (U1-yEuy)O2-x (y=0.2–0.8) were prepared by the citrate gel combustion technique and characterized by X-ray diffraction (XRD). Single phase fluorite structure was observed in those solid solutions with y≤0.6. The solid solutions with y>0.6 were found to be biphasic, with the second phase being cubic Eu2O3. Heat capacity and enthalpy increment measurements were carried out by using differential scanning calorimeter (DSC) and drop calorimeter in the temperature range 298–800K and 800–1800K, respectively. The Cp,m values at 298 K for (U1-yEuy)O2-x (y=0.2, 0.4, 0.6) are 64.8, 64.6, and 63.5 J·K-1·mol-1, respectively. An anomalous increase was observed in the heat capacity in all of the solid solutions with the onset temperature around 950 K. This could be attributed to the contribution from Frenkel pair oxygen defects. From the excess heat capacity data, the enthalpy for the formation of these defects was computed and found to be in the range of 2.10±0.02 eV.


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Thermophysical properties of uranium–europium mixed oxides

Show Author's information R. VENKATA KRISHNANR. BABUAbhiram SENAPATIG. JOGESWARARAOK. ANANTHASIVAN( )
Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, Tamil Nadu, India

Abstract

Uranium–europium mixed oxides (U1-yEuy)O2-x (y=0.2–0.8) were prepared by the citrate gel combustion technique and characterized by X-ray diffraction (XRD). Single phase fluorite structure was observed in those solid solutions with y≤0.6. The solid solutions with y>0.6 were found to be biphasic, with the second phase being cubic Eu2O3. Heat capacity and enthalpy increment measurements were carried out by using differential scanning calorimeter (DSC) and drop calorimeter in the temperature range 298–800K and 800–1800K, respectively. The Cp,m values at 298 K for (U1-yEuy)O2-x (y=0.2, 0.4, 0.6) are 64.8, 64.6, and 63.5 J·K-1·mol-1, respectively. An anomalous increase was observed in the heat capacity in all of the solid solutions with the onset temperature around 950 K. This could be attributed to the contribution from Frenkel pair oxygen defects. From the excess heat capacity data, the enthalpy for the formation of these defects was computed and found to be in the range of 2.10±0.02 eV.

Keywords:

uranium, europium, solid solution, calorimetry, heat capacity, Frenkel defects
Received: 16 April 2015 Revised: 12 May 2015 Accepted: 18 May 2015 Published: 22 September 2015 Issue date: April 2015
References(25)
[1]
Olander DR. Fundamental Aspects of Nuclear Reactor Fuel Elements. Virgina, USA: Springfield, 1985.
[2]
Matzke Hj. Science of Advanced LMFBR Fuels. Amsterdam: Elsevier, 1986.
[3]
IAEA-TECDOC-1168. Compilation and evaluation of fission yield nuclear data. 2000. Available at .
[4]
Crouch EAC. Calculated independent yields in thermal neutron fission of sup233U, sup235U, sup239Pu, sup241Pu, and in fission of sup232Th, sup238U, and sup240Pu. Technical Report AERE-R-6056. 1969.
[5]
Grossman LN, Lewis JE, Rooney DM. The system UO2–Eu2O3 at high temperatures. J Nucl Mater 1967, 21: 302-309.
[6]
Fujino T, Ouchi K, Mozumi Y, et al. Composition and oxygen potential of cubic fluorite-type solid solution EuyU1-yO2+x (x≡0) and rhombohedral Eu6UO12+x′ (x′<0). J Nucl Mater 1990, 174: 92-101.10.1016/0022-3115(90)90426-N
[7]
Haug H, Weigel F. Mischoxidsysteme von lanthaniden- und actinidenelementen: I. Röntgen-untersuchungen im system Uranoxid-Europiumoxid. J Nucl Mater 1963, 9: 355-359.
[8]
Omichi T, Fukushima S, Maeda A, et al. On the relation between lattice parameters and O/M ratio for uranium dioxide–trivalent rare earth oxide solid solution. J Nucl Mater 1981, 102: 40-46.
[9]
Park K, Olander DR. Defect models for the oxygen potentials of gadolinium- and europium-doped urania. J Nucl Mater 1992, 187: 89-96.
[10]
Matsui T, Kawase T, Naito K. Heat capacities and electrical conductivities of (U1-yEuy)O2 (y=0.044 and 0.090) from 300 to 1550 K. J Nucl Mater 1992, 186: 254-258.
[11]
Venkata Krishnan R, Mittal VK, Babu R, et al. Heat capacity measurements and XPS studies on uranium–lanthanum mixed oxides. J Alloys Compd 2011, 509: 3229-3237.
[12]
Venkata Krishnan R, Babu R, Panneerselvam G, et al. Solubility studies and thermophysical properties of uranium–neodymium mixed oxides system. Ceram Int 2014, 40: 4395-4405.
[13]
Venkata Krishnan R, Panneerselvam G, Manikandan P, et al. Heat capacity and thermal expansion of uranium–gadolinium mixed oxides. J Nucl Radiochem Sci 2009, 10: 19-26.
[14]
Venkata Krishnan R, Nagarajan K, Vasudeva Rao PR. Heat capacity measurements on BaThO3 and BaCeO3. J Nucl Mater 2001, 299: 29-31.
[15]
Venkata Krishnan R, Nagarajan K. Heat capacity measurements on uranium–cerium mixed oxides by differential scanning calorimetry. Thermochim Acta 2006, 440: 141-145.
[16]
International Centre for Diffraction Data. Powder diffraction files (inorganic phases). Joint Committee on Powder Diffraction Data (JCPDS), ICDD card number 00-034-0392. 2013.
[17]
Knacke O, Kubaschewski O, Hesselmann K. Thermochemical Properties on Inorganic Substances. Berlin: Springer, 1991.
[18]
Fink JK. Thermophysical properties of uranium dioxide. J Nucl Mater 2000, 279: 1-18.
[19]
Inaba H, Naito K, Oguma M. Heat capacity measurements of U1-yGdyO2 (0.00≤y≤0.142) from 310 to 1500 K. J Nucl Mater 1987, 149: 341-348.
[20]
Matsui T, Arita Y, Naito K. Heat capacity measurements of U1-yLayO2 (y=0.044, 0.090, 0.142) from 300 to 1500 K. J Radioan Nucl Ch Ar 1990, 143: 149-156.
[21]
Matsui T, Kawase T, Naito K. Heat capacities and electrical conductivities of (U1-yEuy)O2 (y=0.044 and 0.090) from 300 to 1500 K. J Nucl Mater 1992, 186: 254-258.
[22]
Mills KC, Ponsford FH, Richardson MJ, et al. Heat capacity and enthalpy of UO2 and gadolinia-doped UO2. Thermochim Acta 1989, 139: 107-120.
[23]
Arita Y, Matsui T, Hamada S. High temperature heat capacities of (U0.91M0.09)O2 (where M is Pr, Ce, Zr) from 290 to 1410 K. Thermochim Acta 1995, 253: 1-9.
[24]
Arita Y, Hamada H, Matsui T. High-temperature heat capacities and electrical conductivities of UO2 doped with simulated fission products for 2–10 at% burnup. Thermochim Acta 1994, 247: 225-236.
[25]
Inaba H, Naito K, Oguma M, et al. Heat capacity measurement of gadalonia doped (7.3 mol%) UO2 from 310–1370 K. J Nucl Mater 1986, 137: 176-178.
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Publication history

Received: 16 April 2015
Revised: 12 May 2015
Accepted: 18 May 2015
Published: 22 September 2015
Issue date: April 2015

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© The author(s) 2015

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