Tungsten (W), with its primary advantages, is considered as the most promising candidate for plasma facing materials (PFMs) for the next generation of fusion devices such as ITER. However, continuous bombardment with ...Tungsten (W), with its primary advantages, is considered as the most promising candidate for plasma facing materials (PFMs) for the next generation of fusion devices such as ITER. However, continuous bombardment with 14.1 MeV neutron introduces Frenkel defects as the primary damage in W [1]. The Frenkel defects, composed of self-interstitial atoms (SIAs) and vacancies, can develop to extended defects such as voids and interstitial clusters, resulting in hardening, swelling and embrittlement of W, thus degrading the properties of W [2]. The recombination of SIAs and vacancies is an effective way to reduce the Frenkel defects in bulk W, which enhances the radiation resistance of W based on recent theoretical calculations [3,4]. The moving of the SIA to the vacancy could finish the recombination process through instantaneous or thermally activated way [3]. The instantaneous recombination region is an ellipse with the semi-minor axis of 5.4 ? and semi-major axis of 18 ? according to the molecular dynamics calculation [4].展开更多
Uranium-europium mixed oxides(U_(1-y)Euy)O_(2-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 ...Uranium-europium mixed oxides(U_(1-y)Euy)O_(2-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 298-800 K and 800-1800 K,respectively.The,pm C values at 298 K for(U_(1-y)Euy)O_(2-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.展开更多
基金supported by the National Magnetic Confinement Fusion Program (Grant No. 2013GB109002)the National Natural Science Foundation of China (Grant Nos. 11405006, and 51371019)
文摘Tungsten (W), with its primary advantages, is considered as the most promising candidate for plasma facing materials (PFMs) for the next generation of fusion devices such as ITER. However, continuous bombardment with 14.1 MeV neutron introduces Frenkel defects as the primary damage in W [1]. The Frenkel defects, composed of self-interstitial atoms (SIAs) and vacancies, can develop to extended defects such as voids and interstitial clusters, resulting in hardening, swelling and embrittlement of W, thus degrading the properties of W [2]. The recombination of SIAs and vacancies is an effective way to reduce the Frenkel defects in bulk W, which enhances the radiation resistance of W based on recent theoretical calculations [3,4]. The moving of the SIA to the vacancy could finish the recombination process through instantaneous or thermally activated way [3]. The instantaneous recombination region is an ellipse with the semi-minor axis of 5.4 ? and semi-major axis of 18 ? according to the molecular dynamics calculation [4].
文摘Uranium-europium mixed oxides(U_(1-y)Euy)O_(2-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 298-800 K and 800-1800 K,respectively.The,pm C values at 298 K for(U_(1-y)Euy)O_(2-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.
