کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9781736 | 1511636 | 2005 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Heat capacity anomaly in UO2 in the vicinity of 1300Â K: an improved description based on high resolution X-ray and neutron powder diffraction studies
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
مواد الکترونیکی، نوری و مغناطیسی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Heat capacity anomaly in UO2 in the vicinity of 1300Â K: an improved description based on high resolution X-ray and neutron powder diffraction studies Heat capacity anomaly in UO2 in the vicinity of 1300Â K: an improved description based on high resolution X-ray and neutron powder diffraction studies](/preview/png/9781736.png)
چکیده انگلیسی
X-ray and neutron powder diffraction studies of UO2 were performed under controlled oxygen partial pressure between room temperature and 1673Â K. More than 40 neutron diffraction patterns were recorded. The thermal expansion coefficient of UO2 and the temperature dependence of Debye-Waller factors for oxygen and uranium atoms were determined. The dependence of Debye-Waller factors as a function of temperature is linear and the thermal expansion coefficient follows the classical Debye regime within the temperature range 300-1000Â K. Above 1200Â K, a departure from this quasi-harmonic behavior is clearly observed. Both an abnormal increase of the thermal expansion and of the oxygen sublattice disorder are evidenced. The departure of the lattice parameter from a linear thermal variation is found to be thermally activated with an effective activation energy close to 1Â eV, very similar to the activation energy already found for the electrical conductivity. This new result suggests that polarons may affect the mean lattice parameter. A new thermodynamic model is then proposed to explain the heat capacity thermal variation by only three contributions: harmonic phonons, thermal expansion and polarons.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Physics and Chemistry of Solids - Volume 66, Issue 5, May 2005, Pages 823-831
Journal: Journal of Physics and Chemistry of Solids - Volume 66, Issue 5, May 2005, Pages 823-831
نویسندگان
P. Ruello, L. Desgranges, G. Baldinozzi, G. Calvarin, T. Hansen, G. Petot-Ervas, C. Petot,