کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
216735 1426285 2010 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Size-dependence of the heat capacity and thermodynamic properties of hematite (α-Fe2O3)
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Size-dependence of the heat capacity and thermodynamic properties of hematite (α-Fe2O3)
چکیده انگلیسی

The heat capacity of a 13 nm hematite (α-Fe2O3) sample was measured from T = (1.5 to 350) K using a combination of semi-adiabatic and adiabatic calorimetry. The heat capacity was higher than that of the bulk which can be attributed to the presence of water on the surface of the nanoparticles. No anomaly was observed in the heat capacity due to the Morin transition and theoretical fits of the heat capacity below T = 15 K show a small T3 dependence (due to lattice contributions) with no T3/2 dependence. This suggests that there are no magnetic spin-wave contributions to the heat capacity of 13 nm hematite. The use of a large linear term to fit the heat capacity below T = 15 K is most likely due to superparamagnetic contributions. A small anomaly within the temperature range (4 to 8) K was attributed to the presence of uncompensated surface spins.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: The Journal of Chemical Thermodynamics - Volume 42, Issue 9, September 2010, Pages 1142–1151
نویسندگان
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