Thermodynamics of CoO-MgO solid solutions

被引:17
作者
Wang, L [1 ]
Navrotsky, A [1 ]
Stevens, R [1 ]
Woodfield, BF [1 ]
Boerio-Goates, J [1 ]
机构
[1] Brigham Young Univ, Dept Chem & Biochem, Provo, UT 84602 USA
关键词
CoxMg1-xO solid solution; enthalpy; standard entropy; calorimetry; interaction parameter;
D O I
10.1016/S0021-9614(03)00083-1
中图分类号
O414.1 [热力学];
学科分类号
摘要
Enthalpies of mixing in CoxMg1-xO solid solutions at T = 298 K have been determined using high temperature drop solution calorimetry in molten sodium molybdate (3Na(2)O . 4MoO(3)) solvent at T = 973 K. Slightly positive enthalpies of mixing were observed, which conform to a regular solution model with interaction parameter W = (5.1 +/- 0.3) kJ . mol(-1), which is similar to the interaction parameter calculated from previously measured activity-composition relations. Standard molar entropies S-m(0) at T = 298 K calculated from subambient C-p data for CoO, MgO are (52.8 +/- 0.1) J . K-1 . mol(-1) and (28.1 +/- 0.1) J . K-1 . mol(-1), respectively. Integration of the C-p,C-m/T of the Co0.50Mg0.50O mixture yields an entropy of (40.3 +/- 0.1) J . K-1 . mol(-1). This value does not include configurational entropy from the Co/Mg site disorder. The excess entropy of Co0.50Mg0.50O is zero within experimental error. Heat capacities were also measured between T = 298 K and T = 973 K. The enthalpies of mixing do not depend on temperature in this range. (C) 2003 Elsevier Science Ltd. All rights reserved.
引用
收藏
页码:1151 / 1159
页数:9
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