Activities in the spinel solid solution FeXMg1−XAl2O4
Activities in the spinel solid solution FeXMg1−XAl2O4
复制标题
尖晶石固溶体 FeXMg1−XAl2O4 中的活性
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
R. Patil
中科院分区：
文献类型：
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作者：
K. Jacob;R. Patil
用双电解质固态原电池在1100 - 1350 K之间测量了α-Al 2 O3饱和的尖晶石固溶体FeXMg 1-XAl 2 O 4在0<X<1组成范围内的活度，其可以表示为Pt，Fe + FeXMg 1-XAl 2 O 4 +α-Al 2 O3//（Y2 O3）ThO 2/（CaO）ZrO 2//Fe + FeAl 2 O 4 +α-Al 2 O3，铝酸亚铁和铝酸镁的铂活度与拉乌尔定律有较小的负偏差。固溶体混合的过量自由能是组成的对称函数，与温度无关：ΔGE=−1990 X（1−X）J/mol。尖晶石固溶体中阳离子分布的理论分析也表明与理想情况有轻微的负偏差。在1300 K淬火的样品中，晶格常数与成分呈线性关系.根据本研究的结果和文献中的辅助热力学数据，推导了1300 K时FeO-MgO-Al_2O_3体系的相关系。计算表明，在尖晶石结构的非等效晶体位置之间的晶内离子交换平衡的一氧化物和尖晶石固溶体（联络线）之间的晶间离子交换平衡的影响。在1300 K下，对固溶体Fe + FeXMg 1 − XAl 2 O 4 +α-Al 2 O3和Fe + FeyMg 1 −YO+ FeXMg 1 − XAl 2 O 4的三相平衡进行了氧分压的成分依赖性评估。X，表示的尖晶石固溶体的组成，对参数Y，表征的一氧化物固溶体与岩盐结构的组成，在涉及两个固溶体的相场的依赖关系被阐明。连接线稍微偏向MgAl 2 O 4角。
Activities in the spinel solid solution FeXMg1−XAl2O4 saturated with α-Al2O3 have been measured for the compositional range 0<X<1 between 1100 and 1350 K using a bielectrolyte solid-state galvanic cell, which may be represented as Pt, Fe + FeXMg1−XAl2O4+α-Al2O3//(Y2O3)ThO2/(CaO)ZrO2//Fe + FeAl2O4+α-Al2O3, Pt Activities of ferrous and magnesium aluminates exhibit small negative deviations from Raoult’s law. The excess free energy of mixing of the solid solution is a symmetric function of composition and is independent of temperature: ΔGE=−1990 X(1−X) J/mol. Theoretical analysis of cation distribution in spinel solid solution also suggests mild negative deviations from ideality. The lattice parameter varies linearly with composition in samples quenched from 1300 K. Phase relations in the FeO-MgO-Al2O3 system at 1300 K are deduced from the results of this study and auxiliary thermodynamic data from the literature. The calculation demonstrates the influence of intracrystalline ion exchange equilibrium between nonequivalent crystallographic sites in the spinel structure on intercrystalline ion exchange equilibrium between the monoxide and spinel solid solutions (tie-lines). The composition dependence of oxygen partial pressure at 1300 K is evaluated for three-phase equilibria involving the solid solutions Fe + FeXMg1−XAl2O4+α-Al2O3 and Fe + FeyMg1−YO+FeXMg1−XAl2O4. Dependence of X, denoting the composition of the spinel solid solution, on parameter Y, characterizing the composition of the monoxide solid solution with rock salt structure, in phase fields involving the two solid solutions is elucidated. The tie-lines are slightly skewed toward the MgAl2O4 corner.