Ca2.9M0.1Co4O9 (M=Ag,La, Ba)复合氧化物体系的制备及电输运性能

采用柠檬酸溶胶-凝胶结合放电等离子烧结方法制备了p型Ca位掺杂的Ca2.9M0.1Co4O9(M=Ag, La, Ba)复合氧化物块体试样, 对其进行X 射线衍射(XRD)分析, 表明产物为单一物相, Ca位掺杂原子可以改变Ca2.9Co4O9多晶体的取向度, 掺杂试样取向度随着掺杂原子电负性的降低而提高|对其进行扫描电子显微镜(SEM)分析结果表明, 试样呈层状结构, 且层状结构随掺杂原子电负性降低而逐渐明显; 电性能分析结果表明, 测试温度范围内掺杂试样各温度点的电阻率随着掺杂原子电负性的降低而升高, 所有试样的载流子传输层未受影响, 导电机理未发生变化. 其中掺杂电负性最高的Ag原子的烧结体保持最低取向度的同时具有最低的电阻率, 在973 K时达6.87 mΩ·cm, 而掺杂电负性最低的Ba原子的烧结体具有高的取向度的同时具有较高的电阻率, 在973 K时达8.22 mΩ·cm.

Preparation and Electrical Transport Properties of Ca2.9M0.1Co4O9 (M=Ag,La, Ba) Oxide Composite System

Bulk samples of a p-type Ca2.9M0.1Co4O9(M=Ag, La, Ba) oxide composite were fabricated by a nitric acid sol-gel and a spark plasma sintering method. X-ray diffraction (XRD) analyses showed a single phase for the samples. The orientation of polycrystalline Ca3Co4O9 could be modified by substituting the Ca. The orientation degree could be improved by decreasing the electronegativity of the substituting atom. Scanning electron microscopy (SEM) analyses showed that these samples were layer-structured and that this layer-structure could be enhanced by decreasing the electronegativity of the substituting atom. Electrical property analyses showed that the reduced resistivity in the measured temperature region could be increased by decreasing the electronegativity of the substituting atom. The conduction path was not disturbed and the transportation mechanism was unchanged for all samples. The Ca2.9Ag0.1Co4O9 sample that was substituted by Ag (the highest electronegativity) exhibited the lowest orientation degree and its resistivity was 6.87 mΩ·cm at 973 K. The Ca2.9Ba0.1Co4O9 sample substituted by Ba (the lowest electronegativity) exhibited the highest orientation degree and its resistivity was 8.22 mΩ·cmat 973 K.