Electrical conductivity increase by order of magnitude through controlling sintering to tune hierarchical structure of oxide ceramics
Electrical conductivity increase by order of magnitude through controlling sintering to tune hierarchical structure of oxide ceramics
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DOI：
10.1016/j.jssc.2020.121831
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发表时间：
2020-10
影响因子：
3.3
通讯作者：
Sergio A. Paredes-Navia;Liang Liang-Liang;Cesar-Octavio Romo-De-La-Cruz;Ellena Gemmen;Andre Fernandes;J. Prucz;Yun Chen;Xueyan Song
中科院分区：
文献类型：
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作者：
Sergio A. Paredes-Navia;Liang Liang-Liang;Cesar-Octavio Romo-De-La-Cruz;Ellena Gemmen;Andre Fernandes;J. Prucz;Yun Chen;Xueyan Song
过氧化钙CaMnO 3-δ是一种具有独特物理现象的半导体代表，包括巨磁阻和热电性能。对于需要利用氧化物陶瓷的大规模应用，可以通过调整陶瓷烧结条件来控制并最终优化多晶材料的物理性质，例如导电性。本文系统研究了烧结温度对CaMnO 3-δ结构和热电性能的影响。对于由使用化学溶胶-凝胶反应合成的前体粉末制成的陶瓷颗粒，烧结温度的增加显著地增加了导电性的数量级，同时增加了塞贝克系数。同时，随着烧结温度的升高，材料的导热系数也随之增大。在不同温度下烧结的样品中，纯CaMnO_（3-δ）的峰值热电优值Z_T达到0.28，比纯CaMnO_（3-δ）的最高热电优值Z_T提高了2.5倍，接近掺杂的单相CaMnO_（3-δ）。基于氧化物陶瓷分级结构的演变，从单胞水平到微米尺度，由烧结温度的变化引起的电学和热学性能的变化进行了解释。
Perovskite calcium manganate CaMnO3-δis representative of an essential group of semiconductors with unique physical phenomena including colossal magnetoresistance and thermoelectric properties. For the large-scale applications that require the utilization of oxide ceramics, the polycrystalline materials’ physical properties such as conductivity can be controlled and ultimately optimized through tuning the ceramics sintering conditions. In the present study, the impact of the sintering temperature on the structure and thermoelectric performance of CaMnO3-δis systematically studied. For the ceramics pellets made of precursors powders synthesized using the chemical sol-gel reaction, the increase in the sintering temperature dramatically increases the electrical conductivity by order of magnitude and simultaneously increases the Seebeck coefficient. Meanwhile, the thermal conductivity increases with the rise of the sintering temperature. Among the samples sintered at different temperatures, the peaking thermoelectric Figure of MeritZTof pristine CaMnO3-δreached 0.28, which is a factor of 2.5 higher than the highest reportedZTfor pristine CaMnO3-δand approached that of the doped single-phase CaMnO3-δ. The electrical and thermal properties changes were interpreted based on the oxide ceramics hierarchical structure evolutions, from unit cell level to micron scales, induced by changes of sintering temperatures.