In this study, CoCuMnO ceramics with dual phases and twin defects were successfully prepared by the thermal decomposition of oxalate precursors. The effects of sintering temperature on the phase composition, microstructure, and electrical properties of CoCuMnO ceramics were investigated. X-ray diffraction results show that the ceramics are composed of cubic and tetragonal spinel phases and the content of the cubic spinel phase increases with increasing sintering temperature. Scanning electron microscopy images revealed that the grain size increases with increasing sintering temperature and the bulk density first increases and then decreases. Transmission electron microscopy results revealed a change in the twin configuration from needle-shaped twins to lamella without internal twins and finally to lamella with internal twins with increasing sintering temperature. X-ray photoelectron spectroscopy results showed that an increase in the sintering temperature causes the oxidation of Cu to Cu, and the average valence state of Mn ions to first increase and then decrease. However, during the aging process, Cu did not oxidize to Cu and the Cu content increased. CoCuMnO ceramics sintered in the temperature range of 1000°C–1200°C exhibited excellent electrical properties. The resistivity (), material constant (), and aging values were 17.6–106.66 Ω·cm, 2836–3338 K, and 1.63%–3.41%, respectively. Herein, the relationships among the microstructures, valence states, and electrical properties are also discussed in detail.

中文翻译：

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烧结温度引起的 Co0.98Cu0.4Mn1.62O4 陶瓷晶体结构、微观结构、孪晶缺陷和电性能的演变

本研究通过草酸盐前驱体的热分解成功制备了具有双相和孪晶缺陷的CoCuMnO陶瓷。研究了烧结温度对CoCuMnO陶瓷的物相组成、显微结构和电性能的影响。 X射线衍射结果表明，陶瓷由立方尖晶石相和四方尖晶石相组成，且立方尖晶石相的含量随着烧结温度的升高而增加。扫描电子显微镜图像显示，随着烧结温度的升高，晶粒尺寸增大，体积密度先增大后减小。透射电子显微镜结果显示，随着烧结温度的升高，孪晶结构从针状孪晶转变为无内部孪晶的片层，最后转变为具有内部孪晶的片层。 X射线光电子能谱结果表明，烧结温度的升高导致Cu氧化成Cu，Mn离子的平均价态先升高后降低。但在时效过程中，Cu并没有氧化成Cu，而且Cu含量有所增加。在1000°C~1200°C温度范围内烧结的CoCuMnO陶瓷表现出优异的电性能。电阻率()、材料常数()和老化值分别为17.6–106.66 Ω·cm、2836–3338 K和1.63%–3.41%。在此，还详细讨论了微观结构、价态和电性能之间的关系。