Effect of CaO-doped in NiMn2O4–LaMnO3 composite ceramics on microstructure and electrical properties
Effect of CaO-doped in NiMn2O4–LaMnO3 composite ceramics on microstructure and electrical properties
复制标题
DOI：
10.1007/s10854-012-0654-4
复制
发表时间：
2012-02
期刊：
影响因子：
--
通讯作者：
Fang Guan;Huimin Zhang;Aimin Chang;Pengjun Zhao;Bo Zhang
中科院分区：
文献类型：
--
作者：
Fang Guan;Huimin Zhang;Aimin Chang;Pengjun Zhao;Bo Zhang
采用经典固相反应法制备了尖晶石结构的NiMn 2 O 4和钙钛矿结构的CaO掺杂的LaMnO 3组成的（NiMn 2 O 4）0.50（La 1 − xCaxMnO 3）0.50（0 ≤x≤ 0.3）复合陶瓷。X射线衍射（XRD）图谱表明，烧结样品中存在的主要物相是具有尖晶石结构的NiMn 2 O 4化合物，具有钙钛矿结构的La 1-xCaxMnO 3。扫描电子显微镜（SEM）照片显示，复合陶瓷的晶粒尺寸从约100 μ m减小到约200 μ m。6.5当CaO的摩尔分数从0增加到0.3时，晶粒尺寸减小到2.0 μm。复合样品的ρ25 ° CandB 25/50常数分别在0.234-8.61 Ω cm和2，600 - 2，962 K范围内。特别地，CaO掺杂导致（NiMn 2 O 4）0.50（La 1-xCaxMnO 3）0.50复合NTC（负温度系数）陶瓷在老化测试后的电阻漂移减小。这表明，与不含Ca的（NiMn 2 O 4）0.50（La 1 − xCaxMnO 3）0.50陶瓷相比，CaO掺杂的（NiMn 2 O 4）0.50（LaMnO 3）0.50 NTC陶瓷显示出高的电稳定性。X射线光电子能谱（XPS）分析表明，Mn离子在B位以Mn 2+、Mn 3+和Mn 4+高度混合的价态存在。复合陶瓷的导电机理可以用离子迁移机制来解释。
The composite ceramics (NiMn2O4)0.50(La1−xCaxMnO3)0.50(0 ≤x≤ 0.3) consisting of spinel-structured NiMn2O4and perovskite-structured CaO-doped LaMnO3were prepared by classical solid state reaction. The X-ray diffraction (XRD) patterns have shown that the major phases presented in the sintered samples are NiMn2O4compounds with a spinel structure, La1−xCaxMnO3with a perovskite structure. The Scanning Electron Microscope (SEM) pictures have exhibited that the grain size of the composite ceramics decreases from ca. 6.5 to 2.0 μm as the mole fraction of CaO increases from 0 to 0.3. Theρ25 °CandB25/50constants of the composite samples are in the range of 0.234–8.61 Ω cm and 2,600–2,962 K, respectively. In particular, CaO-doped leads to a decrease in the resistance drift of the (NiMn2O4)0.50(La1−xCaxMnO3)0.50composite NTC (negative temperature coefficient) ceramics after aging test. This indicates that the CaO-doped (NiMn2O4)0.50(La1−xCaxMnO3)0.50NTC ceramics display high electrical stability in comparison with the Ca-free (NiMn2O4)0.50(LaMnO3)0.50ceramics. The X-ray photoelectron spectroscopy (XPS) analysis verifies that the valence states of the manganese ions have a highly mixed state of Mn2+, Mn3+and Mn4+at B site. And the electrical conduction of the composite ceramics can be elaborated by the ions migration mechanism.