The introduction of La2O3 to Mn0.75Ni1.25CuO4 ceramics was studied on the microstructure and electrical properties. The sintered Mn0.75Ni1.25CuO4-xLa(2)O(3) (0x0.3) bodies was typical polycrystalline, with cubic spinel structure of copper manganese oxide, rocksalt structure of nickel copper oxide, along with monoclinic phase of copper oxide and orthorhombic perovskite structure of lanthanum manganese oxide. It is found that La doping reduces the material grain size and changes its morphology from the plate-like form to a spherical staking-like form. The shape and size of the grains are strongly influenced by the addition of La to the system. The X-ray photoelectron spectroscopy analysis corroborates the presence of nonequivalent ions at octahedral sites. The obtained (77K), B-77K/90K constant and activation energy of the negative temperature coefficient (NTC) Mn0.75Ni1.25CuO4-xLa(2)O(3) thermistors were in the range of 13.19-30.39 cm, 315-326K, and 0.0272-0.0281eV, respectively. This means that the electrical properties can be adjusted to desired values, depending on the La content. Such ceramics could be used as potential candidates for NTC thermistors in a temperature range from 20K to 90K. So these prepared NTC thermistors were intended to be used under low-temperature conditions.
Chinese Acad Sci, Xinjiang Tech Inst Phys & Chem, Urumqi 830011, Peoples R China;Xinjiang Key Lab Elect Informat Mat & Devices, Urumqi 830011, Peoples R China;Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China
Yao Jincheng,Wang Junhua,Zhao Qing,et al. Effect of La2O3 Addition on Copper-Nickel Manganese Thermistors for Low-Temperature Applications[J]. INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY,2013,10(增刊: 1):E106-E112.