New high temperature negative temperature coefficient (NTC) thermistor ceramics based on a xMgAl(2)O(4)-(1-x)YCr0.5Mn0.5O3 (x = 0.1, 0.4, 0.6) composite system have been successfully fabricated through sparkplasmasintering (SPS) with a low sintering temperature and a short sintering period. The X-ray diffraction analysis indicates that the SPS-sintered compositeceramics consist of a cubic spinel MgAl2O4 phase and an orthorhombic perovskite YCr0.5Mn0.5O3 phase isomorphic to YCr0.3. The SPS-sintered compositeceramics have high relative density ranging from 94.1 to 97.4% of the theoretical density. X-ray photoelectron spectroscopy analysis corroborates the presence of Cr3+, Cr4+, Mn3+, and Mn4+ ions on lattice sites, which may result in the hopping conduction. The obtained p(25), B25-150, and B700-1000 of the SPS-sintered compositeNTC thermistors are in the range of 1.53 x 10(6)-9.92 x 10(9) Omega cm, 3380-5172 K, and 7239-9543 K, respectively. These values can be tuned by adjusting the MgAl2O4 concentration.
Chinese Acad Sci, Xinjiang Tech Inst Phys & Chem, Xinjiang Key Lab Elect Informat Mat & Devices, Key Lab Funct Mat & Devices Special Environm, Urumqi 830011, Peoples R China;Univ Chinese Acad Sci, Beijing 100049, Peoples R China;Alfred Univ, New York State Coll Ceram, Kazuo Inamori Sch Engn, Alfred, NY 14802 USA
Zhang, Bo,Zhao, Qing,Chang, Aimin,et al. Spark plasma sintering of MgAl2O4-YCr0.5Mn0.5O3 composite NTC ceramics[J]. Journal of the European Ceramic Society,2014,34(12):2989-2995.