Preparation and characterization of Ni0.6Mn2.4O4 NTC ceramics by solid-state coordination reaction

• Published in: Journal of materials science. Materials in electronics Vol. 24; no. 12; pp. 5183 - 5188
• Main Authors: Ma, Chengjian, Liu, Yunfei, Lu, Yinong, Gao, Hong, Qian, Hao, Ding, Jianxiang
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.12.2013; Springer
• Subjects: Annealing; Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Heat treatment; Materials; Materials Science; Metals. Metallurgy; Optical and Electronic Materials; Physics; Porous materials; granular materials; Production techniques; Specific materials; Treatment of materials and its effects on microstructure and properties; Mn3O4; Spinel Structure; Calcination Temperature; Electrical Resistivity; Sinter Temperature; Annealing; Electrical conductivity; Phase composition; Electrical properties; Annealing temperature; Compact design; High temperature; Lattice parameters; Porous material; Calcining; Temperature coefficient; Spinels; Solid state reaction; Reaction time; Porosity; Ceramic materials; Electrical characteristic
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-013-1542-2

The impact of synthesis parameters, such as calcination temperature and reaction time, on the microstructure, phase compositions and electrical properties of Ni 0.6 Mn 2.4 O 4 negative temperature coefficient (NTC) ceramics, which were synthesized via solid-state coordination reaction method, was systematically explained. With enhancing calcination temperature and time, the relative densities were raised, while the porosities diminished. A compact single-phase cubic spinel ceramic could be obtained after annealing at 1,100 and 1,150 °C, while a secondary phase Mn 3 O 4 was detected when the annealing temperature raised to 1,200 °C. For the ceramics calcinated at 1,100 or 1,150 °C for 3 h, their resistivities were 2,133 and 2,178 Ω cm, the thermal constant B, which reflects the temperature sensitivity of the NTC ceramics, were 3,820 and 3,857 K. While the ceramic prepared at 1,200 °C for 3 h, the resistivity and the B value reached 2,273 Ω cm and 3,810 K, respectively. This phenomenon was attributed to the increase of lattice parameters and the reduction of Mn 4+ –Mn 3+ at high temperatures.