Enhanced aging and thermal shock performance of Mn1.95-xCo0.21Ni0.84SrxO4 NTC ceramics

Abstract

Herein, the Mn1.95-xCo0.21Ni0.84SrxO4 (MCNS) (0 ≤ x ≤ 0.15) negative temperature coefficient (NTC) materials are prepared by co-precipitation method. The replacement of Mn by Sr plays a critical role in controlling the lattice parameter, relative density, microstructure and electrical properties. The lattice parameter and relatively density increase with the increase of Sr content. Moreover, a small amount of Sr retards the grain growth and increases the bulk density. Moreover, the ρ25, B25/50, Ea and α values of MCNS ceramics are influenced by the Sr content and ranged from 1535.0-2024.1 Ω•cm, 3654–3709 K, 0.3149–0.3197 eV and 4.111–4.173%, respectively. The XPS results explain the transformation of MCNS ceramics from n- to p-type semiconductors. Moreover, the aging coefficient (△R/R) of MCNS ceramics is found to be < 0.2%, which indicates the stable distribution of cations in the spinel. Finally, the MCNS ceramics demonstrate excellent thermal durability with < 1.3% of resistance shift after 100 thermal shock cycles.

Fast response and high stability Mn–Co–Ni–Al–O NTC microbeads thermistors

“…8 Mg 0.3 O 4 and MCN spinel nanoceramic microbeads via inkjet printing with a thermal time constant of about 147 ms. 10,11 Besides, suitable room temperature (RT) resistivity and receivable stability are desirable properties for commercial NTC thermistors. 12,13 Herein, Al-doped Mn 1.95x Co 0.21 Ni 0.84 Al x O 4 (MCNA) microbead thermistors were fabricated using in situ ink-jet printing, and the structure, microstructure, and electrical properties were systematically explored. The thermal stability and thermal time constant of ceramic materials were also characterized.…”