Studies of temperature dependent ac impedance of a negative temperature coefficient Mn-Co-Ni-O thin film thermistor

Abstract

Mn 1.85 Co 0.3 Ni 0.85 O 4 thin films with single cubic spinel phase and compact surface were prepared by chemical solution deposition method on Al2O3 substrates. Temperature dependent ac impedance spectroscopy was employed to analyze the contributions of grain boundary (GB) and grain to the conduction mechanism. The major characteristics (hopping type, resistance versus temperature behavior, and characteristic temperature T0) of the GB and grain were obtained. The hopping type of GB is nearest-neighbor-hopping (NNH), and that of grain might be a transition from variable-range-hopping to NNH. The GB shows dominating resistance while the grain shows stronger temperature dependence.

Effect of Cu and Fe addition on electrical properties of Ni–Mn–Co–O NTC thermistor compositions

“…Ni-Mn-Co-O ceramic system has already been identified as an excellent choice of NTC composition for many applications [9][10][11]. The electrical properties can be fine tuned by co-doping various transition metal ions including Cu, Fe, Zn, etc.…”

Hopping conduction in (Ni,Co,Mn)O4 prepared by different synthetic routes: Conventional and spark plasma sintering

“…As can be seen in Figure. In VRH conduction mode, activation energy as well as hopping distance may vary as a function of temperature. [10,[17][18][19] To calculate hopping distance as a function of temperature, the DOS at the vicinity of Fermi level ( g ) need to be obtained, and g is related with the characteristic temperature (T 0) as,…”

Zr-substituted SnO2-based NTC thermistors with wide application temperature range and high property stability

“…Traditional NTC ceramic thermistors are always composed of transition-metal compounds with the Ni-and Mn-based spinel structure such as Mn-Ni-O, Ni-Cu-Mn-O and Mn-CoNi-O systems, etc. [1][2][3]. However, the structural relaxation taken place in those compounds leads to property degradation, known as aging, and limits their applications at elevated temperatures such as [200°C [4,5].…”