In-plane impedance spectroscopy in aerosol deposited NiMn2O4 negative temperature coefficient thermistor films

Abstract

Temperature dependent in-plane impedance spectroscopy measurements were carried out in order to analyze the charge transport properties of functional oxide NiMn2O4 negative temperature coefficient thermistor films deposited via aerosol deposition techniques onto glass and Al2O3 substrates. The in-plane resistivity (ρ) versus temperature (T) curves of all films were uniform over a large temperature range (180 K to 500 K) and showed the typical exponential power-law behavior associated with variable-range hopping. The ρ-T dependences of annealed and as-deposited films exhibited power-law exponents p of about 0.6 and thermistor constants B in the range of 3500 K to 5000 K. As-deposited films showed higher p values as compared to annealed films. As-deposited films exhibited also increased B values, leading to increased sensitivity of the resistance to temperature changes, whereas annealed films deposited on Al2O3 showed the lowest scatter in differentiated ρ-T data and might display superior reliability for temperature sensing applications.

LaNiO3 conducting particle dispersed NiMn2O4 nanocomposite NTC thermistor thick films by aerosol deposition

“…For the NMO powders, the composition selected was NMO + 0.05Co + 0.05Fe, since it shows not only a very high B constant (>5500 K), but also high RT resistivity (>100 kX cm) [16]. The detailed powder preparation procedures are described in our previous reports [9,14,15]. The average particle size of both NMO and LNO was in the vicinity of 1.5 lm.…”

“…In 2009, we reported the success of NMO thick films by using a room temperature powder spray in the vacuum process (so-called aerosol deposition (AD)) [14,15]. According to our previous report, AD can be used to fabricate nano-grained NTC thermistors which have a high thermistor B constant, but their RT resistivity is also very high, because of the large area of grain boundaries compared to the bulk ceramics with the same composition [14,15].…”

Electrical conduction of intrinsic grain and grain boundary in Mn-Co-Ni-O thin film thermistors: Grain size influence

“…It was shown previously that the macroscopic impedance of the NTC materials could be fitted with an equivalent circuit containing a series of one R-CPE (constant phase elements) and one R-C element or two parallel R-C elements representing GB and grain contributions. 8,[16][17][18][19][20] The data fitting was performed using commercial software (Z-View 2), where, for each experimental data point, an optimal value was obtained from the model. A temperature testing chamber with programming controller (MPC-2000 A) was used to support ac impedances at various temperatures.…”

Thermal Treatment of Aerosol Deposited NiMn2O4 NTC Thermistors for Improved Aging Stability

“…A new approach to produce film-based NTCR devices utilizes the Aerosol Deposition Method (ADM) [15,16,17,18,19,20]. With this novel spray coating process, dense ceramic NTCR films can be produced at room temperature and directly from a ceramic spinel-based starting powder on various substrate materials [21,22].…”