Aging of nickel manganite NTC ceramics

Abstract

Effect of thermal history and chemical composition on aging of Ni x Mn 3−x O 4+δ (0.56≤x≤1.0) ceramics was investigated. It was found that all the Ni x Mn 3 − x O 4+δ ceramic samples metallized by co-firing at 1050°C showed significant electrical stability with an aging coefficient less than 1.0%, while aging of those metallized by annealing at 850°C was increasingly serious with a rise in Ni content x, the aging coefficient ranging from 0.2% to 3.8%. However, the ceramic samples with Ni content x≤0.70, whether metallized by co-firing or by annealing, exhibited extraordinarily high electrical stability with an aging coefficient less than 0.5%. The composition dependence of aging of the ceramic samples was explained qualitatively, based on the electrical conduction mechanism of small polaron hopping and on the aging mechanism of the cationic vacancy-assisted migration of cations to their thermodynamically preferable sites under thermal stress.

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

“…Due to their high negative temperature coefficient (NTC), nickel manganites are a well-known and a widely used base materials class for ceramic NTC thermistors in industry [2,3]. They are characterized by low costs and high reliability and are used in particular for temperature measurement and compensation [4,5,6]. Their high temperature dependence of the electrical resistance is the result of a small polaron hopping-based conductivity mechanism [7] and can be simplified by the Arrhenius relationship: R ( T ) = R 0 exp( E A /( k B · T )) where R 0 is the resistivity at an infinite temperature, E A the activation energy for the hopping process, k B the Boltzmann constant and T the absolute temperature [8,9].…”

“…Especially the temperature, the atmosphere, and the cooling rate during sintering, but also during subsequent electrode firing (e.g., ‘serigraphy’, a process commonly used in industry), have been found playing a decisive role [6,24,26,27]. While the aging resistance of bulk ceramics decreases due to thermal post-treatment (e.g., by metallization at 850 °C [6]), the aging resistance of thin films is improved by subsequent tempering up to 750 °C [28]. To what extent thermal treatment affects the aging resistance of aerosol-deposited thick films and whether there are interactions with the electrodes will be investigated in this paper.…”

Preparation and characterization of Cu and Zn modified nickel manganite NTC powders and thick film thermistors

“…The material constant B (B-value) is defined as E a /k (with unit temperature in Kelvin) and represents the measure of sensitivity of the thermistor device over a given temperature range. Three parameters are most often used to characterize NTC thermistors: 25 -the specific resistivity at room temperature (usually 25 • C), B -the material constant and the aging value that describes the stability of NTC thermistors over time [17]. The electrical properties of nickel manganite based spinel oxides depend strongly on the composition of metal oxides and the microstructure of ceramic materials that effect the cation distribution in the spinel structure [18].…”

“…Besides Ni and Mn present in the cubic nickel manganite spinel oxide, different elements such as Cu, Zn, Fe, Co, Mg, Si have been added in varied amounts and combinations while retaining the cubic spinel structure [1,3,8,14,15]. Addition of other metal elements influences the three basic thermistor parameters -25 , B-value and stability in different ways [17][18][19][20][21][22][23][24][25]. These parameters are also strongly influenced by the manufacturing conditions that include the powder preparation procedure and processing conditions such as the sintering temperature, rate of cooling and sintering duration.…”

Low-frequency noise and reliability of infrared detectors based on ternary Mn-Ni-Co

“…The effect of thermal and current stress on the resistivity of the infrared detectors during ageing mainly arises from four sources: (1) The disproportionation of [Mn3+]/[Mn4+] ions in the octahedral sites combined with an exchange of nickel between sublattice, results in a decrease in effective concentration of charge carriers, Mn3+Mn4+, and a consequent increase in resistivity [3], (2) The cationic vacancy-assisted migration of cations to their thermodynamically preferable sites under stress [4], (3) The thermal treatment during the metallization used to bond electrodes on ceramics may trigger the ageing phenomenon [5], [6], and (4) The oxidation which occurs during cooling down in air after sintering may also trigger ageing [7]. Fig.…”