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

Abstract

Ceramic are used in a wide range of applications such as temperature sensors, controllers, infrared detectors, voltage regulators, and delay devices due to their many excellent properties and negative temperature coefficient. [1][2] Moreover, ternary spinel compounds, i.e. (Mn 3x-y Co x Ni y )O 4 (MCN), render promising electrical properties due to their easy fabrication and outstanding properties. 3,4,5 Recently, the high sensitivity to temperature changes and fast response NTC materials are urgently needed for use in special environments, such as flexible temperature sensor, biomaterials, food engineering, and heat flow. Microbead NTC thermistors present several advantages, such as relative small size, fast responses, and lower energy consumption. 6,7 As a novel additive manufacturing (AM) technique, ink-jet printing (IJP) has been widely used to fabricate numerous materials such as Li-ion batteries and sensors. 8,9 Comparing

The Effects of Sn Doping MnNiFeO4 NTC Ceramic: Preparation, Microstructure and Electrical Properties

“…Negative temperature coefficient (NTC) ceramic thermistors based on transition metal oxides, are widely applied in temperature measuring, controllers, time-delay devices, infrared detectors, and voltage regulators [1][2][3][4][5][6]. NiMn 2 O 4 based spinel-type NTC ceramic thermistors have been researched widely for their modifiable structure and properties [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. For pure NiMn 2 O 4 , the homogeneous spinel phase is obtained with difficultly due to the NiO phase segregation occurring above 950 • C during sintering in air, and separation of α-Mn 2 O 3 and the ilmenite type NiMnO 3 during cooling below 730 • C. In contrast, ternary or plural transition metals systems can form more stabilized spinel structures, especially for ternary Mn-Ni-Fe-O 4 or Mn-Co-Fe-O 4 systems [5,7].…”

“…Tetravalent ions Zr 4+ , Si 4+ , Sn 4+ and Ti 4+ doped in Mn 3−x−y Ni x Fe y O 4 were studied, in order to modify properties of the spinel thermistors by B-site ion substitution in the spinel structure, and the specific resistivity and sensitivity were increased [19][20][21][22][23]. Doping strategies of trivalent ions In 3+ , Al 3+ and Cr 3+ [13][14][15][16][17][18] and bivalent ions Cu 2+ , Zn 2+ and Mg 2+ [9][10][11][12] were reported as well, which all modulated the thermistor properties by the B-site ion substitution. It is well-accepted that the conductivity mechanism for transition metal oxide thermistors belongs to a thermally activated phonon-assisted hopping mechanism of charge carriers between Mn 4+ and Mn 3+ on crystallographically equivalent lattice B sites in the spinel structure.…”