Synthesis, Phase Characterization, and Properties of Chemical Solution‐Deposited Nickel Manganite Thermistor Thin Films

Abstract

Nickel manganite spinel thin films prepared by chemical solution deposition exhibit negative temperature coefficient of resistance (TCR) values between −3.3 and −4.5%/K. In contrast to bulk thermistors, dense films could be prepared completely within the spinel phase field. Thus, decomposition into the NiO phase and a Mn‐rich spinel, which is problematic in bulk ceramics, is minimized in thin films. For films prepared outside of the single‐phase field, phase separation cannot always be detected using X‐ray diffraction. In such cases, transmission electron microscopy is useful in identifying decomposition. It is found that the lattice parameters for films with compositions ranging between Mn/(Mn+Ni)=0.14 and 0.77 are smaller than the values reported for nickel manganite spinels, suggesting cation deficiency. Single‐phase spinel films are compared with single‐phase bixbyite films synthesized between 630° and 930°C. The bixbyite phase exhibits lower TCR and lower resistivity (TCR=−3.1 to −3.3%/K and resistivity values=400–1600 Ω·cm) compared with spinel (TCR=−3.6 to −4.1%/K and resistivity values=3500–21 000 Ω·cm). Composite films (achieved by controlling the pyrolysis to create a low local pO2 during annealing) show intermediate values (TCR=−3.0 to −3.8%/K and resistivity values=470–6600 Ω·cm).

Preparation and characterization of NiMn2O4 negative temperature coefficient ceramics by solid-state coordination reaction

“…NiMnO 3 and aMn 2 O 3 were not detected in the 700-, 750-, and 800°C-calcined powders. As previously reported [2,13,[23][24][25][26], within the temperature range of 450-550°C, NiMn 2 O 4 reacts with oxygen and decomposes into NiMnO 3 and aMn 2 O 3 , but it does not occur in inert atmosphere. The NiMnO 3 and a-Mn 2 O 3 phases are stable in the temperature range of 550-750°C [27,28].…”

“…Manganese-based, transition metal, spinel oxide ceramics, with the general formula AB 2 O 4 , have generated much interest as negative temperature coefficient (NTC) thermistors in various domestic and industrial applications owing to their high temperature sensitivity, fast response, convenience in use, and low cost [1][2][3]. In the spinel structure, the oxygen anions are arranged in a cubic close-packed configuration with cations occupying one-eighth of the tetrahedral interstices (A sites) and half of the octahedral interstices (B sites) [4,5].…”

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

“…[12][13][14] Nevertheless, the pure NMO compound is still the subject of recent research efforts in order to establish new and more efficient synthesis routes [15][16][17][18][19][20][21] and thin and thick film production techniques. [22][23][24][25][26][27][28][29][30][31] Furthermore, the interplay between the physical properties and the Ni and Mn cation distribution on the tetrahedral and octahedral sublattices is still a matter of debate.…”

Effect of La2O3 Addition on Copper‐Nickel Manganese Thermistors for Low‐Temperature Applications

“…X-ray Diffraction Analysis Figure 1 shows the X-ray diffraction patterns of Mn 0.75 Ni 1.25 CuO 4 -xLa 2 …”

“…[1][2][3][4][5] They can also be employed at low temperatures for high resistance to magnetic field-induced errors and ionizing radiation. [1][2][3][4][5] They can also be employed at low temperatures for high resistance to magnetic field-induced errors and ionizing radiation.…”