Preparation and characterization of manganese and cobalt based semiconducting ceramics

Electrical Properties of Mn3−xCoxO4 (0 ≤ x ≤ 3) Ceramics: An Interesting System for Negative Temperature Coefficient Thermistors

“…). The substitution of Mn 3+ ions by Co 2+ and Mn 4+ ions according to the transformation schematic 2Mn 3+ oh → Co 2+ oh + Mn 4+ oh , with the creation of Mn 3+ /Mn 4+ couples, was also considered in the past , but the Co 2+ [Co 2+ y Mn 3+ 2−2 y Mn 4+ y ]O 2− 4 model, with 0 < y < 1 and y = x − 1, gives a y value of 1. Therefore, MnCo 2 O 4 should be an insulator, in contradiction with the experiments that showed a maximum of conductivity around this composition (see Fig.…”

Structural variations and cation distributions in Mn3−xCoxO4 (0≤x≤3) dense ceramics using neutron diffraction data

“…The medium resolution and high intensity powder diffractometer Polaris has four detector banks that measure simultaneously: the backscattering and low angle banks using 3 He gas tube detectors, and 90 and very low angle detector banks using ZnS scintillators. Only the time-of-flight data collected from the 58 backscattering detectors, that offer the best resolution over a large range of d-spacings (0.2-3.2 ), and obtained after 30 min-2 h depending on the amount of sample, were used for structural determination.…”

“…Neutron diffraction patterns were also collected at room temperature with the high resolution 2D neutron detector available at the ILL. The Super D2B instrument has a 135 take-off angle and 128 3 He detectors. Powder diffraction patterns were recorded using a 1.5941 Å wavelength in the 10-145 2q domain with a 0.05 step and nine scans of 200,000 Â 1,2 or 4 counts.…”

“…due to their element abundance, low cost and toxicity, and electrical characteristics. These materials are often used as negative temperature coefficient (NTC) thermistors in microelectronic systems due to their non-linear resistivity variation with temperature [1][2][3][4].…”

Microstructure of single-phase cobalt and manganese oxide spinel Mn3−xCoxO4 ceramics

“…Very few studies [34][35][36][37][38][39][40][41] had been performed on the Mn-Co-O system before the works conducted in our laboratory. They have involved more detailed works on films and powders than on ceramics.…”