Cation distribution in manganese cobaltite spinels Co3−x Mn x O4 (0 ≤ x ≤ 1) determined by thermal analysis

Abstract

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Conduction mechanism in cobalt rich Co3-xMnxO4 (0.1 ≤ x ≤ 1.0) spinel oxide ceramics

“…These observations are in close agreement to those reported results on Co3-xMnxO4 ceramics prepared by spark plasma sintering [8,11]. The authors [11] suggest that the observed trend and changes in the electrical resistivity with varying Mn content in the range (0.1 < x < 0.…”

“…These observations are in close agreement to those reported results on Co3-xMnxO4 ceramics prepared by spark plasma sintering [8,11]. The authors [11] suggest that the observed trend and changes in the electrical resistivity with varying Mn content in the range (0.1 < x < 0. Considering the possibility for the two substitution mechanisms Co 3+  Mn 3+ or 2 Co 3+  Mn 4+ + Co 2+ to occur, it is seen clearly that from the analysis of the structural data, it is difficult to conclude the exact mixed valence states of cation distribution in the octahedral sites.…”

“…On the other hand it is a clear consensus towards the complete existence of Co 2+ cations at the tetrahedral sites. Bordeneuve, et al [11], have evoked the idea of the double mixed valence state at the octahedral sites involving Co 2+ /Co 3+ and Mn 3+ /Mn 4+ pairs occupying the octahedral sites to explain the significant increase in the resistivity and the semiconducting nature observed in the Co3-xMnxO4 system for Mn content (x < 0.4) by them. They also concluded that with the mixed valency cations distribution as proposed by them could explain the electron conduction through a polaron hopping mechanism, but did not report any detailed temperature dependent dc or ac conductivity studies to further corroborate their observations on mixed double valency that was established through thermo-gravimetric analysis.…”

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

“…Although the Co 2þ and Mn 4þ were independently refined by the BVS calculations, the results showed a similar trend for both concentrations and the variations of the cation distributions with composition using the two methods of calculation were generally very close. Finally, we compared the cation distributions determined in our ceramics with TGA analyzes performed on the Mn 3Àx Co x O 4 powders (1.99 x 3) used for preparing the ceramics (data to be published) [45]. For each composition of cubic spinel structure obtained at room temperature and measured in air up to 1300 C, two steps of decomposition were observed, corresponding to the reduction of Co III to Co 2þ followed by the reduction of Mn 4þ to Mn 3þ .…”

A Simple Preparation Process of Pure Mn3-Xcoxo4 (X= 1, 1.5 and 2) Desert Rose-Like Nanoparticles and Their Optical Properties

“…A final mass loss is observed for Co 2 MnO 4 and Co 1.5 Mn 1.5 O 4 starting at ~1000 °C and 1180 °C, respectively. According to our previous studies performed on ceramics of similar compositions (Bordeneuve, Rousset, Tenailleau, Guillemet-Fritsch, 2010b) . However, the reduction processes are not fully completed at the highest temperature of TGA measurements (T = 1300 °C) and it is not observed for CoMn 2 O 4 nanopowders, in accordance with previous results obtained on ceramics (Bordeneuve et al, 2010a).…”