Nickel manganese oxide explained

Nickel manganese oxides,^[1] or nickel manganates, are spinel structure compounds of Nickel, Manganese and Oxygen of the form: ^{[2] [3]}

Some common forms are Ni₂MnO₄, NiMn₂O₄, and Ni_1.5Mn_1.5O₄

They are most commonly formulated for use in thin film resistors and thermistors.^[4] The resistivity and temperature coefficient can be accurately controlled in the manufacturing process. In nickel-metal hydride batteries the addition of manganese oxide provides for formation of spinel structure nickel manganates in various oxidation states, with higher conductivity and charge capacity than nickel hydroxides alone.

Magnetic properties of nickel manganates.Although nickel manganates exhibit ferromagnetic behaviour at low temperatures, they have a paramagnetic behavior at room temperature. The magnetic behavior depends on the cation distribution and spin alignment among them. In nickel manganates, the Ni²⁺ and Mn⁴⁺ ions have a strong preference for occupying octrahedral sites instead of tetrahedral sites. Mn²⁺ ion is in tretrahedral sites and Mn³⁺ ion can be in both sites. Also, these compounds has been studied as electrodes for supercapacitors and as photocatalyst taking advantage of the Change in the oxidation state of the Mn catios. ^[5]

Notes and References

1. Alkaline-stable nickel manganese oxides with ideal band gap for solar fuel photoanodes . Chemical Communications. 54. 36. Suram . Santosh K. . Zhou . Lan . 2018-05-01 . 4625–4628 . en-US . US . 10.1039/c7cc08002f . 29671420 . Shinde . Aniketa . Yan . Qimin . Yu . Jie . Umehara . Mitsutaro . Stein . Helge S. . Neaton . Jeffrey B. . Gregoire . John M..
2. Periyasamy. Sivakumar. Subramanian. Palaniappan. Levi. Elena. Aurbach. Doron. Gedanken. Aharon. Schechter. Alex. 2016-05-18. Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction. ACS Applied Materials & Interfaces. 8. 19. 12176–12185. 10.1021/acsami.6b02491. 27123873. 1944-8244.
3. Web site: Structure and Physical Properties of Nickel Manganite NiMn2O4 Obtained from Nickel Permanganate Precursor. ResearchGate. en. 2019-01-20.
4. Sarrión. Maria Luisa Martínez. Morales. Manuel. 1995. Preparation and Characterization of NTC Thermistors: Nickel Manganites Doped with Lithium. Journal of the American Ceramic Society. en. 78. 4. 915–921. 10.1111/j.1151-2916.1995.tb08414.x. 1995JACS...78..915M. 1551-2916.
5. Ortiz-Quinonez . Jose Luis . Ramos Ramon . Jesús Alberto . de Anda Reyes . Maria Eunice . Ray . Apurba . Das . Sachindranath . Pal . Umapada . Structure and magnetic behavior of sol-gel grown spinel NixMn3-xO4 nanoparticles: Effect of Ni fraction and induction of superparamagnetism at room temperature . Materials Research Bulletin . 2021 . 139 . 111267 . 10.1016/j.materresbull.2021.111267. 233976344 .