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Control of Magnetic Properties of NiMn2O4 by a Microwave Magnetic Field under Air

Department of Applied Chemistry, Tohoku University, Aoba Aramaki, Sendai, Miyagi 980-8579, Japan
Author to whom correspondence should be addressed.
Academic Editor: Dinesh Agrawal
Materials 2016, 9(3), 169;
Received: 29 December 2015 / Revised: 3 February 2016 / Accepted: 24 February 2016 / Published: 4 March 2016
(This article belongs to the Special Issue Microwave Materials Processing)
PDF [1372 KB, uploaded 4 March 2016]


NiMn2O4 prepared by conventional heating was irradiated with a microwave H-field using a single-mode cavity under air and magnetic properties of the microwave-irradiated material were investigated. X-ray diffraction and transmission electron microscopy demonstrated that the phase and microstructure are not affected by H-field irradiation. Measurements of the magnetization as a function of temperature revealed that the antiferromagnetic sublattice disappeared and electron spin resonance showed the existence of Mn2+, suggesting that Mn3+ is partially reduced. Moreover, the magnetization of NiMn2O4 was controlled from 35.3 to 18.2 emu/g and the coercivity from 140 to 750 Oe by changing the sample temperature during microwave irradiation. The reduction reaction of NiMn2O4 is controlled by microwave H-field irradiation, resulting in control over the magnetic properties. View Full-Text
Keywords: microwave H-field irradiation; manganese spinel oxides; reduction reaction microwave H-field irradiation; manganese spinel oxides; reduction reaction

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Goto, H.; Fukushima, J.; Takizawa, H. Control of Magnetic Properties of NiMn2O4 by a Microwave Magnetic Field under Air. Materials 2016, 9, 169.

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