Modification of the Structure and Magnetic Properties of Al2O3/Co(P) Composite Particles during Mechanical Activation
E. A. DENISOVA1,2, L. A. KUZOVNIKOVA3, S. V. KOMOGORTSEV1,2, R. S. ISKHAKOV1, I. V. NEMTSEV4, and N. A. SHEPETA2
1Kirensky Institute of Physics, Federal Research Center Krasnoyarsk Science Center, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, Russia
E-mail: len-den@iph.krasn.ru
2Siberian Federal University, Krasnoyarsk, Russia
3Krasnoyarsk Institute of Railways Transport, Krasnoyarsk, Russia
4Federal Research Center Krasnoyarsk Science Center, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, Russia
Keywords: composite particles, mechanoactivation, magnetic properties
Pages: 495-499
Abstract
Changing the structure and magnetic properties of composite Al2O3/Co(P) particles was investigated in a ball mill. The initial particles were produced by electroless plating of the crystal Co95P5 shell characterized by the hexagonal dense packed structure into Al2O3 granules by chemical reduction. It was determined that the sequences of phase transitions during mechanoactivation was different for Co95P5 particles and composite Al2O3/Co95P5 species. The use of composite particles allows significantly reducing mechanoactivation time required for producing the optimum phase ratio of α/β cobalt in powders. Grain size reduction during milling causes an increase in the fraction of superparamagnetic particles reaching 12 % upon mechanical activation for 75 min, which causes a decrease in the value of saturation magnetization. Changing the magnetic properties of composite particles during ball milling correlates with structural modification of samples. The amount of the hexagonal dense packed cobalt phase in the sample determines the value of the field of local magnetic anisotropy. The latter is reduced from 8.4 to 3.8 kOe upon an increase in mechanoactivation time to 75 min.
DOI: 10.15372/CSD20180507
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