ARTICLE INFO Keywords: A powders: chemical preparation D transition metal oxides D spinels C magnetic properties

This paper presents synthesis and analysis of critical behavior of (Ni,Zn,Fe,Cu,Mn)(3)O-4 spinel-oxide ceramics near magnetic phase transition. In order to investigate the critical point, a modification of the standard analysis of Arrott-Noakes diagrams was proposed. This new approach takes into account the quality of straightness of isotherms and the fact that the critical straight line (at T = Tc) must pass through the origin of the coordinate system. The determined values of critical parameters beta = 0.446, gamma =1.179, and delta = 3.637 are close to those of the mean-field model (beta = 0.5, gamma = 1, and delta = 3) signifying mainly the isotropic, long-range exchange interactions in the studied ceramic oxide. The self-consistency of the obtained results was confirmed taking into account the scaling theory, and the asymptotic relations for the behaviour of magnetization M in the limits as T-*T-c and H-*0.

Automated summary

This paper presents the synthesis and analysis of critical behavior of (Ni,Zn,Fe,Cu,Mn)(3)O-4 spinel-oxide ceramics near magnetic phase transition. A new approach of analyzing Arrott-Noakes diagrams is proposed, which considers the quality of the straightness of isotherms and the requirement of the critical straight line passing through the origin. The obtained results indicate mainly isotropic, long-range exchange interactions in the studied ceramic oxide.