Cluster-glass-like behavior in zinc ferrite nanograins

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:467

Article

Procopio, E. F.¹  Larica, C.¹  Muniz, E. P.²  Litterst, F. J.³  Passamani, E. C.¹ 

[1] Univ Fed Espirito Santo, Phys Dept, BR-29075910 Vitoria, ES, Brazil

[2] Univ Fed Espirito Santo, Nat Sci Dept, BR-29932540 Sao Mateus, ES, Brazil

[3] Tech Univ Carolo Wilhelmina Braunschweig, Inst Phys Kondensierten Mat, D-38106 Braunschweig, Germany

关键词: Ferrites;    Fe-57 Mossbauer spectroscopy;    Magnetic susceptibility;    Cluster glass;   

DOI  :  10.1016/j.jmmm.2018.07.057

来源: Elsevier

【 摘 要 】

Structural and magnetic properties of ZnFe2O4 nanograins, prepared by high-energy ball milling and annealed, were systematically studied by X-ray diffraction, Fe-57 Mossbauer spectroscopy and AC magnetic susceptibility measurements. Disordered spinel-like structure, with a grain size of 12 nm, is established after 200 h of milling. While the 300 K Mossbauer spectrum of the as-milled sample (200 h) displays broad magnetic absorption lines, characteristic of a disordered system, the magnetization data do not show a magnetic phase transition between 4 and 300 K. At low temperatures, the Mossbauer spectra suggest the presence of two distinct ferrite magnetic phases: one attributed to the grain core (crystalline-like phase), with magnetic ordering temperature of about 90 K, and one showing a magnetic hyperfine field distribution; the latter is associated with a chemically disordered phase (grain boundary contributions). Annealing the 200 h sample at 973 K leads to an improvement of atomic ordering of the spinel structure (reduction of cationic inversion) and average grain size of about 17 nm. AC magnetic susceptibility shows a cusp at about T approximate to 30 K, whilst Mossbauer experiments in the same sample reveal magnetic blocking in the same temperature range. The frequency dependence of susceptibility suggests the formation of a cluster-glass-like state. High temperature susceptibility can be described with a Fulcher law of interacting magnetic clusters.

【 授权许可】

Free