Evolving microstructure, magnetic properties and phase transition in a mechanically alloyed Ni0.5Zn0.5Fe2O4 single sample

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:351

Article

Ismail, Ismayadi¹  Hashim, Mansor¹  Kanagesan, Samikannu¹  Ibrahim, Idza Riati¹  Nazlan, Rodziah¹  Ab Rahman, Wan Norailiana Wan¹  Abdullah, Nor Hapishah¹  Idris, Fadzidah Mohd¹  Bahmanrokh, Ghazaleh¹  Shafie, Mohd Shamsul Ezzad¹  Manap, Masni² 

[1] Univ Putra Malaysia, Inst Adv Technol ITMA, Mat Synth & Characterizat Lab, Serdang 43400, Selangor, Malaysia

[2] Univ Putra Malaysia, Fac Sci, Dept Phys, Serdang 43400, Malaysia

关键词: Ferrite;    Mechanical alloying;    Sintering temperature;    Microstructure evolution;    Ferromagnetic state;   

DOI  :  10.1016/j.jmmm.2013.09.041

来源: Elsevier

【 摘 要 】

We report on an investigation to unravel the dependence of magnetic properties on microstructure while they evolve in parallel under the influence of sintering temperature of a single sample of Ni0.5Zn0.5Fe2O4 synthesized via mechanical alloying. A single sample, instead of the normally practiced approach of using multiple samples, was sintered at various sintering temperatures from 500 degrees C to 1400 degrees C. The morphology of the samples was studied by means of scanning electron microscopy (SEM) equipped with EDX; density measurement was conducted using the Archimedes principle; and hysteresis measurement was carried out using a B-H hysteresisgraph system. XRD data showed that the first appearance of a single phase was at 800 degrees C and an amorphous phase was traced at lower sintering temperatures. We correlated the microstructure and the magnetic properties and showed that the important grain-size threshold for the appearance of significant ordered magnetism (mainly ferromagnetism) was about >= 0.3 mu m. We found that there were three stages of magnetic phase evolution produced via the sintering process with increasing temperatures. The first stage was dominated by paramagnetic states with some superparamagnetic behavior; the second stage was influenced by moderately ferromagnetic states and some paramagnetic states; and the third stage consisted of strongly ferromagnetic states with negligible paramagnetic states. We found that three factors sensitively influenced the sample's content of ordered magnetism-the ferrite-phase crystallinity degree, the number of grains above the critical grain size and the number of large enough grains for domain wall accommodation. (C) 2013 Elsevier B.V. All rights reserved.

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