Synthesis and magnetic properties of nano Ba‐hexaferrite/NiZn ferrite composites

Abstract

Ba‐hexaferrite and Ni0.5Zn0.5 ferrite nano composites have been successfully fabricated by a self‐propagating combustion method. Transmission electron microscopy and X‐ray diffractometer analysis showed that two ferrite phases were homogeneously distributed and the measured grain size of them around 20nm. The saturation magnetizations of the composites were revealed to be increased compared with the theoretical values. These increments of the saturation magnetization values could be explained by the exchange spring interaction between soft and hard magnetic phases. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrochemical preparation and magnetic properties of submicrometric core–shell CoPt–CoNi particles

“…The energy product of the core-shell particles (area included in the hysteresis loop) can be regulated from the ratio of the core and shell phases. The electrodeposition method has been demonstrated useful to prepare core-shell particles than can actuate as an exchange-spring system as an easier and alternative method to other preparation ones [18,26].…”

“…These systems can combine the high magnetization of soft phase with the coercivity of hard phase to attain a high energy product to obtain a maximum magnetic energy product [17]. A system is recognized as an exchange spring magnet when both phases are coupled to each other [18,19]. In this case, the high saturation magnetization of the soft phase and the high coercivity of the hard phase confer better magnetic properties of the composite compared to the individual soft and hard phases, thus providing high magnetic energy product [20].…”

“…Although recently there has been an important increase in the interest of modulated magnetic properties, the study of these kinds of systems combining soft and hard ferromagnets has not improved significantly because of the lack of effective fabrication methods. It is desirable to work with moderate particle size of soft and hard phases, which guarantees a high remanence and sufficient high coercivity [18].…”

Preparation of magnetic composites through SrO-Fe2O3-Al2O3-B2O3 glass crystallization

“…Their size markedly exceeds the critical size for single-domain behavior of strontium hexaferrite, and hence their coercivity is not very high. This sample has a wasp-waisted magnetic hysteresis loop, characteristic of materials consisting of both high-and low-coercivity particles [11,12]. At the same time, the sample prepared at 850°ë has a pot-bellied loop (Fig.…”

Magnetic hard/soft nanocomposite ferrite aligned hollow microfibers and remanence enhancement

“…There are several processes to prepare hard-soft nanocomposite ferrites, such as co-precipitation [21], self-propagate [22], solid-state reaction [6], decomposition [23,24] and sol-gel method [25,26]. But, most works are focused on the powders.…”