Properties of Barium Ferrite Nanoparticles and Bacterial Cellulose-Barium Ferrite Nanocomposites Synthesized by a Hydrothermal Method

Abstract

<p>Barium ferrite (BFO) is a class of hard magnetic materials which is technologically important for many applications. Likewise, bacterial cellulose (BC) is a natural cellulose with a unique nanostructure and properties. Particularly, magnetic BC membrane, produced by incorporation of magnetic nanoparticles (NPs) in the BC structure, has recently been a research focus of many research groups. In this work, BFO NPs and BC/BFO nanocomposites were fabricated by hydrothermal synthesis. The BFO NPs could be fabricated only when the synthesis temperature reached 290 °C, with the faceted plate-like shape. Increasing the synthesis temperature gradually changed the magnetic properties from paramagnetic to superparamagnetic and ferromagnetic. Maximum M<sub>s</sub>, M<sub>r</sub> and H<sub>c</sub> of 43 emu/g, 21 emu/g, and 1.6 kOe, respectively, were found. For BC/BFO nanocomposites, the hydrothermal synthesis conditions were limited by the stability of BC, i.e., 150 – 210 °C (for 1 h), or 1 – 7 h (at 190 °C). Using the higher temperature or time resulted in disintegration or decomposition of BC. It was found that very small NPs were coated on the BC nanofibers but the BFO phase was not observed by XRD. However, the magnetic measurement showed the hysteresis loops for the nanocomposites synthesized at 190 °C for 3 – 7 h. The observation of the hysteresis loops could be attributed to a small fraction of BFO in the nanocomposite that cannot be detected by XRD. The BC/BFO nanocomposite membranes were demonstrated for their magnetic attraction, flexibility, and lightness, which make them potential uses for flexible information storage or lightweight magnets.</p>