Effect of temperature on magnetic and impedance properties of Fe3BO6 of nanotubular structure with a bonded B2O3 surface layer

Abstract

In this investigation, we explore a facile synthesis of Fe<inf>3</inf>BO<inf>6</inf> in the form of small crystallites in the specific shape of nanotubes crystallized from a supercooled liquid Fe<inf>2</inf>O<inf>3</inf>-B<inf>2</inf>O<inf>3</inf> precursor. This study includes high resolution transmission electron microscopy (HRTEM) images, magnetic, optical, and impedance properties of the sample. HRTEM images reveal small tubes of Fe<inf>3</inf>BO<inf>6</inf> of 20 nm diameter. A well resolved hysteresis loop appears at 5 K in which the magnetization does not saturate even up to as high field as 50 kOe. It means that the Fe<inf>3</inf>BO<inf>6</inf> nanotubes behave as highly antiferromagnetic in nature in which the surface spins do not align along the field so easily. The temperature dependent impedance describes an ionic Fe<inf>3</inf>BO<inf>6</inf> conductor with a reasonably small activation energy E<inf>a</inf> ? 0.33 eV. Impedance formalism in terms of a Cole-Cole plot shows a deviation from an ideal Debye-like behavior. We have also reported that electronic absorption spectra are over a spectral range 200-800 nm of wavelengths in order to find out how a bonded surface layer present on the Fe<inf>3</inf>BO<inf>6</inf> crystallites tunes the 3d ? 3d electronic transitions in Fe3+ ions. © 2018 Author(s).