Faculty Publications
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Item Effect of temperature on magnetic and impedance properties of Fe3BO6 of nanotubular structure with a bonded B2O3 surface layer(American Institute of Physics Inc. subs@aip.org, 2018) Kumari, K.; Ram, S.; Kotnala, R.K.In this investigation, we explore a facile synthesis of Fe3BO6 in the form of small crystallites in the specific shape of nanotubes crystallized from a supercooled liquid Fe2O3-B2O3 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 Fe3BO6 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 Fe3BO6 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 Fe3BO6 conductor with a reasonably small activation energy Ea ? 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 Fe3BO6 crystallites tunes the 3d ? 3d electronic transitions in Fe3+ ions. © 2018 Author(s).Item Structural, vibrational and surface analysis of Fe3BO6 nanoplates synthesized by combustion method(Elsevier B.V., 2018) Kumari, K.In the present investigation, a simple synthesis method is explored involving a self-combustion of a solid precursor mixture of iron oxide (Fe2O3) and boric acid (H3BO3) using camphor (C10H16O) as fuel in microwave oven in order to form a single phase Fe3BO6 crystallites. An as-prepared ceramic powder in this way after combustion of a precursor, which contained a lot of residual carbon left after the combustion, was reheated at 400 °C to burn it out as oxide in a reaction with air. This is a very simple and fast method to form a phase pure compound from usual metal salts with functional properties. The size and morphology of the Fe3BO6 crystallites has been characterized in terms of X-ray diffraction (XRD) pattern in correlation to the field emission scanning electron microscopy (FESEM) image. A single phase compound Fe3BO6 of an orthorhombic crystal structure with Pnma space group and average crystallites size D = 46 nm is analyzed from the XRD pattern. IR/Raman and X-ray photoelectron spectroscopy (XPS) spectra studied for the Fe3BO6 samples in this investigation elucidate how the density of states of the phonons and valence electrons confine in small crystallites. The XPS bands in Fe3+, B3+ and O2? species and IR/Raman bands in the oxygen polygons confer the results of forming Fe3BO6 with a bonded surface layer. © 2018 Elsevier B.V.Item Thermal stability and spectroscopic properties of Fe 3 BO 6 of small crystallites with a bonded carbon surface layer(Elsevier Ltd, 2019) Kumari, K.A well-known canted antiferromagnetic Fe 3 BO 6 with functionalized properties is an important material useful for light energy carrier, electrodes, gas sensors, and biological probes. In this investigation, a facile synthesis is explored in order to obtain Fe 3 BO 6 of small crystallites in a specific shape of nanoplates by self-combustion method. To access (i) whether Fe 3 BO 6 is formed at the as-prepared stage and (ii) how it stands stable with a residual carbon surface layer, thermal gravimetric (TG) analysis has been carried out by heating 10–20 mg powder (as-prepared) at a typical 10 K/min heating rate over 300–1100 K under air or argon atmosphere. The electronic absorption, infrared (IR) and Raman spectra studied for the Fe 3 BO 6 sample in this investigation elucidate how the density of states of the phonons and valence electrons confine in small crystallites. IR and Raman bands in the oxygen polygons also confer the results of forming Fe 3 BO 6 with a bonded surface carbon layer. A stable bonded surface layer supports thermal stability of small crystallites and it affects other useful functional properties. © 2018 Elsevier B.V.