Strain induced anomalous red shift in mesoscopic iron oxide prepared by a novel technique

Abstract

Nano magnetic oxides are promising candidates for high density magnetic storage and other applications. Nonspherical mesoscopic iron oxide particles are also candidate materials for studying the shape, size and strain induced modifications of various physical properties viz. optical, magnetic and structural. Spherical and nonspherical iron oxides having an aspect ratio, ~2, are synthesized by employing starch and ethylene glycol and starch and water, respectively by a novel technique. Their optical, structural, thermal and magnetic properties are evaluated. A red shift of 0⋅24 eV is observed in the case of nonspherical particles when compared to spherical ones. The red shift is attributed to strain induced changes in internal pressure inside the elongated iron oxide particles. Pressure induced effects are due to the increased overlap of wave functions. Magnetic measurements reveal that particles are superparamagnetic. The marked increase in coercivity in the case of elongated particles is a clear evidence for shape induced anisotropy. The decreased specific saturation magnetization of the samples is explained on the basis of weight percentage of starch, a nonmagnetic component and is verified by TGA and FTIR studies. This technique can be modified for tailoring the aspect ratio and these particles are promising candidates for drug delivery and contrast enhancement agents in magnetic resonance imaging.

Magnetic, X-ray and Mössbauer studies on magnetite/maghemite core–shell nanostructures fabricated through an aqueous route

“…S2 †). 55 It is interesting to note that the estimated (D XRD ) from the W-H technique for all the nanocrystals are within D TEM À2.5 nm as the shell of amorphous layer has not contributed to the X-ray diffraction. The deviation is more in the crystals synthesized at higher temperatures.…”

Artificially Stacked Atomic Layers: Toward New van der Waals Solids

“…After characterizing structurally our new-stacked solid, we address the optical properties of this material. − We first look at the ultraviolet–visible absorption spectrum shown in Figure d. The adsorption edge of exfoliated h-BN is located at 236 nm, which corresponds to an optical band gap of 5.26 eV.…”

Sol-gel synthesis and characterization of magnetic TiO2 microspheres

“…1(a)) gave sharp peaks at 18.32, 30.10, 35.46, 43.08, 53.66, 57.07, and 62.64°in 2ª, showing that the synthesized nanoparticles could be identified as £-Fe 2 O 3 with a spinel structure (ICDD = 39-1346). 20) As shown in Fig. 1(b), the obtained iron oxide powder had an average particle size around 24 nm.…”