Self-Assembled Bismuth Oxide Microrods Prepared by a Facile Chemical Method

Bismuth oxides (Bi2O3) are of interest because of their suitable band gaps for photocatalytic activity. Herein, a-Bi2O3 microrods were synthesized by a facile chemical method, and were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The results showed that the particles were rod-shaped with lengths in the range of 5-10 mm. Crystalline structure of the particles was monoclinic, and the band gap was around 2.88 eV.  When citric acid was used in the synthesis, the bismuth oxide microrods can self-assemble into the hierarchical flower-like structures leading to the alteration of band gap. This self-assembled a-Bi2O3 microstructure can be employed as a photocatalyst with alterable band gap

Synthesis of Patterned Media by Self-Assembly of FePt Nanoparticles

Patterned media is one of the most promising candidates for ultrahigh magnetic storage. Commonly, electron beam lithography is used to synthesize a very high areal density media beyond 1 Tb/in2. However, such techniques require very high budgets and are time consuming. Self-assembly of magnetic nanoparticles, especially FePt nanoparticles, has been realized as another prominent technique. Nevertheless in order to successfully exploit FePt nanoparticle self-assembly in patterned media fabrication, FePt nanoparticles of proper composition with the desired size and shape as well as a technique to control the assembled behavior of the particles in long range order are required. This review is focused on the chemical synthesis of FePt nanoparticles and how the particles self-assemble into regular arrays. Graphical abstrac

Magnetic Properties and Morphology Copper-Substituted Barium Hexaferrites from Sol-Gel Auto-Combustion Synthesis

The copper (Cu) substitution in barium hexaferrite (BaFe12O19) crystals from the sol-gel auto-combustion synthesis is demonstrated as a cost-effective pathway to achieve alterable magnetic properties. Subsequent heat treatments at 450 °C and 1050 °C result in irregularly shaped nanoparticles characterized as the M-type BaFe12O19 with the secondary phase of hematite (α-Fe2O3). Despite the mixed phase, the substantial coercivity of 2626 Oe and magnetization as high as 74.8 emu/g are obtained in this undoped ferrite. The copper (Cu) doing strongly affects morphology and magnetic properties of BaFe12−xCuxO19 (x = 0.1, 0.3, and 0.5). The majority of particles become microrods for x = 0.1 and microplates in the case of x = 0.3 and 0.5. The coercivity and magnetization tend to reduce as Cu2+ increasingly substitutes Fe3+. From these findings, magnetic properties for various applications in microwave absorbers, recording media, electrodes, and permanent magnets can be tailored by the partial substitution in hexaferrite crystals

Synchrotron X-Ray Absorption Spectroscopy Study of Self-Assembled Nanoparticles Synthesized from Fe(acac)3 and Pt(acac)2

The synchrotron X-ray absorption technique was used to complement electron microscopy in the investigation of nanoparticles synthesized from the coreduction of iron acetylacetonate, Fe(acac)3 and platinum acetylacetonate, Pt(acac)2. A much higher Pt composition than Fe leads to an extended X-ray absorption fine structure (EXAFS) spectrum for the sample that differs from that of fcc FePt nanoparticles. Most importantly, X-ray absorption near-edge structure (XANES) spectra clearly indicate the existence of α-Fe2O3 and Pt metal. Since these monodisperse nanoparticles have a diameter of around 4 nm and tend to self-assemble into hexagonal arrangements, they can be modeled as Pt-rich cores with an α-Fe2O3 shell stabilized by organic surfactants

Composition study of FePt nanoparticles synthesized from modified polyol process

338-342F<span style="mso-bidi-font-size: 15.0pt;mso-bidi-language:TH" lang="EN-GB">ive different conditions for modified polyol processes using iron(III) acetylacetonate and platinum(II) acetylacetonate as starting materials reveal significantly different products in terms of composition. The initial Fe:Pt molar ratio is not retained in the final products and Pt-rich nanoparticles are obtained from 1:1 molar ratio of Fe:Pt sources. The imbalance between Fe and Pt indicate that the nanoparticles formation can be explained by the heterocoagulation mechanism rather than the binary nucleation model. The increase in refluxing time and initial Fe:Pt molar ratio improved the amount of Fe in nanoparticles. However, the highest molar ratio of 3:1 apparently affected the uniformity of particles. The co-existence of iron oxide and Pt-rich nanoparticles is clearly evident in the case of 3:1 molar ratio combined with 1,2 hexadecanediol as a reducing agent. </span