Formation mechanism and magnetic properties of three different hematite nanostructures synthesized by one-step hydrothermal procedure

Abstract

The spindle-like, tubular, and tire-like hematite were successively fabricated by a facile, one-step hydrothermal procedure, which is of great importance in facilitating the controllable-synthesis process of commercial industrialization. A mechanism involving a formation-dissolution process was proposed based on the X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy analysis. It was demonstrated that the presence of phosphate ions during the reaction process is crucial to the morphology evolution of hematite. Their different adsorption ability on the different crystallographic planes of hematite and a coordination effect with ferric ions could promote the preferential dissolution of the spindle-like hematite precursors along the long axis [001] from the tips down to the interior, and thus yield the tubular and tire-like hematite one by one with the increasing reaction time. The magnetic measurements have also been performed to investigate the different magnetic properties such as coercivity and low-temperature transition behavior of three different hematite nanostructures.hematite (-Fe 2 O 3 ), hydrothermal synthesis, nanospindle, nanotube, nanotire

Additive-Free Rice Starch-Assisted Synthesis of Spherical Nanostructured Hematite for Degradation of Dye Contaminant

“…The space group and spinel structure of the Sp-HNP was a R-3c, crystals system which was in good agreement with the literature [ 35 ]. Previously, the identical XRD pattern of the obtained α-Fe 2 O 3 was also reported by others [ 10 , 36 ]. From the XRD analysis, the highly crystalline Sp-HNP suggested that the particles were free from other impurity peaks such as b-FeOOH, Fe 3 O 4 , or g-Fe 2 O 3 [ 37 ].…”

Periodical structural conversion and its mechanism in hematite: from nanospindles, to nanotubes, to nanotires

“…2h) occur again. It should be noted that the dissolution mechanism of spindle-like nanostructures after 60 h cannot be interpreted by the previous H + attacking process, 27 but by the varied concentration of OH 2 anions during the reaction process. A schematic illustration of the recurring formation process is shown in Fig.…”

“…With increasing reaction time, the dissolution mechanism during the growth process of the hematite products has been put forward in a previous study. 27 The spindle-like precursors (Fig. 2a) were gradually dissolved from the tips toward the interior along the long axis [001], resulting in a sequential formation of obtuse nanospindles, concave nanospindles, nanotubes and nanotires (Fig.…”

Morphology control of α-Fe2O3 towards super electrochemistry performance

“…4a. A distinct peak at 3450 cm À1 is ascribed to the bending frequency of surface hydroxyl group, 26 and the strong absorption band centred at 573 cm À1 is due to the Fe-O vibrational mode, which is the typical lattice vibration peak of a-Fe 2 O 3 . 27,28 Some weak peaks between 1010 and 1022 cm À1 conrm the presence of some phosphate impurity in samples.…”