Interplay of surface conditions, particle size, stoichiometry, cell parameters, and magnetism in synthetic hematite-like materials

  title={Interplay of surface conditions, particle size, stoichiometry, cell parameters, and magnetism in synthetic hematite-like materials},
  author={M.-Z. Dang and Denis Rancourt and John E. Dutrizac and Gilles Lamarche and Robert Provencher},
  journal={Hyperfine Interactions},
We have studied several synthetic hematite-like materials, produced via different reactions using various hydrothermal conditions and various temperatures of annealing in air, by bulk elemental analysis, weight loss measurements, scanning electron microscopy, powder X-ray diffraction, Mössbauer spectroscopy, and SQUID magnetometry. We conclude that hematite-like materials cannot be related to pure stoichiometric hematite via a single stoichiometric or physical parameter and that at least two… 

Morin transition in hematite: Size dependence and thermal hysteresis

Hematite is a frequently used mineral in paleomagnetic and environmental magnetic studies. Just below room temperature, it undergoes a magnetic phase transition, the Morin transition, whose nature is

A refined monoclinic structure for a variety of “hydrohematite”

Abstract In ferruginous soils, nano- to microscale hematite (α-Fe2O3) plays a central role in redox processes and contaminant cycling. Hematite is known to incorporate structural OH- and water, and

Size-dependent structural transformations of hematite nanoparticles. 1. Phase transition.

A general model is developed that considers spinel defects and absorbed/adsorbed species as dominant controls on structural changes with particle size in hematite nanoparticles, including solid-state phase transitions, and supports the existence of intermediate phases during dehydration of goethite.

Changes in the structural and magnetic properties of Ni–substituted hematite prepared from metal oxinates

Samples prepared by the novel method based on the thermal decomposition at 700 °C in air of mixed Fe and Ni oxinates were characterized by thermogravimetric analysis, X-ray diffraction, magnetization

Magnetic properties of hematite with large coercivity

The magnetic properties of hematite powders produced by a solid state nucleation-and-growth process are studied as a function of temperature T and applied field H. Independently of the temperature,

Field-induced spin–flop transitions of interacting nanosized α-Fe2O3 particles dispersed in a silica glass matrix

Nanoparticles of 10 mol% Fe2O3 doped in silica glass (Fe10) samples prepared by a sol–gel method followed by calcination at various temperatures in the range 700–1000 °C are studied by x-ray,



Mössbauer effect study of the spin structure in natural hematites

Three natural hematites, α-Fe2O3, from the region of Elba have been investigated by means of 57Fe Mössbauer spectroscopy at variable temperatures between 80 and 400K. The samples were selected on the

Magnetic properties of microcrystalline iron (III) oxides and related materials as reflected in their Mössbauer spectra

Iron (III) oxides are common constituents of geologic materials, they are products and by-products of many industrial processes, they are involved in biological processes, and they are the outcome of

Particle size determination in supported iron oxide (.alpha.-Fe2O3)

The techniques of high-angle x-ray diffraction line profile analysis, transmission electron microscopy, and Moessbauer effect spectroscopy have been applied to the study of ..cap alpha..-Fe/sub

Mössbauer effect studies of surface ions of ultrafine α‐Fe2O3 particles

Since in ultrafine particles a considerable fraction of the atoms is located near or at the surface the behaviour of these atoms is studied using the Mossbauer technique. The contribution to the

Evidence for pigmentary hematite on Mars based on optical, magnetic, and Mossbauer studies of superparamagnetic (nanocrystalline) hematite

Features attributed to ferric iron in remotely sensed spectral data of Mars and the magnetic nature of Martian soil at the Viking landing sites are consistent with the occurrence of hematite