Iron oxides, neutron diffraction

The structures of iron oxides have been determined principally by single crystal X-ray diffraction or neutron diffraction with supplementary information coming from infrared spectroscopy, electron diffraction and high resolution electron microscopy. A few years after the first successful application of X-ray diffraction to crystal structure determination, this technique was used to establish the major features of the structures of magnetite (Bragg, 1915 Nishikawa, 1915) and hematite (Bragg Bragg, 1918). 

The magnetic properties of iron oxides can be determined using Mossbauer spectroscopy, neutron powder diffraction and magnetometry (see Chap. 7). The characteristic parameters are the magnetic moment, the permeability, the saturation magnetization, the magnetic anisotropy constants and the Bhf (Tab. 6.2). 

In addition to X-ray and neutron-diffraction structural characterization, the physical properties of iron oxides have been studied by a wide variety of techniques. Most common are conventional transport, optical, dielectric, calorimetric and magnetic measurements. In addition, NMR and Mossbauer are widely used. 

According to the formula of CaFesO compound, the Fe species presents both +2 and +3 oxidation state and a charge ordering (CO) mechanism is expected like previously reported in ref [4]. The [hOl] zone axes that exhibit extra dots have been also studied. However, these extra dots (blue arrows in Fig.3a) are not stable under electron beam the superstracture previously observed on ED pattern disappears when the microscope is switched into image mode. Such a nanostructural behaviour reinforces the hypothesis of a CO between the iron species. Thermal dependence and neutron diffraction data analyses are in progress to valid such a scenario. 

BOURIDAH A, DALARD F, DEROO D, CHERADAME H, LE NEST J F (1985), Poly(dimethlsilo-xane)-poly(ethylene oxide) based polyurethane networks used as electrolytes in lithium electrochemical solid state batteries . Solid State Ionics, 15,233-240. CHADWICK B M, JONES D w, WILDE H J, YERKESS J (1985), X-ray and neutron diffraction studies of the crystal structures of the dicesium lithium hexacyanometallates of iron(III) and cobalt(III) , J Cryst Spectrosc, 15,133-146. 

In Chapters I and 2, an introduction is made to the synchrotron Mossbauer spectroscopy with examples. Examples include the/ns/tu Mossbauer spectroscopy with synchrotron radiation on thin films and the study of deep-earth minerals. Investigations of in-beam Mossbauer spectroscopy using a Mn beam at the RIKEN RIBF is presented in Chapter 3. This chapter demonstrates innovative experimental setup for online Mossbauer spectroscopy using the thermal neutron capture reaction, Fe (n, y) Fe. The Mossbauer spectroscopy of radionuclides is described in Chapters 4-7. Chapter 4 gives full description of the latest analysis results of lanthanides Eu and Gd) Mossbauer structure and powder X-ray diffraction (XRD) lattice parameter (oq) data of defect fluorite (DF) oxides with the new defect crystal chemistry (DCC) Oq model. Chapter 5 reviews the Np Mossbauer and magnetic study of neptunyl(+l) complexes, while Chapter 6 describes the Mossbauer spectroscopy of organic complexes of europium and dysprosium. Mossbauer spectroscopy is presented in Chapter 7. There are three chapters on spin-state switching/spin-crossover phenomena (Chapter 8-10). Examples in these chapters are mainly on iron compounds, such as iron(lll) porphyrins. The use of Mossbauer spectroscopy of physical properties of Sn(ll) is discussed in Chapter I I. 

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