The defect structure of Fe1−xO

Koch, Friedrich; Cohen, J. B.

doi:10.1107/s0567740869002111

Cited by 300 publications

(104 citation statements)

References 7 publications

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“…The values can be compared with R =0-62 obtained by Koch & Cohen for their model without displacements. As indicated by the small differences in R, the values for the average structure factor show only small variations from one model to another; typically a few tenths on the scale used by Koch & Cohen (1969) (Table 1). Since changes expected from adjustment of atomic positions are several times larger, the correct model cannot be selected.…”

Section: Structure Analysismentioning

confidence: 99%

“…If all defects are bound to eight clusters, the closest ideal number is found to be ten iron vacancies (Vm) and three iron interstitials (MI) which gives the vacancy to interstitial ratio 3.3 and the formula Fe444Osoo which is in good agreement with reports of the observed single-phase compositions Feo.9o20, Fe0.880 and Feo.870 of P' phase. An increase to the next possible ideal number, 13Vm+4Mi as in the Koch & Cohen (1969) type of cluster, leads to the composition Fe0.8560 which is outside the range of P'-phase. It is then necessary to have a non-ideal occupancy number to make up for the discrepancy in compositions as no decomposition has been observed in connexion with the transition to P".…”

Section: Structure Analysismentioning

confidence: 99%

“…The selection of the correct model has been attempted on the basis of X-ray intensity measurements reported by Koch & Cohen (1969). Calculated intensities must in this case be added for the six orientations of the orthorhombic cell, however, and difficulties in distinguishing the different models are considerable.…”

Section: Structure Analysismentioning

confidence: 99%

“…The presence of interstitial iron atoms as well as octahedral vacancies was established through neutron and X-ray studies by Roth (1960) and Smuts (1966). The concentrations were first determined accurately for quenched Fe0.90zO by Koch & Cohen (1969) to 3"3 % iron interstitials and 13.1% vacancies. From high-temperature measurements between 800 and 1200°C Cheetman, Fender & Taylor (1971) found a ratio between vacancies and interstitials of about 3 to 4 for all compositions.…”

Section: Introductionmentioning

confidence: 99%

“…From X-ray studies on one ordered structure near the phase boundary towards F%O 4 Koch & Cohen (1969) and Hoang et al (1973) both proposed a cubic structure based on clusters consisting of interstitials surrounded by vacancies. The proposals differ, however, both in regard to the cluster itself and the distance between clusters.…”

Section: Introductionmentioning

confidence: 99%

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Decomposition and ordering in Fe_1−xO

Andersson¹,

Sletnes²

1977

Acta Cryst Sect A

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Samples in the composition range Fe0.gsO-Feo.880 quenched from about 1000°C, have been studied by electron diffraction/microscopy with special emphasis on the dark-field technique. The set of morphologies obtained by quenching and annealing confirms a spinodal-like decomposition in an oxygen-rich and an almost stoichiometric component. The diffraction spots and dark-field images reveal a considerable degree of order which is enhanced upon heat treatment below 300°C. Previous diffraction studies have been interpreted in terms of an ordered phase with cubic symmetry. Dark-field microscopy, particularly at the symmetric composition, showed that the compositional fluctuation wave contained domains of tetragonal or orthorhombic symmetry at a very early stage. The range of order was found to increase during decomposition. An ordered phase of orthorhombic symmetry developed in oxygen-rich samples. Superstructure spots could be indexed by an A-faced orthorhombic cell with dimensions five times the fundamental cell.Extinctions lead to the space group Abm2 and a periodic antiphase relation. Only four types of clusters, all of which are based on three connected defect tetrahedra, are then possible.

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Section: Structure Analysismentioning

confidence: 99%

Section: Structure Analysismentioning

confidence: 99%

Section: Structure Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Decomposition and ordering in Fe_1−xO

Andersson¹,

Sletnes²

1977

Acta Cryst Sect A

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Introduction

Catlow¹

1998

Inorganic Reactions and Methods

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Diffusion Kinetics in Solids

Murch

2013

Materials Science and Technology

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The sections in this article are Introduction Macroscopic Diffusion Fick's Laws Types of Diffusion Coefficients Tracer or Self‐Diffusion Impurity and Solute Diffusion Chemical or Interdiffusion Intrinsic or Partial Diffusion Coefficients Surface Diffusion Coefficients Phenomenological Equations of Irreversible Thermodynamics Tracer Diffusion Chemical Diffusion Einsteinian Expressions for the Phenomenological Coefficients Relating Phenomenological Coefficients to Tracer Diffusion Coefficients Short‐Circuit Diffusion Microscopic Diffusion Random Walk Theory Mechanisms of Diffusion The Einstein Equation Tracer Correlation Factor Impurity Correlation Factor Correlation Factors for Concentrated Alloy Systems Correlation Factors for Highly Defective Systems The Physical or Conductivity Correlation Factor Correlation Functions (Collective Correlation Factors) The Nernst–Einstein Equation and the Haven Ratio The Isotope Effect in Diffusion The Jump Frequency The Exchange Frequency Vacancy Concentration Diffusion in Materials Diffusion in Metals Self‐Diffusion Impurity Diffusion Diffusion in Dilute Alloys Substitutional Alloys Interstitial Alloys Diffusion in Concentrated Binary Substitional Alloys Diffusion in Ionic Crystals Defects in Ionic Crystals Diffusion Theory in Ionic Crystals Experimental Methods for Measuring Diffusion Coefficients Tracer Diffusion Methods Chemical Diffusion Methods Diffusion Coefficients by Indirect Methods Relaxation Methods Nuclear Methods Surface Diffusion Methods Acknowledgements

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The defect structure of Fe1−xO

Cited by 300 publications

References 7 publications

Decomposition and ordering in Fe_1−xO

Decomposition and ordering in Fe_1−xO

Introduction

Diffusion Kinetics in Solids

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The defect structure of Fe1−xO

Cited by 300 publications

References 7 publications

Decomposition and ordering in Fe1−xO

Decomposition and ordering in Fe1−xO

Introduction

Diffusion Kinetics in Solids

Contact Info

Product

Resources

About

Decomposition and ordering in Fe_1−xO

Decomposition and ordering in Fe_1−xO