The commensurate (10/4) cluster model in quenched wüstite P''. New simulation of HREM direct images

Abstract

In the case of non-stoichiometric quenched wfistite P" with the formula Fel-zO (z = 0.096), the defect structure is shown to consist most probably of clusters composed of ten vacancies and four interstitial Fe III ions. These clusters are in agreement with a long-range ordering (2.5X, 2.5X, 5)0, with some disorder in their local arrangement. The direct im~iges of the quenched phase P", previously obtained by various authors, are reinterpreted from a (10/4) cluster model: computer simulations have been carried out using this new model. The simulated images are in good agreement with the experimental images found in the literature.

The complex nonstoichiometry of wüstite Fe1-O: Review and comments

“…They develop a detailed analysis of diffuse scattering and Bragg peaks, and conclude to the existence of a mixture of clusters (13:4) and asymmetric new clusters (5:2) constituted of 5 vacancies and 2 interstitials corresponding to the ideal ratio R = 2.5. They propose an ordering of these clusters with an average repetition distance of 2.5a, close to the hypothetic value of 2.55a proposed in [149] [150].…”

“…When re-interpreting the images obtained from electron microscopy experiments by Ishiguro and Nagakura [148], Gavarri, Carel, Weigel [149], then Nihoul, Gavarri, Carel [150] show that this cluster corresponding to the ideal ratio R = 2.5 is compatible with the experimental data available (at least for quenched wüstites). This cluster depicted in Fig.…”

Defect Clusters and Superstructures of Zr4+Dissolved Ni1−xO

“…Wu¨stite (Fe \V O) is an oxide with the rock-salt structure that shows a considerable degree of nonstoichiometry, extending to x"0.15 at high temperatures (1), and defect clustering and ordering (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). The first indication of defect clustering was the detection of tetrahedral interstitials by powder neutron diffraction measurements on samples quenched to room temperature (2).…”

“…When the lateral translations of the P phase are suppressed, the superlattice P phase appears (15). The P phase was suggested to consist of clusters composed of 10 vacancies and 4 interstitial ferric irons, according to computer simulation of the HRTEM image (21).…”