Etude des phases ordonnées à longue période irrationelle. Les alliages AuCu II et AuCu–Zn

Guymont, M.; Portier, R.; Gratias, D.

doi:10.1107/s0567739480001581

Cited by 25 publications

(3 citation statements)

References 10 publications

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“…Satellites, which are far less diffuse, are due, on the contrary, to a periodic order, or, more generally, to the periodic 'component' in the disorder along the directions of corresponding pairs of satellites. This latter effect is rendered evident in, for instance, AuCu II (Guymont, Portier & Gratias, 1980). The highresolution images show that, in this case also, there is only a mean periodic order.…”

Section: Suggested Interpretation Of Satellite Distribution Intensitymentioning

confidence: 77%

Structural study of CdY₂S₄

Tomas¹,

Guittard²,

Flahaut

et al. 1986

Acta Crystallogr Sect B

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Section: Suggested Interpretation Of Satellite Distribution Intensitymentioning

confidence: 77%

Structural study of CdY₂S₄

Tomas¹,

Guittard²,

Flahaut

et al. 1986

Acta Crystallogr Sect B

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“…6,60 There is also a mediumtemperature CuAu-II phase around the equiatomic composition, which is a long-period superstructure based on the L1 0 ordered phase. [61][62][63] The stabilization of this phase has most probably a statistical origin coupled with local lattice relaxations near antiphase boundaries, which leads to specific local disordering. 64 Energetically this is a very small effect which cannot be described on the basis of the usual effective interactions alone, and it is therefore not considered here.…”

Section: Ordering In Cuaumentioning

confidence: 99%

Atomic and magnetic configurational energetics by the generalized perturbation method

et al. 2004

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It is shown that, using the generalized perturbation method (GPM) with screened Coulomb interactions that ensures its consistency with the force theorem, one is able to obtain effective interactions that yield an accurate and physically transparent description of configurational energetics in the framework of the Korringa-KohnRostoker method within the atomic sphere and coherent potential approximations. This is demonstrated with calculations of ordering energies, short-range order parameters, and transition temperatures in the CuZn, CuAu, CuPd, and PtCo systems. Furthermore, we show that the GPM can be used to obtain Heisenberg exchange interaction parameters, which, for instance, capture very well the magnetic configurational energy in bcc Fe.

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“…Within a given Fe layer (defined by its position within the sulfur sublattice), these local jumps cause lateral transitions of the layer type from V to F or vice versa and result in a mixed state with patches of V and F types measuring tens of nanometers. The importance of recognizing these structural details is exemplified by the fact that the concept of stochastic waviness of APBs in TIM structures is well established in materials sciences (e.g., Jehanno and Perio 1964;Guymont et al 1980). Guymont (1991) showed by entropy considerations that in TIM modulated alloys at elevated temperatures wavy APBs are thermodynamically preferred over straight APBs.…”

Section: A Translation Interface Modulation Model For Nc-pyrrhotitesmentioning

confidence: 98%

Translation interface modulation in NC-pyrrhotites: Direct imaging by TEM and a model toward understanding partially disordered structural states

Harries

Pollok

Langenhorst

2011

American Mineralogist

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The crystallographic complexity of "hexagonal" or "intermediate" pyrrhotites (Fe 1-x S with 0.125 > x > 0.080) is a long-standing and challenging problem. Integral (e.g., 5C) and non-integral NC type structures found within this group at ambient temperatures are characterized by sharp but complicated electron diffraction patterns, which were found to be interpretable in terms of a translation interface modulation (TIM) superstructure. Transmission electron microscopy (TEM) dark-field images obtained using superstructure reflections show dense arrangements of stripes, which can be interpreted as arrays of closely spaced anti-phase domain boundaries (APB). The displacement vector at the interface is R = 1/8[001] of a metrically hexagonal 4C superstructure cell and the involved translations are solely confined to the Fe sublattice. The vacancy arrangement of the APB-free monoclinic 4C-pyrrhotite serves as a base of the TIM superstructure and therefore NC structures can be regarded as two super-imposed ordering phenomena relating to the arrangements of individual vacancies and APBs, respectively. APBs are chemically non-conservative and govern the higher Fe/S ratios of intermediate NC-pyrrhotites. If oriented strictly parallel to (001) the APBs can be regarded as completely filled Fe double layers within the 4C stacking sequence. However, direct imaging of APBs shows waviness and variable disorder on mesoscopic scales, yielding essentially aperiodic structures. A high degree of self-organization among APBs has been observed within apparent diffusion profiles around exsolved troilite lamellae and along interfaces with 4C-pyrrhotite, where complicated eightfold node arrangements occur. Our TEM observations indicate that all NC-type pyrrhotites can be treated by the TIM approach and that the concepts of polytypism and polysomatism in pyrrhotite are not fully capable in representing the observed structural complexities.

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Etude des phases ordonnées à longue période irrationelle. Les alliages AuCu II et AuCu–Zn

Cited by 25 publications

References 10 publications

Structural study of CdY₂S₄

Structural study of CdY₂S₄

Atomic and magnetic configurational energetics by the generalized perturbation method

Translation interface modulation in NC-pyrrhotites: Direct imaging by TEM and a model toward understanding partially disordered structural states

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Etude des phases ordonnées à longue période irrationelle. Les alliages AuCu II et AuCu–Zn

Cited by 25 publications

References 10 publications

Structural study of CdY2S4

Structural study of CdY2S4

Atomic and magnetic configurational energetics by the generalized perturbation method

Translation interface modulation in NC-pyrrhotites: Direct imaging by TEM and a model toward understanding partially disordered structural states

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Structural study of CdY₂S₄

Structural study of CdY₂S₄