High resolution study of Σ=41 grain boundary in molybdenum

Pénisson, J.M.; Gronsky, R.; Brosse, J.B.

doi:10.1016/0036-9748(82)90474-4

Cited by 35 publications

(8 citation statements)

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“…Grain boundaries are more similar to the bulk than surfaces, possessing comparable coordination, and should provide additional information on the importance of angular dependent interactions due to the different atomic arrangements. Other potential forms which incorporate angular dependent interactions are being pursued by a number of investigators [10,14,15], but, at present, little experimental data exist for grain-boundary structures in bcc transition metals [16,17].High-resolution transmission electron microscopy (HREM) is a useful tool for characterizing the atomic structure of certain high symmetry grain boundaries [18,19]. Likewise, theory is limited to studying "special" grain boundaries which are periodic in the plane of the boundary.…”

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Atomic structure of the (310) twin in niobium: Experimental determination and comparison with theoretical predictions

et al. 1993

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The atomic structure of the (310) twin in Nb was predicted using interatomic potentials derived from the embedded atom method (EAM), Finnis-Sinclair theory (FS), and the model generalized pseudopotential theory (MGPT). The EAM and FS predicted structures with crystal translations which break mirror symmetry. The MGPT predicted one stable structure which possessed mirror symmetry. This defect was experimentally determined to have mirror symmetry. These findings emphasize that the angular dependent interactions modeled by the MGPT are important for determining defect structures in bcc transition metals. PACS numbers: 61.16.Bg, 61.72.MmAtomistic simulations which can model the interactions of many tens of thousands of atoms are increasingly used as a predictive tool and have the potential to play an important role in the overall understanding of the properties of the solid state [1], such as the atomic structure of defects [2], segregation [3l, and fracture [41. The present investigation seeks experimental distinction between several models of the interatomic interactions used in these types of calculations. In particular, the interest is to assess the differences among the embedded atom method (EAM) [5,6], Finnis-Sinclair theory (FS) [7], and the model generalized pseudopotential theory (MGPT) [8] for predicting the atomic structure of defects in body-centered-cubic (bcc) transition metals and whether the predictions correspond with experimental observations. The predictive power of the EAM and FS for face-centered noble metals is well established [2,9]. Defect structures in bcc transition metals may be less easily predicted due to the partial filling of the d bands which is expected to add an angular dependence to the interactions [10].The grain-boundary calculations studied here differ primarily by the absence or inclusion of angular dependent interactions. The EAM and FS potentials are both of the pair-functional form [10], where the energy contains a term which is a function of a simple pairwise sum over neighbors. They incorporate the trend that higher coordination implies longer, weaker bonds. However, they include no angular dependence of the atomic interactions. In contrast, the MGPT potentials incorporate three-and four-body interactions based on a model treatment of canonical d bands [8]. Only potentials which incorporate angular dependencies have been shown to predict the correct reconstruction of Mo and W (100) surfaces [11,12], while this is not possible with pairfunctional methods [13]. Grain boundaries are more similar to the bulk than surfaces, possessing comparable coordination, and should provide additional information on the importance of angular dependent interactions due to the different atomic arrangements. Other potential forms which incorporate angular dependent interactions are being pursued by a number of investigators [10,14,15], but, at present, little experimental data exist for grain-boundary structures in bcc transition metals [16,17].High-resolution transmission electron microscopy (...

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Atomic structure of the (310) twin in niobium: Experimental determination and comparison with theoretical predictions

et al. 1993

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“…Micrographs of <001> tilt grain boundaries in nickel oxide bicrystals, as shown in Figure 7, also indicate that crystallinity is usually preserved right up to the boundary; the preponderance of asymmetrical structural units along these grain boundaries was also unexpected (Merkle and Smith, 1987). The interfacial dislocations along C 41 grain boundaries in Mo have been characterized (Penisson et al, 1982), and several coherent and incoherent <110> tilt boundaries in gold have been analyzed (Ishida et al, 1983). Despite such results, it must nevertheless be noted that the interpretability of many images in these materials seems to be limited by the lack of structural order along the beam direction: improvements in resolution alone will not necessarily provide further information about the defect or feature of interest.…”

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confidence: 91%

Achievement of atomic resolution electron microscopy

Smith

1989

J. Elec. Microsc. Tech.

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Atomic-level details are easily resolved in the latest generation of intermediate voltage electron microscopes, but structural information on the same scale can only be extracted under certain specific conditions. Some understanding of imaging theory, as well as an awareness of correct operating conditions, is required for reliable image interpretation. Several representative examples are chosen to illustrate the possibilities for atomic-resolution imaging of materials, and perspectives and outlook for the technique are briefly discussed.

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“…structure (Penisson & Bourret, 1979), b.c.c. structure (Penisson et al, 1982) and recently in h.c.p. (De Crecy et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

Are the core structures of dislocations and grain boundaries resolvable by HREM?

Bourret¹,

Thibault‐Desseaux²,

d'Anterroches

et al. 1983

Journal of Microscopy

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K E Y w ORDS. Structure, defects in crystals, electron microscope. S U M M A R YLinear or planar defect structures have been recently studied by high resolution electron microscopy (HREM). Defects are generally difficult to solve for several reasons: they are nonperiodic and their images are limited to a very few projections along low index axes. For edge dislocations in materials having a high lattice friction, image analysis is possible and relatively fine details are now available about core radii and location of the atom pairs. The accuracy, however, of the proposed structures is within 0.025 nm if a priori information is known. This is not always sufficient to distinguish between several models. For a high angle tilt grain boundary the situation is comparable. A discussion of the errors introduced by several factors (object orientation, optical axis alignment) and measurement of experimental parameters is presented. At present all the information content of an image is not used: intensity profiles and quantitative comparison of simulated and experimental images should provide better ways for solving an unknown structure. However, the improvement of the point resolution is the key factor for further progress in defect analysis.

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High resolution study of Σ=41 grain boundary in molybdenum

Cited by 35 publications

References 11 publications

Atomic structure of the (310) twin in niobium: Experimental determination and comparison with theoretical predictions

Atomic structure of the (310) twin in niobium: Experimental determination and comparison with theoretical predictions

Achievement of atomic resolution electron microscopy

Are the core structures of dislocations and grain boundaries resolvable by HREM?

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