The symmetry of electron diffraction zone axis patterns

Buxton, Bernard F.; Eades, J.; Steeds, John W; Rackham, G. M.

doi:10.1098/rsta.1976.0024

Cited by 416 publications

(125 citation statements)

References 13 publications

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“…The symmetries of both the patterns are illustrated. It is shown, as an example, for the diffraction group 31R that the symmetries of a SMB CBED pattern can be also obtained by the graphical method used by Buxton et al (1976). The symmetries of the patterns obtained for all but five of the diffraction groups are illustrated and tabulated.…”

Section: Introductionmentioning

confidence: 99%

Point-group determination by convergent-beam electron diffraction

Tanaka¹,

Saito²,

Sekii³

1983

Acta Cryst Sect A

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The method of point-group determination from convergent-beam electron diffraction patterns has been established by Buxton, Eades, Steeds & Rackham [Philos. Trans. R. Soc. London (1976), 281, 171-194]. However, Table 2 given by them is inconvenient for practical purposes, since many symmetries of the dark-field and +G dark-field patterns are not given and are left for the reader's consideration. The table is improved and completed with the help of some new symmetry symbols and illustration of symmetries. The new table makes the point-group determination easy and quick. The symmetries of the symmetrical manybeam convergent-beam electron diffraction patterns have been studied by Tinnappel [PhD Thesis (1975), Tech. Univ. Berlin l using group theory. It is shown that the graphical method used by Buxton et al. can reveal the symmetries of these patterns. A method of * Present address: Hitachi Research Laboratory, Hitachi 319-12, Japan. point-group determination which uses three types of symmetrical many-beam patterns, the hexagonal sixbeam, square four-beam and rectangular four-beam patterns, is described. This method requires only one photograph in determining most diffraction groups. This fact means that the method is more convenient and reliable than that of Buxton et al., since their method requires two or three photographs for most cases. Experimental results which verify the theoretical ones are given. The characteristic features of the symmetrical many-beam method are discussed.

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Section: Introductionmentioning

confidence: 99%

Point-group determination by convergent-beam electron diffraction

Tanaka¹,

Saito²,

Sekii³

1983

Acta Cryst Sect A

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“…These are 1, the vertical symmetry elements 2, 3, 3, 4, 4, 6, 6, m and the horizontal symmetry elements 2, ], 4, 7~, 6, 6, m. The relationship between the diffraction groups and crystal point groups is shown in Table 1 which is taken from Buxton et al (1976). It is not necessary, for the purposes of this paper, to explain the symbols used by Buxton et al for the diffraction groups.…”

Section: Symmetry Of Cbed Patternsmentioning

confidence: 99%

“…The CBED patterns contain three-dimensional crystallographic information, despite being viewed and recorded in two dimensions. The symmetry of a CBED pattern that has been recorded with the electron beam travelling exactly along a zone axis belongs to one of 31 diffraction groups that are isomorphic with the crystallographic point groups of two-dimensional plane figures (the Shubnikov groups of coloured, plane figures) (Buxton et al, 1976). The symmetry elements of the point group that are 'seen' by the electron beam, and thus determine the diffraction group for the zone axis, are those that leave the beam direction, but not necessarily its sense, unchanged (Eades et al, 1983).…”

Section: Symmetry Of Cbed Patternsmentioning

confidence: 99%

Convergent beam electron diffraction

Champness

1987

Mineral. mag.

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In convergent-beam electron diffraction (CBED) a highly convergent electron beam is focussed on to a small (~< 50 nm) area of the sample. Instead of the diffraction spots that are obtained in the back focal plane of the objective lens with parallel illumination in conventional selected-area electron diffraction, CBED produces discs of intensity. The point group can be determined uniquely from the symmetry within the individual discs and the overall pattern. In order to determine the point group, it is usually necessary to record a number of CBED patterns with the electron beam aligned along different zone axes, but sometimes only one, high-symmetry pattern is required. The positions of reflections in higher-order Laue zones can be used to identify the crystal system and lattice type and to detect the presence of certain glide planes. The repeat along the zone axis that is parallel to the beam c~n be calculated from the diameters of the Laue zones. Hence the presence ofpolymorphs can be detected. Doubly-diffracted discs in CBED often contain a 'line of dynamic absence', the orientation of this line with respect to the symmetry seen in the bright field disc allows the symmetry element responsible for it (glide plane or screw diad) to be identified. This allows 191 of the 230 space groups to be uniquely identified. The measurement of specimen thickness, extinction distance and ceil parameters are also briefly discussed. K E Y WORD S: convergent beam electron diffraction, electron microscopy, electron diffraction.

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“…Symmetry analysis of the CBED pattern shown in Fig. 6͑a͒ gives rise to the possible diffraction groups 6mm1 R and 6mm for the diffraction pattern, suggesting the type of the crystal system to be hexagonal 33,34 and thus aiding lattice parameter determination. A d-spacing of d = 0.5219 nm is derived from the ZOLZ reflections, and applying Eq.…”

Section: Treatment At 1000°cmentioning

confidence: 99%

Thermal stability of SrFeO3/Al2O3 thin films: Transmission electron microscopy study and conductometric sensing response

Wang

Tunney

et al. 2008

Journal of Applied Physics

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Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1063/1.2957073Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Thermal stability of SrFeO3/Al2O3 thin films: transmission electron microscopy study and conductometric sensing response Wang, Dashan; Tunney, Jim; Du, Xiaomei; Post, Michael; Gauvin, Raynald http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/droits L'accès à ce site Web et l'utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D'UTILISER CE SITE WEB. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/eng/view/object/?id=69375db3-8b17-42fe-957d-a990a0a2ef6d http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/voir/objet/?id=69375db3-8b17-42fe-957d-a990a0a2ef6d The SrFeO 3 / Al 2 O 3 thin film system has been studied using transmission electron microscopy ͑TEM͒. The thin films of SrFeO 3 were grown by pulsed laser deposition onto single crystal and sintered polycrystalline Al 2 O 3 substrates at room temperature ͑RT͒ and 700°C and subjected to annealing for various periods of time at 700-1000°C. TEM characterization showed that the morphology of the film varied with changes of deposition temperature. Films deposited at RT featured a columnar structure and those deposited at 700°C showed layers with crystalline grains. The interfacial structures of the films remained unchanged below 700°C. Interfacial reactions were observed following annealing at 850°C for 5 h. The phase transformation at the interface was characterized for the film annealed at 1000°C for 5 h, for which the principal phases were identified as SrAl 2−x Fe x O 4 and SrFe 12−y Al y O 19 . Evaluation for thin film conductometric sensing applications indicated that the untreated films deposited at 700°C onto both single crystal and sintered Al 2 O 3 substrates exhibited a p-type gas sensor response to oxygen at 500°C.

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The symmetry of electron diffraction zone axis patterns

Cited by 416 publications

References 13 publications

Point-group determination by convergent-beam electron diffraction

Point-group determination by convergent-beam electron diffraction

Convergent beam electron diffraction

Thermal stability of SrFeO3/Al2O3 thin films: Transmission electron microscopy study and conductometric sensing response

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