E.s.d.'s and estimated probable error obtained in Rietveld refinements with local correlations

Bérar, J. F.; Lelann, P.

doi:10.1107/s0021889890008391

Cited by 386 publications

(274 citation statements)

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“…Table 1 shows crystallographic data and details of the Rietveld refinement of γ-Ca 3 N 2 and Table 2 displays the occupied Wyckoff sites, refined atomic coordinates and isotropic displacement parameters. Estimated standard deviations are calculated in agreement with ref 42.…”

Section: ' Results and Discussionsupporting

confidence: 71%

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Ca₃N₂ and Mg₃N₂: Unpredicted High-Pressure Behavior of Binary Nitrides

et al. 2011

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Section: ' Results and Discussionsupporting

confidence: 71%

“…229) space group symmetry (Table 5) and only atoms on the 2a-site (0, 0, 0) is proposed (Table 6). Estimated standard deviations are calculated in agreement with ref 42.…”

Section: ' Results and Discussionsupporting

confidence: 71%

Ca₃N₂ and Mg₃N₂: Unpredicted High-Pressure Behavior of Binary Nitrides

et al. 2011

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“…The observed and calculated patterns are illustrated in Figure 1, and crystal data are given in Table 1. It is obvious that a well-known problem of underestimated standard uncertainties in the Rietveld analysis exists (Bérar & Lelann 1991). Even after a correction by a program-proposed score-factor of 2.4686, standard uncertainties for kutinaite are still considered underestimated.…”

Section: Introductionmentioning

confidence: 99%

THE CRYSTAL STRUCTURE OF SYNTHETIC KUTINAITE, Cu14Ag6As7

Karanović

Poleti

Makovicky

et al. 2002

The Canadian Mineralogist

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The crystal structure of synthetic kutinaite, Cu 14 Ag 6 As 7 , was determined from powder-diffraction data recorded on a Guinier diffractometer and refined by Rietveld method with the program FULLPROF. The final refinement (⌬/ max < 0.2) with 31 (9 profile and 23 structural) parameters using 4600 data points and 226 reflections yielded the following agreement indices: R wp = 18.2%, R p = 13.4%, R exp = 14.7%, S = 1.54, R(B) = 1.78%. The cubic structure has a equal to 11.78079(2) Å (standard uncertainties are underestimated by a score-factor of 2.4686) and space group Pm3m, Z = 4. Apart from partially ordered Cu vacancies, the arrangement of atoms is very close to that in Fm3m. The Pm3m structure of kutinaite is a result of the frozen-in partial order of Cu vacancies which, in a presumed high-temperature Fm3m structure, should be completely disordered. The atoms Cu2 and Cu3 are tetrahedrally coordinated by As, the atoms Cu1 and Cu4 (with partial occupancies) have trigonal planar As coordination. Atoms of Ag form octahedral Ag 6 clusters in octahedral cavities of the Cu-As framework. On the one hand, the structure of kutinaite contains a multitude of short metal-metal and metal-semimetal contacts, resulting in high coordination-numbers and indicating direct metal-metal interactions. The presence of metal-metal bonding contacts is supported by an electron-density analysis, which gives the following bonding contact limits: 2.70 Å (Cu-Cu), and 3.05 Å (Ag-Cu). On the other hand, a network of important Cu-As bonds forms a three-dimensional complex with a nominal net negative charge balanced by nominal positive charges of localized Ag 6 complexes. This situation results in two complementary descriptions of the structure of kutinaite: kutinaite as an icosahedral alloy and kutinaite as an arsenide with metal clusters.Keywords: kutinaite, X-ray diffraction, powder method, crystal structure, icosahedral alloy, arsenide, metal clusters. SOMMAIRENous avons établi la structure cristalline de la kutinaïte synthétique, Cu 14 Ag 6 As 7 , à partir de données en diffraction X obtenues sur poudre, enregistrées avec un diffractomètre Guinier et affinées par la méthode de Rietveld avec le logiciel FULLPROF. L'affinement final (⌬/ max < 0.2), avec 31 paramètres (9 portant sur le profil et 23 sur la structure), repose sur 4600 données et 226 réflexions, et ont mené aux indices de concordance suivants: R wp = 18.2%, R p = 13.4%, R exp = 14.7%, S = 1.54, R(B) = 1.78%. Le paramètre a de la structure cubique est égal à 11.78079(2) Å (l'écart-type est sous-estimé par un facteur de 2.4686); le groupe spatial est Pm3m, Z = 4. Mis à part les lacunes aux sites du Cu, partiellement ordonnées, l'agencement des atomes se rapproche de celui du groupe spatial Fm3m. La structure Pm3m de la kutinaïte résulterait de la mise en ordre partielle des lacunes aux sites Cu; dans un précurseur de haute température, dont le groupe spatial est Fm3m, ces lacunes devraient être complètement désordonnées. Les atomes Cu2 et Cu3 ont une coordinence tétraédri...

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“…These were corrected by multiplication on the correcting coefficients, M e.s.d. (see Table 1), calculated by means of Berrar's procedure [62] implemented in W inCSD. Additionally, for the CNG_AQ sample, two non-indexed reflections of an unknown phase were detected at 2θ = 25.88…”

Section: Experimental Details Of the Co 50 Ni 21 Ga 32 Nanoparticlesmentioning

confidence: 99%

Effects of Annealing on the Martensitic Transformation of Ni-Based Ferromagnetic Shape Memory Heusler Alloys and Nanoparticles

Fichtner

Wang

Levin

et al. 2015

Metals

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We report on the effects of annealing on the martensitic phase transformation in the Ni-based Heusler system: Mn 50 Ni 40 Sn 10 and Mn 50 Ni 41 Sn 9 powder and Co 50 Ni 21 Ga 32 nanoparticles. For the powdered Mn 50 Ni 40 Sn 10 and Mn 50 Ni 41 Sn 9 alloys, structural and magnetic measurements reveal that post-annealing decreases the martensitic transformation temperatures and increases the transition hysteresis. This might be associated with a release of stress in the Mn 50 Ni 40 Sn 10 and Mn 50 Ni 41 Sn 9 alloys during the annealing process. However, in the case of Co 50 Ni 21 Ga 32 nanoparticles, a reverse phenomenon is observed. X-ray diffraction analysis results reveal that the as-prepared Co 50 Ni 21 Ga 32 nanoparticles do not show a martensitic phase at room temperature. Post-annealing followed by ice quenching, however, is found to trigger the formation of the martensitic phase. The presence of the martensitic transition is attributed to annealing-induced particle growth and the stress introduced during quenching.

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E.s.d.'s and estimated probable error obtained in Rietveld refinements with local correlations

Cited by 386 publications

References 7 publications

Ca₃N₂ and Mg₃N₂: Unpredicted High-Pressure Behavior of Binary Nitrides

Ca₃N₂ and Mg₃N₂: Unpredicted High-Pressure Behavior of Binary Nitrides

THE CRYSTAL STRUCTURE OF SYNTHETIC KUTINAITE, Cu14Ag6As7

Effects of Annealing on the Martensitic Transformation of Ni-Based Ferromagnetic Shape Memory Heusler Alloys and Nanoparticles

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E.s.d.'s and estimated probable error obtained in Rietveld refinements with local correlations

Cited by 386 publications

References 7 publications

Ca3N2 and Mg3N2: Unpredicted High-Pressure Behavior of Binary Nitrides

Ca3N2 and Mg3N2: Unpredicted High-Pressure Behavior of Binary Nitrides

THE CRYSTAL STRUCTURE OF SYNTHETIC KUTINAITE, Cu14Ag6As7

Effects of Annealing on the Martensitic Transformation of Ni-Based Ferromagnetic Shape Memory Heusler Alloys and Nanoparticles

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Ca₃N₂ and Mg₃N₂: Unpredicted High-Pressure Behavior of Binary Nitrides

Ca₃N₂ and Mg₃N₂: Unpredicted High-Pressure Behavior of Binary Nitrides