Or Ffe--a Fortran Crystallographic Function and Error Program

Busing, W. R.; Martin, K.O.; Levy, H. A.

doi:10.2172/4037571

Cited by 251 publications

(199 citation statements)

References 4 publications

(5 reference statements)

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“…Les intensit6s ainsi obtenues correspondaient fi des maximums de la s6rie de Fourier des diff6rences (F o -Fc (Busing, Martin & Levy, 1964). La Fig.…”

Section: Preparationunclassified

Structure du nitrate d'argent hexaméthylènetetramine

Michelet¹,

Viossat²,

Khodadad³

et al. 1981

Acta Crystallogr Sect B

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AgNO 3. C6H~2N 4 is orthorhombic, space group Pnma with a unit cell a = 13.832 (7), b = 6.535 (4) and and Z = 4. The structure was refined by a full-matrix least-squares technique to a final R = 0.045 for 807 independent reflections measured on an automatic diffractometer. It is made up of sheets which contain • .• Ag-hexamethylenetetramine-Ag-hexamethylenetetramine.., chains and which are parallel to the (100) plane. In each sheet, the chains are linked to one another through Ag-N bonds. Each Ag atom is surrounded by three N atoms which belong to three C6H~2N 4 molecules and two O atoms of a nitrate group. Moreover, a C6H~2N 4 molecule links three Ag atoms. The NO 3 group occupies two positions in statistical disorder. Interatomic distances and bond angles are in good agreement with previously published values. Cohesion between sheets is due to van der Waals interactions.

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“…Les intensit6s ainsi obtenues correspondaient fi des maximums de la s6rie de Fourier des diff6rences (F o -Fc (Busing, Martin & Levy, 1964). La Fig.…”

Section: Preparationunclassified

Structure du nitrate d'argent hexaméthylènetetramine

Michelet¹,

Viossat²,

Khodadad³

et al. 1981

Acta Crystallogr Sect B

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“…Interatomic distances and bond angles (Tables 5 and 6), uncorrected for the effects of thermal motion, were computed by the program ORFFE (Busing, Martin & Levy, 1964). As compared with dravite, the 9(b) octahedra in buergerite have been flattened parallel with the basal plane and are less regular.…”

Section: Refinement Of the Crystal Structure Of Buergeritementioning

confidence: 99%

Refinement of the crystal structure of buergerite and the absolute orientation of tourmalines

Barton¹

1969

Acta Crystallogr Sect B

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The crystal structure of buergerite from Mexico has been refined by least-squares by use of singlecrystal X-ray intensity data collected by counter diffractometry. Buergerite, ideally NaFel+B3A16Si6030F, crystallizes in R3m; the hexagonal cell dimensions for the specimen used are: a= 15.869+ 2, c=7-188 + 1/~ at 21°C. Din=3.30+ 1 at 23°C; with Z=3, Dx=3.29 g.cm-3. Of 3909 independent reflections measured, 3121 were observed; the residual R for the observed reflections is 0.046. The structure is very similar to the refined dravite structure of Buerger, Burnham & Peacor (Acta Cryst. (1962), 15, 583) which was used as the starting model. Refinement of the (Fe3+, A1) distribution shows that some fenic iron replaces octahedral aluminum in the 18(c) position, a substitution not required by the chemical analysis. The absolute orientation of the crystal structure with respect to the macroscopic polar properties of tourmaline was determined by anomalous dispersion, mostly due to iron, under copper radiation. The SiO4 tetrahedra point toward the analogous pole of the c axis, the pole that becomes positively charged on heating.

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“…An electron density difference map indicated the position of the potassium atoms. The structural and thermal parameters were refined for 155 unique re- flections by a full-matrix least-squares program, ORFLS (Busing, Martin & Levy, 1963 (Busing, Martin & Levy, 1964) are given in Table 2. * A view of the unit cell drawn with ORTEP (Johnson, 1965) is shown in Fig.…”

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confidence: 99%