X-ray Rietveld refinement using Debye–Scherrer geometry

Thompson, Paul; Wood, I. G.

doi:10.1107/s0021889883010845

Cited by 34 publications

(25 citation statements)

References 45 publications

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“…A number of methods have been tried and various diffraction geometries have been used, Guinier by Malmros & Thomas (1977), BraggBrentano by the other authors mentioned and, more recently, Debye-Scherrer (Thompson & Wood, 1983). Each has advantages and disadvantages regarding the application of the Rietveld method.…”

Section: Introductionmentioning

confidence: 99%

Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al₂O₃

Thompson¹,

Cox²,

Hastings³

1987

J Appl Crystallogr

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2,617

1,752

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The application of the Rietveld refinement technique to synchrotron X-ray data collected from a capillary sample of AI20 3 in Debye-Scherrer geometry is described. The data were obtained at the Cornell High Energy Synchrotron Source (CHESS) with an Si(111) double-crystal monochromator and a Ge(111) crystal analyzer. Fits to a number of well resolved individual peaks demonstrate that the peak shapes are very well described by the pseudo-Voigt function, which is a simple approximation to the convolution of Gaussian and Lorentzian functions. The variation of the Gaussian and Lorentzian half widths, F~ and Ft+, with Bragg angle can be approximated quite closely by the functions V tan 0 and X/cos 0 which represent the contributions from instrumental resolution and particle-size broadening respectively. Rietveld refinement based on this model yields generally satisfactory results. The refined values of V and X are consistent with the expected vertical divergence (~_ 0-1 mrad) and the nominal particle size (~_ 0-3 I.tm). In particular, the use of a capillary specimen virtually eliminates preferred orientation effects, which are highly significant in flat-plate samples of this material.

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Section: Introductionmentioning

confidence: 99%

Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al₂O₃

Thompson¹,

Cox²,

Hastings³

1987

J Appl Crystallogr

Self Cite

2,617

1,752

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“…Some general aspects of using Debye-Scherrer data in Rietveld analysis have already been covered (Thompson & Wood, 1983;Hill & Madsen, 1992). But, until now, only a few structural studies have been performed on an INEL CPS120-equipped powder diffractometer (Plevert, Auffredic, LouSr & LouSr, 1989;Deroche, Marler, Gies, Kokotailo & Pennartz, 1993;St~.hl & Thomasson, 1992;Jouanneaux, Joubert, Evain & Ganne, 1993).…”

Section: Introductionmentioning

confidence: 99%

Potential of the INEL X-ray position-sensitive detector: a general study of the Debye–Scherrer setting

Evain¹,

Deniard²,

Jouanneaux³

et al. 1993

J Appl Cryst

119

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The INEL diffractometer, equipped with a CPS120 curved detector and set up in a Debye-Scherrer geometry, is a unique tool for carrying out powder diffraction studies on air-sensitive and/or smallvolume samples. Although it has routinely been used in powder diffractometry because of its minute acquisition times, its accuracy in d-spacing and intensity measurements has not been clearly demonstrated before now. Concerning the d spacings, proper linearization of the CPS120 with a cubic Na2Ca3AizF14 standard allowed a mean 620 difference of 0.006 ° . Intensity accuracy was measured with different highly and poorly absorbing samples. The accuracy is fairly good for the latter but poor for the former, except when special procedures such as the dilution of the sample with boron powder are used. A Rietveld calculation carried out on TI4V20 v showed a very good agreement between the INEL Debye-Scherrer-geometry results and those obtained with a Philips diffractometer and Bragg-Brentano geometry.

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“…These features prevent an accurate determination of diffraction-line intensities and of unit-cell parameters. Many sophisticated calculations have been reported in the literature including deconvolution procedures (Louboutin & Lou~r, 1972;Taupin, 1973;Huang & Parrish, 1975;Moraweck, de Montgolfier & Renouprez, 1977;Law & Hogan, 1984), Rietveld refinements (Rietveld, 1969;Pham, Choisnet & Raveau, 1975;Malmros & Thomas, 1977;Young, Mackie & Von Dreele, 1977;Sakata & Cooper, 1979;Hewat & Sabine, 1981;Cooper, 1982;Thompson & Wood, 1983;Ahtee, Unonius, Nurmela & Suortti, 1984) or classical fitting methods (Rietveld, 1967;Mortier & Costenoble, 1973;Sonneveld & Visser, 1975;Hall, Veeraraghavan, Rubin & Winchell, 1977;Langford, 1978;Suortti, Ahtee & Unonius, 1979;Brown & Edmonds, 1980;Prince, 1981;Naidu & Houska, 1982;Toraya, Yoshimura & S6miya, 1983). The first two methods are not easily available for powder patterns of polysaccharides because of their paracrystallinity and typical features such as preferred orientations, granularity or hydration effects.…”

Section: Introductionmentioning

confidence: 99%

Diffraction peak shapes: a profile refinement method for badly resolved powder diagrams

Tran¹,

Buléon²

1987

J Appl Cryst

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430SHORT COMMUNICATIONS course of our test experiments we changed the radius of curvature from R = 60 down to R = 20 m. The FWHM of the rocking curves varied in all cases within 10%.References ARROTT, A. S. & TEMPLETON, T. L. (1985). J. Appl. Cryst. 18, 388-395. KULDA, J. (1984). Acta Cryst. A40, 120-126. MIKULA, P., KULDA, J., HORALiK, L., CHALUPA, B. & LUKAg, P. (1986 AbstractA program has been specially written for biological powder spectra. Most existing programs are not suitable for such poorly resolved diagrams with broad bands in which individual peaks are not well separated. A more efficient version of the COMPLEX algorithm is used and this direct optimization method reduces the risk of false minima. Numerous internal parameters and options in the optimization algorithm as well as in the profile calculations lead to great flexibility. The performance and the limits of this version are tested by two applications on co-lactose monohydrate and native cellulose partial spectra. In the first case the results are excellent, according to values in the literature, and in the second case this program indicates some interesting features. This powerful algorithm can be used for more complicated refinements.

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X-ray Rietveld refinement using Debye–Scherrer geometry

Cited by 34 publications

References 45 publications

Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al₂O₃

Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al₂O₃

Potential of the INEL X-ray position-sensitive detector: a general study of the Debye–Scherrer setting

Diffraction peak shapes: a profile refinement method for badly resolved powder diagrams

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X-ray Rietveld refinement using Debye–Scherrer geometry

Cited by 34 publications

References 45 publications

Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al2O3

Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al2O3

Potential of the INEL X-ray position-sensitive detector: a general study of the Debye–Scherrer setting

Diffraction peak shapes: a profile refinement method for badly resolved powder diagrams

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Product

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Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al₂O₃

Rietveld refinement of Debye–Scherrer synchrotron X-ray data from Al₂O₃