X-Ray Diffraction Profile Analysis of Powdered Samples

Stanisz, Greg J.; Holender, J. M.; Sołtys, J.

doi:10.1017/s0885715600016444

Cited by 7 publications

(1 citation statement)

References 13 publications

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“…Among these pro®le-shape functions, the pseudo-Voigt (Thompson et al, 1987) and the Pearson VII functions (Hall et al, 1977) are, undoubtedly, the most popular, giving the best approximations to the X-ray diffraction pro®les in many cases (Young & Wiles, 1982;Stanisz et al, 1989). Other representations, such as the Voigt function (Suortti et al, 1979), a convolution of Gaussian and Lorentzian functions, and the nonanalytical array-type pro®le function of Toraya (1990), have also been successfully employed in powder data analysis.…”

Section: Introductionmentioning

confidence: 99%

A Gaussian–Hermite polynomials function for X-ray diffraction profile fitting

Sánchez-Bajo

Cumbrera

1999

J Appl Cryst

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In recent years, several pro®le-shape functions have been successfully used in X-ray powder diffraction studies. Here, a new pro®le function for approximating the X-ray diffraction peaks is proposed. This model, based on a Gaussian function multiplied by a correction factor in the form of a series expansion in Hermite polynomials, can be employed in the cases where there are peak asymmetries. The function has been tested by using samples of -Al 2 O 3 and 9-YSZ (yttria-stabilized zirconia), yielding generally satisfactory results.

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Section: Introductionmentioning

confidence: 99%

A Gaussian–Hermite polynomials function for X-ray diffraction profile fitting

Sánchez-Bajo

Cumbrera

1999

J Appl Cryst

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Orientation and mechanical properties of PBT and its blends with a liquid‐crystalline copolyester

Ajji

Brisson

1992

J Polym Sci B Polym Phys

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Blends of poly (butylene terephthalate) (PBT) and a liquid‐crystalline copolyester (60 mol % poly(p‐hydroxy benzoic acid)/40 mol % polyethylene terephthalate) (LCP) were prepared in the melt state. The investigation of mechanical properties indicated that, for the processing conditions used, neither the addition of up to 30 wt % LCP to PBT nor the cooling history affected significantly the tensile modulus E. For oriented specimens, a marked improvement of E was obtained for all the blends, and increased with the LCP content. This improvement was more marked for slowly cooled samples. X‐ray diffraction was used to quantify the orientation of the crystalline PBT and liquid‐crystalline LCP phases. It was shown that neither the thermal history nor the presence of up to 30 wt % LCP affected the orientation behavior of the PBT crystalline phase. For the LCP phase, measurements were not possible for concentrations lower than 10 wt %, and were more difficult and less precise than for PBT. Nevertheless, it was possible to show that a better orientation was obtained for the slowly cooled samples and for higher concentrations of LCP in the blends. This correlated with the enhancement of mechanical properties observed for the oriented samples.

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Study of crystalline orientation in drawn ultra‐high–molecular weight polyethylene films

Lafrance

Debigaré

Prud’homme

1993

J Polym Sci B Polym Phys

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A wide‐angle x‐ray diffraction (WAXD) study of the development of molecular orientation in the crystalline phase of ultra‐high–molecular weight polyethylene films prepared by the gelation–crystallization method is presented. WAXD scans of the undrawn films show that the lamellae are oriented in the plane of the films. Upon drawing at 130°C, the orientation of the molecular chains changes from the direction normal to the film surface (ND) to the elongation direction. The decrease of the 200/020 intensity ratio at low draw ration (λ <10) indicates that double orientation develops during the transformation from the lamellar to the fibrillar morphology, with the a‐axis oriented parallel to ND. The orientation distributions of the 110, 200, 020, and 002 planes of the orthorhombic unit cell of polyethylene were studied and characterized by the coefficients of a Legendre polynomial series. At a draw ratio of 4.5, the second‐order coefficient, 〈P2(cos χ〉, already gets close to its limiting value, but it is shown that higher order coefficients of the polynomial series can be used to describe the evolution of the orentation, even up to λ = 50. The coefficients relative to the molecular chain orientation, 〈Pn(cos χ)〉c, can be calculated from different crystalline reflections. Curve‐fitting calculations were made in order to improve the correlation between the results obtained from the orientation distribution of the 110, 020, and 002 planes. A Person VII function was found to give a better fit of the experimental curves than Gaussian or Lorentzian equations. © 1993 John Wiley & Sons, Inc.

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X-Ray Diffraction Profile Analysis of Powdered Samples

Cited by 7 publications

References 13 publications

A Gaussian–Hermite polynomials function for X-ray diffraction profile fitting

A Gaussian–Hermite polynomials function for X-ray diffraction profile fitting

Orientation and mechanical properties of PBT and its blends with a liquid‐crystalline copolyester

Study of crystalline orientation in drawn ultra‐high–molecular weight polyethylene films

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