X-ray energy-dispersive diffractometry using synchrotron radiation

Abstract

The special features of X-ray energy-dispersive powder and single-crystal diffraction using synchrotron radiation are discussed on the basis of experiments performed at the Deutsches Elektronen-Synchrotron, DESY. The method is shown to be of particular value for fast structure identifications, experiments for which large scattering vectors are important, studies of phase transformations and chemical reactions at elevated temperatures and high-pressure studies. Studies of time-dependent phenomena using pulsed external fields are discussed.

Optimum resolution in X-ray energy-dispersive diffractometry

“…However, this setting would require photons of about 161 keV [-calculated using (3)-] and they are not available at this time with sufficient intensity. DESY with its critical wavelength of 0.42 A* supplies photons with sufficient intensity down to about 0.1 A, which amounts to about 120 keV, and it was shown experimentally that diffraction peaks can be easily recorded at 70 keV (Buras et al, 1977). If we take the latter value in order to be on the safe side in our calculations, then we obtain for d = 1 A and 0o=5.1 ° a practical possibility to achieve an optimum value of 6dFwHM equal to 5"7 x 10-3 A.…”

“…1 depends on A Eamp, and at the same time to test the validity of (5) concerning the E dependence, we used the diffraction data for powdered silicon at 200=34-2 ° with A0o=8 x 10 -4, which were obtained in an experiment performed with synchrotron X-rays at DESY (Buras et al, 1977). We fitted the 18 reflections to Gaussian functions and plotted the 6EFwHM/E values versus E as shown in Fig.…”

“…As will be seen from the present note, this information can be obtained by expressing the full width at half maximum (6dFwHM) in the d scale as function of d, 0o and A0o. It will also be seen that quite different answers are obtained for large and small d0o, the latter being especially important in view of the use of synchrotron radiation as an X-ray source for energy-dispersive diffractometry (Buras, Gerward & Staun Olsen, 1976;Bordas, Munro & Glazer, 1976;Bordas, Glazer, Howard & Bourdillon, 1977;Buras, Staun Olsen, Gerward, Will & Hinze, 1977).…”

A miniature piston-cylinder apparatus for high-pressure X-ray diffraction in conjunction with energy dispersion

“…(1 a) and, consequently, End, sin 0o=hc/2=6.199 (keV A0, {lb) with variable 2 (=variable energy) and constant diffraction angle, 200; dlt denotes dr, at (Giessen & Gordon, 1968;Buras, Olsen. Gerward, Will & Hinze, 1977).…”

Energy-dispersive measurements of diffracted synchrotron radiation as a function of pressure: applications to phase transitions in KCl and KI

“…The only other group, of which we are aware, which has used SR for high-pressure research is that of Buras, Staun Olsen, Gerward, Will & Hinze (1977). They looked at several materials as a function of pressure: (1)diffraction spectra were recorded from TeO z in both the low-pressure (tetragonal) and highpressure (orthorhombic) phases with scans of 2000 and 1000 s duration, respectively; (2)the fluorescent radiation from AgI was measured at two different pressures; and (3)the volume compressibility of FeS was measured.…”