Application of Guinier Camera, Microcomputer Controlled Film Densitometry, and Pattern Search-Match Procedures to Rapid Routine X-Ray Powder Diffraction Analysis

Abstract

In most routine chemical analyses, a trade-off is made between quality of data and time required to obtain and analyze the data.In X-ray powder diffraction, identifications are normally made by Debye-Scherrer film methods or by medium speed (1-2°20/min.) diffractometry, with or without an internal standard. With one notable exception, the inherent precision of the Guinier camera geometry has been virtually ignored as too expensive or time consuming for routine work, or relegated to special projects. The accessibility of microcomputers, however, not only makes it economically and realistically feasible to automate the equipment previously used for special Guinier projects, but to extend the overall precision of observed d-spacings into the area of routine analysis. Search-match procedures benefit from the increased data precision to such an extent that they can be used routinely to propose the identity of major pure phases and release the analyst to concentrate on minor components and impure phases which may be subject to lattice constant shifts.

X-ray diffraction

“…Johnson (341) reviews the present status of this situation. (344), Edmonds (345) and Edmonds and Henslee (346) describe specific computer programs for phase identification. Mayer et al (347) suggest selective crystallization to help identify phases in a mixture, and Nichols et al (109) suggest selective absorption techniques to help tag individual lines prior to the search step.…”

Structural Stability and Phase Transitions in <i>f</i>-Electron Based Systems

“…Investigation of phase transitions in materials at highpressures is a very demanding task and requires a high precision XRD set up. It is well known that a Guinier diffractometer provides high-resolution XRD data with a better S/N ratio in the case of samples at NTP [32,33]. The Guinier geometry has been adapted for high-pressure DAC x-ray diffraction experiments [31].…”