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Precision X-Ray Diffractometry using Powder Specimens*

  • L. F. Vassamillet (a1) and H. W. King (a2)


The counter tube diffractometer method for determining d spacings is often rejected for precision work because of lack of information concerning the nature and significance of the inherent errors. Errors concerned with the geometry of the method, the nature of the X-ray source, and the technique of collecting data have all been analyzed previously in some detail. The findings of these analyses, which are scattered throughout the literature, are reviewed briefly. Errors arising from imperfections in the instrument and misalignment of the X-ray source with respect to the diffractometev have been studied experimentally. The results are presented and discussed in terms of the resultant error in the determination of the lattice parameter of a cubic crystal. Errors determined both analytically and empirically are discussed in relation to the extrapolation procedures commonly used for diffractometers. It is shown that, depending on the construction of the instrument, the effect of imperfections in the gears may almost double the error in the final extrapolated value of a lattice parameter.



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Former Fellow of the Mellon Institute, Pittsburgh 13, Pennsylvania.


This work was supported in part by the U.S. Atomic Energy Commission, Washington, D.C.



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Precision X-Ray Diffractometry using Powder Specimens*

  • L. F. Vassamillet (a1) and H. W. King (a2)


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