Accession Number : AD0611501

Title :   EVALUATION OF TRUNCATION METHODS FOR ACCURATE CENTROID LATTICE PARAMETER DETERMINATION,

Corporate Author : PHILIPS LABS INC IRVINGTON-ON-HUDSON N Y

Personal Author(s) : Taylor,J. ; Mack,M. ; Parrish,W.

Report Date : 13 SEP 1963

Pagination or Media Count : 18

Abstract : The centroid method provides a rational approach to the problem of the accurate determination of lattice parameters. The method requires (1) precise measurement of the line profiles, (2) calculation of the centroid, (3) correction of the centroid for aberrations, goniometer calibration, etc., and (4) knowledge of the centroid of the incident spectral distribution. Four proposed methods for establishing finite limits by truncating a diffraction line profile are reviewed. The methods are evaluated from both a theoretical and practical viewpoint and the superiority of one of the methods is demonstrated. The effects of K beta lines, K alpha satellite lines and the background on the centroid are discussed. Lattice parameters of silicon and tungsten derived using both Fe K alpha and Cu K alpha radiations are given. The results are free of systematic error, and it appears that the centroid method can be used to obtain lattice parameters of greater accuracy than has heretofore been possible, provided accurate spectral centroid data can be obtained. (Author)

Descriptors :   (*CRYSTAL LATTICES, DETERMINATION), (*X RAY DIFFRACTION, CRYSTAL LATTICES), TEST METHODS, SILICON, TUNGSTEN, CRYSTALLOGRAPHY, X RAY SPECTROSCOPY, POWDERS

Distribution Statement : APPROVED FOR PUBLIC RELEASE