UNCERTAINTY ESTIMATION OF LATTICE PARAMETERS MEASURED BY X-RAY DIFFRACTION

Marcos F. de Campos, Jailton C. Damasceno, Rogério Machado, Carlos A. Achete

Abstract

Abstract: The uncertainties in lattice parameters determination, for X-Ray Diffractometers with Bragg- Brentano geometry, were estimated according GUM recommendations using the Monte Carlo simulation approach. The analyzed specimen was a Corundum NIST 1976 SRM Standard. Misalignment of instrument (zero 2theta offset and peak position) is an important error source, and should be kept (2&theta;) < 0.015° to be able to perform lattice parameters measurements with an accuracy = 0.0001 Angstrons. Sample displacement is in general the main source of error, and the above mentioned misalignment of instrument (0.015°) only becomes dominant as error source if the sample displacement is very small (<10 µm). The analysis showed that sample absorption (Corundum) is negligible as error source, if compared with sample displacement and equipment misalignment. Other possible sources of systematic error are discussed.

Keywords

lattice parameters, X-Ray diffraction, error estimative, GUM, diffractometers

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PWC-2006-TC8-008u.pdf

DOI

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IMEKO TC

TC8 - Traceability in Metrology

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