M.Lord and H.K.D.H. Bhadeshia,
Phase Transformations Group,
Department of Materials Science and Metallurgy,
University of Cambridge,
Cambridge, U.K.
Calculates the RELATIVE intensities of electron diffraction spots when forming an electron diffraction pattern from a region of cementite (Fe3C) in a transmission electron microscope.
Language: | FORTRAN |
Product form: | Source code |
Complete program
MAP_CRYSTAL_CEMSTRUCT calculates the relative intensities of electron diffraction spots for lattice spots up to those where h = k = l = 3.
Its most important use is in the identification of the cementite phase using electron diffraction, as some spots have extremely weak diffracted intensities. The calculated 'absence' of such spots aids in the identification of zone axes and thus speeds the identification of the cementite phase.
Calculations are performed to double precision. The accuracy of the results is dependent upon the accuracy of the measured atomic positions within the unit cell (taken from the literature) and upon the simplifying assumption that the atomic scattering factors of Fe and C are constant in relation to each other as a function of diffracted angle. Hence the results provide a guide but should not be considered as exact. The evaluation of scattering angles was performed for a 2 Angstrom plane spacing where Fe=2.91, C=1.15 (Angstroms). All other contributions to diffracted intensity are ignored.
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Program accuracy is constrained by measurement accuracy and by simplifying assumptions. See comments in the Description.
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Complete program.
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H K L INTENSITY(%) - - - ------------ 0 0 1 0.0000 0 0 2 0.0121 0 0 3 0.0000 0 1 0 0.0139 0 1 1 0.0139 0 1 2 0.0139 0 1 3 0.0139 0 2 0 5.0404 0 2 1 7.2831 0 2 2 52.3986 0 2 3 32.8115 0 3 0 1.0879 0 3 1 1.0879 0 3 2 1.0880 0 3 3 1.0879 1 0 0 2.8018 1 0 1 1.5216 1 0 2 2.8017 1 0 3 73.3030 1 1 0 1.1364 1 1 1 1.0842 1 1 2 5.3135 1 1 3 38.1656 1 2 0 11.5978 1 2 1 23.8227 1 2 2 33.8435 1 2 3 2.6991 1 3 0 48.8124 1 3 1 9.5597 1 3 2 0.1778 1 3 3 1.9222 2 0 0 27.8393 2 0 1 4.5394 2 0 2 9.9956 2 0 3 4.5394 2 1 0 58.2569 2 1 1 5.2158 2 1 2 24.9770 2 1 3 2.9052 2 2 0 8.3805 2 2 1 0.9864 2 2 2 24.6676 2 2 3 10.5676 2 3 0 4.6722 2 3 1 7.8497 2 3 2 18.4645 2 3 3 42.2373 3 0 0 0.2118 3 0 1 0.1928 3 0 2 0.2118 3 0 3 0.2603 3 1 0 2.4603 3 1 1 7.7300 3 1 2 54.0989 3 1 3 56.7027 3 2 0 0.9767 3 2 1 0.0713 3 2 2 0.8603 3 2 3 0.0482 3 3 0 100.0000 3 3 1 3.0264 3 3 2 15.6439 3 3 3 2.8346
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electron diffraction patterns, electron microscopy, cementite
MAP originated from a joint project of the National Physical Laboratory and the University of Cambridge.
MAP Website administration / map@msm.cam.ac.uk