A New Diffraction Approach To Crystal Structure Determination of Nano-twined Martensites

The intensity diffracted by crystals containing twin boundaries of the system {110}, 0 1 1 were calculated in the reciprocal space assuming a short-range order in the twin-boundary distribution. The calculated intensity distributions have been analyzed to find the effect on the diffraction pattern of such parameters as (i) ratio b/a (c/a) between the crystal lattice constants, (ii) density of the twin boundaries, (iii) ratio between thicknesses of the twin-related lamellae, and (iv) crystallographic direction along which the intensity distribution is simulated. It is found that each of these parameters affects the diffraction-peak profiles and positions including the diffraction peaks of the basic structure. Therefore, the problem of the diffraction pattern identification for a twin-modulated crystal should be approached only by a combined consideration of the diffraction features.