ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
Three-dimensional intensity profiles of selected diffuse b-type (h + k = odd) reflections in a core pigeonite from lunar rock 12053 have been measured by a point-count method using a single-crystal automatic diffractometer. Sampling reciprocal space about a Bragg reflection yields a 5 × 5 × 5 array of intensity data; contouring shows the shape, size and orientation of the diffuse reflection. It is assumed that the intensity distribution is Gaussian in reciprocal space and the diffuseness of the b-type reflections is primarily due to small antiphase domains. From the intensity data, the average shape, size and orientation of the antiphase domains have been determined by applying Fourier transform theory. The average shape of the antiphase domains can be approximated by an ellipsoid with axial lengths; {\bar z} = 171, ÿ = 141, and {\bar x} = 122 Å. Lengths of these axes have been adjusted by a correction factor which makes the adjacent a-type (h + k = even) reflection conform to its ideal spherical form. The long (z) axis deviates from the crystallographic axis and forms a 44° circle about {\bar 2}11. The average size and shape of the domains agree well with those determined through electron microscopy.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739475000216
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