IMAGE-PLATE SYNCHROTRON LAUE DATA-COLLECTION AND SUBSEQUENT STRUCTURAL-ANALYSIS OF A SMALL TEST CRYSTAL OF A NICKEL-CONTAINING ALUMINOPHOSPHATE

Image plates have advantages over photographic films, which include wi der dynamic range, higher detector quantum efficiency, reduced exposur e time and large size. In this study, an on-line image-plate system ha s been used to record crystallographic data from a small crystal. In p articular, synchrotron Laue data were recorded with lambda(min) = 0.45 5, lambda(max) = 1.180 Angstrom, in 20 images 10 degrees apart and wit h an exposure time of 0.3 s each from a crystal (0.02 x 0.05 x 0.25mm) of a nickel-containing aluminophosphate, NiAPO. The Laue data were an alyzed with the Daresbury Laue software, including the application of an absorption correction. The structure was solved by a combination of the Patterson method and successive difference Fourier calculations u sing SHELXS86 and SHELXL93; the final R value for 1934 unique reflecti ons (all data) and 310 parameters was 7.90%. The structure agrees with that determined by monochromatic diffractometry using the same crysta l and reported by Helliwell, Gallois, Kariuki, Kaucic & Helliwell [Act a Cryst. (1993), B49, 420-428] with an r.m.s. deviation of 0.03 Angstr om. Hence, this study shows the image-plate device to be very effectiv e for synchrotron data collection and subsequent structure analysis fr om small crystals, i.e. 0.02 x 0.05 x 0.25 mm, in chemical crystallogr aphy as well as providing further confirmation of the practicability o f Laue data in structure solution and refinement.