A Novel X-Ray Powder Diffraction Experiment Potassium fluoride1 and 8-zinc sulfide, or sphalerite, are examples of campounds with a faeecentered cubic close packing arrangement. However, with one ion a t (0,0,0; 'h?k,O; 'h,O,?h; O,'h,'h,I, the other ion in the first case packs a t the octahedral site 1%,0,0; 0,g.O; 0,0,%; 'h,'h,K), and in the second case, packs a t every other tetrahedral site (Y4,Y4,Y6;%,3/r,Y4;Sir,%,%; %,%,%). These compounds have similar unit cell lengths (5.347 and 5.4060& respectively), similar atomic number ratios (1919, 30/16), and similar d spacings, but because d structural differences, the relative intensities are different for some reflections. These observations (figure ) are the hasis far a student experiment in X-ray powder diffraction. X-ray powder spectra for top: potassium fluoride, baflorn: 8zinc sulfide (CUK radiation: Ni filtered)
K. G. Shields C. H. L. Kennard University of Queensland, Brisbane Queensland 4067, Australia
Volume 51. Number4. April 1974
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