Powder neutron-diffraction measurements of the frustrated kagome latti
ce antiferromagnets Na- and K-jarosites (AFe(3)(OH)(6)(SO4)(2): A = Na
and K) were carried out. The determined magnetic structure at 10 K is
the so-called q = 0 structure and found to be different from one repo
rted previously for K-jarosite. The intensities of magnetic reflection
s show slow decreasing with increasing temperature near T-N and seem t
o imply successive phase transitions observed ina recent NMR study. (C
) 1998 Elsevier Science B.V. All rights reserved.