Redetermination of the Structure of the Ferroelectric Crystal Guanidinium Aluminum Sulfate Hexahydrate, GASH, and its Chromium Isomorph

Calculations with hypothetical data suggest the presence of nonrandom errors in earlier x-ray diffraction data on GASH, which caused the difficulties in refinement of its crystal structure. New data have been collected on GASH and on GCrSH and the structures of the two compounds have been refined to final R values of 0.035 and 0.036, respectively, reducing the estimated standard deviations of the parameters by a factor of about 5.