The true unit cell of ammonium hydrogen sulfate, (NH₄)₃H(SO₄)₂. Errata

Recently discovered errors in sample preparation for the original study by Davis & Johnson [J. Appl. Cryst. (1984). 17, 331-333] have revealed that the reference intensity ratio data of Table 1 are incorrect. The reference intensity ratios for the three sets of reflections given in Table 1 have been remeasured and are as follows: 020 + 10 = 1.92; 021 + 002 = 1.16; and 10 = 0.88. The resulting average reference intensity ratio for the letovicite 111 reflection (the strongest of the pattern) is 1.15(5). Fortunately, the reference constant study was completed independently of the powder diffraction and Laue study and hence the cell constants, diffraction intensities and spacings presented in this paper are not affected by these errors.