KCr3(SO4)2(OH)6: Synthesis, characterization, powder diffraction data, and structure refinement by the Rietveld technique and a compilation of alunite-type compounds

C. L. Lengauer, G. Giester, E. Irran
1994 Powder Diffraction  
The new compound, KCr 3 (SO 4 ) 2 (OH) 6 , was prepared by low-hydrothermal synthesis. The structure was refined by the Rietveld technique in space group R3m (Z=3), a =7.2416(3) A, c = 17.0788(9) A, V=775.63 A 3 , R p =l.l, R wp = \Q.\, R B =6.8. The compound is isotypic with alunite, KA1 3 (SO 4 ) 2 (OH) 6 . The temperature of decomposition under nitrogen atmosphere to a hitherto unknown form is about 550 K. The water content of alunite-type compounds is discussed.
doi:10.1017/s0885715600018984 fatcat:ulccxah2efa2jb6fa5isjlna6u