Crystallisation of Ba(SO_4,CrO_4) solid solutions form aqueous solutions

摘要

Barite (BaSO_4) and barium chromate form a complete solid solution series, where SO~2-_4 ions substitute for CrO~2-_4. Both endmembers are isomoprhous and crysallise int he space group Pnma. In this work we present an experimental study of the crystallsiation behaviour of this solid solution form aqueous solutions. Crysals of Ba(SO_4,CrO_4) were grwon by counter-diffeuson of BaCl_2 and Na_2SO_4＋Na_2CrO_4 through a column of silica hydrogel. A set of experiments starting with parent solutions of different SO~2-_4/CrO~2-_4 ratios was carried out. The jcompostion of the obtained crystals was studied by electron microprobe. A linear influence of the compostion on the strucutral parameters was determined by X-ray diffraction.