The Synthesis of Greigite from a Polysulfide Solution at about 100 °C

Abstract

Favorable synthesis conditions for greigite are examined in FeSO4·(NH4)2SO4–Na2S–Na2Sx systems at about 100 °C. It has been found that greigite formation is influenced by the pH adjustment and by the addition of sulfur. When the final pH is about 6.0 and the dissolved iron concentration is in the 10−3–10−1.5 M range, greigite is synthesized as a single phase. The unit-cell dimensions of greigite range from 9.840 to 9.877 Å, corresponding to variations in compositions between 45.4 and 42.9 atomic % Fe. The formula of synthetic greigite is represented as Fe3+xS4 (x=0–0.4).