Experimental thermodynamics of cobalt sulfides

Low temperature heat capacity data with enthalpies of formation (from elements, orange text) for Co3S4, Co7S8, and Co9S8. Inset figures are heat capacities from 1.8 to ~10 K.
Low temperature heat capacity data with enthalpies of formation (from elements, orange text) for Co3S4, Co7S8, and Co9S8. Inset figures are heat capacities from 1.8 to ~10 K.

CMI researchers from Arizona State University conducted the activity for this highlight

Innovation 
Synthesis and measurement of thermodynamic properties of sulfides Co9S8, Co7.05S8, and Co3S4. The goal is to present a set of recommended thermodynamic values for all solid cobalt sulfides stable at ambient conditions.

Achievement
Enthalpies of formation (from elements) of Co sulfides have been measured using high temperature oxide melt solution calorimetry. Low temperature heat capacity was measured by PPMS. 

Significance and Impact

  • Co demand is expected to outpace supply by the 2030s. New sources and better models are needed to optimize recovery. Sulfides are major co ore minerals, and understanding thermodynamic properties can help.
  • Next steps: obtain high T heat capacity and melting temperatures, determine enthalpy of unquenchable Co4S3 from decomposition of other sulfides.

Hub Target Addressed 
Developing and applying scientific tools to accelerate technology maturation.