Scandium phosphide has the chemical formula ScP. ScP is a solid mineral compound composed of scandium and phosphorus. The compound is produced by the reaction of tris(trimethylsilyl)phosphine with metal halides such as iodine or chlorine. The iodine or chlorine liberates the phosphide which is then separated by distillation. The resulting pure substance can be further purified by precipitation in acidic conditions. The resulting concentrate is high in Sc and low in Al and other impurities. This makes it a suitable material for further purification steps such as solvent extraction with less stages.
Due to its limited supply and unique applications such as in Al-Sc alloys for strength, weldability, heat and corrosion resistance1,2,3, and in solid oxide fuel cells (SOFCs) for extreme oxygen ion conductivity4, the demand for Sc is growing rapidly. Most of the world supply of Sc is sourced from industrial byproducts, such as the red mud from bauxite processing5. Phosphate precipitation is an effective separation and purification process to harvest dissolved Sc ions from acidic leachate solutions. However, the resulting Sc phosphate is difficult to separate from other components and cannot be readily converted to Sc2O3 because of its insoluble nature in water.
When naming ionic compounds, the magnitude of the charge for a transition metal cation is usually included using Roman numerals in parentheses after the name of the element, such as Cr2+