Before revision: Synthesis Heating powdered holmium and red phosphorus in an inert atmosphere or vacuum: Ho + P -> HoP Physical properties Holmium phosphide forms dark crystals of a cubic system, stable in air, does not dissolve in water.
After revision: Synthesis Heating powdered holmium and red phosphorus in an inert atmosphere or vacuum: 4Ho + P4 -> 4HoP Physical properties Holmium phosphide forms dark crystals of a cubic system, stable in air, does not dissolve in water.