This volume focuses on thorium compounds with silicon, germanium, and all 5th main group elements except nitrogen. It includes ternary and polynary compounds containing oxygen, specifically those with phosphorus, such as phosphates, hypophosphates, and phosphinates. Compounds involving other elements, like silicates and arsenates, were covered in a previous volume. The compounds discussed here are of scientific interest due to their unique physical and chemical properties, as well as technological relevance, particularly in the nuclear field. Refractory compounds like ThSi and ThP are notable for their potential as nuclear fuel in specialized reactors, thanks to their excellent heat conductivity and chemical stability against corrosion of cladding alloys. However, the full potential of these compounds in the thorium nuclear fuel cycle remains largely unexplored. While there is substantial knowledge about the preparation and properties of many binary and ternary phases, significant questions persist regarding phase equilibria, solid solutions, and the homogeneity of some phases described in this volume.
