Crystalline and glassy phases of transition-metal–metalloid systems

Glasses formed in the Ni-P and Fe-B systems are known to be polymorphic. The crystalline phases in these systems display markedly different metalloid environments and a one-to-one relationship can be made between those environments and the glassy phases for Ni-P. It is the purpose of the present paper to explore the prospects for polymorphism in other transition-metal-rich metalloid glassy systems in which the metalloids are P, Si, B, C, and N. The known crystal structures of the phosphides, silicides, carbides, nitrides, and borides have been inspected using radical Voronoi (Wigner-Seitz) -cell constructs to deduce metalloid-site nearest-neighbor arrangements. The occurrence of differences, such as those obtained in Ni-P and Fe-B, is taken as indicative of possible polymorphism in the glasses. A list of such glasses has been constructed. It is seen that polymorphism is most likely to occur in the phosphides and silicides, and very unlikely in the nitrides.