Novel Ordered Phase, Pt₈Ti

Abstract

DURING an investigation of platinum-rich alloys in the titanium–platinum binary system an intermediate phase of the composition Pt₈Ti was discovered. The crystal structure of this phase has been determined by me¹. This arrangement of atoms is of particular interest because of the fact that it is an ordered configuration which is not greatly different from AuCu (ref. 2), Au₅Mn₂ (ref. 3), and Au₄Ti (ref. 4). These phases are characterized by the fact that the location of atoms represents minor deviations from a face-centred cubic solid solution, and also that different species of atoms display a preference for particular crystallographic sites. The ordered phase Pt₈Ti exists over a region of homogeneity as does Au₄Ti. Furthermore, it is quite interesting to note that the addition of titanium to platinum decreases the lattice parameter of the parent terminal phase. A similar effect was observed in the titanium–gold system⁵.