Ion-beam induced metastable Pt2Si3 phase. I. Formation, structure, and properties

Abstract

A metastable silicide phase with a composition of Pt₂Si₃ has been obtained by using ion‐beam mixing techniques. To form the phase, a thin PtSi film on a Si substrate was first converted into a Si‐rich amorphous Pt‐Si alloy by implantation with energetic ions through the PtSi‐Si interface. The amorphous alloy then transformed into the metastable crystalline phase upon post annealing at 350–500 °C. X‐ray diffraction analysis showed that the Pt₂Si₃ phase has a hexagonal crystal structure with lattice parameters a=3.841 Å and c=11.924 Å and there are ten atoms per unit cell. The phase was unstable at temperatures above 550 °C and transformed back to PtSi and Si. The metastable Pt₂Si₃ phase was found to exhibit a superconducting transition onset at about 4.2 °K and becomes completely superconductive below 3.6 °K.