Investigation of New Routes for the Synthesis of Mn4Si7

Abstract

In this work, we investigated two different ways to synthesize the higher manganese silicide (HMS) Mn4Si7. In the first approach, a bulk material was subjected to a heating treatment at 773 K (500 °C) under high pressure (5 GPa) in a multianvil system, whereas in the second one, thin manganese layers deposited onto silicon substrate (Mn/Si) underwent a rapid thermal annealing at different temperatures under vacuum. The guiding principle of these investigations was to study HMS materials in a constrained environment. The atomic composition of the bulk system we studied was Mn35Si65. At room temperature and atmospheric pressure, the sample was made of two phases, namely Mn27Si47 and pure silicon, the latter one being in small quantity. X-ray diffraction measurements performed on this sample after high-temperature—high-pressure treatment evidenced a complete transformation of Mn27Si47 into Mn4Si7. Rapid thermal annealing performed on Mn/Si systems also led to the formation of Mn4Si7.