Synthesis of SnTe by repeated cold-pressing

The synthesis of intermetallic compounds can be carried out through a repeated cold-pressing (RP) technique for binary metallic systems whose large negative heat of formation ensures the solid state reaction. In some cases, those reactions get started on the surface of highly energized regions, called hot spots. In this work, the intermetallic tin-tellurium compound SnTe has been prepared in air and at room temperature by RP of elemental Sn (granular) and Te (shots) precursors. The elemental structure is gradually cold-deformed until the pressing action supplies it with enough mechanical energy (microstrain) as to take the metallic mixture into a violent interaction, via hot spots formation and announced by means of an explosive reaction. Hot spots of 1–2 μm in diameter were visible on the metals surface when the powder particle size was 10–15 nm. That occurred with accumulation of 0.25–0.35% total strain, after 30 times pressing (1.25 g of the elemental mixture at 343 MPa). This indicates a close relationship of the reaction’s ignition point with both the crystallite size and stored strain in the precursor powders. Hot spots trigger the explosive intermetallic synthesis.