Synthesis of SnTe by repeated cold-pressing

The synthesis of intermetallic compounds can be carried out through a repea ted cold-pressing (RP) technique for binary metallic systems whose large ne gative heat of formation ensures the solid state reaction. In some cases, t hose reactions get started on the surface of highly energized regions, call ed hot spots. In this work, the intermetallic tin-tellurium compound SnTe h as been prepared in air and at room temperature by RP of elemental Sn (gran ular) and Te (shots) precursors. The elemental structure is gradually cold- deformed until the pressing action supplies it with enough mechanical energ y (microstrain) as to take the metallic mixture into a violent interaction, via hot spots formation and announced by means of an explosive reaction. H ot spots of 1-2 mu m in diameter were visible on the metals surface when th e powder particle size was 10-15 nm. That occurred with accumulation of 0.2 5-0.35% total strain, after 30 times pressing (1.25 g of the elemental mixt ure at 343 MPa). This indicates a close relationship of the reaction's igni tion point with both the crystallite size and stored strain in the precurso r powders. Hot spots trigger the explosive intermetallic synthesis. (C) 199 9 Elsevier Science S.A. All rights reserved.