title: Melt-driven mechanochemical phase transformations in moderately exothermic powder mixtures.
abstract: Usually, mechanochemical reactions between solid phases are either gradual (by deformation-induced mixing), or self-propagating (by exothermic chemical reaction). Here, by means of a systematic kinetic analysis of the Bi-Te system reacting to Bi2Te3, we establish a third possibility: if one or more of the powder reactants has a low melting point and low thermal effusivity, it is possible that local melting can occur from deformation-induced heating. The presence of hot liquid then triggers chemical mixing locally. The molten events are constrained to individual particles, making them distinct from self-propagating reactions, and occur much faster than conventional gradual reactions. We show that the mechanism is applicable to a broad variety of materials systems, many of which have important functional properties. This mechanistic picture offers a new perspective as compared to conventional, gradual mechanochemical synthesis, where thermal effects are generally ignored.
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.|Department of Materials, Imperial College, London SW7 2AZ, UK.
authors.forename: Samuel A
authors.identifier: http://orcid.org/0000-0002-8186-9992
authors.initials: SA
authors.lastname: Humphry-Baker
authors.affiliation: Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari, via Vienna 2, 07100 Sassari, Italy.
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Garroni
authors.affiliation: Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Delogu
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Schuh