Complete crystallization of CHAlcogenide glasses: TOwards transparent ceramics FOR infrared applications – CHATOFOR

The main objective of CHATOFOR is to develop new transparent chalcogenide ceramics for infrared optical applications, starting from known glass-forming system including Sn-Ge-S, Sn-Ge-Se and Ba-Ga-Ge-S. This will be achieved by employing full crystallization of chalcogenide glasses. This innovative method has recently been developed to design new transparent oxide ceramics but has never been transposed to chalcogenides.
The use of a dense glass as an intermediate media can allow access to a dense ceramic (no porosity) via a simple heat treatment slightly above glass transition temperature. Thus, the glass :could be crystallized into a functional ceramic while preserving the transparency of the parent glass. This crystallization process therefore avoids the usual complex sintering step required when starting from ceramic powders. Moreover, the shaping of the ceramic is easy since it could be realized via the glass (i.e. molding of the glass). Contrary to oxide compositions, chalcogenide materials exhibit an extended transparency towards infrared which can range from visible to more than 30 µm. Nevertheless, transparent chalcogenide ceramics are difficult to develop due to the challenges posed by conventional powder processing methods. Glass crystallisation offers a way around these constraints enabling exploration of new materials with many possible infrared applications in medical industry (diagnosis), quality control (detection of pollutants, heat losses), automotive (driving assistance during night time), and defense (night vision devices).
Two partners (ISCR of Rennes and CEMHTI of Orléans) have involved in this project. The ISCR, specialist of exotic glasses, will be in charge of glass elaborations and to evaluate the mechanical and optical properties of ceramics. The CEMHTI will be focussed on studying crystallisation mechanisms, especially in situ (XRD, SEM, Raman) and ex-situ HR-TEM and develop transparent chalcogenide ceramics through full crystallization of bulk chalcogenide glasses.