Inorganic materials chemistry

Research in inorganic materials chemistry is developed by the GREENMAT team of CESAM research unit. See below for an overview or here for more detailed information.

For physical vapour deposition techniques, see the activities of Prof. Nguyen and Prof. Silhanek of the Q-MAT team (here).

Powders and coatings from (aqueous) solutions

solution-magMany functional inorganic materials have complex compositions, but a homogeneous distribution of several cations in a material may be difficult to achieve by standard solid-state synthesis. This is one of the reasons for the development of precursor synthesis methods from solutions. Other advantages are the possibility to lower the temperature of the heat treatment and/or to tune grain size. In a typical precursor synthesis, soluble salts of the cations are dissolved in a solvent, then a solid precursor powder or film is obtained by a process such as precipitation, sol-gel or solvent vaporization. We optimize solution chemistry so that the homogeneous cationic distribution in the solution is retained in the solid precursor and make sure that the solution characteristics (pH, viscosity, wettability,...) are adequate for the synthesis equipement (such as spray-dryer, hydrothermal reactor, ultrasonic spray pyrolysis system,...)

 

Powders and coatings from (aqueous) suspensions

greenmat-suspObtaining a stable suspension of powder(s) in a liquid is a prerequisite for many procedures:  granulation of nanopowders, preparation of composites, shaping of 3D objects or deposition of coatings. When optimizing the formulation of a suspension, we have to adapt the granulometric distribution and select adequate dispersing agents, pH,... depending on the surface chemistry of the particles. We also have to take into account the requirements of the shaping method for which the suspension is  being designed. For example, viscosity is often a key parameter and formulation of a suspension with high solid content of nanoparticles and low enough viscosity is not an easy task.

 

Microstructure control

soft-templatingMicrostructural properties (such as grain sizes, grain shapes, porosity, etc) depend on the synthesis technique and in some cases on some intrinsic characteristics of the compound such as preferential growth directions. Appropriate selection of synthesis parameters therefore allows some degree of control on the final microstructure. Beyond this, we also use templating approaches to direct the organisation of the inorganic material around soft templates (such as block copolymer micelles) or hard templates (polymer beads of silica scaffolding).

 

Crystalline phase formation

greenmat-drxMany syntheses require a heat treatment of the precursor or reactant mixture in ordre to obtain the desired compound. We study phase formation pathways by ex-situ or in-situ powder x-ray diffraction.