Functional materials and nanomaterials

Coordinator: Yannick Mugnier

This theme focuses on the preparation and structural, thermodynamic and multifunctional characterization of high value-added (nano)-materials.

It aims to establish or revisit, in particular for solid materials such as alloys and metal oxides, the equilibrium diagrams between phases of binary and higher order systems, and to supply diagrammatic (liquidus temperature, invariant equilibria, structural transformations, etc.) and integral (heat capacity, enthalpy of academics, etc.) databases for thermodynamic modeling of systems. The aim is to use this knowledge to develop innovative materials and contribute to the control and optimization of industrial processes, for example, in the fields of nuclear safety (Zr-based alloys) and electroerosion (control of surface-deposited phases).

(a) SEMSEM image of an In-Zr alloy with composition 66.7 at%Zr alloy produced by powder metallurgyannealed at 1000°C. (b) Evidence of eutectoideutectoid decomposition in an InZr alloy of composition 81.5 at%Zr. (c) Example of quantitative Rietveld type refinement of a multiphase compound.

At the nanoscale, research is focused on establishing the reaction and crystallization mechanisms of materials with non-centrosymmetrical crystal structures (LiNbO3, BiFeO3, LiTaO3 and Sillenite-type phases) in order to control their final morphology. These so-called harmonic nanoparticles possess extremely rich non-linear optical properties (in terms of photostability, wavelength flexibility, imaging depth and response time) which are being quantified and put to good use in the biomedical field. These include early diagnosis after functionalization of their surface for specific marking of cancer cells, or on-demand, targeted release of anti-cancer molecules.

(a) Image multiphoton of lung cancer cells specifically labelled with LiNbO3 nanocrystals, whose second harmonic signal appears in blue, and (b) corresponding TEM imaging of the nanocrystals. (c) Dispositive ss signals non-linear optical signals illustrating second-harmonic harmonic scattering froma colloidal nanocrystal suspension for excitation in the infrared.