Hereafter are the summaries of the short and long projects now closed and selected in the frame of the 2014 Call of LabEx EMC3:
Normandy Initiative for Crystallography using Electrons
Axis 3: Trandisciplinary research – CRISMAT/LCS/CIMAP
The NICE project (2015-2016) aimed at setting up a new process to define the crystal structure of chemical components.
Identify and determine the compounds crystal structure is essential in materials science and the X-ray powder diffraction (DRX) is the main way to obtain that information. However, in laboratory, the spatial resolution of this technique is limited due to the little size of the sensor which only fits for the analysis of 10-micrometer-crystals. Besides, when the material is induced in a matrix or under a thin layer supported by a substrate, the XRD is unrelevant.
The NICE project proposed to address the issue of structural characterisations for these materials with low-diffracting aspects. Setting up methodologies allowing to access accurate cristallographic information by using electronic diffraction via a parallel beam.
The first step was the synthesis of reference materials, and massive materials models then new materials in order to validate the technique of the electronic diffraction. After the synthesis of referenced phases came the study of the component Co-AIPO and new zeotypes phases derived from AIPO was led through PEDT at first, and then through single crystal X-ray diffraction.
The electronic diffraction, which brought significant results and progress in dynamic refinements, was thus applied on this component. And the results overpassed the expectations: not only were the XRD-results reproductible via electron diffraction, but it also led to the validation of theorical calculations after which hydrogene atoms could be obtained more easily then through single crystal XRD.
This new method will undoubtedly define an increasing number of structures, and this, at a level which is now unaccessible. Besides, the applications linked to this new analysis method are numerous, going from energy materials to pharmaceuticals.
Leader : Philippe Boullay (CRISMAT)
Electronic Hybrid Materials based on Conducting Polymers Encapsulated in Zeolites
Axis 1: Materials for energy – LCMT / LCS
The EHMA project (Electronic Hybrid Materials based on Conducting Polymers Encapsulated in Zeolites) was to develop new hybrid materials with a low production cost based on encapsulation of conductive polymers in zeolites for application in energy production and storage (e.g. batteries and photovoltaics). The originality of the EHMA project is in the use of zeolites (microporous structure) as a matrix for stabilization of conductive polymer chains.
The synthesis of nanosized zeolites within this project is very innovative and allowed the stabilization of polymers within their micropores. The results from the EHMA project demonstrate the possibility of controlled arrangement of conductive polymers within the zeolite nanocrystals, thus altering their properties. About 80 % of the volume of the micropores of the zeolites can be loaded with conductive polymers.
The works is related to energy management and storage, indeed, the production of these hybrid materials is low cost and environmentally friendly. The results obtained within the EHMA project confirmed that the formation of polymers is limited by the microporous structure of the zeolites and also is dependent on the Lewis acidity of the materials.
The spectroscopic results confirmed that the polymerization exclusively occurs in the micropores of the zeolite nanoparticles, and no polymerization on the crystallites surface has been observed. The length and diameter of the zeolite crystals are expected to have an impact on the properties of the hybrid material.
Leader : Bernhard Witulski (LCMT)
Synthesis and characterisation of thermoelectric hybrid materials from inorganic layers, MS2 with M=W, Mo, Ti
Axis 1: Materials for energy – CRISMAT / LCS / LCMT
The performances of a thermoelectric material are directly linked to the nature and the chemical composition of this material and its cristallographic structure. These 2 aspects will also strongly impact 2 inherent properties of this material: the electric conductivity due to conducting electrons and its phonons thermal conductivity. A good thermoelectric material is thus a combination between a good electronic conductor (metal) and a good thermal insulator (insulator), that means a degenerated semi-conductor or a highly-doped conductor.
The THERMOS project (2015-2016) – “Synthesis and characterisation of thermoelectric hybrid materials from inorganic layers, MS2 with M=W, Mo, Ti” is led by CRISMAT, LCS and LCMT. It aimed at developing new hybrid materials with thermoelectric properties, from MS2 sulfides with lamellar structures. Afterwards, the integration of organic molecules should reduce the thermal conductivity while keeping the good electronic properties of the sulfide. The goal of this project is to find an alternative to Bi2Te3, which is currently the only material usable at ambient temperature but which is toxic and costly.
The results of these works allowed to elaborate a new material having both electronic properties and being a good thermal insulator, which can offer perspectives. Indeed, via the integration of Li+, molecules composed of one or two functions R-NH3+have been integrated in MS2 (M = Mo, Ti). Besides, benzothiazoliums and a ferrocene have been efficient in this strategy. The new material developed possesses good electronic abilities and regarding the thermal insulation.
Finally, in order to respect the principles of the sustainable development, a study has been carried out on the materials ageing and degradation in function of the time and temperature under different atmospheres. It allows to select the best materials for future applications in the industrial sector.
Leader : Jean-Michel RUEFF (CRISMAT)