Institut de Chimie Moléculaire et des Matériaux d'Orsay

Laboratoire d'Etude des Matériaux Hors Equilibre - LEMHE

Functional Oxides

Staff :

Team leader :

Pr. Nita Dragoe    

Assist. Prof :

Dr. David Berardan

Post-doc :

Dr. Lin Pan
  Dr. Nghi Pham    

Technician :

Céline Byl

Ph’D students :

Céline Barreteau
      Thi-Than-Xuan Vo

Our activities are focused on functional oxide materials, with main interest in thermoelectricity and superconductivity.

We also study the influence of the oxygen stoichiometry and of the nanostructuration on these materials properties.

 

Nanostructuration

Materials nanostructuring is a key step for the development of improved thermoelectric materials. Our current activity is focused on the effect of the nanostructuration on the thermoelectric properties of “simple” oxides which are already known as good thermoelectric materials. Our studies deal with the influence of the grains size, shape, doping and surface on the transport properties.

Préparation de matériaux nanostructurés

The nanostructured materials are obtained through various chimie douce synthesis routes, including precipitation, sol-gel, hydrothermal (…) with or without capping agents. The size and shape of the particles can be controlled by tuning the synthesis conditions. The obtained powders are characterized by electron microscope and XRD.

Created by Digital Micrograph, Gatan Inc.
Example showing the influence of the synthesis conditions on the shape of the particles (here synthesis by precipitation or use of a capping agent)

Spark plasma sintering (SPS) densification

Intrinsic transport properties must be measured using dense materials, as the porosity strongly influences both electrical and thermal conductivities. One of our goals is to optimize the sintering conditions in order to get fully dense samples while retaining the nanostructure. The SPS enables a very rapid heating of the sample with very short sintering time, and therefore a limited crystal growth.

 

 

 
21 février, 2013