1. LAAS‐CNRS University of Toulouse 7 avenue du colonel Roche Toulouse 31031 France
2. University of Toulouse UT3‐Paul Sabatier, 118 route de Narbonne Toulouse 31400 France
3. Department of Materials Science and Engineering University of Texas at Dallas Richardson TX 75080‐3021 USA
4. Centre de Microcaractérisation Raimond CASTAING University of Toulouse CNRS UT3‐Paul Sabatier INP INSA Espace Clément Ader, 3 rue Caroline Aigle Toulouse 31400 France
5. LCC‐CNRS University of Toulouse 205 route de Narbonne Toulouse 31077 France