for the Year 2008
was conferred in Montpelier (France)
During The International Symposium on Non-Oxide Glasses
Prof. Annie Pradel
University of Montpellier II
Main results in the field of Chalcogenide Materials
My first investigation in the field of chalcogenide glasses concerned the domain of Solid State Ionics.
With the development of a twin roller fast quenching apparatus, I was able to prepare large series of lithium
conductive chalcogenide glasses that exhibit very high ionic conductivity and were proposed as solid electrolytes
for all solid state batteries (Solid State Ionics, 17, 147 (1985), Solid State Ionics, 18-19, 351 (1986)).
With time, I slowly moved towards a broader study of chalcogenide glasses that included crystalline and glassy,
bulk and thin film materials with applications in the field of solid state ionics, IR integrated optics,
information storage and environmental control. In the recent years, three aspects were developed that led to important results:
*In the domain of Solid State Ionics, my research has been focused on glasses of interest in the development
of electrical memories and more precisely in the socalled photo-metallization cells (PMC) memories. In the course
of this investigation, our research team carried out experiments based upon the use of the Electrical Field Microscopy,
for the first time in the case of inorganic glasses.
Such a technique helped us in visualizing electrical heterogeneousness in Ag-Ge-Se glasses and showed the percolation threshold
that explain the jump in electrical conductivity observed when increasing the amount of silver in the Ge-Se matrix
(J. Optoelectr. Adv. Materials 8(6) 2112-2116 (2006); J. Non-Crystalline Solids 353 (2007) 1261- 1263). Additional neutron
diffraction experiments showed that the Ag-Ag correlations were drastically different below and above the percolation threshold
(A. Pradel, ANC3, Brasov, Roumania, 2-6 July 2007)
*In the domain of optical storage of information, the main investigation was carried out in the framework of a project (Chalmemstory)
funded be the french "Agence Nationale de la Recherche" and with A. Kolobov as a co-worker during his stay in Montpellier (2005-2007).
We studied the changes occurring in the structure of Ge-Sb-Te materials when they were submitted to a large pressure (up to several tenths of GPa).
The most important result is the amorphization of Ge2Sb2Te5 under pressure. Such a result led us to suggest that the pressure
is a parameter that should not be neglected when one deals with phase change under a laser beam (Phys.Rev. Letters 97 (2006) 035701).
*Finally, in the framework of a more technological project funded by the European Space Agency, we are currently working at developing
integrated IR optical devices to be used in spatial interferometers (Appl. Phys. Lett. 90, 011110 (2007)). Such a project led us to develop
new equipment: a co-evaporator that helped us producing high quality ternary telluride layers and developing waveguides able to transmit light
in the infrared up to 20 um (Optoelectronics and Adanced Materials - Rapid Communications 1(10), 487 - 490 (2007)).
Annie Pradel, University of Montpellier II, France
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