Chalcogenide glasses: microstructure/property relationship from macro to nano scale
Duration: 36 months
Start-up: October 1st, 2018
This thesis will take place within the Materials Physics Group (GPM) of the University of Rouen. The research developed at the GPM concerns not only the crystalline solid materials (metals, metal alloys, semiconductors…), but also the non-crystalline solids (polymeric glasses, chalcogenide glasses…). More specifically, we are interested in the relationships between the microscopic (nanoscopic) structure of these materials and their macroscopic properties (mechanical, magnetic, optical, thermal …). The GPM has played a pioneering role in France by carrying out the design and development of the Atomic Probe Tomography, which allows atom-by-atom analysis of a material and reconstructing its three-dimensional image by knowing the chemical nature of each atom. Recently, this instrument, equipped with a femtosecond laser (laser-assisted atom probe) was used in the study of glasses and ceramics at the nanometric scale. Regarding the property / microstructure relationships in non-crystalline solids, the GPM also has the instrumental parc and skills to be recognized internationally in this field.
The last decades have seen a strong interest in the development of pertinent materials operating in mid-infrared (IR) spectral region of 2–10-μm wavelength range, which offer potential applications in a wide variety of areas including: optical gas sensing and environmental monitoring, optical communications, optical modulators, biomedical and thermal imaging. The main interest of chalcogenide glasses lies in their wide range of transparency, which can extend from the visible to the mid- infrared as a function of the chemical composition of the glass.
Nevertheless, chalcogenide glasses possess mechanical properties (hardness, toughness, etc.) which are relatively low compared to mono- or polycrystals (Ge, ZnSe. . . ) regularly used in the infrared industry, limiting their fields of application. However, these properties can be considerably improved by generating particles of nanometric to micronic size by appropriate heat treatment.
The aim of this thesis is to study the structure of these chalcogenide glasses from macro to nano scale, and to establish the relationship between their structure and their optical, mechanical and thermal properties. This study will be conducted by using the advanced instrumentation of the GPM laboratory for material imaging such as the laser-assisted atom probe tomography (La-APT). The candidate will validate the performances of this instrument on the analysis of glasses. In addition, different laser illumination conditions will be tested, ranging from near ultraviolet to theraherz pulses. Moreover, these glasses
will be analyzed in standard calorimetry and nanocalorimetry to study the kinetics of physical aging in order to validate (or not) certain models of the literature based on experimental studies for which the thermodynamic equilibrium has never been reached. Indeed, the use of nanocalorimetry (an analysis tool mastered in the GPM laboratory) makes it possible to accelerate the kinetics of physical aging, and thus to reach the thermodynamic equilibrium in acceptable times on the experimental scale.
The candidate will take advantage of the experimental facilities at GPM and of the collaboration with the team of Laurent Calvez at the Laboratory “Verres et céramiques” of Rennes 1 University, specialized in the elaboration and characterization of chalcogenide glasses.
The ideal applicant for this PhD should have a very good level in solid state physics and/or laser-matter interactions and optical analysis.
Contacts : Pr Allisson Saiter
Pr Angela Vella