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Senior Research Officer

I. By the way

Courses & Training Teachings & Responsibilities Courses & Training

Habilitation to Supervise Research (March 11, 1999)

PhD "Chemistry of Materials" (July 9, 1992)

Teachings & Responsibilities

Part to be completed by the scientist

Ii. Research activities

Proposed methodology for an in-depth study of disordered systems

The development and synthesis of new functional inorganic materials coupled with the study of their structure by adapted characterization techniques, represent a large part of my research activity "disorganized materials, structure / properties relationship". In addition to conventional spectroscopy (infrared, Raman, Mössbauer, NMR…), I use complementary characterization techniques using synchrotron radiation or neutrons. The possibility of coupling the synthesis/growth methods of a solid material with several characterization techniques depending on temperature, pressure or electric field allows me to understand the study of a solid phase from its conception to its potential applications.

Research themes Collaborations & Contracts Research themes

In 2002, I started a new research project focused on the study of the "structure – property" relationship of massive oxide materials for very high temperature technological applications in the field of nonlinear optics and/or piezoelectricity. This activity concerns the growth, characterization and study of the behavior of single crystals functional oxides applied, among other things, to the development of piezoelectric materials of the quartz family.

Since January 2021, I have also been taking part in a research project whose theme is:

Structure-property relationship in phase change chalcogenide materials

In the field of Information Storage, phase change tellurides play a key role in the development of electrical memories. To optimize these materials, it is necessary to better understand their structure which contains gaps and the nature of their chemical bonds (notion of metavalent bonds). To understand the structure-properties relationship in these materials, experimental characterizations (large instruments, NMR of the Solid) are coupled with theoretical calculations.

The new GdR CHALCO aims to bring together the entire French academic and industrial community working around this family of materials with unique properties that are chalcogenides.

Collaborations & Contracts

• From 2014 to 2019 an ANR project of acronym PIEMON which was part of the societal challenge "Stimulating industrial renewal": GeO₂: PIEzoelectric with high coupling coefficient for applications at very high temperature. Associated industrial growth process for obtaining high quality optical MONocristaux of large dimensions.

The PIEMON project has made it possible to set up a pre-industrial growth chain of α-GeO₂ single crystals of high crystalline quality. For the first time, piezoelectric constants and dielectric properties were measured with good reproducibility on oriented slides, up to temperatures of 600°C. This temperature limit being mainly due to the measuring cell (and the type of connections), additional measurements at higher temperatures are possible. From the complete a-GeO₂ database established during the project, analytical models to predict the temperature behaviour of resonators in extension/compression and bending as well as their thermoelastic losses were established. These first simulations showed temperature behaviors of resonance frequencies of the order of 20 ppm/°C (relative frequency variation) in the crystallographic axes, which demonstrates a very temperature-stable material.

• ANR project selected in 2021 entitled "OVERHEAT : a-GeO₂ a new material for passive SAW sensors usable at very high tEmperATures". I am part of the project team and I am involved in several scientific tasks.

This 48-month project aims to study, design and evaluate a miniaturized SAW piezoelectric temperature sensor operating without wires or batteries, exploitable in a range of very high temperatures (600 – 1000 °C) and in harsh environments, especially in oxidizing atmospheres and/or under irradiation. This sensor will be based on the non-ferroelectric material a-GeO₂ chemically and structurally stable up to 1000 °C, neutral for the environment and whose crystallogenesis is validated by the flow technique.

Given the strong demand from manufacturers to instrument systems operating at high temperatures, this type of remotely searchable temperature sensor would be positioned in markets with high added value such as chemical process monitoring, instrumentation in energy production (Alstom, General Electric and Safran). Indeed, for these applications in the fields of energy (including nuclear energy), defense, aerospace as well as for industries that use high temperatures in their production system, SAW piezoelectric devices integrating this new single crystal and not requiring connecting wires could bring a real gain in quality and generate a turnover of several tens of millions of Euros.

Iii. Scientific production