Sorbonne • Alexandre Courac
High‑Pressure Materials Science

Alexandre Courac (Kurakevych) is Associate Professor (MCF) at Sorbonne University – IMPMC, where he designs and synthesizes new materials under extreme pressure–temperature conditions. His research combines in‑situ synchrotron diffraction and thermodynamic modeling to develop scalable pathways to superhard and optoelectronic solids, such as quasi‑direct band‑gap silicon allotropes. In 2017–2022 he was a member of the Institut Universitaire de France (IUF), leading the project Synthesis of Silicon Allotropes, which provided the first high‑purity crystals of hexagonal and clathrate phases and enabled systematic thermodynamic modeling of their stability. He is principal investigator of the ANR projects POLYCARBS (2017–2021) and BCSi (2021–2024), and task leader in SUPERSTRONG (2022–2026).

From 2011 to 2013, he was postdoctoral fellow at Carnegie Institution of Washington (Geophysical Laboratory, now EPL), after earlier CNRS postdoc and ATER positions in Paris (2007–2011). He obtained his HDR (Habilitation à Diriger des Recherches) in Physics at Université Paris 13 in 2017. His doctoral thesis (Université de Kiev, 2007, co‑funded with CNRS LSPM) on ultra‑hard boron–carbon–nitrogen–oxygen phases laid the foundation for his expertise in high‑pressure chemistry. He began research as a student at the Institute for Superhard Materials (NAS Ukraine) and at the University of Hawaii high‑pressure group, publishing his first articles during his Master’s (2002). Today his trajectory reflects continuity from fundamental phase diagrams to the design of functional crystals, training of young scientists, and leadership of international collaborations across Europe, the US, and Asia.

Researcher ID: ORCID • Google Scholar

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Portrait of Alexandre Courac (Kurakevych)
@ A. Courac

Research

My research explores the design and synthesis of new solids under in‑situ high‑pressure and high‑temperature conditions, focusing on boron‑ and silicon‑based materials with outstanding mechanical, electronic and energy‑related properties. I integrate three pillars: (i) large‑volume experimental synthesis up to multi‑GPa and 3000 K, (ii) synchrotron X‑ray diffraction to probe transformations in real time, and (iii) thermodynamic and CALPHAD modeling to place newly discovered phases onto quantitative phase diagrams. This approach has produced breakthroughs in metastable silicon allotropes. We established synthesis protocols for hexagonal silicon polytypes, the BC8 dense allotrope, and the porous clathrate Si24. For the first time, we obtained millimeter‑scale single crystals suitable for physical property characterization, revealing direct and quasi‑direct band gaps critical for photovoltaic and infrared applications. In parallel, we developed a comprehensive picture of Na–Si and B–C–Si systems at high pressure, discovering novel precursors such as Na4Si24 and extending pathways for bulk synthesis at reduced pressures. Another central theme is the chemistry of boron‑rich solids and carbides. We clarified stability relations in the B–C–N–O and Mg–C systems, synthesized ionic carbides such as Mg2C, and proposed new frameworks for boron‑containing clathrates. These studies contribute both to superhard material design and to broader understanding of bonding under compression. More recently, I contributed to calorimetry under pressure within the ANR SUPERSTRONG project, opening routes to thermodynamic data for superconducting cuprates. Beyond immediate applications, my research emphasizes the dual role of high pressure as a discovery tool and as a guide for sustainable, scalable synthesis strategies.

Projects

ANR SUPERSTRONG — High‑Tc Cuprates

Role: Work Package Manager (2022–2026)

High‑pressure calorimetry and advanced thermodynamics to probe correlated electron systems in strongly overdoped cuprates. Method development is transferrable to semiconductors and superhard materials.
Publications & Highlights: —
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ANR POLYCARBS — Exploring Carbides

Role: PI (2017–2021)

Discovery of new carbides and diamond‑like frameworks; Mg–C chemistry and phase diagrams enabling diamond growth media and superhard compounds; synchrotron campaigns + CALPHAD.
Publications & Highlights: https://doi.org/10.1021/acs.jpcc.2c07176
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Team

1. PI & Senior Researchers / Engineers

Principal Investigator. Alexandre Courac (Kurakevych) — Associate Professor, Sorbonne University — IMPMC. Focus: HPHT synthesis; in‑situ synchrotron diffraction; CALPHAD; HP calorimetry.

  • Y. Le Godec — CNRS DR, thermodynamics & HP platforms
  • W. A. Crichton — ESRF, in‑situ synchrotron diffraction
  • B. Baptiste — IMPMC, crystallography
  • V. L. Solozhenko — LSPM, superhard materials
  • H. Moutaabbid — IMPMC, HP sample environments

2. Current PhD Candidates

  • Tassadit (Fatma) Sadmi (10/2024– ) — High‑pressure synthesis of new phases in B–C–Si–X system.

3. Current Postdocs

  • Vacant — HPHT synthesis (MCSI)
  • Vacant — HPHT calorimetry (ANR)

4. Master fellows

Recent fellows include:
  • Yannick De Macedo (M2, 2024) — HP in‑situ design of photovoltaic silicon forms.
  • Idris Akbaraly (M1, 2023) — In‑situ silicon studies.
  • Martin Demoucron (M2, 2022) — Si‑doped borides → PhD 2022–2025.
  • S.M. Dolatabadi Hamedi (M2, 2021) — Graphite intercalation compounds.
  • Nabil Amoura (M2, 2020; M1, 2018) — Carbides; silicon clathrates/allotropes.
  • Ruben De Barros (M2, 2019) — Graphite insertion compounds.
  • Ioannis Touloupas (M2, 2018) — Magnesium carbides.
  • Enguerrand Preval (M2, 2016) — Si24 synthesis.
  • Kamel Loukkas (M1, 2016) — Na–Si clathrate diagrams.
  • Azamat Khairullin (M1, 2016) — In‑situ resistivity, HP cells.
  • Abdelrahman Emam (M1, 2016) — Cubic Si136, optical characterization.
  • Umranee Rambhunjun (M1, 2013) — Thermodynamics of Mg–C system.

Alumni

PhD Alumni

  • Martin Demoucron (2022–2025) — PhD on B–C–Si–X HP synthesis; Postdoc at ESRF beamline from 01.01.2026.
  • Silvia Pandolfi (2016–2019) — Si‑based materials; now Associate Professor, SU (Besson Prize 2020).
  • Simon Delacroix (2016–2019) — Boron at the nanoscale; Postdoc, École Polytechnique.
  • Rémi Grosjean (2013–2016) — Boron nanomaterials; Project Manager, Swatch Group.
  • Fernando Igoa (2019–2022) — Geology‑inspired boron nanomaterials.
  • Zied Jouini (2014–2018) — Na–Si clathrates; Lecturer & Data Scientist R&D.

Postdoc Alumni

  • Carlos Renero‑Lecuna (2016–2017) — NaSi6 single crystals; Assoc. Prof., Bilbao Univ.
  • Lin Lin (2022–2023) — Si clathrates; Professor & Lab Director, Beihua Univ.
  • Jian Zhang (2022–2023) — Semiconductors under HP; Assoc. Prof., Beihua Univ.
  • Yixuan Zhao (2020–2021) — Carbides (ANR POLYCARBS); Data Scientist R&D.
  • Qiang Bian (2018–2019) — Ab initio carbides; Assoc. Prof., Guangdong Univ. Tech.

Master Alumni

  • Yannick De Macedo (M2, 2024) — HP in‑situ design of photovoltaic silicon forms.
  • Idris Akbaraly (M1, 2023) — In‑situ silicon studies.
  • Martin Demoucron (M2, 2022) — Si‑doped borides → PhD 2022–2025.
  • S.M. Dolatabadi Hamedi (M2, 2021) — Graphite intercalation compounds.
  • Nabil Amoura (M2, 2020; M1, 2018) — Carbides; silicon clathrates/allotropes.
  • Ruben De Barros (M2, 2019) — Graphite insertion compounds.
  • Ioannis Touloupas (M2, 2018) — Magnesium carbides.
  • Enguerrand Preval (M2, 2016) — Si24 synthesis.
  • Kamel Loukkas (M1, 2016) — Na–Si clathrate diagrams.
  • Azamat Khairullin (M1, 2016) — In‑situ resistivity, HP cells.
  • Abdelrahman Emam (M1, 2016) — Cubic Si136, optical characterization.
  • Umranee Rambhunjun (M1, 2013) — Thermodynamics of Mg–C system.

Teaching

ED297 — Scientific Integrity Training. At doctoral and Master levels, I deliver workshops on good research practices, authorship, data management, conflict‑of‑interest prevention, and responsible conduct in experimental design and reporting. Sessions combine case studies from materials science with checklists for lab notebooks, FAIR data, and preregistration when appropriate. Goal: align lab routines with institutional and EU guidance on integrity, reproducibility, and open science.

Professional Orientation (OIP). For L2–L3 students, active workshops on employability: timed self‑presentations, CV/cover‑letter clinics, interview rehearsals, and networking assignments (professional interviews prepared in class). These activities connect physics with job‑market expectations and help students articulate skills for internships and early careers.

Core Teaching — General Physics, Thermodynamics, Materials & Labs. Teaching in L1–L3 and supervision of L3 internships and M1/M2 theses in high‑pressure materials. Practical modules emphasize instrumentation (oscilloscopes, function generators, microcontrollers, sensors, video analysis) and reproducible analysis in Python. Evaluation is transparent and criterion‑based, fostering the translation of physical models into engineering practice.

Selected Publications

  1. Pandolfi, S.; Renero-Lecuna, C.; Le Godec, Y.; Baptiste, B.; Menguy, N.; Lazzeri, M.; Gervais, C.; Spektor, K.; Crichton, W. A.; Kurakevych, O. O.*
    Nature of Hexagonal Silicon Forming via High-Pressure Synthesis: Nanostructured Hexagonal 4H Polytype.
    Nano Letters 2018, 18 (9), 5989–5995. IF = 12.3; 49 citations (6.13/year). https://doi.org/10.1021/acs.nanolett.8b02816
    Discovery of high-purity nanostructured hexagonal Si-4H with strong visible-range photoluminescence. A PhD work under supervision of PI (IUF project).
  2. Patent US 10179740 — Strobel, T. A.; Kim, D. Y.; Kurakevych, O. O.
    Form of silicon and method of making the same.
    US Patent 10,179,740 (2019). https://patents.google.com/patent/US10179740B2/en
    The invention relates to a new phase of silicon, Si24, and a method of making the same. It also relates to Na4Si24 and its synthesis.
  3. Kim, D. Y.; Stefanoski, S.; Kurakevych, O. O.; Strobel, T. A.
    Synthesis of an open-framework allotrope of silicon.
    Nature Materials 2015, 14 (2), 169–173. IF = 38.7; 168 citations (15.7/year). https://doi.org/10.1038/nmat4140
    Discovery of Si24 with superior optoelectronic properties. PI synthesized the phase and resolved its structure.

Novel Crystal Structures (powder XRD)

rhombohedral B13N2
1. Rhombohedral B13N2 (2007, cit. 130) — doi — confirmed by SC
diamond-like BC5
2. Diamond‑like BC5 (2009, cit. 311) — doi
graphite-like turbostratic BCx
3. Graphite‑like turbostratic BCx (2010, cit. 11) — doi
tetragonal pc-B52
4. Tetragonal pc‑B52 (2013, cit. 19) — doi
orthorhombic gamma B28
5. Orthorhombic γ‑B28 (2009, cit. 835) — doi — confirmed by SC
monoclinic beta Mg2C3
6. Monoclinic β‑Mg2C3 (2014, cit. 47) — doi
triclinic gamma Mg2C3
7. Triclinic γ‑Mg2C3 (2023, cit. 3) — doi
antifluorite Mg2C
8. Antifluorite Mg2C (2013, cit. 51) — doi
orthorhombic Si24
9. Orthorhombic Si24 (2015, cit. 266) — doi — confirmed by SC
orthorhombic NaSi6 (Na4Si24)
10. Orthorhombic NaSi6 (Na4Si24) (2013, cit. 78) — doi — confirmed by SC
Non-recoverable HP cold diamond BCxN
11. HP “cold diamond” structure of compressed graphitic BCxN, BCx & BN (2005, cit. 25) — doi
Hexagonal Si-4H (2018)
12. Hexagonal Si‑4H (2018, cit. 49) — doi — confirmed by SC

Contact

Email
alexandre.courac@sorbonne-universite.fr
Affiliation
IMPMC, Sorbonne University — Paris, France
Focus
HPHT synthesis • In‑situ XRD • CALPHAD • Silicon allotropes • Superhard materials • HP calorimetry