Room temperature plasticity and phase transformation of nanometer-sized transition alumina nanoparticles under pressure

I. Issa, L. Joly-Pottuz, J. Réthoré, C. Esnouf, T. Douillard, V. Garnier, J. Chevalier, S. Le Floch, D. Machon, K. Masenelli-Varlot

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


A powder of transition alumina nanoparticles (including γ and a so-called δ-type) is compacted at room temperature in a diamond anvil cell (DAC) under pressures ranging from 5 GPa to 20 GPa. Characterization carried out on thin foils prepared by focused ion beam (FIB), from the compacted powder, unambiguously reveals plasticity. High resolution transmission electron microscopy (HRTEM) and electron diffraction also evidence phase transformation of nanoparticles under high pressure and nanoparticles show faceting parallel to the loading direction with a preferential crystallographic orientation of the facets corresponding to {220} planes of γ−Al2O3. It can also be deduced, from the comparison between the DAC experiments and in situ TEM nano-compression tests on single particles performed in a preceding work, that plasticity is driven by slip bands corresponding to {111} slip planes, common for a spinel structure, such as, for instance, γ−Al2O3. We also demonstrate that at ambient temperature the transition alumina phase is also prone to structural change under high pressures with the following sequence γ-Al2O3 → δ* Al2O3, these two phases coexisting, sometimes, in the same nanoparticle after compaction. Plasticity at room temperature in alumina nanoparticles and the subsequent phase transformation under pressure may have strong impacts on the process of alumina nanostructured ceramics.

Original languageEnglish
Pages (from-to)308-316
Number of pages9
JournalActa Materialia
Publication statusPublished - 2018 May 15
Externally publishedYes


  • Alumina
  • Crystal plasticity
  • Nanoparticles
  • Phase transformation
  • Transmission electron microscopy (TEM)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys


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