Phase stability of rare earth sesquioxides with grain size controlled in the nanoscale

Giora Kimmel, Roni Z. Shneck, Witold Lojkowski, Ze'ev Porat, Tadeusz Chudoba, Dmitry Mogilyanski, Stanislaw Gierlotka, Vladimir Ezersky, Jacob Zabicky

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Rare earth oxides are important materials due to their chemical and physical properties. The rare earth sesquioxides (RESOXs) possess a cubic, monoclinic, or hexagonal structure, depending on pressure, temperature and ionic radius. When RESOXs take the form of single crystalline grains with diameter in the nanoscale range (nanocrystals), it is suspected that the grain size determines the phase stability as well. RESOXs with medium ionic radius such as Gd 2 O 3 , Eu 2 O 3 and Sm 2 O 3 in the low temperature range up to 900°C may take the monoclinic structure or the cubic structure, depending on the synthesis process. The structure determining factor can be, besides temperature, also the grain size. In order to determine the stable structure taking into account grain size as a parameter, we produced Gd 2 O 3 and Sm 2 O 3 nanocrystals embedded in a neutral MgO matrix. This way, we prevented grain growth during annealing. For comparison, we annealed pure Gd 2 O 3 and Sm 2 O 3 nanocrystals in which temperature increase caused grain growth, as in traditional experiments for phase stability determination. We have shown that for coarse grained materials at low temperature monoclinic is the stable structure. For nano-sized crystallites, cubic is the stable structure. This explains the controversial results as far as which phase is the stable one below 900°C and permits to program the needed structure by controlling crystallization kinetics and grain growth.

Original languageEnglish
Pages (from-to)3829-3835
Number of pages7
JournalJournal of the American Ceramic Society
Issue number7
StatePublished - 1 Jul 2019


  • X-ray methods
  • nanomaterials
  • oxides
  • phase diagrams
  • rare earths

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry


Dive into the research topics of 'Phase stability of rare earth sesquioxides with grain size controlled in the nanoscale'. Together they form a unique fingerprint.

Cite this