High thermal robustness of molecularly thin perovskite nanosheets and implications for superior dielectric properties

Bao Wen Li, Minoru Osada*, Yasuo Ebina, Kosho Akatsuka, Katsutoshi Fukuda, Takayoshi Sasaki

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)


A systematic study has been conducted to examine the thermal stability of layer-by-layer assembled films of perovskite-type nanosheets, (Ca 2Nb3O10 -)n (n = 1-10), which exhibit superior dielectric and insulating properties. In-plane and out-of-plane X-ray diffraction data as well as observations by atomic force microscopy and transmission electron microscopy indicated the high thermal robustness of the nanosheet films. In a monolayer film with an extremely small thickness of ∼2 nm, the nanosheet was stable up to 800°C, the temperature above which segregation into CaNb2O6 and Ca2Nb2O7 began. The critical temperature moderately decreased as the film thickness, or the number of nanosheet layers, increased, and reached 700°C for seven- and 10-layer films, which is comparable to the phase transformation temperature for a bulk phase of the protonic layered oxide of HCa2Nb3O10·1. 5H2O as a precursor of the nanosheet. This thermal stabilization of perovskite-type nanosheets should be associated with restricted nucleation and crystal growth peculiar to such ultrathin 2D bound systems. The stable high-k dielectric response (εr = 210) and highly insulating nature (J < 10-7 A cm-2) remained substantially unchanged even after the nanosheet film was annealed up to 600°C. This study demonstrates the high thermal stability of 2D perovskite-type niobate nanosheets in terms of structure and dielectric properties, which suggests promising potential for future high-k devices operable over a wide temperature range.

Original languageEnglish
Pages (from-to)5449-5461
Number of pages13
JournalACS Nano
Issue number6
Publication statusPublished - 2014 Jun 24
Externally publishedYes


  • layer-by-layer assembly
  • nanodielectrics
  • perovskite-type nanosheets
  • thermal stability

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)
  • Physics and Astronomy(all)


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