Controlled synthesis of layered rare-earth hydroxide nanosheets leading to highly transparent (Y0.95Eu0.05)2O3 ceramics

Bin Lu, Ji Guang Li, Tohru Suzuki, Mehdi Estili, Weigang Liu, Xudong Sun, Yoshio Sakka

Research output: Contribution to journalArticle

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Abstract

Chemical precipitation at the freezing temperature of ∼4°C has directly yielded layered rare-earth hydroxide [LRH, Ln2(OH)5NO3·nH2O, Ln = Y0.95Eu0.05] nanosheets (up to 7 nm thick) for the Y/Eu binary system, with the interlayer NO3- exchangeable with SO42-. Calcining the sulfate derivative at 1100°C for 4 h produces well-dispersed and readily sinterable Ln2O3 red phosphor powders (∼14.8 m2/g) that can be densified into highly transparent ceramics via optimized vacuum sintering at the relatively low temperature of 1700°C for 4 h (average grain size ∼14 μm; in-line transmittance ∼80% at the 613 nm Eu3+ emission or ∼99% of the theoretical transmittance of Y2O3 single crystal). Our systematic studies also found that (1) the extent of SO42- exchange and the interlayer distance of LRH are both affected by the SO42-/Ln3+ molar ratio (R), and an almost complete exchange is achievable at R = 0.25 as expected from the chemical formula (one SO42- replaces two NO3- for charge balance). The optimal R value for sintering, however, was found to be 0.03; (2) The Ln3+ concentration for LRH synthesis substantially affects properties of the resultant oxides, and hard agglomeration has been significantly reduced at the optimized Ln3+ concentration of 0.05-0.075 mol/L; (3) Sulfate exchange significantly alters the thermal decomposition pathway of LRH, and was found essential to produce well-dispersed and highly sinterable oxide powders; (4) Both the oxide powders and transparent ceramics exhibit the typical red emission of Eu3+ at ∼613 nm (the 5D07F2 transition) under charge-transfer (CT) excitation. Red-shifted CT band center, stronger excitation/emission, and shorter fluorescence lifetime were, however, observed for the transparent ceramics.

Original languageEnglish
Pages (from-to)1413-1422
Number of pages10
JournalJournal of the American Ceramic Society
Volume98
Issue number5
DOIs
Publication statusPublished - 2015 May 1
Externally publishedYes

Fingerprint

Nanosheets
ceramics
Powders
Oxides
Rare earths
hydroxide
transmittance
oxide
Sulfates
Charge transfer
Sintering
sulfate
precipitation (chemistry)
thermal decomposition
agglomeration
Freezing
Phosphors
freezing
Pyrolysis
fluorescence

ASJC Scopus subject areas

  • Ceramics and Composites
  • Geology
  • Geochemistry and Petrology
  • Materials Chemistry

Cite this

Controlled synthesis of layered rare-earth hydroxide nanosheets leading to highly transparent (Y0.95Eu0.05)2O3 ceramics. / Lu, Bin; Li, Ji Guang; Suzuki, Tohru; Estili, Mehdi; Liu, Weigang; Sun, Xudong; Sakka, Yoshio.

In: Journal of the American Ceramic Society, Vol. 98, No. 5, 01.05.2015, p. 1413-1422.

Research output: Contribution to journalArticle

Lu, Bin ; Li, Ji Guang ; Suzuki, Tohru ; Estili, Mehdi ; Liu, Weigang ; Sun, Xudong ; Sakka, Yoshio. / Controlled synthesis of layered rare-earth hydroxide nanosheets leading to highly transparent (Y0.95Eu0.05)2O3 ceramics. In: Journal of the American Ceramic Society. 2015 ; Vol. 98, No. 5. pp. 1413-1422.
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AU - Sakka, Yoshio

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