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In situ observation of dehydration-induced phase transformation from Na 2Nb 2O 6-H 2O to NaNbO 3

Title
In situ observation of dehydration-induced phase transformation from Na 2Nb 2O 6-H 2O to NaNbO 3
Authors
Jung J.H.Chen C.-Y.Wu W.-W.Hong J.-I.Yun B.K.Zhou Y.Lee N.Jo W.Chen L.-J.Chou L.-J.Wang Z.L.
Ewha Authors
조윌렴
SCOPUS Author ID
조윌렴scopus
Issue Date
2012
Journal Title
Journal of Physical Chemistry C
ISSN
1932-7447JCR Link
Citation
vol. 116, no. 42, pp. 22261 - 22265
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
We have monitored the phase transformation from a Sandia octahedral molecular sieve Na 2Nb 2O 6-H 2O to a piezoelectric NaNbO 3 nanowire through in situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements at high temperatures. After dehydration at 288 °C, the Na 2Nb 2O 6-H 2O becomes significantly destabilized and transforms into NaNbO 3 with the increase of time. The phase transformation time is exponentially proportional to the inverse of temperature, for example, ∼10 5 s at 300 °C and ∼10 1 s at 500 °C, and follows an Arrhenius equation with the activation energy of 2.0 eV. Real time TEM investigation directly reveals that the phase transformation occurs through a thermally excited atomic rearrangement due to the small difference of Gibbs free energy between two phases. This work may provide a clue of kinetic control for the development of high piezoelectric lead-free alkaline niobates and a deep insight for the crystallization of oxide nanostructures during a hydrothermal process. © 2012 American Chemical Society.
DOI
10.1021/jp308289r
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자연과학대학 > 물리학전공 > Journal papers
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