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In Situ Observation of Dehydration-Induced Phase Transformation from Na2Nb2O6-H2O to NaNbO3

In Situ Observation of Dehydration-Induced Phase Transformation from Na2Nb2O6-H2O to NaNbO3
Jung, JH[Jung, Jong Hoon]Chen, CY[Chen, Chih-Yen]Wu, WW[Wu, Wen-Wei]Hong, JI[Hong, Jung-Il]Yun, BK[Yun, Byung Kil]Zhou, YS[Zhou, Yusheng]Lee, N[Lee, Nuri]Jo, W[Jo, William]Chen, LJ[Chen, Lih-Juann]Chou, LJ[Chou, Li-Jen]Wang, ZL[Wang, Zhong Lin]
DGIST Authors
Hong, JI[Hong, Jung-Il]
Issued Date
Article Type
Activation EnergyArrhenius EquationAtomic RearrangementsDehydrationHigh TemperatureHydrothermal ProcessIn-SituIn-Situ ObservationsKinetic ControlLead-FreeLead OxideMolecular SievesNanowiresNiobatesNiobiumNiobium CompoundsOctahedral Molecular SievesOxide NanostructuresPhase TransitionsPiezoelectricityReal-TimeSodiumTransmission Electron MicroscopyTransmission Electron Microscopy TemX Ray Diffraction
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.
American Chemical Society
Related Researcher
  • 홍정일 Hong, Jung-Il 화학물리학과
  • Research Interests Electric and Magnetic Properties of Nanostructured Materials; Spintronics
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Department of Physics and Chemistry Spin Nanotech Laboratory 1. Journal Articles


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