Nanocrystalline NaNbO3 and NaTaO3: Rietveld studies, Raman spectroscopy and dielectric properties

Nanocrystalline NaNbO3 and NaTaO3 have been synthesized by the reverse micellar technique for the first time. The particle size of NaNbO3 was found to be 18 nm while that of NaTaO3 was found to be 40 nm (much smaller size than most of the earlier reports on NaTaO3). Rietveld refinement of X-ray diffraction data and Raman spectroscopy confirm that the nanoparticles of NaNbO3 and NaTaO3 have orthorhombically distorted structures with Pmc21 and Pbnm space groups, respectively. The dielectric constant at 25 °C of NaNbO3 and NaTaO3 was found to be 209 and 147 at 1 kHz, respectively. The antiferroelectric transition in NaNbO3 shifts to lower temperature (325 °C) in the nanocrystalline solid.

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