One-pot, selective synthesis of orthorhombic and rhombohedral NaNbO3 by hydrothermal method

Nguyen Duc Van


The pure orthorhombic- and rhombohedral-structure NaNbO3 microcrystals were obtained selectively by a facile, additive-free hydrothermal procedure using commercialized Nb2O5, NaOH, KOH as starting materials. The obtained samples were characterized by X-ray powder diffraction, field-emission scanning electron microscopy, energy dispersive spectrometry, Raman spectroscopy. The results showed that the required hydrothermal temperatures to synthesize single crystalline phase of rhombohedral and orthorhombic NaNbO3 are as low as 180 and 200 oC for 24 h, respectively. The phase composition of the hydrothermal product was found to be strongly dependent on (K+ + Na+)/Nb5+ molar ratio. Interestingly, by using the (K+ + Na+)/Nb5+ molar ratio of 9.0, the pure metastable phase of NaNbO3 with rhombohedral structure was readily synthesized in the hydrothermal temperature range of 180-200 oC. However, as this molar ratio crossed over 12.0, the polymorphic type of NaNbO3 was received at 180 oC only and the orthorhombic type existed purely when the reaction temperature reached 200 oC.

Keywords. NaNbO3, surfactant-free, polymorphism, hydrothermal method.


NaNbO3, surfactant-free, polymorphism, hydrothermal method

Full Text:



L. A. Reznitchenko, A. V. Turik, E. M. Kuznetsova, V. P. Sakhnenko. Piezoelectricity in NaNbO3 ceramics, J. Phys.: Condens. Matter., 13, 3875-3881 (2001).

D. Kumar, N. Khare. in Recent Trends in Materials and Devices: Proceedings ICRTMD 2015, V. K. Jain, S. Rattan, A. Verma, Eds., Springer, Switzerland, pp. 107-109.

K. U. Kumar, K. Linganna, S. Surendra Babu, F. Piccinelli, A. Speghini, M. Giarola, G. Mariotto, C. K. Jayasankar. Synthesis, structural properties and upconversion emission of Er3+ and Er3+/Yb3+ doped nanocrystalline NaNbO3, Sci. Adv. Mater., 4, 1-7 (2012).

X. Li, G. Li, S. Wu, X. Chen, W. Zhang. Preparation and photocatalytic properties of platelike NaNbO3 based photocatalysts, J. Phys. Chem. Solids, 75, 491-494 (2014).

P. Li, S. Ouyang, G. Xi, T. Kako, J. Ye. The effects of crystal structure and electronic structure on photocatalytic H2 evolution and CO2 reduction over two phases of perovskite-structured NaNbO3, J. Phys. Chem. C, 116, 7621-7628 (2012).

L. Wang, H. Gu, J. He, T. Zhao, X. Zhang, C. Xiao, H. Liu, X. Zhang, Y. Li. Scale synthesized cubic NaNbO3 nanoparticles with recoverable adsorption and photodegradation for prompt removal of methylene blue, J. Alloys Compd., 695, 599-606 (2017).

C. Yan, Li. Nikolova, A. Dadvand, C. Harnagea, A. Sarkissian, D. F. Perepichka, D. Xue, F. Rosei, Multiple NaNbO3/Nb2O5 heterostructure nanotubes: A new class of ferroelectric/semiconductor nanomaterials, Adv. Mater., 22, 1741-1745 (2010).

G. L. Messing, S. Trolier-McKinstry, E. M. Sabolsky, C. Duran, S. Kwon, B. Brahmaroutu, P. Park, H. Yilmaz, P. W. Rehrig, K. B. Eitel, E. Suvaci, M. Seabaugh, K. S. Oh. Templated grain Growth of Textured Piezoelectric Ceramics, Critic. Rev. Solid State Mater. Sci., 29, 45-96 (2004).

S. Kumar, R. Parthasarathy, A. P. Singh, Björn Wickman, M. Thirumal, A. K. Ganguli. Dominant {100} facet selectivity for enhanced photocatalytic activity of NaNbO3 in NaNbO3/CdS core/shell heterostructures, Catal. Sci. Technol., 7, 481-495 (2017).

Y. Lu, T. Karaki, T. Fujii, Y. Ido, Y. Li, Y. Sakai. Morphology control and phase transition of hexagonal sodium niobate particles, Ceram. Int., 43, 9124-9127 (2017).

D. R. Modeshia, R. J. Darton, S. E. Ashbrook, R. I. Walton. Control of polymorphism in NaNbO3 by hydrothermal synthesis, Chem. Comm., Vol. 2009, 68-70 (2009).

K. Zhu, Y. Cao, X. Wang, L. Bai, J. Qiu, H. Ji. Hydrothermal synthesis of sodium niobate with controllable shape and structure, CrystEngComm, 14, 411-416 (2012).

C. Wang, Y. Hou, H. Ge, M. Zhu, H. Wang, H. Yan. Sol-Gel synthesis and characterization of lead-free LNKN nanocrystalline powder, J. Cryst. Growth, 310, 4635-4639 (2008).

Y. Shiratori, A. Magrez, J. Dornseiffer, F-H. Haegel, C. Pithan, R. Waser. Polymorphism in micro-, submicro-, and nanocrystalline NaNbO3, J. Phys. Chem. B, 109, 20122 20130 (2005).