Synthesis and morphology of anisotropic NaNbO3 seed crystals

Large platelet NaNbO3 (NN) seed crystals have been successfully synthesized from bismuth layer-structured ferroelectric Bi2.5Na3.5Nb5O18 (BNN) precursor by topochemical microcrystal conversion method. The effects of synthesis parameters, such as salt/oxide ratio, synthesis temperature and Na2CO3/BNN ratio, on the phase structure and morphology of both the BNN precursor and NN particles were investigated. The results show that large platelet BNN precursor with bismuth layer structure was obtained at 1125 °C with a salt-to-oxide weight ratio of 1.50:1. Besides, by optimizing the synthesis parameters, anisotropic NN seed crystals with pure perovskite phase were obtained at 975 °C with a Na2CO3/BNN molar ratio of 1.50:1. The obtained NN particles are very promising template for texturing (K, Na) NbO3-based ceramics by reactive-template grain growth method.