Preparation technology and crystal structure analysis of NaNbO3 microcrystalline powders with different crystal orientations and morphologies by molten salt method

Abstract

The different crystal orientations of NaNbO3 microcrystalline powders were synthesized by the molten-salt growth method with different precursors. The plate-like (001)-NaNbO3 orthogonal powders were synthesized by topochemical conversion using Bi2.5Na3.5Nb5O18 as precursor particles. The tabular NaNbO3 template particles were about 0.5–1 μm in thickness and about 15–25 μm in length. The rod-like (101)-NaNbO3 orthogonal powders were fabricated with Nb2O5 as a precursor. The preparation of Nb2O5 precursors required two processes: the molten salt method and the ion exchange method, respectively. The rod-like (101)-NaNbO3 orthogonal powders were about 0.6 μm in average diameter, and 8 μm in average length. The plate-like and rod-like orthogonal NaNbO3 powders had high aspect ratios. The diffraction peaks of plate-like NaNbO3 correspond to standards card JCPDS-33-1270, and its space group was Pbma. The crystal cell of Pbma NaNbO3 was a typical antiferroelectric structure. The diffraction peaks of rod-like NaNbO3 correspond to standard card JCPDS-86-0606, and its space group was P2lmc. The cell structure of P2lmc NaNbO3 was a typical ferroelectric structure.