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 Bi_2.5Na_3.5Nb₅O₁₈ 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.

Keywords:

• Crystal orientations
• ferroelectric structure
• microcrystalline powders
• orthogonal NaNbO₃
• space group

Additional information

Funding

This work was financially supported by General Teaching Research project of Anhui Vocational and Adult Education Association (azcg145), Key Project of Natural Science Research of Universities in Anhui Province (KJ2019A0975), Engineering Research Centre of Wuhu (No. sgcjsyjzx10), University-Level Key Scientific Research Projects (wzyzd202114), University-Level Science and Technology Innovation Team Construction (wzykjtd202003).