Abstract: Millimetre-sized NaCo2O4 crystals were grown from a molten flux based on NaCl-Na2CO3 by spontaneous nucleation method.Details of the preparation and growth procedures are provided.The asgrown crystals were characterized by X-ray powder diffraction (XRPD).The morphology and growth mechanism were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM).The results show that the obtained crystal are well crystallized and indexed in a hexagonal crystal system with lattice parameters a =b =0.2842 nm,c =1.0894 nm,and V =0.0761997 nm3.The growth of NaCo2O4 single crystals was controlled by a two-dimensional (2D) layer-by-layer mechanism acting along the c-axis.Furthermore,the morphology of the crystals was also interpreted in the viewpoint of anionic coordination polyhedron growth units.

Key words: Millimetre-sized NaCo2O4 crystals were grown from a molten flux based on NaCl-Na2CO3 by spontaneous nucleation method.Details of the preparation and growth procedures are provided.The asgrown crystals were characterized by X-ray powder diffraction (XRPD).The morphology and growth mechanism were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM).The results show that the obtained crystal are well crystallized and indexed in a hexagonal crystal system with lattice parameters a =b =0.2842 nm,c =1.0894 nm,and V =0.0761997 nm3.The growth of NaCo2O4 single crystals was controlled by a two-dimensional (2D) layer-by-layer mechanism acting along the c-axis.Furthermore,the morphology of the crystals was also interpreted in the viewpoint of anionic coordination polyhedron growth units.