Preparation of single crystalline NaSr₂Nb₅O₁₅ particles with acicular morphology

Well-developed acicular NaSr₂Nb₅O₁₅ (NSN) particles were successfully synthesized by a simple ion-exchange approach based on a molten salt synthesis method. The crystal structure and morphologies of the particles were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscopy, and selected area electron diffraction. The results indicated that uniform acicular NSN particles with large aspect ratio could be obtained by heating of a mixture with a weight ratio of salt-to-mixture of 5:1 for 4h at 1200°C. The acicular NaSr₂Nb₅O₁₅ particle that is formed by the penetration of sodium ions (Na⁺) into the crystal lattice of KSr₂Nb₅O₁₅ to replace potassium ions (K⁺) is single crystalline and the growth direction of the particle is determined to be the <001> crystallography direction.