Laser-Induced Melting and Crystal Growth of Sodium Ion Conductive-NaFeO₂

Laser irradiation of /3-NaFeO2 shows local melting and crystal growth from the melt pool and sodium ion conductivity. Local melting, densification, and crystal growth were confirmed on the /3-NaFeO2 surface through laser irradiation with a wavelength of 1 & mu;m. Scanning electron microscopy and electron backscatter diffraction analysis confirmed anisotropic grain growth and grain boundary shrinkage in the laser -irradiated area. X-ray diffraction results suggested that the laser-irradiated area was in a low crystalline state. In addition, the precipitation of Fe3O4 in laser-irradiated /3-NaFeO2 indicates a reduction reaction, suggesting that the laser-irradiated area is heated to 1500 & DEG;C or higher. We confirmed that the structure change region could be controlled down to a thickness of about 10 & mu;m by laser irradiation with varying laser power to /3-NaFeO2.