Calcium borate α-4CaO•5B₂O₃•7H₂O nanoflake and spherical-, silkworm chrysalis-like 4CaO•5B₂O₃•7H₂O nanostructure constructed by nanoflake have been synthesized under hydrothermal conditions at 120 ℃ with Ca(NO₃)₂•4H₂O and Na₂B₄O₇•10H₂O as materials, using water and ethanol as mixture solvent. The as-prepared products were characterized by the XRD, EDS, FT-IR and SEM. The influences of reaction temperature, reaction time, solvent and surfactant on the morphology and size of calcium borate α-4CaO•5B₂O₃•7H₂O have also been investigated. The possible formation mechanisms of α-4CaO•5B₂O₃•7H₂O nanostructures have been proposed. Furthermore, the flame retardant properties of the prepared α-4CaO•5B₂O₃•7H₂O nanostructures were investigated by the thermal analysis method, demonstrating that they had the better behaviors than the non-nanostructure sample.

Key words: nanostructures, hydrothermal reaction, calcium borate, thermal analysis, flame retardant property