Hierarchical Three-Dimensional Cobalt Phosphate Microarchitectures: Large-Scale Solvothermal Synthesis, Characterization, and Magnetic and Microwave Absorption Properties

Novel hierarchical cobalt phosphate (α- and β-Co 2 P 2 O 7 ) and cobalt hydrogen phosphate hydroxide [Co 11 (HPO 3 ) 8 (OH) 6 ] three-dimensional (3D) architectures with different morphologies were synthesized under a solvothemal condition. The form and shape of cobalt phosphate can be readily tuned by adjusting experimental parameters of the reaction system. The novel hierarchical α-Co 2 P 2 O 7 microcrystals with basketry-like microstructures were obtained with a molar ratio of Co 2+ /H 3 PO 4 /CH 3 NH 2 /HO(CH 2 ) 2 OH of 1:1.2:1:108, the reaction temperature of 180 °C, and the reaction time of 5 days; dumbbell-like β-Co 2 P 2 O 7 microspheres were formed with the same reaction temperature and time but the molar ratio of 1:1.2:1:54, and Co 11 (HPO 3 ) 8 (OH) 6 with peony-like nanostructures was prepared with the same molar ratio and reaction time as β-Co 2 P 2 O 7 but the reaction temperature of 120 °C. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectra (FT-IR) technologies, a Quantum Design superconducting quantum interference device (SQUID) magnetometer, and a network analyzer. The formation mechanism of cobalt phosphate microstructures was investigated in detail.