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

Abstract

Novel hierarchical cobalt phosphate (α- and β-Co2P2O7) and cobalt hydrogen phosphate hydroxide [Co11(HPO3)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-Co2P2O7 microcrystals with basketry-like microstructures were obtained with a molar ratio of Co2+/H3PO4/CH3NH2/HO(CH2)2OH of 1:1.2:1:108, the reaction temperature of 180 °C, and the reaction time of 5 days; dumbbell-like β-Co2P2O7 microspheres were formed with the same reaction temperature and time but the molar ratio of 1:1.2:1:54, and Co11(HPO3)8(OH)6 with peony-like nanostructures was prepared with the same molar ratio and reaction time as β-Co2P2O7 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.

Effects of surface stability on the morphological transformation of metals and metal oxides as investigated by first-principles calculations

“…Maneuvering the surface energies and growth rates of different facets determines the shape of a NC [19,31]. Shape control of crystal growth has been reported for various types of oxide materials by modulating the reactive conditions in the liquid phase [32,33]. In particular, surface charges and polarization have been discussed in previous reports on the synthesis of nanomaterials with some novel morphologies [34,35].…”

Microwave-Assisted Solvothermal Synthesis of Three Polymorphs of LiCoPO4 and Their Electrochemical Properties

“…11 Furthermore, there have been a number of reports of low-temperature solvothermal synthesis of LiMPO 4 employing poly-glycols, including tetraethylene glycol, which have not yet reported or characterized the dependence of the produced polymorphs on the presence of water. [12][13][14][15] Here, we report the low-temperature, MW-ST synthesis of LiCoPO 4 (Cmcm) and LiCoPO4 (Pn2 1 a) nano-particles and their electrochemical activity, for the first time. The already-known Pnma phase (olivine) of LiCoPO4 is also prepared by the MW-ST process at the same temperature of 260 C, and the three crystalline forms are compared.…”

Tunable high-performance microwave absorption for manganese dioxides by one-step Co doping modification

“…Permittivity mainly originates from polarizations of electrons, ions, and intrinsic electric dipoles. Magnetic properties could be affected by crystal structure, special geometrical morphology and size4243. Complex permittivity and complex magnetic permeability of Co-Cryp were analyzed (Fig.…”