Synthesis, characterization, magnetic and ion release properties of NH4MPO4.H2O (M = Mn2+, Fe2+, Co2+, Cu2+) prepared by a simple precipitation method in water solution

In this work, NH 4 MPO 4 .H 2 O (M = Mn 2+ , Fe 2+ , Co 2+ , Cu 2+ ) microstructures were synthesized by a simple precipitation method at room temperature without any templates or surfactants. The materials were characterized by means of thermogravimetric analysis (TGA), differential scanning calorimetric method (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS). The characterization results show that the prepared samples have an orthorhombic structure for M = Mn 2+ , Fe 2+ , Co 2+ samples without any impurity phase, whereas the monoclinic structure is presented in the NH 4 CuPO 4 .H 2 O sample. The morphology of all the obtained samples completely consists of a plate-like shape with the size of several micrometers. In addition, the microflower-like morphology with size about 10 µm was obtained when the metal was Mn. The oxidation state of P ions in all samples is 5 + which is consistent with the surface analysis using XPS. For the magnetic properties, the obtained materials show antiferromagnetic behavior with the highest magnetization value of 26.17 emu.g −1 at 10 kOe in the NH 4 MnPO 4 .H 2 O sample. By using inductively coupled plasma atomic emission spectroscopy (ICP-OES), the ion release properties of NH 4 MPO 4 .H 2 O (M = Mn 2+ , Fe 2+ , Co 2+ , Cu 2+ ) microstructures show the potential application as slow-release fertilizer. This could be beneficial in order to reduce the amount of fertilizer used in plants and may be extended for the commercial.