LiFePO4 nanoparticles, as one of the main cathode materials used in lithium ion batteries, are currently in the center of attention due to its extraordinary characteristics such as low cost, abundancy, environmentally friendly and high quality performance in the batteries. In this study, LiFePO4 nanoparticles were synthesized using various methods, including mechanochemical activation (MA), modified mechanochemical activation (MMA) and hydrothermal methods. The difference between mechanochemical activation and modified mechanochemical activation routes is that there are two steps of heat treatment in the modified route, while there is only one step of heat treatment in the other one. The as-synthesized samples were subsequently characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) in order to study their structural and magnetic properties. The XRD patterns illustrate the formation of the crystals in all three methods with no signs of impurity phases. Obviously, it is well-known that less than a certain amount of impurities (less than 2%) cannot be detected from XRD patterns. However, in our case, some signs of impurity phases are extracted from magnetic data of VSM, which are only attributed to the samples prepared via MA and MMA. These impurity phases might be either strong ferromagnetic γ-Fe2O3 or weak ferromagnetic Fe2P nanoparticles as mentioned in the literature. The sample prepared by the hydrothermal route behaves like a paramagnetic material, which is in good agreement with the behavior of pure LiFePO4 at room temperature. Nevertheless, the samples prepared via the other two methods behave like ferromagnetic materials in the range of small magnetic fields which refers to the magnetic impurity phases. The area of the hysteresis loop observed in VSM is somehow smaller for the modified mechanochemical activation route suggesting that two steps of heat treatment in preparation of LiFePO4 brings about better results regarding the amount of impurity phases. In addition, SEM images confirm the formation of the samples in the size range of less than 100 nm, with the hydrothermally prepared one being the smallest. Thus, it is needless to mention that the hydrothermal method is the most successful route in preparing the smallest sample without any impurity phases.

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