Synthesis and isoconversional kinetic study of the formation of LiNiPO4 from Ni3(PO4)2·8H2O as a new precursor

Abstract

The nanosized LiNiPO4 was successfully synthesized by a solid-state reaction between the new Ni3(PO4)2·8H2O precursor and Li3PO4 at 700 °C in air atmosphere. The formation of LiNiPO4 was generated via three thermal decomposition steps. The samples were characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, atomic absorption/atomic emission spectrophotometers, and thermogravimetric/differential thermal gravimetric/differential thermal analysis techniques. The activation energy (Eα) values of the three steps were calculated by Vyazovkin method and determined to be 90.39 ± 5.79, 197.81 ± 7.46, and 308.66 ± 12.03 kJ mol−1, respectively. The average Eα values from this method are very close to Eα from KAS method. The most probable mechanism functions g(α) of three steps were evaluated by using the masterplots method and found to be the F1/3 (first step), F3/2 (second step), and D4 (final step), respectively. The pre-exponential factors (A) values of three steps were obtained based on the Eα and g(α). The kinetic triplet parameters of the formation of LiNiPO4 from the new precursor are reported in the first time.