Products and non-isothermal kinetics of thermal decomposition of MgFe2(C2O4)3·6H2O

MgFe 2 (C 2 O 4 ) 3 ·6H 2 O was synthesized by solid-state reaction at low heat using MgSO 4 ·7H 2 O, FeSO 4 ·7H 2 O, and Na 2 C 2 O 4 as raw materials. The spinel MgFe 2 O 4 was obtained via calcining MgFe 2 (C 2 O 4 ) 3 ·6H 2 O above 500 °C in air. The MgFe 2 (C 2 O 4 ) 3 ·6H 2 O and its calcined products were characterized by thermogravimetry and differential scanning calorimetry (TG/DSC), Fourier transform FT-IR, X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). The result showed that MgFe 2 O 4 obtained at 800 °C had a specific saturation magnetization of 40.4 emu g −1 . The thermal process of MgFe 2 (C 2 O 4 ) 3 ·6H 2 O experienced three steps, which involves the dehydration of the six waters of crystallization at first, and then decomposition of MgFe 2 (C 2 O 4 ) 3 into amorphous MgFe 2 O 4 in air, and at last crystallization of MgFe 2 O 4 . Based on Flynn–Wall–Ozawa equation, the average values of the activation energies associated with the thermal decomposition of MgFe 2 (C 2 O 4 ) 3 ·6H 2 O were determined to be 148.45 ± 25.50 and 184.08 ± 7.64 kJ mol −1 for the first and second decomposition steps, respectively. Dehydration of the six waters of MgFe 2 (C 2 O 4 ) 3 ·6H 2 O is multi-step reaction mechanisms. Decomposition of MgFe 2 (C 2 O 4 ) 3 into MgFe 2 O 4 could be simple reaction mechanisms, kinetic model that can better describe the thermal decomposition of MgFe 2 (C 2 O 4 ) 3 is the F 3/4 model, and the corresponding function is g (α) = 1 − (1 − α) 1/4 .