Kinetics of BiVO₄ Prepared by Solid Reaction between Bi（NO₃）₃·5H₂O and NH₄VO₃ under Calcination

The kinetics of Bi VO₄ prepared by the solid reaction of Bi (NO₃)₃·5H₂O and NH₄VO₃ was investigated using TG-DSC under different heating rates. The results show that the process undergoes two stages. The first period corresponds to the solid and liquid-state reactions and the second period is a solid-state reaction with 400.67~425.95 K,516.86~551.57 K of peak temperature range in DSC curves,respectively. All the reactions in these periods involve the decomposition of by-products,the transition and perfection of the crystals in product. Employing the Flynn-Wall-Ozawa and Kissinger models,the kinetics parameters for the reactions were determined as follows: for the first period,the apparent activation energy E_a1= 86.56 kJ/mol and frequency factor A₁= 4.49 × 10¹⁰min^-1; for the second period,the apparent activation energy E_a2= 103.11 kJ/mol and frequency factor A₂= 4.12 × 10⁹min^-1.