LaPO 4 : Ce, Tb, Yb phosphor—synthesis and kinetics study for thermal process of precursor by Vyazovkin, OFW, KAS, Starink, and Mastplosts methods

Precursor, La 0.85 Ce 0.05 Tb 0.05 Yb 0.05 PO 4 ·3.91H 2 O was synthesized via solid-state reaction at 60 °C. The experimental results show that the synthesized product is hexagonal La 0.85 Ce 0.05 Tb 0.05 Yb 0.05 PO 4 ·3.91H 2 O, and monoclinic La 0.85 Ce 0.05 Tb 0.05 Yb 0.05 PO 4 is a novel yellowish-green emitting phosphor, which can be obtained after calcining La 0.85 Ce 0.05 Tb 0.05 Yb 0.05 PO 4 ·3.91H 2 O at 800 °C in air. Based on the isoconversional procedures, the values of activation energy E α associated with the thermal decomposition of the precursor were obtained by using OFW, KAS, Starink, and Vyazovkin methods. The values of activation energy E α indicate that the decomposition is single-step kinetic process. The most probable reaction mechanism was estimated by Mastplosts and nonlinear methods. Mechanism equations obtained from the two methods are the same, which the nonlinear method is more efficient than the Mastplosts method. The value of pre-exponential factor A was obtained based on of E α and the reaction mechanism.