SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS OF CALCIUM COBALTATE THERMOELECTRIC POWDERS

摘要

Thermoelectric Ca_1.24Co_1.62O_3.86 powders are synthesized by Self-propagating High temperature Synthesis (SHS), a simple and economical process of synthesis oxides. Prepared powders were analyzed by XRD for phase purity, TG/DSC for thermal stability and SEM for particle size. Post treatment is also applied to improve the phase purity of powders produced by SHS. A short post treatment of 15 minutes in air can convert the SHS product into phase pure Ca_1.24Co_1.62O_3.86. To study the reaction mechanism, TG-DSC analysis was performed on the reaction mixture to establish the reaction mechanism. Prepared powders have high Seebeck coefficient and figure of merit close to those prepared by spark plasma sintering. A finite element mathematical model is used to simulate the temperature profile inside the reactant pellet during the SHS.