Enhancing thermoelectric properties of Ca3Co4O9ceramics through oscillatory pressure sintering

Oscillatory Pressure Sintering (OPS) has been demonstrated to be a favorable manufacturing approach for the control of fine and uniform distribution of grains in various ceramic systems, which can lead to enhanced densification and thus improved physical and mechanical properties. In this study, OPS was utilized to prepare pure Ca3Co4O9thermoelectric material. The results show that the electrical properties and thermoelectric properties of Ca3Co4O9prepared by OPS are superior to those of samples sintered by conventional hot pressing (HP) without oscillation. This may be attributed to the better alignment of plate-like grains in the OPS samples, which increase electrical conductivity, and also the higher density of grain boundaries that enhance the phonon scattering and, thus, the reduction of thermal conductivity. This study suggests that a straightforward oscillatory pressure sintering approach can be utilized to obtain high-quality and high-performance thermoelectric materials without the need for doping, templating, or high-temperature sintering.