Enhancing the thermoelectric performance of cold sintered calcium cobaltite ceramics through optimised heat-treatment. Issue 9 (August 2022)

• Record Type: Journal Article
• Authors: Yu, Jincheng; Nelo, Mikko; Liu, Xiaodong; Shao, Shouqi; Wang, Bing; Haigh, Sarah J.; Jantunen, Heli; Freer, Robert
• Is Part Of: Journal of the European Ceramic Society. Volume 42:Issue 9(2022)
• Page Start: 3920
• Page End: 3928
• Publication Date: 2022-08
• Subjects: Cobaltite -- Thermoelectric -- Cold sintering -- Heat treatment -- Microstructure; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2022.03.017
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: Cold sintering is a promising technology for preparing electronic materials, enabling densification at low temperature, but rarely employed for thermoelectrics. Herein, high-quality Ca2.7 Bi0.3 Co3.92 O9+δ ceramics were synthesised by a combination of cold sintering and annealing processes. Stoichiometric mixtures of raw materials were calcined once or twice at 1203 K for 12 h in air, and then cold sintered at 673 K for 60 min under a pressure of 85 MPa, followed by annealing at 1203 K for 12 h or 24 h in air. The effects of the calcination processes and annealing conditions on the thermoelectric performance of cold sintered samples were investigated. By optimising heat-treatment, the formation of secondary phases, texture development and porosity were controlled, leading to enhanced electrical conductivity and reduced thermal conductivity. Consequently, at 800 K there was 85% increase in power factor and 35% increase in ZT (value of 0.15) compared to previous studies.