Microstructure and thermoelectric properties of Al-doped ZnO ceramic prepared by spark plasma sintering. Issue 3 (March 2023)

• Record Type: Journal Article
• Authors: Radingoana, Precious Manti; Guillemet-Fritsch, Sophie; Noudem, Jacques; Olubambi, Peter Apata; Chevallier, Geoffroy; Estournès, Claude
• Is Part Of: Journal of the European Ceramic Society. Volume 43:Issue 3(2023)
• Page Start: 1009
• Page End: 1016
• Publication Date: 2023-03
• Subjects: ZnO -- Aluminum -- Thermoelectric properties -- Spark plasma sintering -- Ceramics; 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.2022.10.034
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: The high thermal and low electrical conductivities of ZnO ceramics have hindered their thermoelectric applications. The doping of ZnO with group 3 elements can enhance the thermoelectric properties. In this work, Al (2 at%) doped ZnO powder was sintered using spark plasma sintering at varying parameters (such as temperature (550–700 ℃), pressure (250–500 MPa) and the temperature of pressure application (Room Temperature (RT) and Holding Time (HT))). Maximum relative density of 98.9% was achieved at a temperature and pressure of 650 °C and 250 MPa, respectively. The Al-doped ZnO ceramics improved in electrical conductivity which caused a decrease in the Seebeck coefficient because of increased carrier concentration. The reduction in the grain size due to inhibiting growth effects of aluminum lead to a decrease in the thermal conductivity through phonon scattering at the grain boundaries. Hence, ZT of 0016 at 500 °C was obtained. This study indicated that Al-doped ZnO ceramics can be sintered at very low temperature of 650 °C. These conditions allow to retain the nanostructure, which is beneficial in improving the thermoelectric properties.