Effect of Sr/Mg co-doping on the structural, dielectric, and electrical properties of CaCu3Ti4O12 ceramics

• Published in: Journal of materials science. Materials in electronics 2022-03, Vol.33 (7), p.4535-4549
• Main Authors: Rhouma, Salam, Megriche, Adel, El Amrani, Mohamed, Said, Senda, Roger, Sylvain, Autret-Lambert, Cécile
• Format: Article
• Language: English
• Subjects: Capacitors; Ceramics; Characterization and Evaluation of Materials; Chemical Sciences; Chemistry and Materials Science; Condensed Matter; Dielectric breakdown; Dielectric loss; Doping; Electric potential; Electrical properties; Frequency stability; Grain boundaries; Materials Science; Optical and Electronic Materials; Permittivity; Physics; Strontium; Titanium dioxide; Voltage
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-021-07645-0

Thanks to their exceptional dielectric constant, the CaCu 3 Ti 4 O 12 (CCTO) ceramic materials have significantly sparked a lot of research in capacitor applications. Nevertheless, large dielectric loss and a relatively low breakdown voltage preclude their practical applications. The current work focuses on improving the capacitor–varistor properties by simultaneously adding Sr and Mg to the lattice of calcium copper titanate Ca 1-x Sr x Cu 2.9 Mg 0.1 Ti 4 O 12 (with x  = 0, 0.1, 0.15, and 0.2). A correlation between the grain boundary and the dielectric/electrical properties of CCTO was systematically established. It is apparent that the combination of Sr and Mg doping ions gives rise to an obvious enhancement of the dielectric and nonlinear properties of CCTO ceramic. Besides, the increase in Sr content brings about the formation of secondary phases (TiO 2 , CuO, and SrTiO 3 ) at grain boundaries detected by EDS and Raman measurements. More importantly, the dielectric constant increased with increasing Sr content while retaining excellent frequency stability [10 2 –10 6  Hz]. Among ceramic samples, the Ca 0.9 Sr 0.1 Cu 2.9 Mg 0.1 Ti 4 O 12 sample shows the lowest dielectric loss (− 0.05 at 1 kHz), as well as the highest nonlinear coefficient ( α  = 10) and breakdown voltage (− 1009 V/cm). Additionally, the grain boundary effect played an important role in the dielectric and electric responses. The improvement of dielectric losses and nonlinear behaviors is attributed to this enhancement of grain boundary resistance.