Synthesis and Pressure-Assisted Sintering of CaCu3Ti4O12 Dielectrics

• Published in: Ceramics Vol. 4; no. 3; pp. 447 - 466
• Main Authors: Petrášek, Jan, Ctibor, Pavel, Sedláček, Josef, Lukáč, Frantisek
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-09-2021
• Subjects: Annealing; calcium copper titanate; CCTO; Ceramics; Cooling; Dielectric properties; giant dielectric permittivity; Grain boundaries; high-pressure forming; Laboratories; Microhardness; Molten salts; Oxidation; Permittivity; Phase composition; Plasma sintering; Press forming; quadruple perovskite; Raw materials; Single crystals; Sintering (powder metallurgy); Spark plasma sintering; Temperature; United States > US
• ISSN: 2571-6131; 2571-6131
• DOI: 10.3390/ceramics4030033

In this paper, we examined the dielectric properties of CaCu3Ti4O12 (CCTO) ceramics fabricated by various routes and discussed the most important conditions affecting their dielectric behavior. We prepared feedstock powder using a molten salt route and compared it with a commercial powder. Both powders were sintered using SPS. For some samples, annealing was applied after sintering. Other samples were obtained by high-pressure forming and conventional sintering, using both powders. Phase composition, porosity and microhardness were evaluated in comparison with the literature. The results showed that a sintering temperature just below or equal to 1000 °C should be set for the SPS process. However, the best dielectric characteristics were obtained in samples prepared by high-pressure forming and conventional sintering, which showed a relative permittivity of 22,000 and a loss tangent of 0.13 at 1 MHz.