Impact of two-step calcination on microstructure, phase, electronic, and dielectric properties of KCa2Nb3O10 bulk layered perovskite

• Published in: Journal of Asian Ceramic Societies Vol. 11; no. 1; pp. 188 - 196
• Main Authors: Kim, Jeong-Yeon, Lim, Jong-Chan, Kim, Sang-il, Hwang, Seong-Mee, Shin, Weon-Ho, Yang, Heesun, Lee, Kyu Hyoung, Kim, Hyun-Sik
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 02.01.2023; Taylor & Francis Group
• Subjects: dielectric constant; KCa; KCa2Nb3O10; layered perovskite; multi-layer ceramic capacitor; two-step calcination
• ISSN: 2187-0764
• DOI: 10.1080/21870764.2023.2174243

The effects of varying calcination temperature, K content, and the number of calcination steps in the dielectric performance of KCa 2 Nb 3 O 10 synthesized via solid-state reaction are investigated. Adding an extra calcination step at 500°C followed by another calcination at 1100°C suppressed the formation of secondary phases while maximizing the relative density (95%) and the average grain area (2.12 μm 2 ). The first calcination at 500°C ensures the formation of intermediate phases (KNbO 3 and Ca 2 Nb 2 O 7 ), which are prerequisites for single-phase KCa 2 Nb 3 O 10 synthesis. A significantly high dielectric constant of 352 at 100k Hz is achieved in the two-step calcined sample despite the low sintering temperature of 1250°C. The highest resistivity of the two-step calcined sample (2 × 10 8 Ω cm) obtained from complex impedance analysis supports its lowest dielectric loss (0.034 at 100k Hz). When the two-step calcined KCa 2 Nb 3 O 10 powder is exfoliated, much higher dielectric properties of Ca 2 Nb 3 O 10 nanosheets are expected.