Synthesis and dielectric properties of layered-perovskite KCa2Nan-3NbnO3n+1 ceramics

Jong Un Woo, Sang Hyo Kweon, Mir Im, Woong Hee Lee, Chong-Yun Kang, Sahn Nahm

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

KCa2NaNb4O13 (4KCNNO) 1 1KCa2NaNb4O13 defined as 4KCNNO. ceramics are well-sintered at 1325°C without any secondary phase. However, K2O evaporation occurs in KCa2Na2Nb5O16 (5KCNNO) 2 2KCa2Na2Nb5O16 defined as 5KCNNO. ceramics calcined at temperatures higher than 1200°C, resulting in the formation of the KCa2Na3Nb6O19 (6KCNNO) 3 3KCa2Na3Nb6O19 defined as 6KCNNO. secondary phase. Excess-K2O was added to the 5KCNNO specimen to synthesize pure 5KCNNO ceramics by compensating for the evaporated K2O. The 5KCNNO ceramic containing 20mol% excess-K2O sintered well at 1325°C without any secondary phase. However, the 6KCNNO secondary phase also developed in specimens containing a large excess of K2O, owing to the reaction between excess-K2O and the 5KCNNO phase. Dielectric constant (e(open) r ) of the 4KCNNO ceramic is 62 with a dielectric loss (tan δ) of 0.6% at 100kHz and the 5KCNNO ceramic showed increased e(open) r of 70 with tan δ of 0.3% at 100kHz. The increase in the e(open) r value is rationalized by the inc r eased number of NbO6 octahedral layers between the K+ layers. In addition, the structural and dielectric properties of the 5KCNNO ceramic are more important than those of the 4KCNNO ceramic from the application point of view, because the ε r value of the 5KCNNO ceramic is larger than that of the 4KCNNO ceramic.

Original languageEnglish
JournalCeramics International
DOIs
Publication statusAccepted/In press - 2017

Keywords

  • A. Powders: solid state reaction
  • C. Dielectric properties
  • D. Perovskite
  • Nanosheets

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Process Chemistry and Technology
  • Surfaces, Coatings and Films
  • Materials Chemistry

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