Composition segregation and grain growth in (K0.5Na0.5)NbO3 piezoceramics prepared by two‐step cold sintering process. Issue 2 (17th October 2022)

• Record Type: Journal Article
• Authors: Jiang, Jiahao; Chen, Shuaimin; Zhao, Chunlin; Lin, Cong; Wu, Xiao; Gao, Min; Lin, Tengfei; Fang, Changqing
• Is Part Of: Journal of the American Ceramic Society. Volume 106:Issue 2(2023)
• Page Start: 913
• Page End: 922
• Publication Date: 2022-10-17
• Subjects: composition segregation -- grain growth -- (K0.5Na0.5)NbO3 -- piezoelectric property -- two‐step cold sintering process; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.18847
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: Cold sintering process (CSP) is a new method to prepare ceramics under quite low temperature. In this work, two‐step CSP under different pressures was employed to prepare (K0.5 Na0.5 )NbO3 (KNN) ceramics. The density of KNN green pellets can be raised by enhancing the pressure of second‐step CSP. Energy‐dispersive spectroscopy reveals the composition segregation of A‐site cations in large grains. The dissolution rate of K + in an aqueous medium is faster than Na +, and high pressure can accelerate K + dissolution, resulting in more Na + in some grains. Besides, the diffusion rate of Na + in grains is better than K +, which promote the grains growth. Finally, the piezoelectric property is improved even with low ceramic density due to the larger grains, which possess the higher performance composition. This result demonstrates that the pressure and inhomogeneous dissolution of alkali metal ions among CSP play an important role in grain growth and piezoelectric enhancement. Abstract : The breakthrough in piezoelectricity was achieved in KNN ceramic via two‐step cold sintering process under different pressures. The high pressure in second‐step cold sintering process can promote K/Na segregation and grain growth, then the piezoelectricity is improved even with low ceramic density because the large grains possess high‐performance composition.