Journal of Inorganic Materials ›› 2015, Vol. 30 ›› Issue (1): 59-64.doi: 10.15541/jim20140232

• Orginal Article • Previous Articles     Next Articles

Preparation and Properties of Nanocrystalline Potassium Sodium Niobate Ceramics

Chao WANG1(), Jing CHEN1, Hong-Li CHEN1, Yu-Dong HOU2, Man-Kang ZHU2   

  1. 1. Logistics School, Beijing Wuzi University, Beijing 101149, China
    2. Key Laboratory of Advanced Functional Materials of China Education Ministry, Beijing University of Technology, Beijing 100124, China
  • Received:2014-05-14 Revised:2014-08-05 Online:2015-01-20 Published:2014-12-29
  • Supported by:
    National Natural Science Foundation of China (31101337)

Abstract:

Using average 30 nm grain sized potassium sodium niobate powders obtained by a novel Sol-Gel method as starting materials, nanocrystalline potassium sodium niobate ceramics with pure orthorhombic phase, relative density of above 99% and grain size of 40 nm were prepared by spark plasma sintering method under sintering temperature of 900 ℃, sintering pressure of 30 MPa and sintering time of 1 min. The phase structure, micro-morphology, dielectric properties and ferroelectric properties of the ceramics were investigated. The results show that, differently from common micro-grain ceramics, dielectric constant of nanocrystalline potassium sodium niobate ceramics decreases to 341, which changes little with the temperature, and the ceramics have obvious dielectric relaxation (dispersion factor γ is 1.60), and a well saturated ferroelectric hysteresis loop with coercive field of 13.5 kV/cm and remanent polarization of 1.5 μC/cm2. The abnormal properties can be attributed to the significant increasing content of grain boundary in nanocrystalline potassium sodium niobate ceramics, and it can be expected that if potassium sodium niobate ceramic has the critical size at room temperature, it would be less than 40 nm.

Key words: potassium sodium niobate, nanocrystalline ceramic, dielectric relaxation, ferroelectric hysteresis loop

CLC Number: 

  • TM282