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Particle Size Effect on the Electrical Properties of Spark-Plasma-Sintered Relaxor Potassium Sodium Niobate Ceramic

C. Wang, J. Chen, L. Shen, J. Rui, X. Yang, M. Zhu, Y. Hou

Journal of Ceramic Science and Technology, Vol. 8, No. 2 (2017), pp. 255-258

DOI: 10.4416/JCST2016-00116

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Abstract

30-nm-grain-sized potassium sodium niobate ((K0.5Na0.5)NbO3 (KNN)) powders were obtained with the sol-gel method. From these powders as starting materials, high-density KNN ceramics with a relative density of 98.9 % and grain size of 500 nm were prepared with the spark plasma sintering (SPS) method. The processing parameters were a sintering temperature of 900 °C, sintering pressure of 30 MPa and sintering time of 3 min. The phase composition, microstructure and electrical properties of the ceramics have been investigated. The results show that, unlike common micro-grained ceramics, submicron-grained ceramics prepared with the SPS method show obvious dielectric relaxation (dispersion factor γ is 1.31). Meanwhile, the KNN ceramics exhibit good electrical properties such as dielectric constant εr = 753, piezoelectric constant d33 = 142 pC/N and electromechanical coupling factor kp = 0.41.

Keywords

Lead-free piezoelectric ceramics, potassium sodium niobate, submicron-grained, dielectric relaxation, electrical properties.

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