Compositional inhomogeneity and segregation in (K0.5Na0.5)NbO3 ceramics |
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| Affiliation: | 1. School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, PR China;2. Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA;1. Department of Chemical Engineering and Material Science, Doshisha University, 1-3 Miyakodani, Tatara, Kyotanabe, Kyoto 610-0321, Japan;2. Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan;1. School of Mechanical Systems Engineering, Kookmin University, Seoul 136-702, Republic of Korea;2. School of Materials Science and Engineering, Changwon National University, Changwon 641-773, Republic of Korea;3. Technical Research Laboratories, POSCO, Pohang 790-785, Republic of Korea;1. State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, Hubei, China;2. Materials Research Institute, Pennsylvania State University, University Park, PA 16802, USA;1. Department of Physics, Konkuk University, Seoul 05029, Republic of Korea;2. Functional Ceramics Laboratory, Department of Materials Science and Engineering, The University of Seoul, Seoul 02504, Republic of Korea;3. National Institute for Materials Science, Ibaraki 305-0044, Japan;1. State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, PR China;2. School of Materials Science and Engineering, Yunnan University, Kunming 650091, PR China;3. Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, PR China;4. Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Jilin University, Changchun 130012, PR China;1. Department of Physics, Zhejiang Normal University, Jinhua 321004, China;2. College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China |
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| Abstract: | In this report, the effects of the calcination temperature of (K0.5Na0.5)NbO3 (KNN) powder on the sintering and piezoelectric properties of KNN ceramics have been investigated. KNN powders are synthesized via the solid-state approach. Scanning electron microscopy and X-ray diffraction characterizations indicate that the incomplete reaction at 700 °C and 750 °C calcination results in the compositional inhomogeneity of the K-rich and Na-rich phases while the orthorhombic single phase is obtained after calcination at 900 °C. During the sintering, the presence of the liquid K-rich phase due to the lower melting point has a significant impact on the densification, the abnormal grain growth and the deteriorated piezoelectric properties. From the standpoint of piezoelectric properties, the optimal calcination temperature obtained for KNN ceramics calcined at this temperature is determined to be 800 °C, with piezoelectric constant d33=128.3 pC/N, planar electromechanical coupling coefficient kp=32.2%, mechanical quality factor Qm=88, and dielectric loss tan δ=2.1%. |
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| Keywords: | Lead-free piezoelectric Compositional inhomogeneity Compositional segregation Liquid phase sintering Potassium–sodium niobate Calcination temperature |
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