Electrical properties and relaxor phase evolution of Nb-Modified Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3-SrTiO3 lead-free ceramics |
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Authors: | Xuefan Zhou Zhongna Yan He Qi Lu Wang Siyu Wang Yuan Wang Chao Jiang Hang Luo Dou Zhang |
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Affiliation: | 1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, China;2. School of Aeronautics and Astronautics, Central South University, Changsha, Hunan 410083, China |
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Abstract: | In this work, the crystalline phase, domain structure, and electrical properties of Bi0.5(Na0.84K0.16)0.5]0.96Sr0.04Ti1-xNbxO3 (x = 0.010–0.030) ceramics are investigated. Increasing the Nb content induces the phase transition from coexistent rhombohedral and tetragonal phases to a single pseudo-cubic phase, and the lamellar ferroelectric domains evolve into polar nanoregions. Decreased ferroelectric-to-relaxor transition temperature and enhanced frequency dispersion are found in the temperature-dependent dielectric constant and loss, implying a transition from the non-ergodic to ergodic relaxor state. The Nb substitution significantly degrades the long-range ferroelectric order with sharply decreased piezoelectric coefficients from ? 140 to ? 1 pC/N. However, a large strain of 0.32% at 5 kV/mm (normalized strain of 640 pm/V) is obtained around the critical composition of x = 0.0225. The composition of x = 0.030 shows good temperature insensitivity of the strain response, characterized by 308 pm/V with less than 15% reduction from 25 °C to 125 °C. |
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Keywords: | Corresponding author Phase structures Strain response Dielectric properties |
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