Phase Structure, Microstructure and Electrical Properties of Lead-Free (1-x) [Na_0.515K_0.485]_0.94Li_0.06(Nb_0.99Ta_0.01)O_{3 -} BiAlO₃ Ceramics

Abstract:

Lead-free (1-x)[(Na_0.515K_0.485)_0.94Li_0.06(Nb_0.99Ta_0.01)O₃]-xBiAlO₃ (NKLNT-BA; x = 0, 0.005, 0.010, 0.015, and 0.020) ceramics were fabricated by a conventional mixed-oxide method. The effects of BiAlO₃ addition on the phase structure, microstructure and electrical properties of ceramic were then studied. The result indicated that grain size decreased with increasing of BiAlO₃ content. In the composition range studied, the perovskite phase with the coexistence of the orthorhombic and tetragonal phases was identified at approximately x 0.005 by the X-ray diffraction analysis and dielectric spectroscopy, which led to a significant enhancement of the piezoelectric properties. The tetragonality increased with further increasing x. The temperature dependence of dielectric properties showed that the addition of BiAlO₃ slightly decreased the ferroelectric tetragonal-paraelectric cubic phase transition temperature (T_C), but greatly shifted the polymorphic phase transition from the ferroelectric orthorhombic to the ferroelectric tetragonal phase (T_OT) to lower room temperature. The dielectric and piezoelectric properties are enhanced for the composition near the orthorhombic-tetragonal polymorphic phase boundary. The unmodified-(Na_0.515K_0.485)_0.94Li_0.06(Nb_0.99Ta_0.01)O₃ ceramics exhibit optimum electrical properties (d₃₃ = 225 pC/N and T_C = 418°C).

• Periodical: Advanced Materials Research (Volume 747)
• Pages: 781-784
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.747.781
• Online since: August 2013
• Authors: Pornsuda Bomlai
• Keywords: Doping, Electrical Properties, Lead-Free Materials, Non-Stoichiometry

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