Research articles
ScienceAsia (): 261-267 |doi:
10.2306/scienceasia1513-1874...261
Phase transition behaviour and dielectric properties of Na0.5K0.5NbO3-LiTaO3-LiSbO3 lead-free piezoceramic
Pornsuda Bomlaia,c,*, Supasarote Muensitb,c, Steven J. Milned
ABSTRACT: Lead-free piezoelectric ceramics have attracted considerable attention as new piezoelectric materials for replacing Pb(Zr,Ti)O3 (PZT)-based ceramics because of environmental protection reasons. Among lead-free piezoelectric systems, the ternary system of Na0.5K0.5NbO3-LiTaO3-LiSbO3 has proven to be an outstanding lead-free piezoceramic with properties almost comparable to undoped PZT. In this study, addition of LiSbO3 to the 0.95Na0.5K0.5NbO3-0.05LiTaO3 lead-free piezoceramic composition showed a change from an orthorhombic to a tetragonal crystal system in samples prepared by reaction-sintering. The limit of solid solution along the compositional join, (0.95−x)Na0.5K0.5NbO3-0.05LiTaO3-xLiSbO3, occurred at x∼0.06. Differential scanning calorimetry analysis and measurements of dielectric constant as a function of temperature indicated broad Curie peaks from which it was inferred that the samples were not chemically homogeneous. Curie temperatures decreased from ∼425 °C for x=0, to ∼345 °C for the limiting x=0.06 composition. Improvement of dielectric properties was obtained for LiSbO3 modified samples. Microstructures exhibited secondary recrystallization, with LiSbO3 addition giving rise to a small reduction in average grain size.
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| a |
Materials Science Program, Faculty of Science, Prince of Songkla University, Songkhla 90112, Thailand |
| b |
Department of Physics, Faculty of Science, Prince of Songkla University, Songkhla 90112, Thailand |
| c |
NANOTEC Centre of Excellence at Prince of Songkla University, Songkhla 90112, Thailand |
| d |
Institute for Materials Research, University of Leeds, Leeds LS2 9JT, UK |
* Corresponding author, E-mail: ppornsuda@yahoo.com
Received 22 May 2009, Accepted 27 Aug 2009
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