| Autor: |
Yamada, H., Matsuoka, T., Kozuka, H., Yamazaki, M., Ohbayashi, K., Ida, T. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 6/7/2015, Vol. 117 Issue 21, p214102-1-214102-6, 6p, 1 Black and White Photograph, 2 Diagrams, 4 Graphs |
| Abstrakt: |
Two phases of (K,Na)NbO3 (KNN) co-exist in a KNN-based composite lead-free piezoelectric ceramic 0.910(K1-xNax)0.86Ca0.04Li0.02Nb0.85O3-δ-0.042K0.85Ti0.85Nb1.15O5-0.036BaZrO3-0.0016Co3O4-0.0025Fe2O3-0.0069ZnO system, over a wide range of Na fractions, where 0.56-x-0.75. The crystal systems of the two KNN phases are identified to tetragonal and orthorhombic by analyzing the synchrotron powder X-ray diffraction (XRD) data, high-resolution transmission electron microscopy (HR-TEM), and selected-area electron diffraction (SAD). In the range 0.33≤x≤0.50, the main component of the composite system is found to be single-phase KNN with a tetragonal structure. Granular nanodomains of the orthorhombic phase dispersed in the tetragonal matrix have been identified by HR-TEM and SAD for 0.56≤x≤0.75. Only a trace amount of the orthorhombic phase has been found in the SAD patterns at the composition x=0.56. However, the number of orthorhombic nanodomains gradually increases with increasing Na content up to x<0.75, as observed from the HR-TEM images. An abrupt increase and agglomeration of the nanodomains are observed at x=0.75, where weak diffraction peaks of the orthorhombic phase have also become detectable from the XRD data. The maximum value of the electromechanical coupling coefficient, kp=0.56, has been observed at the composition x=0.56. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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