Piezoelectric anomalies at the ferroelastic phase transitions of lead-free tungsten bronze ferroelectrics
| Autor: | Hiroshi Funakubo, Toshihiro Ifuku, Bong-Yeon Lee, Nobuhiro Kumada, Takayuki Watanabe, Takanori Matsuda, Takashi Iijima, Houzhona Yu, Jumpei Hayashi |
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| Rok vydání: | 2010 |
| Předmět: |
Phase transition
Phase boundary Materials science Condensed matter physics chemistry.chemical_element General Chemistry Dielectric Atmospheric temperature range Tungsten Condensed Matter Physics Piezoelectricity Crystallography Tetragonal crystal system chemistry Materials Chemistry Ceramics and Composites Curie temperature |
| Zdroj: | Journal of the Ceramic Society of Japan. 118:717-721 |
| ISSN: | 1348-6535 1882-0743 |
| DOI: | 10.2109/jcersj2.118.717 |
| Popis: | This paper reports on the piezoelectric anomalies at the temperature or composition-induced ferroelastic phase transitions of tungsten bronze ferroelectrics. First, the temperature-dependent piezoelectric properties of Sr1.9Ca0.1NaNb5O15 (SCNN) ceramics were characterized using a resonance/anti-resonance method. SCNN has a ferroelastic phase transition manifested by a broad dielectric peak in the temperature range of −60°C to 20°C. The electromechanical coupling factor and elastic compliance showed the maximum at −40°C, increasing the transverse piezoelectric constant (d31) by 38% compared with the room temperature value. Tungsten bronze ferroelectrics follow a trade-off relationship between the longitudinal piezoelectric constant (d33) and the Curie temperature, while SCNN deviates significantly from the trend curve. This deviation is attributed to the ferroelastic phase transition close to room temperature.Second, the ferroelastic phase transition was investigated for epitaxial films of (1 − x)(Sr3Ba2)Nb10O30–xBa4Bi2/3Nb10O30 as a function of the composition. A careful structural analysis by X-ray diffraction revealed that there is a ferroelastic phase boundary between tetragonal and orthorhombic crystals at x = 0.06–0.3. The electric field-induced strain and the relative dielectric constants characterized at 80 K for the epitaxial films increased in the vicinity of the phase boundary composition. These results suggest that engineering the ferroelastic phase transition is an approach to improving the piezoelectric properties of lead-free tungsten bronze ferroelectrics. |
| Databáze: | OpenAIRE |
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