| Effect of Firing Temperature and DC Poling on Acoustic Wave Velocities in Barium Titanate Piezoelectric Ceramics |
| Taiki IKEGAYA |
| Shizuoka Institute of Science and Technology |
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The longitudinal and transverse wave velocities in barium titanate (BT) ceramics made by different firing temperatures were measured using an ultrasonic precision thickness gauge with high-frequency pulse generation to evaluate elastic constants, such as Young¡¯s modulus and Poisson¡¯s ratio [1, 2]. With increasing firing temperature, the longitudinal and transverse wave velocities increased, as a result, Young¡¯s modulus increased because of BT ceramics being mechanical hard (Figure 1). Poisson¡¯s ratio after DC poling, however, was almost independent of the firing temperature since Poisson¡¯s ratio is an intrinsic materials constant. It was found that there was an important factor for giving piezoelectricity regarding changes in Young¡¯s modulus and Poisson¡¯s ratio after DC poling in comparison with before poling, that is, lowering Young¡¯s modulus and enhancing Poisson¡¯s ratio. Furthermore, the increase in modulus of rigidity and bulk modulus increased with firing temperature because of the increase in the ceramic bulk density. The modulus of rigidity decreases and bulk modulus increases after poling because of domain alignment.
Figure 1 Firing temperature (FT) vs (a) longitudinal wave velocity (VL), (b) transverse wave velocity (VS), (c) Young¡¯s modulus (Y) and (d) Poisson¡¯s ratio (¥ò) in BT ceramics before and after DC poling.
References:
[1] T. Ogawa and T. Nishina: Advances and Applications in Electroceramics II, eds. K. M. Nair and S. Priya (Wiley, Hoboken, 2012) Ceramic Transactions, Vol. 235, p. 105.
[2] T. Ogawa: Piezoelectric Materials and Devices £Practice and Applications, ed. F. Ebrahimi (InTech, Rijeka, 2013) p. 35
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| Acknowledgements : This work was partially supported by Grant-in-Aids for Scientific Research C (Nos. 21560340 and 26420282), a Grant of Strategic Research Foundation Grant-aided Project for Private Universities 2010-2014 (No. S1001032) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT), and a Research Foundation 2014 between Academy and Industry of Fukuroi City, Shizuoka, Japan. |
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