Piezoelectric lead-free

Kimura T, Yi Y, Sakurai F (2010) Mechanisms of texture development in lead-free piezoelectric ceramics with perovskite stmcture made by the templated grain growth process. Materials 3 4965-4978... 

Tani, T. and Kimura, T. (2006) Reactive-templated grain growth processing for lead free piezoelectric ceramics. Adv. Appl. Ceram., 105 (1), 55-63. 

Takenaka, T., and Nagata, H. 2005. Current status and prospects of lead-free piezoelectric ceramics. Journal of the European Ceramic Society 25, pp 2693-2700. 

T. Takenaka, K. Maruyama andK. Sakata, (Bil/2Nal/2)Ti03-BaTi03 system for lead-free piezoelectric ceramics , Jpn. J. Appl. Phys., 30 [93] Part 1, No. 9B, 2236-2239 (1991). 

KNbOi (LB Number 1A-2). This crystal is ferroelectric below about 418 °C. Further phase transitions take place at about 225 °C and about — 10°C, retaining ferroelectric activity. The crystal has large electromechanical coupling constants and is useful in lead-free piezoelectric elements and SAW (surface acoustic wave) filters in communications technology (Fig. 4.5-13,4.5-14). 

Hosono, Y., Harada, K., and Yamashita, Y. (2001) Crystal growth and electrical properties of lead-free piezoelectric material. Jpn. J. Appl. Phys., 40, 5722-5726. 

Lead-free piezoelectric ceramics of (Bil4Na%)Ti03-/4(Bi203 SC2O3) system. Jpn.J. Appl. Phys., 36, 6055-6057. 

The development of characterization and fabrication methods approaching the unit-cell size of known piezoelectric materials has reenergized the area of piezoelectric materials research in the past few years. By tailoring the structure of piezoelectric materials to maximize the polarizability, strength, and maximum strain, major advances are just beginning to appear. Work on applying the replete knowledge of bulk piezoelectric materials to thin-film materials research remains incomplete, from fabrication of PMN-PT to lead-free ceramics at small scales. 

The known lead-free piezoelectric materials can be categorized into three broad families (i) perovskite titanates such as barium titanate and bismuth... 

Certain ternary solid solutions containing BTO as one of their major phase components show excellent piezoelectric properties in the vicinity of MPB. They have been considered as a potential replacement for existing lead-based piezoelectric perovskite, PbZrOs-PbTiOs, PMT-PT, and so on. In fact, the extremely high piezoelectric response of PZT and PMN-PT has been partially attributed to the presence of a MPB between rhombohedral and tetragonal phases at that concentration [12]. Therefore, the presence of a MPB is considered as a necessary component of a lead-free replacement material due of the enhancement in properties observed for compositions at or near MPB. The basic approach to achieve high piezoelectricity is to choose the composition of the material at the proximity of a MPB of the phase diagram. The strong piezoelectric and dielectric responses at the vicinity of MPB have been ascribed to the low polarization anisotropy (rotation of FE polarization between two equivalent states) and elastic softness at MPB. 

In addition to BZT-xBCT, the other system that has been studied extensively by the researchers for both fundamental understanding and applications is sodiimi bismuth titanate, Nao.5Bio.5Ti03 (NBT). NBT and its solid solutions have been extensively studied because of their exceptionally high electrostrain [20,21]. In addition, NBT coidd be a potential candidate in the search for lead-free piezoelectric materials. From the structural aspects, NBT is... 

Figure 10.5 shows a schematic of a simple experiment that demonstrates the response of NBT ceramics for external mechanical stimuli. A fiber-reinforced composite sheet was fixed at one edge to act like a cantilever sheet An actuator whose frequency and amplitude could be controlled externally was fixed imder-neath the sheet and with no additional power supply the NBT ceramic was fixed on the sheet. The effective response of the NBT ceramic pellets connected to an oscilloscope is seen in Figure 10.5b. The amplitude of the signal was on the order of 3-5 mV, which could be conditioned, amplified, and further utilized later for various apphcations. Thus, NBT ceramics exhibit promising features in the search for lead-free piezoelectrics.

Ullah, A., Ahn, C.W., Hussain, A., and Kim, I.W. (2010) The effects of sintering temperatures on dielectric, ferroelectric and electric field-induced strain of lead-free Bio,s(Nao,78Ko.22)o.sTi03 piezoelectric ceramics synthesized by the sol-gel technique. Curr. Appl Phys., 10 (6),... 

Maiwa H, Jia TT, and Kimura H Energy harvesting using PLZT and lead-free ceramics and their piezoelectric properties on the nano scales. Ferroelectr., 2015 475 71-81. 

The zincblende (ZB), or sphalerite, structure is named after the mineral (Zn,Fe) S, and is related to the diamond structure in consisting entirely of tetrahedrally-bonded atoms. The sole difference is that, unlike diamond, the atoms each bond to four unlike atoms, with the result that the structure lacks an inversion center. This lack of an inversion center, also characteristic of the wurtzite structure (see below), means that the material may be piezoelectric, which can lead to spurious ringing in the free-induction decay (FID) when the electric fields from the rf coil excite mechanical resonances in the sample. (Such false signals can be identified by their strong temperature dependence due to thermal expansion effects, and by their lack of dependence on magnetic field strength). 

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