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CHAPTER 22: APPLICATIONS OF LEAD-FREE PIEZOELECTRICS
Our 21 st century will face to a " sustainable society " , which requires (a) usage of non-toxic materials, (b) disposal technology for existing hazardous materials, (c) new energy source creation, and (d) energy-efficient device development. Piezoelectric devices seem to be all-around contributors and a key component to the above mentioned four R&D areas in the sustainable society. Since the most widely used piezoelectric lead zirconate titante (PZT) ceramics will be regulated in less than 10 years in European and Japanese communities due to their toxicity (Pb 2+ ion), lead-free piezoelectric ceramics have been developed with performance equivalent to the PZTs. This paper introduces the current status of promising applications of Pb-free piezoelectrics developed recently: (1) piezoelectric transducers for ultrasonic cleaners, (2) piezoelectric transformers, and (3) ultrasonic motors with multilayer piezo-actuators.
Journal of The European Ceramic Society, 2018
The prohibition of lead in many electronic components and devices due to its toxicity has reinvigorated the race to develop substitutes for lead zirconate titanate (PZT) based mainly on the potassium sodium niobate (KNN) and sodium bismuth titanate (NBT). However, before successful transition from laboratory to market, critical environmental assessment of all aspects of their fabrication and development must be carried out in comparison with PZT. Given the recent findings that KNN is not intrinsically 'greener' than PZT, there is a tendency to see NBT as the solution to achieving environmentally lead-free piezoelectrics competitive with PZT. The lower energy consumed by NBT during synthesis results in a lower overall environmental profile compared to both PZT and KNN. However, bismuth and its oxide are mainly the by-product of lead smelting and comparison between NBT and PZT indicates that the environmental profile of bismuth oxide surpasses that of lead oxide across several key indicators, especially climate change, due to additional processing and refining steps which pose extra challenges in metallurgical recovery. Furthermore, bismuth compares unfavourably with lead due to its higher energy cost of recycling. The fact that roughly 90-95% of bismuth is derived as a by-product of lead smelting also constitutes a major concern for future upscaling. As such, NBT and KNN do not offer absolute competitive edge from an environmental perspective in comparison to PZT. The findings in this work have global practical implications for future Restriction of Hazardous Substances (RoHS) legislation for piezoelectric materials and demonstrate the need for a holistic approach to the development of sustainable functional materials.
Lead Zirconate Titanate: A Piezo electric material
Journal of chemical and pharmaceutical research, 2015
Lead Zirconate Titanate [Pb ZrxTi1-x]O3 ((0≤x≤1) - is an intermetallic inorganic piezoelectric material have been the subject of active research in recent years because of its remarkable applications in many field like microelectromechanical (MEMS) and nano-electromechanical (NEMS) devices. PZT is a metallic oxide based piezoelectric material developed by scientists at the Tokyo Institute of Technology around 1952. In comparison to the previously discovered metallic oxide based piezoelectric material Barium Titanate (BaTiO3), PZT materials exhibit greater sensitivity and have a higher operating temperature. PZT based materials are components of ultrasound transducers and ceramic capactitors. Ceramics also exhibit certain extremely useful magnetic and electronic properties that provide for a very wide range of possible applications.
Lead-free piezoelectrics—The environmental and regulatory issues
MRS Bulletin, 2018
The search for lead-free alternatives to Pb(Zr, Ti)O3 piezoelectric ceramics (PZT) has become a major topic in functional materials research due to legislation in many countries that restricts the use of lead alloys and compounds in commercial products. This article examines both the necessity for regulation and the impacts those regulations have created in the context of piezoelectric materials. It reviews the toxicity of lead, describes the current legislation to control the spread of lead in the environment, and attempts to define the risks associated with the manufacture, use, and disposal of lead-based piezoelectric materials. The consequences of the current legislation, both intended and unintended, are examined.
Review on Advanced Piezoelectric Materials (BaTiO3, PZT)
Journal of emerging technologies and innovative research, 2019
Piezoelectric materials are some naturally occurring materials which produces mechanical stresses when subjected to some voltages. But natural piezoelectric materials suffers a lot of disadvantages like low strength, sensitivity toward moisture, limited operating temperature range so, to overcome these drawbacks piezoelectric ceramics are made. Two major piezoelectric ceramics used are barium titanate (BaTiO3) and lead zirconium titanate (PZT).BaTiO3 is ferroelectric ceramic which exhibit photorefractive effect and piezoelectric properties. BaTiO3 has a disadvantage of low Curie temperature which can be further overcome by processing. Lead Zirconate titanate is an inorganic compound with chemical formula Pb[ZrxTi1-x] O3(0< x<1). Also called PZT, it is a ceramic perovskite material that shows a marked piezoelectric effect, meaning that the compound changes shape when an electric field is applied. Nowadays, they become the dominant piezoelectric materials in the fields of piezoelectric applications such as actuators, sensors, and transducers in intelligent systems and smart structures, dominating the world market today. Therefore, the aim of this review is giving a state of art in polycrystalline piezoelectric ceramic materials, like BaTiO3 and PZT and their applications. This review is organized in the following way. In the first part, the history and processing of piezoelectric ceramic materials are briefly introduced, and then the general characteristics of BaTiO3 and PZT are described with an emphasis on the piezoelectric parameters, compositions and properties, and piezoelectric constitutive relationships. Characterization methods for piezoelectric properties and ferroelectric domain structures of piezoelectric ceramic materials are addressed in the third part. Finally, various applications of piezoelectric ceramic materials in ultrasonic actuators, sensors, transducers, and active vibration controlling, are described.
Crystals
In this paper, in order to develop composition ceramics for an acoustic emission sensor application for nondestructive testing, Pb(Ni,Nb2/3)O3-Pb(Zr,Ti)O3-Pb(Mg,W)O3 [PNN-PZT-PMW] system ceramics were manufactured by conventional mixed oxide method using Li2CO3 and CaCO3 as sintering aids. Their microstructural, dielectric and piezoelectric properties were also investigated. At x = 0.0075 Sm, the substituted specimen sintered at 980 (°C), and high values of piezoelectric properties appeared: the dielectric constant (εr) of 2824, piezoelectric coefficient d33 of 630 [pC/N], planar electromechanical coupling factor kp of 0.665, piezoelectric voltage constant g33 of 25.2 [mV.m/N], and high Curie temperature (Tc) = 270 (°C), respectively. These values were applicable for devices such as acoustic emission sensor and ultrasonic transducer.
Journal of the European Ceramic Society, 2007
In the present investigation we studied the effect of lead content on a hard type ceramics starting from lack to excess PbO. Specimens of Pb x (Mn 0.017 Sb 0.033 Zr 0.48 Ti 0.47)O 3 with 0.96 ≤ x ≤ 1.06 were prepared by conventional oxide mixing technique and sintered at temperatures between 1280 and 1350 • C. In samples with lower Pb concentration the pyrochlore phase appeared, while in those with higher Pb an excess of PbO phase was detected. These phases proved detrimental for the properties of sintered ceramics. The highest values of piezoelectric properties were observed only for samples with an excess lead of about 2% sintered at 1340 • C, indicating that it represents the optimum amount of PbO. For such samples, the density ρ was 7.77 g/cm 3 , the remnant polarization P r was 37 C/cm 3 the planar coupling coefficient k p was 0.57 and the charge constant d 33 was 340 pC/N.
Are lead-free piezoelectrics more environmentally friendly?
MRS Communications
Considered as a less hazardous piezoelectric material, potassium sodium niobate (KNN) has been in the fore of the search for replacement of lead (Pb) zirconate titanate for piezoelectrics applications. Here, we challenge the environmental credentials of KNN due to the presence of ~60 wt% Nb2O5, a substance much less toxic to humans than Pb oxide, but whose mining and extraction cause significant environmental damage.
Journal of The European Ceramic Society, 2011
Li/Na/K)(Nb/Ta/Sb)O 3 lead free piezoelectric materials (LTLS), "pure" or doped by 1 mass% ZrO 2 , were elaborated. The sintering was investigated both by classical way and buried in a powder-bed in order to prevent the alkali-elements losses. The effects of doping and of these processes on densification and piezoelectric properties (d 33 , k t and k p) were studied. The results demonstrated that the final densification is enhanced for ZrO 2 doped samples. The sintering in powder-bed clearly enhanced the piezoelectric properties. The best results corresponds to d 33 ≈ 180 pC/N and k t ≈ 45-50% for non-doped samples and, d 33 ≈ 150 pC/N, with k t ≈ 45-50% for ZrO 2 doped samples. Finally, the ultrasonic properties of piezoelectric transducers based upon these materials were also investigated experimentally and theoretically. The results clearly demonstrated that their bandwidth and sensitivity are suitable for use in piezoelectric transducers and comparable with similar PZT based transducers.