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Actuator Materials
Published in Kenji Uchino, Micro Mechatronics, 2019
Piezoelectric ceramics from the Pb(Zr,Ti)O3 solid solution system have been widely used because of their superior piezoelectric properties. The phase diagram for the Pb(ZrxTi1-x)O3 system appears in Figure 3.7. The symmetry of a given composition is determined by the Zr content. Lead titanate also has a perovskite structure and a tetragonally distorted ferroelectric phase. With increasing Zr content, x, the tetragonal distortion, decreases, and at x > 0.52, the structure changes from tetragonal 4 mm to another ferroelectric phase with rhombohedral 3 m symmetry. The line dividing these two phases in Figure 3.7 is called the morphotropic phase boundary (MPB). The composition at the MPB is assumed to be a mixture of the tetragonal and rhombohedral phases. The dependence of several piezoelectric strain coefficients (d) on composition over a narrow compositional range near the MPB is shown in Figure 3.8. All the d coefficients are observed to peak at the morphotropic phase boundary. The enhancement in the piezoelectric effect at the MPB has been attributed to the coexistence of the two phases, whose polarization vectors become more readily aligned by an applied electric field when mixed in this manner than may occur in either of the single-phase regions.
Ceramic Capacitor Technology
Published in Lionel M. Levinson, Electronic Ceramics, 2020
Manfred Kahn, Darnall P. Burks, Ian Burn, Walter A. Schulze
Lead titanate-derived dielectrics. Lead titanate is ferroelectric with a Curie temperature of 490°C. The dielectric constant at 25°C is about 350, but polycrystalline PbTiO3 is very difficult to sinter. When modified with Pb (Mg0.5W0.5)O3, however, the ceramic can be sintered near 1000°C and a high K can be obtained (27). Dielectrics of this type have been adapted for multilayer capacitor applications (28) using the basic composition (SrxPb1-xTiO3)a(PbMg0.5W0.5O3)b, where 0 ≥ x ≥ 0.1, 0.35 ≥ a ≥ 0.5, and 0.5 ≥ b ≥ 0.65.
Correlation between cubic-based polymorphic phase boundary structures and the piezoelectric properties of 0.96(Na0.5K0.5)(Nb1- x Sb x )-0.04BaTiO3 ceramics
Published in Journal of Asian Ceramic Societies, 2020
Xing-Hua Ma, Zhenlu Zhang, Tiewei Xu, Shuling Zhang
So far, lead-based piezoelectric materials, especially the lead titanate (PT) based materials have dominating the piezoelectric market due to their excellent properties [1–6]. However, with the increasing awareness of environmental protection, lead-free piezoelectric materials have been paid more and more attention to replace their lead-based counterparts [7–12]. Among the various lead-free piezo-materials, since the textured NKN-based ceramics were reported to show a high d33 value of 416 pC/N [13], which is comparable to that of PZT ceramics, extensive research has been conducted on alkali niobate systems [14–19]. To achieve the desirable high piezoelectric properties, two common strategies have been proposed. One way is to make the textured ceramics as former part mentioned [13]. The other approach is to chemically modify NKN matrix ceramics by substituting the A or (and) B site for other ions or adding additives to construct various phase boundaries at room temperature [16–30].
Ferroelectric, Piezoelectric Mechanism and Applications
Published in Journal of Asian Ceramic Societies, 2022
Arun Singh, Shagun Monga, Neeraj Sharma, K Sreenivas, Ram S. Katiyar
More recently, with development in the technology of electronic ceramics, polycrystalline materials such as BaTiO3, lead zirconate titanate (PZT), and lead titanate have been widely developed for their piezoelectric properties. In fact, PZT and its varied compositions with different dopants are now widely used in most of the commercial piezoelectric applications.
Compositional-driven multiferroic and magnetoelectric properties of NdFeO3-PbTiO3 solid solutions
Published in Journal of Asian Ceramic Societies, 2021
Sunil Kumar, Kanika Aggarwal, Jaswinder Pal, Shubhpreet Kaur, Mehak Arora, Parambir Singh Malhi, P. D. Babu, Mandeep Singh, Anupinder Singh
Lead titanate (PT) is well-known ferroelectric material having a highly distorted perovskite structure (c/a ~ 1.064). The ferroelectric transition temperature of PbTiO3 is ~760 K making it the most important parent compound for the synthesis of mixed perovskite materials [17,18]. It has been reported that magnetic character can be introduced in purely ferroelectric materials by substitution of the magnetic ion at B-site [19]. However, the substitution of transition metals (Fe) at the Ti site is also known to enhance the leakage current which generally deteriorates the ferroelectric properties of even strongly ferroelectric materials [20]. The issue of the leakage current can be resolved by carrying out simultaneous lanthanide substitution at A-site [21,22]. Multiferrocity can hence be introduced with PT by combing it with Neodymium ferrite (NdFeO3) (an orthoferrite) where Fe3+ will impart magnetic character to the material and Nd3+ will keep leakage current in check. Neodymium ferrite has an orthorhombic crystal structure with antiferromagnetic ordering, TN ̴ 760 K [23,24]. We recently reported the multiferroic properties of (NdFeO3)0.2-(PbTiO3)0.8 binary solid solutions [25]. Peng et al. reported the structural, ferroelectric, and magnetic properties of (1-x)PbTiO3-xNdFeO3 solid solutions. They reported that solid solutions undergo a structural phase transition from tetragonal to pseudocubic from x = 0.3–0.5. A simultaneous decrease in the remnant polarization (Pr) from 2.74 to 0.78 μC/cm2 as x increases from 0.2 to 0.3 is also reported by them [18]. However, a sudden decrease of Pr from 2.74 to 0.78 μC/cm2 as x varies from 0.2 to 0.3 has to be related to either a structural transition or a decrease in grain size but they are reporting the structural transformation between x = 0.3–0.5. This makes it critical to investigate the (1-x)PbTiO3-xNdFeO3 system for x varying between 0.21 and 0.30.