Piezoelectric Characteristics of 0.55Pb(Ni1/3Nb2/3)O3-0.45Pb(Zr,Ti)O3 Ceramics with Different MnO2 Concentrations for Ultrasound Transducer Applications
Abstract:In this study, we investigate the piezoelectric characteristics of 0.55Pb(Ni1/3Nb2/3)O3-0.45Pb(Zr,Ti)O3 (PNN-PZT) with MnO2 additive (0, 0.25, 0.5, 1, 2, and 3 mol%). We focus on the fabrication of a piezoelectric ceramic for use as both actuator and sensor for ultrasound transducers. The actuator and sensor properties of a piezoelectric ceramic depend on the piezoelectric strain coefficient d and piezoelectric voltage coefficient g, related as g = d/εT. To increase g, the dielectric constant εT must be decrea… Show more
“…The samples were polarized by applying a direct current electric field of 2.5 kV/mm for 30 min at 120°C in silicon oil. 19,20 The photo of the PZTNMML ceramic disc is shown in Figure 2.Figure 2.Photo of PZTNMML ceramic disc.…”
Section: Piezoelectric Flexible Line Sensormentioning
Blades play a critical role in the wind turbine system. Therefore, their structural health monitoring is very important. Blades are damaged by sudden changes in wind load, cracks due to collision of foreign objects, and disasters, such as lightning strikes, hail, and typhoons. Moreover, blades are expensive to maintain. Defects or damages to wind turbine blades reduce the life span and power generation efficiency of the wind turbine and increase safety risks and maintenance costs. Therefore, it is very important to detect blade damage to prevent problems in the wind turbine. Ultrasonic inspection is suitable for blades made of composite materials. Piezoelectric ceramic, which is a typical piezoelectric element, has relatively high sensitivity compared to other sensors. However, it suffers from brittle fractures and thus difficult to apply to curved structures. To overcome the limitations of piezoelectric ceramics, a piezoelectric flexible line sensor that can be applied to curved surfaces was manufactured using the dice-and-fill method for a [Pb(Li0.25Nb0.75)]0.06 [Pb(Mg0.33Nb0.67)]0.06 [Pb(Zr0.50Ti0.50)]0.88O3 with 0.7 wt% MnO2 (PZTNMML) ceramic disc. Instead of a typical ultrasonic inspection method with limited surface contact, a laser capable of producing ultrasonic excitation of ultrasonic waves over a large area from a long distance was used. The possibility of detecting a defect on the wind turbine blade using a piezoelectric flexible line sensor and laser ultrasound was confirmed in this study.
“…The samples were polarized by applying a direct current electric field of 2.5 kV/mm for 30 min at 120°C in silicon oil. 19,20 The photo of the PZTNMML ceramic disc is shown in Figure 2.Figure 2.Photo of PZTNMML ceramic disc.…”
Section: Piezoelectric Flexible Line Sensormentioning
Blades play a critical role in the wind turbine system. Therefore, their structural health monitoring is very important. Blades are damaged by sudden changes in wind load, cracks due to collision of foreign objects, and disasters, such as lightning strikes, hail, and typhoons. Moreover, blades are expensive to maintain. Defects or damages to wind turbine blades reduce the life span and power generation efficiency of the wind turbine and increase safety risks and maintenance costs. Therefore, it is very important to detect blade damage to prevent problems in the wind turbine. Ultrasonic inspection is suitable for blades made of composite materials. Piezoelectric ceramic, which is a typical piezoelectric element, has relatively high sensitivity compared to other sensors. However, it suffers from brittle fractures and thus difficult to apply to curved structures. To overcome the limitations of piezoelectric ceramics, a piezoelectric flexible line sensor that can be applied to curved surfaces was manufactured using the dice-and-fill method for a [Pb(Li0.25Nb0.75)]0.06 [Pb(Mg0.33Nb0.67)]0.06 [Pb(Zr0.50Ti0.50)]0.88O3 with 0.7 wt% MnO2 (PZTNMML) ceramic disc. Instead of a typical ultrasonic inspection method with limited surface contact, a laser capable of producing ultrasonic excitation of ultrasonic waves over a large area from a long distance was used. The possibility of detecting a defect on the wind turbine blade using a piezoelectric flexible line sensor and laser ultrasound was confirmed in this study.
“…Kang et al investigated 0.55Pb(Ni 1/3 Nb 2/3 )O 3 –0.45Pb(Zr,Ti)O 3 (0.55PNN–0.45PZT) ceramic with MnO 2 additive. [ 5 ] The mechanical properties of ceramics were improved, and Q m and Young's modulus increased with the MnO 2 content ( Q m from 42.70 to 139.70 and from 7.14 to 9.56 × 10 10 N m −2 ). Dielectric loss (tanδ) of ceramics decreased from 5.6% to 1.6%, showing great electric insulation.…”
0.35Pb(NixNb1−x)O3–0.65Pb(Zr0.39Ti0.61)O3 (x = 1/4,1/3,1/2 and 2/3) ceramics are prepared by the conventional solid reaction method and their structure, dielectric, and ferroelectric properties are studied. All compositions show tetragonal perovskite structure and Ni2+ segregated at grain boundaries in ceramics with high Ni/Nb (x = 1/2,2/3). Oxygen vacancies exist in nonstoichiometric ceramics and increase with the increase in Ni/Nb. Due to the pinning effect of defects, the P–E loops become unsaturated, accompanied by a softening–hardening transition. Dielectric relaxation is detected in both PNN–PZT(x = 1/2) and PNN–PZT(x = 2/3), and the activation energies of relaxation and conduction are calculated by Arrhenius law. The results show that both grain and grain boundary contribute to dielectric relaxation which can be explained on the basis of equivalent circuit containing two parallel RC elements connected in series. The relaxation at low frequency is induced by dipoles concentrating on the grain boundary while the relaxation at high frequency is attributed to the first ionization of oxygen vacancies in the grain.
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