Inspection of interfaces between corroded steel bars and concrete using the combination of a piezoelectric zirconate-titanate transducer and an electromagnetic acoustic transducer

We have conducted an inspection of the interface between a steel bar and concrete using the combination of a piezoelectric zirconate-titanate transducer (PZT) and an electromagnetic acoustic transducer (EMAT). The PZT is used for generating elastic waves by mechanical vibration and then the EMAT is used for receiving the transmitted ultrasonic guided waves. This arrangement is made in order to overcome the major shortcomings of the PZT, i.e., the requirement of a couplant, and of the EMAT, i.e., relatively low transmitted ultrasonic energy. To investigate the applicability of this technique in the field, outside the laboratory environment, the experiments are conducted on different types of steel bars: corrosion-free, naturally corroded, and zinc-coated as well as corroded bars. It is shown that the PZT-EMAT combination is very effective for inspecting the steel bar-concrete interface. Using this technique, small separation at the steel bar-concrete interface can be effectively detected for corroded as well as corrosion-free specimens. This method can be applied in the field to pre-stressed tendons and soil nails, where one side of the reinforcement is exposed.     

Effect of excess Pb on crystallinity and ferroelectric properties of PZT(40/60) films on LaNiO3 coated Si substrates by MOD technique

Pb(Zr_0.4Ti_0.6)O₃ [PZT(40/60)] films were deposited onto LaNiO₃ (LNO) coated Si substrates by metal-organic decomposition (MOD) technique. Excess Pb was incorporated in the film by using excess Pb (2%–15%) in the solution. The crystallinity and ferroelectric properties of PZT films were investigated by using X-ray diffraction (XRD), RT66A test system and HP4194 impedance analyzer, respectively. Rayleigh law was employed to analyze the defect concentration in the films. The results show that all the PZT films show the (1 0 0) preferential orientation with complete perovskite structure except for the 2% film displaying some pyrochlore phase. The (1 0 0) preferential orientation is mainly attributed to LNO bottom electrode, which has the highly (1 0 0) preferential orientation. The 10% film shows the best polarization and dielectric properties. The remnant polarization and coercive field are about 10.1 μC/cm² and 73 kV/cm under an electric field around 330 kV/cm, respectively. And the dielectric constant and dissipation factor are about 656 and 0.022 at a frequency of 1 kHz, respectively. The good ferroelectric properties of the 10% film are mainly attributed to the low defect concentration in the film.     

以有效值计算的热声键合PZT换能器阻抗分析

在热超声芯片键合过程中,PZT换能器阻抗是键合系统的一个重要的研究参数。本文在提取PZT换能器驱动电信号实部数据的前提下,采用连续加窗的有效统计值计算的广义阻抗表征整个键合周期内的PZT换能器阻抗变化,由此获得键合过程PZT换能器阻抗的动态变化规律。文中详细介绍了PZT换能器阻抗的试验方法,并分析了试验结果。     

Fabrication of the hydrogen resistive ferroelectric film of the (Pb0.72La0.28)Ti0.93O3/Pb(Zr0.52Ti0.48)O3/(Pb0.72La0.28)Ti0.93O3 heterostructure by a pulsed laser deposition method

(Pb_0.72La_0.28)Ti_0.93O₃ (PLT)/Pb(Zr_0.52Ti_0.48)O₃ (PZT)/PLT heterostructure was fabricated by using a pulsed laser deposition method. After depositing this structure, the hydrogen annealing process was performed in the forming gas (95% N₂ + 5% H₂) at a substrate temperature of 400 °C for 30 min to study the effects of hydrogen passivation.The heterostructure was not degraded by the hydrogen annealing in contrast with the case of PZT film without buffer layers. This heterostructure showed almost no degradation in terms of the remanent polarization even after the H₂ annealing, while the PZT film exhibited 64% reduction, which is from 20.1 to 7.3 μC/cm² after the annealing. The leakage current was decreased by an order in the case of the heterostructure, while the leakage current of the PZT film increased by an order.These can be explained that the PLT bottom buffer layer works as a seeing layer to help the PZT growth and the top PLT buffer layer acts as a barrier for penetrating hydrogen atoms.     

压电晶体位移特性曲线干涉自动测量方法

本文提出了压电晶体(PZT)位移物曲线自动干涉测量方法,该方法利用干涉仪把PZT的微位移量转化成干涉条纹相位变化量,通过快速傅里叶变换(FFT)方法自动复原干涉条纹中包含的相位的变化量,从而高精度地检测出PZT的位移特性曲线.根据该方法,利用CCD摄象机、图象板和干涉仪组合成一套光、机、电一体化的微位移自动测试系统,实际测量了我们研制的PZT随电压变化的位移特性曲线.实验表明,该方法原理实现简单,且能实现高精度、自动、实时和动态测量.     

Determination of piezoelectric coefficients of ferroelectric thin films using GaAs:Cr adaptive interferometer

We report on simple interferometric technique for the measurement of piezoelectric coefficients of thin films using GaAs:Cr adaptive photodetectors in the geometry of modified Mach–Zehnder interferometer. The technique needs no special vibroinsulation and automatically adjusts and keeps the operation point of the interferometer. Strong hysteresis effects with a slightly asymmetric form of the hysteresis loop were observed at the dependence of d₃₃ coefficients of the Pb(Zr,Ti)O₃ (PZT) thin film versus DC electric field. The obtained values of d₃₃ coefficients are in agreement with known data.     

Sol-Gel Synthesis of Nanocrystalline PZT Using a Novel System

A simple system has been developed for the preparation of lead zirconate titanate, Pb(Zr _x Ti_{1 – x} )O₃ powders by sol-gel process. To achieve stable and homogeneous precursor solutions, chelating ligands such as acetic acid and acetylacetone have been used for the chemical modification of titanium and zirconium starting precursors. Phase-pure PZT powders were obtained, through a pyrochlore-free pathway, from the amorphous xerogel after heat treatment at 600°C. The formation of the crystalline phase, compositional homogeneity, sinterability, dielectric and piezoelectric characteristics of PZT are reported.     

Powderless processing of ceramics: Thin-layer electroceramics

A review is made of progress on the sol-gel processing of dense insulating electroceramics by polymeric condensation routes. Up until the past ten years, powders and porous coatings were principally made for optical and conductive applications. Much effort was expended on silica (SiO₂) and silicate-based systems. Recently, these approaches have been extended to non-silicate systems [1]. In this paper information is presented for the powderless processing of selected electroceramics in thin-layer form. Materials include PbTiO₃, BaTiO₃, Ba_1–x Pb _x TiO₃, PbZrO₃, Pb(Zr_1–y Ti _y )O₃ and (Pb_1–x La _x )(Zr_1–y Ti _y )O₃ which find applications in ceramic capacitors, piezoelectric transducers and electrooptic modulators. The approach is to avoid powders, and the attendent problems of powder handling, flow, packing, etc., and make use of polymerization condensation reactions to form extended networks with chemical linkage. Data are reported for the synthesis and low temperature processing routes for amorphous and polycrystalline ceramics.     

Lead Zirconate-Titanate Films Prepared from Soluble Powders

Precursor powders for Pb(Zr1 – xTix) O3 (PZT) thin films were produced by the reaction of zirconium-and titanium-n-propoxides with acetylacetone and lead acetate trihydrate. The subsequent complete removal of volatile components yielded powders that can be handled in air. The powders are indefinitely stable under ambient conditions.High molarity (>2m) coating sols were prepared by dissolution of the precursor powders in mixtures of 1,3-propanediol, triethanolamine (TEA) and water. Excess amounts of lead to compensate lead loss during firing were easily introduced into these solutions.The deposition of these sols on steel substrates and firing at 600°C yielded PZT films. Many physical parameters like film thickness, morphology and electrical performance could be influenced by choice of the solvent mixture composition and oxide content of the sols. Depending on the preparation dielectric permittivities, r of up to 840 were measured at 1 kHz. By hysteresis measurements at 50 Hz and a field amplitude of 50 V/m a remanent polarization of about 40 C/cm2 and coercivity of about 8 V/m was obtained. The films were stable against dielectric breakdown up to 70V/m.     

电极对PZT铁电薄膜的铁电和光学性能的影响

采用射频磁控溅射(RF Magnetron Sputtering)工艺在Si片上分别制备Pt/Ti和LaNiO3 (LNO)底电极,然后在不同的底电极上沉积PbZr0.52Ti0.48O3(PZT)铁电薄膜,在大气环境中对沉积的PZT薄膜进行快速热退火处理(RTA).用X射线衍射(XRD)分析PZT薄膜的相结构和结晶取向,原子力显微镜(AFM)分析薄膜的表面形貌和微结构.再沉积LNO作为顶电极制成"三明治"结构的LNO/PZT/Pt和LNO/PZT/LNO样品,用 RT66A标准铁电测试系统分析样品的电学特性,傅立叶红外光谱仪分别测得样品的反射谱和透射谱.分析了不同电极对PZT铁电薄膜的铁电和光学性能的影响.