Caifeng Chen

Fabrication of Flexible Piezoelectric PZT/Fabric Composite

Flexible piezoelectric PZT/fabric composite material is pliable and tough in nature which is in a lack of traditional PZT patches. It has great application prospect in improving the sensitivity of sensor/actuator made by piezoelectric materials especially when they are used for curved surfaces or complicated conditions. In this paper, glass fiber cloth was adopted as carrier to grow PZT piezoelectric crystal particles by hydrothermal method, and the optimum conditions were studied. The results showed that the soft glass fiber cloth was an ideal kind of carrier. A large number of cubic-shaped PZT nanocrystallines grew firmly in the carrier with a dense and uniform distribution. The best hydrothermal condition was found to be pH 13, reaction time 24 h, and reaction temperature 200°C.

Preparation and piezoelectric properties of textured PZT ceramics using PZT nano fibers

PZT nano piezoelectric fibers were prepared by hydrothermal-template method. The effects of some reaction conditions on preparation were investigated, such as PH value, reaction temperature and time. The optimal hydrothermal conditions for preparing PZT nano fibers are that pH value is 13, reaction temperature is 190 °C, hydrothermal reactor filling degree is 60 %–70 %, reaction time is 10h, and the activated carbon is as the template. Based on the observation from scanning electron microscopy (SEM) show that the diameter of PZT fibers is around 100nm with the length up to a few microns, and the fibers are arranged orderly in one direction. PZT ceramics made of the fibers was obtained through pressing carefully the fibers along a direction as possible, then sintering at the temperature of 1050 °C for 1.5 hour. The textured PZT ceramic microstructure was analyzed using X-ray diffraction (XRD) techniques. The piezoelectric properties were determined by impedance analyzer. The results indicated that the PZT ceramic had a high value of kt/kp (1.8567) compared with the conventional PZT ceramic made of milled PZT powder. It means that the novel textured PZT ceramic shows very good anisotropic property and has potential application as a sensor or device with high direction sensitivity.

Dielectric and piezoelectric properties of lead-free (Na 0.5 Bi 0.5 )TiO 3 -(K 0.5 Bi 0.5 )TiO 3 -(Li 0.5 Bi 0.5 )TiO 3 ceramics with Ba2 + and Ca2 + doped

In this work, (0.935-x)Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>-0.05(Bi<inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf>-0.015(Bi<inf>0.5</inf>Li0.5)TiO<inf>3</inf>-x(Ba<inf>1−y</inf>Ca<inf>y</inf>)TiO<inf>3</inf>(BNKLT-BCT) system by keeping the KBT and LBT ratio constant is investigated. The primary purpose of this study is to deal with the effects of barium calcium titanate (BCT) additive on dielectric and piezoelectric properties of BNKLT-BCT ceramics. In the paper, BNKLT-BCT ceramics were fabricated by conventional solid state reaction. XRD results show that the crystalline structure of the ceramics is perovskite. At the same time, a significant change of the dielectric behavior and piezoelectric properties takes place with increasing the content of barium calcium titanate. The ceramics show a rhombohedral-tetragonal morphotropic phase boundary (MPB) in the range of x = 0.05, y=0∼0.04, which results in ceramics providing superior dielectric and piezoelectric properties. The values of piezoelectric constant d<inf>33</inf>, dielectric constant ε<inf>r</inf>, and mechanical quality factor Q<inf>m</inf> of BNKLT-BCT ceramics are higher than that of BNKLT ceramics while the dielectric loss factor tanδ is lower. It is found that a small amount of barium calcium titanate additive was of great help in providing higher dielectric constant ε<inf>r</inf>, and piezoelectric constant d<inf>33</inf>.

Effect of preparation method on properties of BNT-BKT-BT piezoelectric ceramics

0.852Bi<inf>0.5</inf>Na<inf>0.5</inf>TiO<inf>3</inf>-0.120Bi<inf>0.5</inf>K<inf>0.5</inf>TiO<inf>3</inf>-0.028BaTiO<inf>3</inf>(BNT-BKT-BT) ceramics prepared by solid state reaction and hydrothermal method is investigated in this paper. The study is aimed at finding out the effects of different preparation methods on dielectric and piezoelecrtic properties of BNT-BKT-BT ceramics. BNT-BKT-BT ceramics were fabricated by conventional solid state reaction and hydrothermal method. XRD results show that a pure perovskite without a secondary phase is structured, while the diffraction intensity of the powder by solid state reaction is higher than that of the powder by hydrothermal method. At the same time, SEM shows a significant difference of surface topography between the ceramics comes up with different preparation methods, which also takes place in dielectric and piezoelectric properties of the ceramics. The values of piezoelectric constant d<inf>33</inf>, dielectric constant ε<inf>r</inf>, mechanical quality factor Q<inf>m</inf>, and electromechanical planar coupling coefficients k<inf>p</inf> of BNT-BKT-BT ceramics by solid state reaction are higher than that of ceramics by hydrothermal method while the dielectric loss factor tanδ and thick electromechanical coupling factor k<inf>t</inf> is lower. The experimental results reveal that the preparation method is of great help in taking effect on dielectric constant ε<inf>r</inf>, and piezoelectric constant d<inf>33</inf>.

Fabrication of 1-3 piezo-composites using new micro PZT fibers

This paper presents a novel fabrication method of PZT micro-fibers using activated carbon template with the aim of manufacturing PZT/epoxy 1-3 composites. Porous carbon was first prepared by chemical activation technology. The pore diameter formed in an activated carbon template is of several microns and lengths are up to several millimeters. These pores provide a basic platform to grow PZT fibers inside. Then the carbon template is removed at high calcination temperatures to form PZT micro-fibers. Subsequently, thermo-gravimetric analysis (TG) and differential scanning calorimetry (DSC) were performed to analyze the process of removing the template as temperature changing. For manufacturing 1-3 piezo-composites, the PZT fibers were carefully aligned in one direction and infiltrated by epoxy resin. Based on the observation from X-ray diffraction (XRD) the fibers show a pure pervoskite phase at low sintering temperature of 950°C. The fibers embedded orderly in the epoxy matrix are smoothly distributed and straightened which were observed using a scanning electron microscopy (SEM). The diameter of fibers is around several microns with the length up to a few millimeters, matching well with pores in the template. The new micro-fiber composite material can be potentially used in a sensor with high directivity in structural health monitoring.

Fabication and piezoelectric property characterization of a novel Mico/Nano PZT epoxy 1–3 composite

Piezoelectric composites show high promise as components in ultrasonic transducers for higher resolution medical imaging, and structural health monitoring systems as they have excellent piezoelectric properties, such as high piezoelectric coefficients, high electromechanical coupling coefficients, and high dielectric constant. A novel Mico/Nano PZT epoxy 1–3 composite was fabricated in this work. Carbon template with porous and structurally-ordered pattern was prepared firstly by chemical activation technology. Mico/Nano PZT fibers were fabricated by the carbon template method. In addition, Mico/Nano PZT epoxy 1–3 composites had been prepared by arranging Mico/Nano PZT fibers and casting epoxy resin. The fiber samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The impedance-frequency of PZT/epoxy 1–3 composites were directly measured using an HP impedance analyzer. Effective electromechanical coupling of PZT/epoxy 1–3 composites were measured and calculated using a standard IEEE technique. The initial results show that the piezoelectric epoxy 1–3 composite has good piezoelectric properties and diameter of PZT fiber is only about ten microns, the length up to several millimeters. In addition, PZT fibers are smooth, straight and have the crystal structure of perovxkite type. The fabricated PZT/epoxy micro/nano composite has strong piezoelectric properties.

Fabrication and properties of PZT and PMN-PT piezoelectric fibers and piezoelectric fiber composites

PZT powder is synthesized by solid reaction and PMN—PT is synthesized by columbite method. PZT and PMN—PT piezoelectric fibers are prepared by sol-powder mixture extrusion. 1–3 piezoelectric fiber composites are fabricated by arraying-casting technique. The influence of fiber composition on dielectric properties and piezoelectric properties are studied. The results show that the values of k t and k t /k p of 1–3 composite are higher than ceramic bulks, the values of Q m , k p , d 33 and eT of 1–3 composite are lower than ceramic bulks. It is also indicated that the variation law of composite properties is the same as ceramic bulk properties. Both the piezoelectric constant d 33 and the rate k t /k p of PMN—PT PFC are higher than that of PZT PFC‥

Preparation of piezoelectric fiber composites by method of carbon templet

PZT fibrous material has many important applications in sensors, actuators and transducers. In this paper, piezoelectric fibers had been fabricated by carbon template method using lead acetate trihydrate, zirconium nitrate pentahydrate , titanium butoxide as raw materials, and glycol monomethyl ether as the organic solvent. In addition, 1–3 piezoelectric composite had been prepared by arranging PZT fibers and casting epoxy resin. The fiber and its composite samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results showed that PZT fibers with the diameter of a few microns had been obtained by carbon template method within right ingredient and water. The fibers were straight and sleek, and had the crystal structure of perovskite type after sintered at the temperature of 850°C for 30 min. The piezoelectric fiber composites with order structure had also been made out.

Fabrication of PZT fibers by active carbon micro-reactor method

PZT fibers have many important using in sensors, actuators and transducers. PZT fibers have been successfully fabricated by much technology, such as Sol-Gel method, extrusion method and so on, but for the micro-reactor method very little study work has been done. Porous, structurally-ordered active carbon was used in this work. Due to a high rate of pore with microns diameter, millimeters length, run-through, and easy to remove at high temperature of active carbon, the pore was regarded as a field of localized reaction. Chemical reaction was limited in a small pore. The fabrication of PZT (Pb(Zr0.53Ti0.47)) fibers using these pores was studied, and the method was called active carbon micro-reactor method. The fiber samples were characterized by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results shown that PZT fibers with the diameter about a few microns, the length up to several millimeters had been obtained, and PZT fibers was smooth, straight and high pure. The PZT fiber had the crystal structure of perovskite type after calcination and sintering at the temperature of 1000square for 1 hour.