Effect of Cd on The Piezoelectric Properties of Modified Lead Titanate Ceramics

• Main Authors: C.I Lin, 林傳義
• Other Authors: L. Wu
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/54862430890937675019

碩士 === 國立成功大學 === 電機工程研究所 === 81 === In 1880,Pierre and Jacques Curie found the direct and converse piezoelectric effect. In half of century, Langevin use quartz having the effect of piezoelectricity in the application of under- water acoustics. although this effect of quartz is not very strong.the resonant curve of quartz is very sharp,and stable in temperature.Today Quartz is still in the application of frequency control. One of the most important problems for ultra- sonic transducers applied in underwater acoustics, ultrasonic diagnostic imaging, and NDT technicque is to increase the piezoelectric anisotropy(kt/kp) In the past few years,PZT was the only ceramics be- ing used for high frequency array transducers.How- ever, this material has not only a high thickness coupling factor (kt=0.50) but also a coupling fac- tor for the planar mode of the same order. There- fore, the piezoelectric anisotropy is low and the image resolution is not good. For the best response when thickness and pla- nar modes are decoupled,i.e.,the ratios of kt/kp is as high as possible. The composition (Pbp.76-x Ca0.24Cdx)((Co0.5W0.5)0.04Ti0.96)O3+ 1wt% MnO was prepared by conventional ceramics processes.In this thesis,the fundamental object is to investigate the effects of CdO additives on the piezoelectric and dielectric properties of Ca-modified lead titanate ceramics.Dense ceramic bodies were achieved by add- ing 1 mole% CdO,and great doping amounts produced a considerable grain growth and porosity decreasing The electromechanical behavior of the ceramics as a function of CdO concentration was studied,kt is maximal (kt=0.52) and the piezoelectric anisotropy (kt/kp) exceeds 12 for 1 mole% CdO doping.Neverthe- less,kp is minimal at the same doping amounts (kp=0.0424).