超音波加湿器.ppt

Piezoelectric Ceramics
Dr. & Prof. Chun-Huy Wang
Electronic Engineering
Nan-Jeon Institute of Technology
Tainan, Taiwan
OUTLINE
Introduction
Electronic Ceramics
Piezoelectricity
Piezoelectric Ceramics
Fabrication Process of Piezoelectric Ceramics
Piezoelectric Ceramics: Applications
<Electronic Ceramics >
Ferroelectric
Pyroelectric
Piezoelectric
Dielectric
Dielectric Property
Piezoelectricity
Pyroelectricity
Ferroelectricity
Piezoelectricity
Mechanical and electrical energy conversion phenomena, discovered by France Scientist Pierre and Jacques Curie brother in 1880.
Direct Piezoelectric Effect
Mechanical Electrical
Converse Piezoelectric Effect
Piezoelectric Ceramics
The famous one is the lead zirconium titanium, Pb(Zr,Ti)O3 [abbrev. as PZT].
PZT was first reported as ferroelectric materials in 1950 by Shirane et al., and reported as a useful piezoelectric materials by Jaffe et al. in 1954.
Below the Curie temperature, PZT ceramics is ferroelectrics with piezoelectricity, and it was paraelectrics without piezoelectricity at the temperature higher than Curie Temperature.
Piezoelectric Ceramics
The crystal structure of most traditional piezoelectric ceramics are pervoskite structure, with the chemical formula as ABO3.
A is a larger divalent metal ions, usually lead(Pb) or barium(Ba). Located at the corner of the cubic.
B is a smaller trivalent metal ions, usually titanium(Ti) or zirconium(Zr). Located at the center of the cubic.
O is oxygen ion. Located at the center of the faces.
Piezoelectric Ceramics
(perovskite)結構,化學式為
Pervoskite structure, with the chemical formula as ABO3 . : BaTiO3
cornal
center
face
center
Piezoelectric Ceramics
Piezoelectric Ceramics
For a three-dimensional unit cell, there are six possible directions to displace the central positive ion towards the face centered negative ions.
 Therefore, there are six different choices for spontaneous polarization in the ferroelectric phase,
Piezoelectric Ceram