MODES OF VIBRATION FOR PIEZOELECTRIC ELEMENTS

table 1-8

table1-82

SYMBOL	DEFINITION	UNITS
ε 33 T , ε 11 T	Free Relative Dielectric Constant
ε 33 S , ε 11 S	Clamping Relative Dielectric Constant
tgδ	Dissipation Factor at Low Field
ρ	Density	g/cm 3
T c	Curie Point	ºC
V	Velocity	m/s
Z a	Accoustic Impedance	Mrayl
K p, K 33, K t, K 31, K 15	Electromechanical Coupling Factors
N p , N 33, N 31, N 15, N t, N c	Frequency Constants	Hz - m
d 33, d 31, d 15	Piezoelectric Strain Constants	10 -12 C/N
d h	Hydrostatic Piezoelectric Strain Constants	10 -3 Vm/N
Q pm	Mechanical Quality Factor at Planar mode
Y 11 E , Y 33 E	Young's Modulus under Short Circuit	10 10 N/m 2
σ	Poisson Ratio
ε 33 T (% Per Decade)	Aging Rate of Free Relative Dielectric Constant
K p (% Per Decade)	Aging Rate of Planar Electromechanical Coupling Factor
K t (% Per Decade)	Aging Rate of Coupling Factor at Thickness mode
N p (% Per Decade)	Aging Rate of Frequency Constant of Planar Mode
N t (% Per Decade)	Aging Rate of Frequency Constant at Thickness Mode
ε 33 T ( / o C)	Thermal Stability of Free Relative Dielectric Constant
GLOSSARY
BT	Barium Titanate
Hard PZT	Hard Lead Titanate Zirconate Compound
Soft PZT	Soft Lead Titanate Zirconate Compound