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2024-10-20 06:55:50
The
piezoelectric
effect
as
early
as
discovered
in
1880,
by
no
meansbrings
to
people's
attention
at
first
in
during
several
dozens
years,the
First
World
War
period,
because
surveys
technical
the
and
so
onnaval
vessel
and
sunken
wreck
demand,
western
some
countries
havelaunched
some
research
to
the
piezoelectric
crystal
practicaltechnology,
but
has
not
still
obtained
the
widespread
applicationuntil
the
20th
century
30's,
after
two
world
wars,
the
newpiezoelectricity
ceramic
material
developed
successfully
only
thencauses
the
piezoelectricity
ceramics
the
application
to
open
the
newpage,
has
obtained
the
universal
application
to
the
present.
We
maysee:
Any
physical
effect
from
discovered
all
must
experience
a
quitelong
time
to
the
application
The
new
material
appearance
is
thephysical
effect
can
the
widespread
application
foundation,
each
kindof
new
technical
demand
is
the
physical
effect
can
the
applicationpromoter.
By
physics
knowledge,
some
ion
crystals
dielectric
media
(for
examplequartz,
potassium
tartrate
sodium,
barium
titanate
and
so
on)
not
onlyunder
electrical
field
intensity
function,
moreover
under
themechanical
power
function,
can
have
the
phenomenon
of
polarization.Namely:
Exerts
when
in
these
dielectric
media
certain
directions
themechanical
power
has
the
distortion,
can
cause
its
interior
positiveand
negative
electric
charge
center
relative
shift
to
have
theelectricity
polarization,
thus
causes
its
two
relative
surfaces(极化面)
on
to
appear
the
mark
opposite
bound
charge,
also
itselectric
displacement
D
(in
MKS
单位制
center
is
electric-chargedensity
sigma)
has
the
direct
ratio
with
external
stress
tensor
T;When
the
external
force
vanishes,
also
restores
not
the
chargedoriginal
condition;
When
the
external
force
changes
to,
the
electriccharge
polarity
changes
along
with
it.
This
kind
of
phenomenon
iscalled
the
piezoelectric
effect,
or
abbreviation
piezoelectric
effect.
If
exerts
the
pressure
to
the
piezoelectricity
material,
it
then
canhave
the
potential
difference
(to
call
it
piezoelectric
effect),otherwise
exerts
the
voltage,
then
has
the
mechanical
stress
(to
becalled
counter
piezoelectric
effect).
If
the
pressure
is
one
kind
ofhigh
frequency
vibration,
then
produces
is
the
high-frequency
current.But
the
high
frequency
electrical
signal
adds
when
thepiezoelectricity
ceramics,
then
produces
the
high
frequency
soundsignal
(machinery
to
vibrate),
this
is
the
ultrasonic
wave
signalwhich
we
usually
said.
In
other
words,
the
piezoelectricity
ceramicshave
between
the
mechanical
energy
and
the
electrical
energytransformation
and
the
counter
transformation
function
experimentproved
that,
every
has
the
piezoelectric
effect
the
crystal,
alsocertainly
has
the
counter
piezoelectric
effect.
Now
the
piezoelectric
effect
also
applies
on
the
polycrystal,
forinstance
the
present
piezoelectricity
ceramics,
including
the
bariumtitanate
piezoelectricity
ceramics,
PZT,
the
niobate
are
thepiezoelectricity
ceramics,
niobium
magnesium
sour
leadpiezoelectricity
ceramics
and
so
on.
When
you
when
light
the
coal
gasstove
or
the
water
heater,
had
one
piezoelectricity
ceramics
quietlyto
serve
for
you.
Produces
the
factory
in
this
kind
ofpiezoelectricity
firing
device,
is
hiding
together
thepiezoelectricity
ceramics,
when
the
user
presses
down
the
firingdevice
the
spring,
the
transmission
device
on
exerts
the
pressure
onthe
piezoelectricity
ceramics,
causes
it
to
produce
the
very
highvoltage,
then
courses
the
electrical
energy
the
fuel
gas
theexportation
electric
discharge,
thereupon,
the
fuel
gas
on
was
lit
bythe
electric
spark
Crystal
crystal
when
not
stress,
its
positive
charge
center
and
thenegative
charge
center
superposition,
the
entire
crystal
totalelectricity
is
rectangular
is
zero,
the
crystal
plane
not
charged,when
crystal
stress,
causes
the
positive
and
negative
electric
chargecenter
as
a
result
of
the
deformation
no
longer
to
superpose,
crystalbeginnings
and
ends
surface
charged,
this
kind
of
positive
andnegative
electric
charge
center
does
not
superpose
the
phenomenon
iscalled
the
polarization
Also
has
the
minority
piezoelectric
crystalas
a
result
of
itself
interior
special
structure,
in
outside
in
theelectric
field
situation
has
not
had
the
phenomenon
of
polarization,such
polarization
for
spontaneous
polarization
This
kind
hasspontaneous
polarized
in
the
crystal
to
have
some
spontaneouspolarized
orientation
consistent
small
regions,
is
called
电畴After
it
is
put
in
the
electric
field,
the
original
stochastic
chaoticorientation
电畴
can
along
the
electric
field
direction
orientation,if
electric
field
again
reverse,
spontaneously
polarizes
the
unit
alsoto
be
able
with
to
be
reverse,
its
polarized
and
the
electric
fieldrelations
are
a
return
wire,
calls
it
the
dielectric
hysteresis
returnwire,
with
ferromagnet
hysteresis
loop
shape
similar,
therefore
thepeople
类晶体
are
called
this
the
ferroelectricity
body
(actuallyin
crystal
certainly
not
to
include
iron),
this
return
wire
is
theferroelectricity
body
symbol
Obviously,
the
ferroelectricity
body
isin
the
piezoelectricity
body
one
kind.
In
the
nature
has
the
piezoelectric
effect
the
piezoelectric
crystalto
be
very
many,
but
often
will
become
the
ceramic
material
later
notto
present
the
piezoelectricity
performance,
this
mainly
will
bebecause
the
ceramics
will
be
one
kind
of
polycrystal,
as
a
result
ofeach
tiny
crystal
grain
disorder
orientation,
thus
each
intergranularpiezoelectric
effect
will
be
able
mutually
to
counterbalance,macroscopic
will
not
present
the
piezoelectric
effect.
In
theferroelectric
ceramics
although
has
the
spontaneous
polarization,
buteach
intergranular
spontaneous
polarization
direction
is
disorderlytherefore
macroscopic
无极
nature.
If
passes
through
in
advance
theferroelectric
ceramics
the
strong
direct-current
field
function,causes
various
crystal
grains
the
spontaneous
polarization
directionall
according
to
qualification
orientation
to
become
has
the
rule
thearrangement
(this
process
to
be
called
artificial
polarization),
after当直
flows
the
electric
field
to
remove,
in
the
ceramics
still
couldretain
the
suitable
surplus
polarization
intensity,
then
the
ceramicmaterial
macroscopic
had
the
polarity,
also
had
the
piezoelectricityperformance.
Therefore,
the
ferroelectric
ceramics
only
have
process"
Polarizes
"
Processing,
the
ability
has
thepiezoelectricity.
The
piezoelectricity
ceramics
generally
are
theferroelectricity
body,
only
has
the
ferroelectric
ceramics
to
be
ableunder
the
outfield
function,
causes
the
spontaneous
polarized
unitmovement
to
change,
achieves
"
Polarizes
"
The
goal,
becomesthe
piezoelectricity
ceramics,
thus
is
called
this
kind
of
ceramicsthe
ferroelectricity,
the
piezoelectricity
ceramics.