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Dielectric constant of pressed powder materials
Journal of Electrostatics, 10 (1981) 289--292
289
Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands
DIELECTRIC
K.-J.
CONSTANT
EULER
and H.-J.
Arbeitsgruppe Kassel
OF P R E S S E D
POWDER MATERIALS
KILIAN
Technische
Physik
der G e s a m t h o c h s c h u l e
Kassel,
(G.F.R.)
ABSTRACT In our e x p e r i m e n t s Pb304
the d i e l e c t r i c
has been m e a s u r e d
pressure marked
was
200 MPa.
maxima
at room
temperature.
In the course
of the d i e l e c t r i c
have been observed,
which
could
constant
e of p r e s s e d The m a x i m a l
of our m e a s u r e m e n t s
constant
depending
be i n t e r p r e t e d
PbO and
practicable more
or less
on the p r e s s u r e
as phase
transforma-
tions.
INTRODUCTION Powder materials materials
only
possibility
During
which
effects
are
mixing
involved,
behaviour
well
as with
e.g.
The d i e l e c t r i c closely
connected
F. O e h m e m e a s u r e d materials
(refs.
constant
of powders
with
purely
covered
charges
of a s u b s t a n c e
the d i e l e c t r i c
forces,
powders.
In the
constant
As
technologies electrostatic
friction, powders
insulating
a comprehensive
factor
each other.
often
insulating
with
many
is the
precision
of p o w d e r m e t a l l u r g y
these phenomena,
with
because reason
by u s i n g
of s m a l l e s t
in a d d i t i o n a l
powders
and the loss
A second
and energy
number
by m e a n s
resulting
metallic
constant
in significance,
or c o m p a c t i n g
has been o b s e r v e d
to u n d e r s t a n d
dielectric
the great
are p r o d u c e d
This
order
raw m a t e r i a l s
we can q u o t e
transport,
gain
in the form of powders.
of saving
an e x a m p l e pieces,
increasingly
exist
etc. as
layers.
knowledge
In
of the
is i n d i s p e n s a b l e .
and its s t r u c t u r e fifties
in this
in d i f f e r e n t
are
connection
kinds
of
I-2).
RESULTS In the course constant PbO
of our first e x p e r i m e n t s
of p r e s s e d
(rhombic
red PbO p o w d e r s
structure),
0304~886/81/0000--0000/$02.50©
and Pb304 1981EI~
we m e a s u r e d
(tetragonal powders
the d i e l e c t r i c
structure),
(tetragonal
Scientific PublishmgCompany
yellow
structure)
at
290
T o = 293 cone and
K.
with
The
measuring
an o p e n i n g
a generated
press
and
F Pmax
angle
surface
reached
condenser of
T =
formed
11-4°,
of A = 25
a maximum
was
c m 2,
pressure
like
a height
see
Fig.
a truncated
of
h = 2.7
I . We
used
cm,
a
105 N
of
max
=
= 2 0 0 MPa. 2
sin
(7/2)
(I)
• A
1
71 I press tool
Fig. I. P r e s s tool. T h e c a p a c i t y h a s b e e n m e a s u r e d w i t h a S c h e r i n g b r i d g e at 1OO Hz. T h e r e e x i s t n e g l i g i b l e l o s s a n g l e s , b e c a u s e the electric conductivity o f t h e s e p o w d e r s is v e r y s m a l l ( d i m e n s i o n I O - I O / ~ cm).
As
expected,
smallest less
marked By
constant
c of
12 M H z ,
in b o t h the
using
what
the
powder room
as w e l l
as
the
13
< c < 17.
found
in o u r
c b ~ 27 of b u l k
results
are
exhibits All
method,
Oehme
has
and
experiments
PbO
the
with
we
worth
a straight
assume
a rather forward
or
transfor-
dielectric between
powders
nor
Thus,
2.
of
agreement
PbO.
in Fig.
the
the
a more
phase
in g o o d
behaviour,
given
from
found
Pb304
show
a frequency
constant
is n o t
the
powders
result
dielectric
own
greatest,
might
temperature
This
the
investigated
eventually
at
pressure-depending The
PbO
constant.
Pb304
cases
results
constant
yellow
maximum,
mations.
and
the
dielectric
O.1 (ref.
neither
3),
with
dielectric complicated investigation.
291
,°I
/
t'-
~
in co u
/
=_
/
°"o.~o~ PbO(y)
/
PbO(r)
~"~
U
Pb30&
(u
,S
L..
0
5
10 glcm 3
opparent density
Fig. 2. R e l a t i v e d i e l e c t r i c c o n s t a n t p o w d e r d e n s i t y p o f r e d PbO, y e l l o w
Our
investigations
apparent
density
approximated
log
the
(p)+
specific
These using press,
a logarithmic
4) a n d
function
the p r e s s u r e
p, w h i c h
between
the
c a n be
B
preliminary
constructed pressure
(2)
constants
a guard-ring
maximum
confirm
(ref.
by
p = A log
with
p
e as a f u n c t i o n of a p p a r e n t PbO, a n d P b 3 0 4 . S: s h o o t d e n s i t y .
results
A a n d B. will
be proved
capacitor
as p r e s s
for t h i s
particular
of Pmax
= 400 M P a
tool.
in the n e a r With
purpose,
(referring
future
the h e l p we will
by
of a 106 N
reach
to a c o n d e n s e r
a plain
o f A = 25 cm2) . With
two m u l t i - f r e q u e n c y
the d i e l e c t r i c the
range
constant,
between
investigations
100 Hz
is to g i v e
LCR meters
(Hewlett
Packard
depending
on frequency,
and about
10 MHz.
some
answers
The
to the
will
4270,
4275A),
be m e a s u r e d
a i m of t h e s e following
problems:
in
292
•
s e p a r a t i o n of the e f f e c t i v e d i e l e c t r i c c o n s t a n t core part (shell model, sponge m o d e l (ref. 5));
into
•
influence
of the surface
constant;
•
influence
of the grain
•
mixing
•
influence
rules
(forming
on the mean
dielectric
surface
and
diameter; number
after
Stoecker) ;
G. L e b e r
for helpful
of temperature.
ACKNOWLEDGEMENT We thank Mr. Further
thanks
for p r o v i d i n g stadt,
Ing. should
the
(grad.)
be given
106 N press,
for s u p p l y i n g
the
to the D a i m l e r - B e n z
discussions. AG,
D-35OO
Kassel,
and to the M e r c k - W e r k e ,
D-61OO
Darm-
lead powders.
REFERENCES I F. Oehme, C h e m i s c h e A n a l y s e n durch M e s s u n g von D i e l e k t r i z i t a e t s k o n stanten, Apolda, VEB L a b o r c h e m i e , ]953. 2 F. Oehme, Z. f. N a t u r f o r s c h g . , Ser. B, 14, ]959, p. 779. 3 Gme l i n ' s Handb. d. anorgan. Chem., Lead, part C, Ist delivery, 8th ed., Weinheim, V e r l a g Chemie, 1968, p. ]29. 4 G.A. Weissler, P h . D . Thesis, U n i v e r s i t y (Gesamthochschule) of Kassel, 1978. 5 K.-J. Euler, E l e c t r o c h i m i c a Acta, 14, ]969, p. 115.
289
Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands
DIELECTRIC
K.-J.
CONSTANT
EULER
and H.-J.
Arbeitsgruppe Kassel
OF P R E S S E D
POWDER MATERIALS
KILIAN
Technische
Physik
der G e s a m t h o c h s c h u l e
Kassel,
(G.F.R.)
ABSTRACT In our e x p e r i m e n t s Pb304
the d i e l e c t r i c
has been m e a s u r e d
pressure marked
was
200 MPa.
maxima
at room
temperature.
In the course
of the d i e l e c t r i c
have been observed,
which
could
constant
e of p r e s s e d The m a x i m a l
of our m e a s u r e m e n t s
constant
depending
be i n t e r p r e t e d
PbO and
practicable more
or less
on the p r e s s u r e
as phase
transforma-
tions.
INTRODUCTION Powder materials materials
only
possibility
During
which
effects
are
mixing
involved,
behaviour
well
as with
e.g.
The d i e l e c t r i c closely
connected
F. O e h m e m e a s u r e d materials
(refs.
constant
of powders
with
purely
covered
charges
of a s u b s t a n c e
the d i e l e c t r i c
forces,
powders.
In the
constant
As
technologies electrostatic
friction, powders
insulating
a comprehensive
factor
each other.
often
insulating
with
many
is the
precision
of p o w d e r m e t a l l u r g y
these phenomena,
with
because reason
by u s i n g
of s m a l l e s t
in a d d i t i o n a l
powders
and the loss
A second
and energy
number
by m e a n s
resulting
metallic
constant
in significance,
or c o m p a c t i n g
has been o b s e r v e d
to u n d e r s t a n d
dielectric
the great
are p r o d u c e d
This
order
raw m a t e r i a l s
we can q u o t e
transport,
gain
in the form of powders.
of saving
an e x a m p l e pieces,
increasingly
exist
etc. as
layers.
knowledge
In
of the
is i n d i s p e n s a b l e .
and its s t r u c t u r e fifties
in this
in d i f f e r e n t
are
connection
kinds
of
I-2).
RESULTS In the course constant PbO
of our first e x p e r i m e n t s
of p r e s s e d
(rhombic
red PbO p o w d e r s
structure),
0304~886/81/0000--0000/$02.50©
and Pb304 1981EI~
we m e a s u r e d
(tetragonal powders
the d i e l e c t r i c
structure),
(tetragonal
Scientific PublishmgCompany
yellow
structure)
at
290
T o = 293 cone and
K.
with
The
measuring
an o p e n i n g
a generated
press
and
F Pmax
angle
surface
reached
condenser of
T =
formed
11-4°,
of A = 25
a maximum
was
c m 2,
pressure
like
a height
see
Fig.
a truncated
of
h = 2.7
I . We
used
cm,
a
105 N
of
max
=
= 2 0 0 MPa. 2
sin
(7/2)
(I)
• A
1
71 I press tool
Fig. I. P r e s s tool. T h e c a p a c i t y h a s b e e n m e a s u r e d w i t h a S c h e r i n g b r i d g e at 1OO Hz. T h e r e e x i s t n e g l i g i b l e l o s s a n g l e s , b e c a u s e the electric conductivity o f t h e s e p o w d e r s is v e r y s m a l l ( d i m e n s i o n I O - I O / ~ cm).
As
expected,
smallest less
marked By
constant
c of
12 M H z ,
in b o t h the
using
what
the
powder room
as w e l l
as
the
13
< c < 17.
found
in o u r
c b ~ 27 of b u l k
results
are
exhibits All
method,
Oehme
has
and
experiments
PbO
the
with
we
worth
a straight
assume
a rather forward
or
transfor-
dielectric between
powders
nor
Thus,
2.
of
agreement
PbO.
in Fig.
the
the
a more
phase
in g o o d
behaviour,
given
from
found
Pb304
show
a frequency
constant
is n o t
the
powders
result
dielectric
own
greatest,
might
temperature
This
the
investigated
eventually
at
pressure-depending The
PbO
constant.
Pb304
cases
results
constant
yellow
maximum,
mations.
and
the
dielectric
O.1 (ref.
neither
3),
with
dielectric complicated investigation.
291
,°I
/
t'-
~
in co u
/
=_
/
°"o.~o~ PbO(y)
/
PbO(r)
~"~
U
Pb30&
(u
,S
L..
0
5
10 glcm 3
opparent density
Fig. 2. R e l a t i v e d i e l e c t r i c c o n s t a n t p o w d e r d e n s i t y p o f r e d PbO, y e l l o w
Our
investigations
apparent
density
approximated
log
the
(p)+
specific
These using press,
a logarithmic
4) a n d
function
the p r e s s u r e
p, w h i c h
between
the
c a n be
B
preliminary
constructed pressure
(2)
constants
a guard-ring
maximum
confirm
(ref.
by
p = A log
with
p
e as a f u n c t i o n of a p p a r e n t PbO, a n d P b 3 0 4 . S: s h o o t d e n s i t y .
results
A a n d B. will
be proved
capacitor
as p r e s s
for t h i s
particular
of Pmax
= 400 M P a
tool.
in the n e a r With
purpose,
(referring
future
the h e l p we will
by
of a 106 N
reach
to a c o n d e n s e r
a plain
o f A = 25 cm2) . With
two m u l t i - f r e q u e n c y
the d i e l e c t r i c the
range
constant,
between
investigations
100 Hz
is to g i v e
LCR meters
(Hewlett
Packard
depending
on frequency,
and about
10 MHz.
some
answers
The
to the
will
4270,
4275A),
be m e a s u r e d
a i m of t h e s e following
problems:
in
292
•
s e p a r a t i o n of the e f f e c t i v e d i e l e c t r i c c o n s t a n t core part (shell model, sponge m o d e l (ref. 5));
into
•
influence
of the surface
constant;
•
influence
of the grain
•
mixing
•
influence
rules
(forming
on the mean
dielectric
surface
and
diameter; number
after
Stoecker) ;
G. L e b e r
for helpful
of temperature.
ACKNOWLEDGEMENT We thank Mr. Further
thanks
for p r o v i d i n g stadt,
Ing. should
the
(grad.)
be given
106 N press,
for s u p p l y i n g
the
to the D a i m l e r - B e n z
discussions. AG,
D-35OO
Kassel,
and to the M e r c k - W e r k e ,
D-61OO
Darm-
lead powders.
REFERENCES I F. Oehme, C h e m i s c h e A n a l y s e n durch M e s s u n g von D i e l e k t r i z i t a e t s k o n stanten, Apolda, VEB L a b o r c h e m i e , ]953. 2 F. Oehme, Z. f. N a t u r f o r s c h g . , Ser. B, 14, ]959, p. 779. 3 Gme l i n ' s Handb. d. anorgan. Chem., Lead, part C, Ist delivery, 8th ed., Weinheim, V e r l a g Chemie, 1968, p. ]29. 4 G.A. Weissler, P h . D . Thesis, U n i v e r s i t y (Gesamthochschule) of Kassel, 1978. 5 K.-J. Euler, E l e c t r o c h i m i c a Acta, 14, ]969, p. 115.