1. technology and computing

July 16, 1968
3,393,060
G. E. BLAIR ETAL
METHOD OF CHANGING THE CONDUCTIVITY OF CERAMIC MATERIALS
Original Filed March 18, 1963
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DAVID
P.
HAMBLEII
ROBE!!! A. WEIDEL
BY
ATTORKEYS
July 16,
1968
G. E. BLAIR ETAL
3,393,060
METHOD OF CHANGING THE CONDUCTIVITY OF CERAMIC MATERIALS
Original Filed March 18, 1963
2 Sheets-Sheé‘t 2
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BLAIR
DAVID R BAMBI-EN
ROBERT A. WEIDEL
ATTORNE 8
1
United States Patent O cice
3,393,060
Patented July 16, 1968
1
2
3,393,060
vanadium oxide potassium metaphosphate glass;
FIG. 3 is a graphical representation showing the elfect
tionship between speci?c resistivity and temperature for a
METHOD OF CHANGING THE CONDUCTIVITY
OF ‘CERAMIC MATERIALS
Gerald E. Blair, Galita, Calif., and David P. Hamblen,
Gates, and Robert A. Weidel, Webster, N.Y., assignors
on speci?c resistivity when the vanadium oxide potassium
metaphosphate glass is held at various temperatures for
?ve hours; annealed and measured at 40° C.;
FIG. 4 is a graphical representation showing the varia
tion in speci?c resistivity when samples of vanadium meta
phosphate glass are held at 310° C. for various times,
to Bausch 8: Lomb Incorporated, Rochester, N.Y., a
corporation of New York
Continuation of application Ser. No. 265,636, Mar. 18,
1963. This application Oct. 13, 1966, Ser. No. 586,573
2 Claims. (Cl. 65-33)
10 then are annealed and measured at 40° C. and,
FIG. 5 is a graphical representation showing the infra
red transmission of one sample of vanadium phosphate
glass at various temperatures.
ABSTRACT OF THE DISCLOSURE
The novel treatment may be defined as promoting nu
A method is disclosed vfor reducing the speci?c resis
tivity of a glass composition including the major portion 15 cleation and subsequently crystallization in a vitreous ma
terial, frequently called devitri?cation. It is presently pre
of vanadium pentoxide and a minor portion of numerous
ferred
to treat the materials ‘by subjecting them to heat,
metal phosphates. The glass substrate is heated in a tem
i.e. to a temperature between the liquidus temperature
perature range between the transition temperature and
and the transformation temperature for a period of ap
the liquidus temperature for a period of time sut?cient to
cause crystallization. The crystallization effectively re 20 proximately 1/2 hour.
The compositions set forth hereinafter show the raw
duces the speci?c resistivity of the glass.
batch analysis of various vanadium phosphate glasses
which have been used to illustrate the effect of treating
such compositions by the novel method according to the
This application is a continuation of Ser. No. 265,636,
25 present invention. As shown in the examples, the ceramic
?led Mar. 18, 1963, now abandoned.
semiconductors can be prepared from batch ingredients
This invention relates to a method of changing the con
containing
a major portion (by weight) of vanadium
ductivity of ceramic materials and more particularly to a
pentoxide with a minor portion of numerous metal phos
method of treating vanadium phosphate materials in
phates. Glass compositions containing vanadium pentoxide
order to change the electrical characteristics thereof.
30 in the amount of 60 to 84 weight percent in the batch
The increased interest in ceramic semi-conductors has
have been shown to undergo devitri?cation during reheat
led to several studies of the electrical properties of vari
ing. After casting the molten glass, the ceramic material
ous ceramic compositions. Such studies have indicated
is heated in the temperature range between the transition
that glass compositions which contain high percentages of
temperature and the liquidus temperature for a period of
vanadium oxide produce glasses which have characteristic
time sufficient to alter the resistivity. The semiconductors
low resistivities. Glasses of this type have been disclosed
in the British Patents 744,205 and 744,947 which were
published on Feb. 1, 1956, and Feb. 15, 1956, respectively.
Attempts to utilize vanadium compositions as semi
conductor materials led to the development of certain 40
metaphosphate compositions which are disclosed and
claimed in our copending application entitled, “Ceramic
are ordinarily used at ambient temperatures.
COMPOSITION A
Ingredient
and which nevertheless had the desired electrical proper 45
ties.
It has now been found that vanadium phosphate glass
containing a major portion of vanadium pentoxide can be
treated according to the novel method disclosed herein in
order to produce various degrees of crystallization. This
crystallization is effective to produce a relatively large
change in the speci?c resistivities‘of the materials. For
example, a vanadium glass containing potassium meta
phosphate was treated by a method according to the 55
Speci?c
Resistivity
as. 22
75. o
NaPOs ___________________________ ._
30. 7s
25. 0
626K
COMPOSITION B
v20, ______________________________ ..
71. 90
84.0
LiPO3 ____________________________ _.
28.10
10.0
}
10K
}
157K
}
239K
}
186K
}
39K
}
27K
}
10K
}
870K
COMPOSITION o
v20. ............................. ..
70. 42
70. 0
PbPOa ___________________________ _.
29.58
30.0
COMPOSITION D
V205 _____________________________ .1
60. 52
75. 0
KPO; ____________________________ ..
33.48
25.0
COMPOSITION E
V205 _____________________________ _-
72.0
76.0
Enrol), ......................... ..
28.0
24.0
present invention to thereby reduce its speci?c resistivity
COMPOSITION F
from about 103 ohms per centimeter to 10 ohms per
centimeter.
Brie?y, the present invention contemplates heat treat
ing vitreous samples to produce varying amounts of crys
tallization to thereby produce a relatively large change in 60
the speci?c resistivity. This change in electrical resistance
is particularly dependent upon the thermal history below
the liquidus temperature but above the transformation
range of the material. The aforementioned thermal history
Wgt.,
Percent
V205 ............................. . .
Compositions,” Ser. No. 266,062 ?led Mar. 18, 1963, now
Patent No. 3,278,317. This approach resulted in obtaining
glass-es which could be produced in relatively large melts
Mole
Percent
V705 ________________________________________ ..
65.0
Gd(PO3)2 .................................... ._
35.0
COMPOSITION G
V205 _________________ ..
70.0
Cd(PO3)2 ............. __
30.0
COMPOSITION H
V205 ________________________________________ ..
75.0
Cd(PO3)2 .................................... ..
relates to a heat treaatment which may be subsequent to 65
COMPOSITION r
25.0
the normal casting and annealing procedures.
The invention will now be described in more detail in
connection with the accompanying drawings in which:
FIG. 1 is a graphical representation showing the change 70
in resistivity with respect to the change in vanadium oxide;
FIG. 2 is a graphical representation showing the rela
V205 ________________________________________ ._
60
VzO3Z3P2O5 __________________________________ ._
40
COMPOSITION J
V205 ________ ..
70
3,393,060
3
' 4
The speci?c resistivities shown were measured prior
to subjecting the samples to the novel method which is
the subject of the present claims.
The relationship between speci?c resistivity and meas
uring temperature is illustrated by the graphical repre
sentation shown in FIG. 2. The graphical data was ob
COMPOSITION K
V205 _________________ __
V20323P205 ___________ __
The speci?c resistiivties shown above relate to the spe
ci?c resisitivites of the vitreous glasses prior to subjecting
the glasses to crystallization.
The glasses set forth in the various examples may be
prepared in various ways. For example, the ingredients
taken from the melt identi?ed as Composition D, i.e. a
in an electric resistance furnace and the ingredients are
melted therein at a temperature of approximately 900° C.
reheated material.
FIG. 3 shows the eifect of subjecting the glass taken
tained by measuring the speci?c resistivity of glass samples
composition containing 75 weight percent V205 and 25
in the powdered form are mixed and placed in a platinum 10 weight percent KPO3 at various temperatures. The lower
curve shows the temperature-resistivity relation for the
crucible. The crucible containing the mixture is placed
Relatively small melt-s were made in this manner and were
from the same sample identi?ed as Composition D to
Larger melts were also made at this same temperature,
shows that as a general rule there is a sharp reduction of
resistivity as the temperatures are increased above the
transition range. The rate of change decreases as the tem
held at this temperature for approximately 3-4 hours. 15 progressively higher temperatures for ?ve hours. This
however, were stirred according to conventional glass
making techniques for approximately 4 hours. The smaller
perature approaches the softening range.
melts were cast at approximately 900° C. on a plate having
The eifect of holding the sample 75 weight percent
a temperature of approximately 100° C. In the case of 20
V205, 25 weight percent KPO3 i.e. Composition D at the
the larger melts the melt was cooled to approximately
same temperature i.e. a temperature which is above the
700° C, with continued stirring prior to casting on a plate
transformation range, for various periods of time is shown
by the graphical representation in FIG. 4. This shows
that the greatest drop in resistivity occurs during the ?rst
of about 100° C. All types of the glass disclosed herein
were annealed at approximately 250° C.
Table I illustrates the effect of heat treating vanadium
half hour of treatment and appears to increase slightly
when held at a longer period of time. In the case of the
phosphate materials at various temperatures and for vari
ous time intervals in accordance with the novel method
cadmium and lithium compounds the crystallized samples
disclosed herein.
gave higher resistances than their vitreous counterparts. In
TABLE I
Temperature,
30 other cases the resistances decrease as crystallization
Time
occurs.
Speci?c
° C.
Resistivity
The infra-red radiation transmission of the phosphate
materials is generally similar to typical phosphate glasses.
380
0"...
E ____________ _.
5 hrs _________ __
It has been noted however, as the vanadium content of
59K
260
250
706K
294K
250
276K
5K
250
250
250
260
310
290
250
270
290
310
330
350
43K
233K
5K
0. 021K
10K
5.2K
0. 65K
0v 44K
[124K
0. 097K
0. 011K
290
0. 26K
290
290
290
290
310
0.12K
0.13K
0. 15K
0. 23K
240K
310
310
210K
150K
these glasses is increased visible radiation is absorbed and
with a further increase in vanadium content this absorp
tion extends into the near infrared region of the spectrum.
The transmission characteristics of the glasses are shown
by the graphical representations in FIG. 5.
40
What is claimed is:
1. A method for manufacturing a ceramic semi-con
ductor material comprising
heating a vanadium glass in the temperature range of
about 250° C. to 380° C. for at least one-half hour
45
to produce crystallization and change the resistivity
of the ceramic material,
said vanadium glass consisting essentially of 60 to 84
weight percent V205 and 16 to 40 percent of a metal
phosphate selected from the group consisting of
50
FIG. 1 is a typical curve showing the change in re
sistivity with respect to a corresponding change in com
position. This curve was plotted for changes in the rates
barium metaphosphate, lead metaphosphate, lithium
metaphosphate, sodium metaphosphate, cadmium
metaphosphate, potassium metaphosphate and vana
dium metaphosphate.
2. The method of claim 1 wherein the vanadium glass
of V205 in weight percent with respect to changes in
Ba(PO3)2 in weight persent. These changes are shown 55 consists essentially of about 75 weight percent vanadium
pentoxide and 25 percent potassium metaphosphate, and
in tabular form in Table 11.
wherein the glass is crystallized at about 310° C.
TABLE II
Ingredient
xlgiai isgeli t’
References Cited
UNITED STATES PATENTS
Iigiilsig?y,
3,278,317
é
}
1, 700K
as
58: 8
5313
33:8
}
}
}
}
193K
240K
93K
19K
65
10/1966
Blair et al. ________ __ 106—47
OTHER REFERENCES
Snell: “Electrical Properties and Uses of Glass,” Glass
Industry, September 1962, page 484 only.
DONALL H. SYLVESTER, Primary Examiner.
G. R. MYERS, R. L. LINDSAY, Assistant Examiners.
UNITED STATES PATENT OFFICE
CERTIFICATE OF CORRECTION
Patent N0 . 3 ,393,()60
July 16 , 1968
Gerald E. Blair et a1.
It is certified that error appears in the above identified
patent and that said Letters Patent are hereby corrected as
shown below:
47 ,
Column _4, line 45, "change" should read -— reduce —- ; line
line 48, "40" should read -— 30
“60“
should
read
--
7O
— ~ ;
weight -—; lines 51 and 52, cancel "cadmium metaphosphate —-.
Signed and sealed this 24th day of February 1970.
(SEAL)
Attest:
Edward M. Fletcher, Jr.
Attesting Officer
WILLIAM E. SCHUYLER, JR.
Commissioner of Patents