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Патент USA US3076777

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United Ltd-rates
add
d?l'h?h?
rammed Feb. 5, 1953
1
2
3,El76,7¢57
described in more detail with reference to the examples
which follow.
Example 1
PROCESS FUR PRQDUCING ELECTRO
LUMINESCENT FROSPHGRS
Copper sulfate was thoroughly mixed with .1000 grams
of zinc sul?de powder in an amount suilicient to establish
Sixdeniel Faria, Lindenhurst, and Paul Goldberg, Long '
Beach, N.Y., assiguors to General Telephone and Elec
tronics Laboratories, Inc, a corporation of Delaware
No Drawing. Filed June 27, 1961, Ser. No. 110,820
‘10 Claims. (Ci. 252~30l.6)
a copper concentration of l><10-3 gram atoms per mole
of zinc sul?de. A chloride flux'was blended with the
mixture in an amount equal to about 8% by weight of
the zinc sul?de, the flux consisting of 3% barium chloride,
Our invention relates to electroluminescent phosphors 10 3% magnesium chloride and 2% sodium chloride, each
and processes for making the same.
percentage being by weight of zinc sul?de. This blend
Electroluminescent phosphors are phosphors which
was then ?red in a covered crucible in air to a tempera
emit light-in the presence of an electric ?eld. Conven
ture of 1150" C. for six hours resulting in a non-electro
tionally, such phosphors are dispersed in a dielectric me—,
luminescent, Well crystallized phosphor starting material.
'dium and the dispersion is placed between two electrodes, 15 The phosphor was next washed in water until excess
at least one of which permits the passage of light there
halides were removed.
‘
thr‘ough to produce an electroluminescent lamp. When a
This essentially non~electroluminescent phosphor start
voltage is applied between the electrodes, light is emitted
ing material was then chemically reacted with a 30% con
from the dispersion.
centration of hydrogen peroxide tor a period of ten min
'
We have succeeded in developing a new process for 20 utes at a temperature maintained between 60° and 85° C.
produce electroluminescent phosphors which results in a
phosphor with signi?cantly increased efficiency and en
At the end of the ten minute reaction time, the sample
was stopped from further oxidation by adding water and
then decanting the excess reacting solution. The oxidized
_ hanced brightness.
Accordingly, it is an object of the present invention
to provide a new and improved process for making elec
phosphor, together with the adhering products of reac~
25 tion (mostly ‘sulfur and zinc oxide), was dried at a tem—
troluminescent phosphors.
Another object is to improve the processing of electro
' luminescent phosphors in such manner as to sharply in
crease their e?iciency.
perature of about 110° C. The phosphor was next acti
vated by mixing 1X 10*3 gram atoms of copper per mole
of zinc sul?de and 5% zinc oxide with the phosphor and
?ring in a motile furnace at 800° C. for 40 minutes. This
Still another object is to provide a process for making 30 thermal treatment was carried on in an air atmosphere.
electroluminescent phosphors having greatly increased elli
After activation, the samples were washed with 50%
ciency and enhanced brightness.
acetic acid, water and 3% potassium cyanide solution-s
These and other objects of our invention will either be
in that order and then dried at a temperature of about
explained or will become apparent hereinafter.
110° C.
In accordance with the principle of our invention, a cop 35
This phosphor‘when tested in an electroluminescent
per activator and at least one halide coactivator selected
lamp was found to have increased efficiency as compared
from the class consisting of chloride, iodide and bromide
to electroluminescent phosphors which had not been
are added to a base material of zinc sul?de. The resultant
treated with hydrogen peroxide. More speci?cally, the
mixture is then ?red to a temperature falling within the
efficiency of our phosphor when dispersed in a demount
approximate range l000°4l3000° C. to produce a start 40 able caster oil cell having 2:1 ratio of phosphor to di
ing material having a copper activator concentration fall
electric and activated by a 200 volt, 4-00 cycles per sec
ond alternating voltage source was 7.4 lumens per Watt.
ing within the approximate range 1X10‘4 to 5><l0~3
The e?iciency of a control phosphor which had not been
gram atoms per mole of base material, and a halide co~
activator concentration also falling within the approxi
treated with hydrogen peroxide was 6.0 lumens per watt.
V mate range 1x10“1 to 5><l0—3 gram atoms per mole of 45 The ‘color of the electroluminescence emitted by the phos
phor varies from green to blue as the frequency is varied
from 60 to 6000 cycles per second. With higher copper
is then etched with an aqueous solution of hydrogen per
concentration, about l.3><l0—3 gram atom per mole zinc
oxide for a predetermined period of time within the tem
sul?de, the color of the emission is green at all frequencies.
perature range 60°-85° C. The partially oxidized phos 50
The measurements Were repeated with phosphors which
phor, together with solid reaction products, is next dried,
had been reacted with a 30% concentration of hydrogen
mixed with at least 1X10-5 gram atoms of copper per
peroxide for different intervals of time. The e?ciencies
mole of base material and ?red at a temperature in the
obtained were as follows:
range 750° to 950° C. The e?iciency of the resulting
Time, minutes:
Efficiency, lumens per watt
electroluminescent phosphor is considerably greater than
20 ____________________________________ __ 8.8
that of electroluminescent phosphors which have not been
30 ____________________________________ __ 7.8
treated with hydrogen peroxide in the manner described.
60 ____________________________________ __ 9.4
An additional treatment which provide increased bright
ness and ef?ciency consists of reacting the electrolumi
This improvement was signi?cant when compared with
nescent phosphor with an acid solution of hydrogen per
the e?iciency of 6.0 lumens per watt obtained with the
oxide at a temperature of about 70° C. After washing,
control sample.
an electroluminescent phosphor is produced having an e?i
base material.
This essentially non-electroluminescent starting material
ciency and brightness which is considerably greater than
that of conventionally prepared phosphors.
Illustrative embodiments of our invention will now be 65
Example 11
The process of Example I was repeated using a start
sprayer
3
ing material having a copper concentration of 1.3 X l0~3
same conditions of brightness showed an improvement
as indicated in the following table:
‘gram atom per mole of zinc sul?de and various concen
trations of hydrogen peroxide. The electroluminescent
color emitted by the resulting phosphor was green. The
Ef?ciency of Un
etched Electrolumi
e?iciency in lumens per watt obtained in a castor oil cell
operated at 400 cycles per second and 200 volts is given
below.
Etching Time (Minutes)
E?icienc in lumens or watt
y
p
nescent Phosphor,
lumens per watt
Eli'icicncy of Pre
and Post-etched
Electroluminescent
Phosphor, lumens
per watt
10
1. 9
2. 8
2. 7
3. 6
‘5. 7
4. 0
15% H202 7.5% H202 3.8% H20:
Further tests disclosed that the pre-treatment may be
successfully carried out when the concentration of the
15 aqueous solution of hydrogen peroxide is in the range
3.75-30 percent and the etching time is between 10 and
60 minutes. In .addition, tests ‘indicate that the post
An electroluminescent phosphor produced from the
treatment may be successfully employed for a period of
samelstarting material but not treated with hydrogen
10 to 60 minutes‘in an acid solution of hydrogen peroxide
peroxide had an ef?cieney of 5.8 lumens per watt.
20 having a concentration in the range 3.75% to 30%
hydrogen peroxide in hydrochloric acid having a con
Example III
centration between 3 normal and 6 normal.
As many changes could be‘i'nade in the above described
The process of Example I was repeated for a yellow
6. 8
6. 6
8. 2
8- 2
6. G
6. 9
7. 5
8- 0
6. 6
7. 4
8. 6
8- 8
emitting manganese activated phosphor. This material
, process it is intended ‘that all matter contained therein
70° C. It was then washed with ethanol to remove the
‘water after which it was rinsed with carbon disul?de to
3.75-30 percent for an interval of 10-60 minutes at a
was prepared as follows: The starting phosphor mate 25 shall be interpreted as illustrative and not in a-limiting
sense.
rial, having a copper concentration of 2x104 gram
What is claimed is:
atoms per mole of zinc sul?de and a chloride concentra
1. A process for producing an electroluminescent pho's
tion of 5x104 gram per mole of zinc sul?de was etched
phor from copper activated-halide c'oa'ctivated non-elec
with a 15% solution of hydrogen peroxide for 30 min
utes at a temperature in the range 60° C.-85° C. After 30 troluminescent zinc sul?de comprising the steps of etch
ing said non-electroluminescent ‘zinc sul?de with a hydro
drying, 4% manganese as manganese carbonate and 1%
gen peroxide solution having a concentration in the
copper as copper sulfate, each percentage being by weight
range 3.75-30 percent vfor an interval of 10-60 minutes
\Of zinc sul?de, were added to the etched phosphor. The
at a temperature range of 60° C.-85° C., mixing said
mixture was next ?red at a temperature of 800° C. The
non-electroluminescent zinc sul?de with at least 1X10-5
ei?ciency of the phosphor was found to be 4.4 lumens
gram atoms of copper per mole of zinc sul?de, and ?ring
er watt as compared to 3.2 lumens per watt for the un
said mixture in a temperature range of approximately
etched phosphor. The brightness at the same conditions,
750° C. to 950° C. for approximately 40 minutes, the re
i.e. 400 cycles per second, 67 volts per mil, was 11 foot
lamberts as compared to 8.5 foot-lamberts for the un 40 sulting electroluminescent phosphor having an ei?ciency
greater than that of an equivalent unetched phosphor.
etched phosphor.
2. A process for producing an electroluminescent phos
This electroluminescent phosphor was next given a
phor from copper activated-halide coactivated non-ele
post-etching treatment which further increased its bright
ctroluminescent zinc sul?de comprising the steps of etch
ness and e?iciency. The phosphor was ?rst reacted with
ing said non-electroluminescent zinc sul?de with a hydro
a 7.5% solution of hydrogen peroxide in 3 normal hy
gen peroxide solution having a concentration in the range
drochloric acid for 15 minutes at a temperature of about
temperature range of 60° C.-85° C., mixing said non
electroluminescent zinc sul?de with at least 1X 10"‘5 gram
remove the yellow coloration due to sulphur on the phos
atoms of copper per mole of zinc sul?de, ?ring said
phor particles. The phosphor Was again Washed with
ethanol to dissolve the carbon disul?de, rinsed with cold 50 mixture in a temperature range of approximately 750°
C. to 950° C., reacting said ?red mixture with a solu
Water, and then washed with 5% potassium cyanide to
tion of hydrogen peroxide in hydrochloric acid, the con
remove any exposed copper. Finally, the phosphor was
centration of said hydrogen peroxide being in the range
rinsed with hot water until the potassium cyanide was
3.75-30 percent and the concentration of said hydro
no longer detectable.
A series of electroluminescent phosphors which re 55 chloric acid being in the range 3 normal to 6 normal.
3. A process for producing an electroluminescent phos
cieved this treatment showed 40% to 50% increases in
phor from copper activated-halide coactivated non-elec
brightness over that of the untreated phosphors. These
troluminescent zinc sul?de comprising the steps of etch
tests were made in a cell energized at 400 cycles per
ing said non-electroluminescent zinc sul?de with a hydro
second, 67 volts per mil with a ratio of phosphor to di
electric of 2:1. The following table indicates the rela 60 gen peroxide solution having a concentration in the range
3.75-30 percent for an interval of 10-60 minutes at a
tive brightness of the untreated electroluminescent phos
temperature range ‘of 60° C.-85° C., ‘mixing said non
phor and the phosphors which were pre- and post-treated
electroluminescent zinc sul?de with at least 1X10‘3 gram
as described.
atoms of copper per mole of zinc sul?de, ?ring said mix
ture in a temperature range of approximately 750° C. to
Brightness of Unetched Eleetrolumi-
Brightness of Pre
and Post-etched
nescent Phosphor,
foot-lambert-s
Electroluminescent
Phosphor, foot
lamberts
7.0
9.1
7. 5
10. 5
13.0
11.0
950° C., reacting said ?red mixture with a solution of hy
drogen peroxide in hydrochloric acid for between 10 and
60 minutes at a temperature of about 70° C., the concen
tration of said hydrogen peroxide being in the range
70 3.75-30 percent and the concentration of said hydrochlo
ric acid being in the range 3 normal to 6 normal.
4. A process for producing an electroluminescent phos
phor from a zinc sul?de starting material having a cop
per concentration within the approximate range 1X10"?
The e?iciency of the phosphor when tested at the 75 5X10‘3 gram atoms per mole of base material and a
3,076,767
5
halide concentration with the approximate range 1><10-4
5><10-3 gram atoms per mole of base material compris
ing the steps of etching said starting material with a hy
drogen peroxide solution having a concentration in the
range 3.75-30 percent for an interval of 10-60 minutes at
6
electroluminescent zinc sul?de comprising the steps of
etching said non-electroluminescent zinc sul?de with a hy
drogen peroxide solution having a concentration of 3.8%
for a period of 60 minutes at a temperature maintained
between 60° C. and 85 ° C., mixing said phosphor with
1x10"3 gram atoms of copper per mole of zinc sul?de,
and ?ring the mixture in air to 800° C. to produce a green
a temperature range of 60°C.-85° C., mixing the etched
base material with at least 1X10"5 gram atoms of copper
electroluminescent phosphor.
per mole of base material, and ?ring said mixture in a
9. A process for producing a yellow-emitting electro
temperature range of approximately 750° C. to 950° C.
5. A process for producing an electroluminescent phos 10 luminescent phosphor from a zinc sul?de starting mate
rial having a copper concentration of 2><1O-4 gram
phor from a copper activated-chloride coactivated non
electroluminescent zinc sul?de comprising the steps of
etching said non-electroluminescent zinc sul?de with a hy
drogen peroxide solution having a concentration of 30%
for a period of 10 minutes at a temperature maintained
between 60° C. and 85 ° C., mixing said phosphor with
l><10-3 gram atoms of copper per mole of zinc sul?de,
and ?ring the mixture in air to 800° C. to produce a
atoms per mole of zinc sul?de and a chloride concentra
tion of 5X10-4 gram atoms per mole of zinc sul?de com
prising the steps of etching said starting material with a
hydrogen peroxide solution having a concentration of
15% for 30 minutes at a temperature in the range 60°
C.-85 ° C., mixing said starting material with 4% manga
nese and 1% copper by weight of zinc sul?de, and ?ring
said mixture at a temperature of 800° C.
green electroluminescent phosphor.
10. A process for producing a yellow-emitting electro
6. A process for producing an electroluminescent phos 20
phor from a copper activated-chloride coactivated non
electroluminescent zinc sul?de comprising the steps of
etching said non-electroluminescent zinc sul?de with a
luminescent phosphor from a zinc sul?de starting material
having a copper concentration of 2x10“4 gram atoms per
mole of zinc sul?de and a chloride concentration of
5><l0-‘1 gram atoms per mole of zinc sul?de comprising
30% for a period of 60 minutes at a temperature main 25 the steps of etching said starting material with a hydro
gen peroxide solution having a concentration of 15 % for
tained between 60° C. and 85° C., mixing said phosphor
30 minutes at a temperature in the range 60° C.-85° C.,
with 1X10“3 gram atoms of copper per mole of zinc
mixing said starting material with 4% manganese and
sul?de, and ?ring the mixture in air to 800° C. to pro
1% copper by weight of zinc sul?de, ?ring said mixture
duce a green electroluminescent phosphor.
7. A process for producing an electroluminescent phos 30 at a temperature of 800 C., reacting said mixture with a
solution of hydrogen peroxide in hydrochloric acid for
phor from a copper activated-chloride coactivated non
15 minutes at a temperature of approximately 70° C.,
electroluminescent zinc sul?de comprising the steps of
the concentration of said hydrogen peroxide being 7.5%
etching said non-electroluminescent zinc sul?de with a hy
and the concentration of said hydrochloric acid being 3
drogen peroxide solution having a concentration of 3.8%
for a period of 10 minutes at a temperature maintained 35 normal, and washing said phosphor to remove excess sul
fur and copper.
between 60° C. and 85 ° C., mixing said phosphor with
1><10-a gram atoms of copper per mole of zinc sul?de,
References Cited in the ?le of this patent
and ?ring the mixture in air to 800° C. to produce a green
UNITED STATES PATENTS
electroluminescent phosphor.
8. A process for producing an electroluminescent phos 40 2,743,238
Hunt et al. __________ .... Apr. 24, 1956
phor from a copper activated-chloride coactivated non
Hunt et a1 _____________ __ Ian. 28, 1958
2,821,509
hydrogen peroxide solution having a concentration of
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