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Patented F eb. 14, ‘51950
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40
_ ium'rso STATES PATENT oFFicE
METHOD or MAKIUFACTURE or
' LpMiNEsosNr MATERIALS
James H; Schulman, Cambridge, Mass, assignor
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to Sylvania'Electric Products In'c., Salem, Mass.,
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‘a corporation of Massachusetts
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No Drawing. .Application Matti; 28, 1946,
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Serial No. 657,922
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8Claims.
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(01. 252430110
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This invention‘ relates to luminescent materials and more particularly to phosphors ‘used
in the preparation of a coating of ?uorescent ma-
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mixture of a calcium salt and a manganese salt
with silicic acid in the presence of the vapor of
a lead compound. This lead-bearing vapor may
terial for an electric gaseous discharge device,
he produced in the ?ring chamber by placing
such ‘as a ?uorescentilam'p.
therein a separate vessel containing a suitable
"
An object of this invention. is to provide a, ?uorescent material of ?ne and uniform particle
lead compound. Alternatively, the activator
compound 'may be‘ disposed in the‘ bottom‘ of ‘a
size.
suitable container and the phosphor charge piled
..
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‘. .Another object ‘is to‘provide a fluorescent maon top of it or it may be disposed on top of the
terial which, when applied to a lamp,.will pro- ll phosphor charge. If desired, a blend of a cal
vide. the lamp with a coating which will maintain
cium and a manganese compound with silicic acid
good brightness throughout the life of the lamp.
can be pre?red to give CaMnSiOs which is, inert
. Afurther object is to provide a?uorescent ma-
to 2537 A. U. radiation.
This ?red material
terial which, when applied to alamp, will promay then be further heated in the vapor of a
time the lamp with a smooth even coating.
15 suitable lead compound, whereupon lead enters
. Further objects, advantages and features will
the Structure and forms the Carrol/[113103 Phos
Ice-apparent from the following speci?cation.
phorwwhich ?uoresces pink under 2537 A. U.
In theipreparationl of certain luminescent ma-
excitation.
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terials it has been the pralltice 170 add an actiThe amount of the activator which enters the
vator such as lead in order to obtain a product 20 phosphor may be controlled by the temperature
which will ?uoresce under 2537 A. U. excitation.
and time of firing and by the Choice of act-,1;
It has‘also been the practice, in 501119081568, in
yator compounds of diiferent vapor pressures.
preparing lummescent materials to ut1l1Ze a flux
AS suitable lead compounds I have used lead
or catalyst to accelerate the reaction of phosphor ’ _ ?uoride, lead dioxide, lead monoxide and mad
synthesis. In both of these cases the activator 2v chloride but any other lead compounds giving
and/Or the catalyst have usually been mixed as a
a su?icient concentration of lead-bearing vapor
solid with the phosphor charge. In'the case of
at the ?ring temperatures employed are Satis_
the ‘activator. many activator compounds fuse at
factory. I have found 2100° F. to be a satisfacé
comparatively low temperatures before any Sub‘
tory ?ring temperature. Thus an activator can
stantial reaction. takes place with the phosphor 30 be added to a raw material blend or a ?nished
ingredients.
This 'sintering is undesirable be-
phosphor by this method
cause it causes the ?nal phosphor product ‘to be
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characterized by larger particle sizes than are
I 11,1261“; @1123??? gggdnnigoof
desired. When a catalyst is mixed as a solid
prp?red CaMnSiOg in onse’ Crucibfé and a1 sing
with‘ the phosphor charge‘ it has been found that 1'3- abie lead com ound 1
another 0
$3065?
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I th
sometimes the stimulated reaction of the fluorescent material does not take place uniformly
throughout the entire mass, some particles of the
put‘ thése twg crucigll S in n rum 6‘ ? .811
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b
.th th 1 d e
a ovenbclw ring
CF11; erhwl
e ea, compound “Wm B on 0D
?uorescent material reacting slower than others.
0
e p osphor chalge‘ The crumbles are then
- Themethod Of my invention embodies the idea ‘~40 covefled and. t?red' when the temperature
pf introducing the activator and/or the catalyst
zeac es 2.‘ pom Where .the lead compound starts
into the‘ phosphor charge in a vapor state instead
0 Vaponze’ lead'bearmg Vapor permeates the
ofsonliixirigtin
the activator and/ or the catalyst in
id s a e.‘ -I have found that when thisvis done
2151114‘; soifoscacTiz’
iiisrigtgil’t ag?slsaigi ‘1311;312:1333
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:intering of the phosphor is avoided and ?ner
highty satisfactqry in the Preparation of a 595'
particle Sizes are obtainable; and in the caseof
pension of luminescent material to be applied
the catalyst, the reaction of the ?uorescent materiaycompound is stimulated-uniformly-through
the entire mass,-all particleslappearing to react
P0 the Walls of a glass tube to be manufactured
into a ?uorescent lamp, because a ?ner particle
Size and a lower powder Weight is thereby 010
at a more uniform rate
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:-Actwa.tors
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i510 tained. The lower powder weight reduces manu
facturing costs and the ?ner particle size pro
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> The process. which I have employed in-‘syn-
vides'a smoother coating on the lamp.
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~ The. principle of vapor-phase activators may
thesizing an activated-_:phosphor,.sucl'ilasicalcium
beextended to activators other thanlead without
leadi silicate, lforlzexample, ~‘~ comprises ?rin‘g- a 755 departing from the spirit of the invention.
2,497,140
3
Catalysts
The action of catalysts in promoting solid state
reactions is well known. Such agents have been
used in the synthesis of sul?de and silicate phos
phors. In both cases the catalyst has usually
4
said vapors to permeate the solid state compo
nents of said phosphor.
2. The process of preparing a manganese acti
vated calcium silicate phosphor which comprises
disposing a blend of CaCOa, MnCOa, and SiOz,
in
the solid state, in the proportions necessary
been mixed as a solid with the material to be
to form the phosphor, in an enclosed chamber;
reacted. With reference to catalyst-accelerated
disposing at least ongcompound selected from
silicate reactions, a theory has been advanced
the
group consisting of CdClz, ZnClz, HgCl, PbClz,
that the catalyst dissolves away a barrier layer 10
PbFz, PhD, and PbO2, in the solid state, in said
of reacted silicate, thus uncovering the under
chamber physically separate from said blend but
lying unreacted metal oxides which can further
in
close proximity thereto; and heating said blend
react.
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and said compound to a temperature high enough
In the method of my invention volatile ?uxing
agents are not admixed as a solid with the phos
to vaporize said compound and cause said vapors
15 to permeate the solid state blend of said phosphor.
phor charge but their vapors alone are su?‘icient to
3. The process of preparing a manganese acti
adequately accelerate the reaction of phosphor
vated silicate phosphor selected from the group
synthesis. A flux, such as cadmium chloride, may
consisting of zinc orthosilicate, zinc beryllium
be placed in the bottom of a ?ring vessel and the
silicate, magnesium orthosilicate, cadmium sili
phosphor blend to be ?red piled on top of it or
cate and calcium silicate which comprises dispos
it may be disposed on top of the phosphor blend. 20 ing the components thereof, in the solid state,
Alternatively, the phosphor mix and the flux may
in the proportions necessary to form the phos
be disposed in separate containers, so long as the
phor, in an enclosed chamber; disposing lead
?ux vapor has good access to the phosphor
oxide in the solid state, in said chamber physically
charge. Since the vapors alone perform the ca 25 separate from said components but in close prox
talysis, this action is different from that normally
imity thereto; and heating said components and
ascribed to ?uxes, the vapors not being able to
said lead oxide to a temperature high enough
dissolve any barrier layer of silicate.
to vaporize said lead oxide and cause said vapors
I have found the above-mentioned process ex
to permeate the solid state components of said
tremely satisfactory in the synthesis of manga
phosphor.
nese-activated silicate phosphor when one of the
4. The process of preparing a manganese acti
volatile halides is used as a ?uxing agent. For
vated calcium silicate phosphor which comprises
example, I have prepared zinc ortho-silicate ac
disposing a blend of CaCOx, MnCOs and $102,
tivated with manganese by ?ring a dry blend of
in the solid state, in the proportions necessary
ZnO, MnCOa and S102 in the presence of a 35 to form the phosphor, in an enclosed chamber;
volatile halide such as CdCl2, ZnClz, PbClz, and
disposing lead oxide in the solid state, in said
HgCl. This method has also been found ad
chamber physically separate from said blend but
vantageous in the preparation of zinc beryllium
in close proximity thereto; and heating said blend
silicate activated with manganese, magnesium
and said lead oxide to a temperature high enough
orthosilicate activated with manganese and cad 40 to vaporize said lead oxide and cause said vapor
mium silicate activated with manganese when the
to permeate the solid state blend of said phosphor.
dry blend of the phosphor charge is ?red in the
5. The process of preparing a manganese acti
presence of a volatile halide, such as one of the
vated silicate phosphor selected from the group
halide compounds mentioned above for example.
consisting of zinc orthosilicate, zinc beryllium
The ?uxing agent may be placed in a con
silicate, magnesium, orthosilicate, cadmium sili
tainer separate from the container in which the
cate and calcium silicate which comprises dispos
phosphor charge is disposed or it may be placed
ing the components thereof, in the solid state,
in the bottom of the same vessel in which the
in the proportions necessary to form the phos
phosphor charge is ?red. Although it is possible
phor, in an enclosed chamber; disposing PbClz
to ?re the materials in open containers where
in the solid state, in said chamber, physically
no provision is made to prevent escape of the
separate from said components but in close prox
?ux vapor it is not the preferred method. Pref
imity thereto; and heating said components and
erably provision should be made to prevent the
said PbC12 to a temperature high enough to
vaporize said PbCl2 and cause said vapors to per
escape of the volatilized material by ?ring the
charge in a closed container.
55 meate the solid state components of said phos
phor.
The principle of vapor-phase catalysts may
6. The process of preparing a manganese acti
also be extended to sul?de and other type phos
vated calcium silicate phosphor which comprises
phors without departing from the spirit of the
disposing a blend of CaCO3, MDCO: and SiOz,
invention.
60 in the solid state, in the proportions necessary
What I claim is:
to form the phosphor in an enclosed chamber;
1. The process of preparing a manganese acti
disposing PbCh in the solid state, in said chamber
vated silicate phosphor selected from the group
physically separate from said blend but in close
consisting of zinc orthosilicate, zinc beryllium
proximity thereto; and heating said blend and
silicate, magnesium orthosilicate, cadmium sili
cate and calciiun silicate which comprises dispos 85 said PbClz to a temperature high enough to
vaporize said PbCh and cause said vapor to per
ing the components thereof, in the solid state,
meate the solid state blend of said phosphor.
in the proportions necessary to form the phos
7. The process of preparing a manganese acti
phor, in an enclosed chamber; disposing at least
vated silicate phosphor selected from the group
one compound selected from the group consist
ing of CdClz, ZnClz, HgCl, PbClz, PbFz, PbO, and 70 consisting of zinc orthosilicate, zinc beryllium
silicate, magnesium orthosilicate, cadmium sili
PbOz, in the solid state, in said chamber, phys
cate and calcium silicate which comprises dispos-‘
ically separate from said components but in
ing the components thereof, in the solid state,
close proximity thereto; and heating said com
in the proportions necessary to form the phos
ponents and said compound to a temperature
phor, in an enclosed chamber; disposing PbFi
high enough to vaporize said compound and cause
2,497,140
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in the solid state, in said chamber, physically
REFERENCES CITED
separate from said components but in close prox
imity thereto; and heating said components and
said PbFz to a temperature high enough to vapor
ize said PbFz and cause said vapors to permeate
the solid state components of said phosphor.
8. The process of preparing a manganese acti
vated calcium silicate phosphor which comprises
disposing a blend of CaCOa, MnCOs, and S102,
in the solid state, in the proportions necessary 10
to form the phosphor, in an enclosed chamber;
disposing PbFz in the solid state, in said chamber
physically separate from said blend but in close
proximity thereto and heating said blend and
said PbFz to a temperature high enough to vapor 15
ize said PbFz and cause said vapor to permeate
the solid state blend of said phosphor.
JAMES H. SCHULMAN.
The following references are of record in the
?le of :this patent:
Number
UNITED STATES PATENTS
Name
Date
1,954,691
2,124,225
2,238,926
De Boer _________ __ Apr. 10, 1934
Batchelor ________ __ July 19, 1938
Moore ___________ __ Apr. 8, 1941
2,247,192
Fonda ___________ __ June 24, 1941
2,254,956
2,299,510
Aschermann _____ __ Sept. 2, 1941
Steadman ________ __ Oct. 20, 1942
2,462,517
Leverenz _________ __ Feb. 22, 1949
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