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Патент USA US3070432

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United States
3,070,422
atent
Patented Dec. 25, 1962
1
3,070,422
NEW CHROMIUM-TUNGSTEN OXIDE AND
PREPARATION
Gerhard Bayer, Zurich, Switzerland, assignor to Owens
Illinois Glass Company, a corporation of Ohio
No Drawing. Filed Aug. 30, 1960, Ser. No. 52,778
5 Claims. (Cl. 23-51)
2
800 to about 1100° C. An oxidizing atmosphere is usu
ally employed, such as air. Temperatures are preferably
in the range from 850 to 1000” C. Times can be from
2 to 30 hours, usually from 5 vto 20 hours, although short
er or longer times than these ranges can be used. If too
short a time is used, the yield is merely lowered. ' T00 long
a time is merely unnecessary. The temperature should
be at least 800° C., but can be somewhat above 1100° C.
This invention relates to a new chromium-tungsten ox
without encountering excessive decomposition of the
ide, and to methods for its preparation.
10 CrzWO? in the time necessary for substantial completion
Rutile-type compounds can be classi?ed into three
of the reaction. Of course, an excessive time of heating,_
groups: A4+O2, A3+B5+O4, A2+B25+O6. The prototype
A4+O2 compound is rutile, TiO2. A3+B5+O4 compounds
at elevated temperatures of 1100° C. or higher can also
cause undesirable decomposition.
[have the same unit cell and are typi?ed by statistical dis~
In preparing the compound, while it is desirable that
tribution of the cations in the lattice. Examples include 15 equimolar ratios of Cr2O3 and W03 be employed in order
tantalates, such as CrTaO4, and antimonates, such as
to obtain a product substantially free from contamination
AlSbO4. A2+B25+O6 compounds have the trirutile struc
of one or the other of the starting materials, any ratio of
ture as reported by Goldschmidt et al., “Geochemische
the starting materials can *be employed. Thus, reactions
Verteilungsgesetze der Elemente: VI, Uber die Kristall
were eifected, as set forth hereinbefore, using molar ratios
strukturen vorn Rutiltypus” (Geochemical Distribution 20 of Cr2O3 to W03 of 1 to 3 and ‘3 to 1. In the ?rst case,
Law of the Elements: VI, Crystal Structure of Rutile
the product, as shown by X-ray patterns, was 'CrZWOG
Type with Remarks on Geochemistry of the Bivalent and
+WO3, and, in the second instance, the product was
Quadrivalent Elements), Skrifter Norske Videnskaps-v : Cr2WO6+Cr2O3, without any change in the lattice con
Akad. Oslo, Mat-Nat. KL, No. 1, 21 pp. (1926); p. 18.
stants or formation of any other vcompound.
The rutile and trirutile structures are closely related. 25
In a series of other speci?c examples of the invention,
The unit cell of the trirutile structure corresponds to three
carried out as outlined hereinbefore, using in each case
unit cells of the monorutile structure, except that the Ti
an equimolar ratio of Cr2O3 and W03, each powdered to
positions are occupied in a regular way by A“ and B5+
less than 10 microns, the compacted samples were heated,
ions. Both belong to the space group P4/mm. Prior to
respectively, at 600, 750, 800, 850, 900, 1000, and 1100°
my invention only compounds of the general type 30 C. for 20 hours in air. X-ray patterns of the respective
A2+B25+O6 have been found to have the trirutile struc~
products showed that the formation of Cr2WO6 ‘started
ture (Anders Bystrom, Brita Hok, and Brian Mason,
at 800 to 850° C. and was complete at about 950° C‘.
“Crystal Structure of Zinc Metantimonate and Similar
Below 800° C. the X-ray pattern of a mixturegof Cr2O3
Compounds,” Arkiv. Kerni, Mineral. Geol., 15B (4) 1-8
and W03 was obtained.
(1941); Brian Mason and C. J. Vitaliano, “Bystromite, 35 On the pure CrZWOG compound obtained in one of the
Magnesium Antimonate, a New Mineral,” Am. Mineralo
foregoing runs, X-ray powder diffraction data were ob
gist, 37, 53-57 (1952)).
tained, and these are shown in Table I, as compared with
An object of the present invention is to provide a new
similar data for rutile and bystromite. Table II shows
type trirutile compound, namely, a chromium-tungsten
for these compounds the ionic radii, axial ratios and den
oxide of the formula Cr2WO6. Another object of the in— 40 sities.
vention is to provide methods for the preparation of such
Table I.—-Lattice Spacings and Intensities for Rutile~
new compound. Other objects of the invention Will be
come apparent from a study of the accompanying dis~
closure.
According to the present invention, I have now discov 45
and Trirutile-Type Compounds (X-Ray Powder Dif
fraction Data)
Rutile
ered a new type of trirutile compound Cr2WO6, and meth
ods for its preparation. In contrast to previous trirutile
compounds, my present compound has the general for~
mula AZBOG, where A is the three-valent ion, Cr“, and
B is the siX-valent ion, W64‘.
50
The general .formula for this compound is in contrast to
the general formula AB2O6 for a normal trirutile com
pound. The lattice positions of A and B ions are there
fore interchanged and the structure of CrZWOB can be
Cl‘gWOs
Bystromites, MgSbgOgi
d
I/Iu
hkl
d
I/Io
hkl
d
I/Io
hkl
3. 245
100
110
2. 489
2. 297
41
7
101
200
4. 43
4. O5
3. 22
2. 614
2. 481
2. 285
2. 217
51
49
100
19
90
16
6
002
101
110
112
103
200
004
4. 63
4. 19
3. 32
2. 69
2. 57
2. 34
40
70
100
30
90
50
002
101
110
112
103
200
20
30
30
202
211
interpreted as an “inverse trirutile structure.” Cr2WO6 55
can be regarded as a superlattice of rutile, with regular
2. 188
22
111
2.181
2. 25 _
9
210
202
211
114
2. 08
2.04
distribution of the Q“ and W“ ions in the tripled rutile
cell. The density of the CrZWOB is much lower than that
2. 036
1. 994
1. 827
9
7
14
8
113
2. 054
1. 687
50
211
1. 624
16
220
l. 681
1. 65
1. 615
61
6
16
213
105
220
1. 58
1. 515
1. 50
1. 476
5
3
3
13
1. 445
1. 375
11
4
204
222
301
006
310
312
of a normal trirutile compound containing cations of sim
ilar atomic weight, e.g., FeTa2O6. This is due to the re 60
verse arrangement of the ions in the unit cell, so that
the number is four A ions and two B ions for Cr2WO6,
as compared with two A ions and tour B ions for nor
mal trirutile compounds.
According to the invention, the new compound is pre
1. 48
1. 453
8
6
002
310
1. 36
16
301
1. 352
- 15
303
1. 347
7
112
1. 344
16
3
4
7
4
9
224
321
206
314
323
1. 73
90
213
1. 65
40
220
1. 54
1. 48
20
40
006
310
1. 39
40
116
pared by intimately admiXing powdered Cr2O3 and W03,
1. 243
3
202
compacting the powdered mixture into a cohesive mass,
and thereafter heat-treating the materials, usually in a
non-reducing atmosphere at a temperature from about
1. 17
4
321
1. 307
1. 256
1.241
1. 221
1. 166
1. 152
10
305
1. 148
4
400
1. 143
5
400
113
303
(116)
1. 28
10
206
1. 19
30
323
.
3,070,422
3
a,
(‘0
rAB
(a.u.) (an. (a.u.
00/30
4
In addition to the foregoing practical uses, the‘new
chromium-tungsten oxide compound of the invention is
useful in expanding the fund of knowledge in the crys
talline and refractory ?elds. Study of this compound of
unusual structure will be helpful to other scienti?c work
Table II.—I0nic ‘Radix’, Axial Ratios, and Densities
00/3/30
ers in the ?eld in suggesting avenues of approach to pre
pare similar new compounds of a trirutile and inverse
. 23
.63
O
trirutile structure.
As will be evident to those skilled in the art, various
The Cr2WO6 is relatively stable. As determined by
modi?cations of this invention can be made or followed
10
‘tests, it begins to lose W03 after ?ring at 11000 C. for
in the light of the foregoing disclosure and discussion
more than 100 hours, as shown by very weak reflections of
without departing from the spirit and scope of the dis
Cr2O3. Its color is a very intense purple-brown; it is
closure or from the scope of the claims.
insoluble in water. Its experimentally determined density
I claim:
'is shown in Table II.
1. A crystalline oxide of the formula Cr2WO6 having
The compound was determined to have very interesting 15 a rutile crystalline structure.
electrical properties. Its dielectric constant is about 16.4,
2. A method of making a crystalline oxide of the for
its dissipation factor (tan 6) about 075, power factor
mula CrZWOB having a rutile crystalline structure by a
' about 0.60, loss angle about 368°, and its resistivity about
solid-state reaction which comprises intimately admixing
163x109 ohm cm.
powders of Cr2O3 and W03, compacting the resulting ad
20
The'new compound of the invention has varied uses.
mixture into a cohesive mass, and heating said mass at a
For instance, it is a useful refractory in furnace construc
temperature of at least 800° C. up to the temperature at
tion in furnaces used to make ferrites by solid-state reac
which CrZWOG begins to decompose at an undesirable
tions carried out at temperatures below 900° C.
rate.
The new compound is also useful as a pigment or
3. A method of claim 2 wherein the temperature is
?ller for paints in normal paint-making processes. For 25 from 800 to 1100° C.
instance, the following paint ‘formula can be used.
4. A method of claim 2 wherein the temperature is
from 850 to 1000" C.
Ingredient:
Lbs.
5. A method of claim 2 wherein a substantially equi
Cr2WO6 ______________________________ __ 300
T102 ..... --
.58
Cl'gW'Os...-
.57
I Il
to»
(CN
.95
.86
Zinc oxide ____________________________ __
25
Long-oil soya alkyd resin (60% nonvolatile) __ 480
30
Mineral spirits _________________________ __ 181
Cobalt naphthenate (6% Co) ____________ _Lead naphthenate (24% Pb) ____________ __
Calcium naphthenate (4% Ca) __________ __
3
3
2 35
Total _______________________________ __ 994
The product is particularly useful because of its un<
usual electrical properties. It can ‘be described as a lossy
dielectric. It can be used in an R.C. (resistance-capaci
tance) circuit Where it continuously acts as a leaky ca
pacitance.
molar ratio of Cr2O3 and W03 is employed.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,721,117
2,735,748
Schoenlaub __________ __ Oct. 18, 1955
Wainer _____________ __ Feb. 21, 1956
2,893.832
Loung ___________ __‘-___ July 7, 1959
2,962,346
Sindlinger et al. ______ _.. Nov. 29, 1960
OTHER REFERENCES
Hoffman: Lexicon der Anorganischen Verbindungen,
Verlag Von Johann Ambrosium Barth, Leipzig, 1912~
1914, Band II, A1 to X, No. 56-81, page 726.
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