Compositions: ceramic – Ceramic compositions – Synthetic precious stones
Patent
1983-10-24
1985-06-25
Bell, Mark L.
Compositions: ceramic
Ceramic compositions
Synthetic precious stones
423263, 423265, 501152, C04B 2700, C30B 2928
Patent
active
045254605
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the art of artificial single crystals and, more specifically, to a single-crystal material based on aluminium garnets.
BACKGROUND OF THE INVENTION
Known in the art is a single-crystal material based on yttrium-aluminium garnet (Y.sub.3 Al.sub.5 O.sub.12) containing chromium as a dyeing additive in an amount of 0.01 to 3% by weight. This material has a green colour and a red luminescence (cf. CSSR Pat. No. 152,908 Cl. B 01 J 17/02, published 08.12.71).
Also known is a single-crystalline Jewelry material based on yttrium-aluminium garnet, wherein as the dyeing additive titanium is used in an amount of from 1.10.sup.-4 to 1% by weight. This material has a clearly pronounced brown colour under daylight passing to a reddish colour at an artificial illumination (cf. USSR Inventor's Certificate No. 594628, Cl. B 01 J 17/00, Bulletin No. 17 published in 1978).
The use of these dyeing additives in the above-mentioned single-crystalline materials does not make it possible to obtain a red dyeing spectrum.
SUMMARY OF THE INVENTION
The present invention is directed to the provision of a single-crystalline material based on aluminium garnets which, through the selection of a novel dyeing additive, would have colours of a red spectrum.
This object is accomplished by that of a single-crystalline material based on aluminium garnets of the general formula: Re.sub.3 Al.sub.5 O.sub.12, wherein Re=Y, Dy, Ho, Er, Lu and incorporating a dyeing additive containing, as the latter, zirconium in an amount of from 10.sup.-2 to 3% by weight.
To impart a red colour to a single-crystalline material based on yttrium-aluminium garnet, it preferably contains zirconium in an amount of from 10.sup.-2 to 3% by weight.
A single-crystalline material based on dyeprosium-aluminium garnet, for the purpose of imparting a red colour thereto, preferably contains zirconium in an amount of from 10.sup.-2 to 3% by weight.
To impart a reddish-brown colour, a single-crystalline material based on holmium-aluminium garnet preferably contains zirconium in an amount of from 10.sup.-2 to 3% by weight. A single-crystalline material based on erbium-aluminium garnet preferably contains, for the purpose of imparting a red-yellow-brown colour thereto, zirconium in an amount of from 10.sup.-2 to 3% by weight.
To impart a red colour, a single-crystalline material based on lutecium-aluminium garnet preferably contains zirconium in an amount of from 10.sup.-2 to 3% by weight.
The single-crystalline material according to the present invention, owing to the use of a novel dyeing additive, has a red colour spectrum sufficiently close to that of corresponding naturally-occurring almandine, pyrope, hessonites or hyacinth.
DETAILED DESCRIPTION OF THE INVENTION
The single-crystalline material based on aluminium garnets according to the present invention can be produced by known methods of growing refractory single crystals from a melt, e.g. using Bridgeman-Stockbarger, Chokhralsky methods, debiteuse and the like. Basically use is made of aluminium garnets of the general formula Re.sub.3 Al.sub.5 O.sub.12, wherein Re=Y, Dy, Ho, Er, Lu. The dyeing additive is introduced into the starting material as zirconia (ZrO.sub.2). For a better understanding of the present invention the following Examples illustrating the single-crystalline material according to the invention are given below.
EXAMPLE 1
A single-crystalline material based on yttrium-aluminium garnet Y.sub.3 Al.sub.5 O.sub.12 containing zirconium as a dyeing additive in the amount of 0.01% by weight is prepared by the Bridgeman-Stockbarger method. A mixture of oxides consisting of the following components, percent by weight:
______________________________________ Y.sub.2 O.sub.3
57.060
Al.sub.2 O.sub.3
42.926
ZrO.sub.2
0.014
______________________________________
order of 2,000.degree. C. and crystallized at the speed of movement of the
drawing mechanism of 2 mm/hr. The thus-produced crystal has a light-red
colour.
EXAMPLE 2
A
REFERENCES:
patent: 3420780 (1969-01-01), Forrat et al.
WO83/02962, PCT/SU/82/00010, Sep. 1, 1983, Petrosian, et al.
Journal of Crystal Growth, vol. 56, No. 3, (Feb. 1982), pp. 677-689.
Bagdasarov Khachik S.
Butaeva Tatyana I.
Kuzanian Armen S.
Ovanesian Karine L.
Petrosian Ashot G.
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