Compositions: ceramic – Ceramic compositions – Synthetic precious stones
Patent
1983-10-24
1985-09-24
Bell, Mark L.
Compositions: ceramic
Ceramic compositions
Synthetic precious stones
423263, 423265, C01F 1700, C04B 3550
Patent
active
045433429
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to artificial single crystals and, more specifically, to a single-crystalline jewelry material based on aluminium garnets.
BACKGROUND OF THE INVENTION
Known in the art are single crystals of yttrium-aluminium garnet Y.sub.3 Al.sub.5 O.sub.12 containing cobalt as a dyeing additive in an amount of from 0.01 to 3% by weight. Depending on the amount of the dyeing additive the crystals have a blue, green-blue or green colour (cf. CSSR Pat. No. 152909 Int. Cl. B 01 j 17/02, published 08.12.71).
Also known are single crystals of yttrium-aluminium garnet Y.sub.3 Al.sub.5 O.sub.12 of a green colour containing, as the dyeing additive, vanadium in the amount of 0.01% by weight (cf. CSSR Pat. No. 153870, Int. Cl. B 01 j 17/02, published 25.10.71).
To produce Y.sub.3 Al.sub.5 O.sub.12 crystals of a deep green colour with a slight sky-blue and emerald shade, chromium oxides are introduced into the starting charge in an amount of 0.11 to 0.27% by weight, cobalt oxide--in an amount of 0.21-1.38% by weight, iron oxide in an amount of 0.20 to 1.33% by weight and neodymium oxide--in an amount of 0.05 to 0.30% by weight (cf. U.S. Pat. No. 3,761,292 Int. Cl. C 04 B 35/00, published 25.09.73).
These materials contain, as dyeing additives, chromium, vanadium, cobalt, iron. Oxides of these dyeing additives have relatively high values of vapour tension which causes difficulties in the process of the production of uniform deep-coloured single crystals, especially under high vacuum conditions. This factor limits the opportunities for a large-scale production of these materials for jewelry applications.
Furthermore, formulations of these materials do not provide for the possibility of controlling the brightness of the material dyeing into a definite colour, smooth colour variation within a broad colour range, as well as obtaining a violet colour which is of interest for simulation of, for example, amethyst in jewelry articles.
SUMMARY OF THE INVENTION
The present invention is directed to the provision, by selection of new combinations of dyeing additives in appropriate proportions, of a single-crystalline jewelry material based on aluminium garnets which would have a colour smoothly varying from green to violet, a predetermined brightness and depth of dyeing into a given colour.
This object is accomplished by a single-crystalline jewelry material base of aluminium garnets corresponding to the general formula: Re.sub.3 Al.sub.5 O.sub.12, wherein Re is Y, Dy, Ho, Er, Tm, Lu in combination with dyeing additives. According to the present invention, two additives used include one which is selected from the group of europium, in an amount of 10.sup.-3 to 3% by weight and ytterbium in an amount of from 0.1 to 61.3% by weight and the other is selected from a group of zirconium or silicon in an amount of 10.sup.-4 to 1.0% by weight, or hafnium in an amount of from 10.sup.-3 to 3% by weight.
To impart to the material according to the present invention a green colour of a moderate brightness, ytterbium in an amount of from 0.1 to 9% by weight and zirconium in an amount of from 10.sup.-3 to 1% by weight are used as dyeing additives. To impart a bright-green colour to the material according to the present invention, it preferably contains, as the dyeing additives, ytterbium in an amount of from 0.1 to 25% by weight and silicon in an amount of from 10.sup.-2 to 1% by weight. To impart a green-sky-blue or sky-blue colour to the material according to the present invention, it is advisable that it contain ytterbium as the dyeing additive in an amount of from 25 to 61.3% by weight and silicon in an amount of from 10.sup.-4 to 0.1% by weight. To obtain colour of from blue to violet-blue, the material according to the present invention should preferably contain, as the dyeing additive, ytterbium in an amount of from 10 to 61.3% by weight and zirconium in an amount of from 10.sup.-4 to 0.1% by weight. To impart a bright-blue colour imitating that of a naturally-occurring sapphire, the material a
REFERENCES:
patent: 3761292 (1973-09-01), Lepore et al.
Reviews on Electronic Technique by B. N. Grechushnikov, et al, Serial No. 10, issue 3(418), 4(423), published 1976 ("Elektronika" Moscow), B. N. Grechushnikov et al., Opticheskie svoistva i primenenie v lazerakh kristallov ittrii-aluminievogo granata, pp. 83-87.
Kristall und Technik Crystal Research and Technology, Heft 2, 1975, Band 10, by Kvapil et al, pp. 161-165, Dated 1975, "O Centre Formation in YAG Crystals Doped with Rare Earth Ions".
"Sintez mineralov i eksperimentalnye issledovania", Editor A. A. Shaposhnikova to al. (Nedra, Moscow), pp. 72-75.
6 Mezhdunarodnaya konferentsia po rostu kristallov, Rasshirennye tezisy, vol. III, "Rost iz rasplavov i vysokotemperaturnykh rastvorov", 1980, Moscow S. F. Akhmetov et al, Growing coloured varieties of yttrium-aluminium garnets by the method of horizontally directed crystallization, pp. 83-84.
Avetisian Ashot A.
Butaeva Tatyana I.
Kuzanian Armen S.
Ovanesian Karine L.
Petrosian Ashot G.
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