ALUMO-YTTRIUM GARNET CRUCIBLES MADE BY SLIP CASTING
FOR WORK WITH HIGH-PURITY POWDERS
Yu. G. Trifonov,
G. A. Dosovitskii,
D. E. Kuznetsova,
and V. P. Tarasovskii
Translated from Novye Ogneupory, No. 2, pp. 38 – 41, February, 2016.
Original article submitted November 11, 2015.
The method of slip casting is used to make dense ceramic crucibles of cerium-doped alumo-yttrium garnet.
Use of the crucibles to heat-treat this material does not lead to its contamination at temperatures up to 1600°C.
A laboratory technology for making the crucibles is described.
Keywords: ceramic, alumo-yttrium garnet, powder, slip casting, crucibles.
When high-purity chemical substances undergo heat
treatment in crucibles of a different chemical composition,
the substances may become contaminated by their interac-
tion with the crucible material. One of the standard ap-
proaches to resolving this problem is the use of crucibles
which are made of the same material as the substance being
We have developed a technology for making crucibles
that can be used to heat-treat powders of alumo-yttrium gar
(YAG). Alumo-yttrium garnet is frequently
employed as a matrix in the production of luminescent mate
rials. The luminophores that are most commonly used to pro
duce white light in solid-state lighting are based on
alumo-yttrium garnet activated by cerium (YAG:Ce) [1 – 3].
Cerium-activated YAG is also a widely used scintillator .
Nickel-activated YAG is used to make the working media of
solid-state lasers . A method that is often employed to ob
tain powders of alumo-yttrium garnet in one stage of the
YAG production process includes the high-temperature heat
treatment of an oxide mixture that is itself mixed with hy
droxides, carbonates, or other compounds of Y and Al. The
heat treatment is usually carried out in a crucible made of
aluminum oxide, and this material can contaminate the prod
uct of the heat-treatment operation. Such contamination is
particularly undesirable when small samples are being pro-
duced for laboratory studies, due to the large ratio of the cru-
cible/sample contact areas. Since crucible manufacturers do
not make the products that are needed, we attempted to make
them independently by using materials that will not contami-
nate the contents of the crucible with foreign impurities.
The technology of slip casting in gypsum molds is
widely used to obtain thin-walled products of complex
shape. The main distinction of this method is that it can be
realized in a standard chemical laboratory. In order to obtain
a product having the requisite characteristics, it is necessary
to optimize the properties of the slip. The foremost objec
tives in doing so are to increase the slip’s fluidity and resis
tance to delamination. We used pH regulators that do not
contaminate slips with foreign impurities in order to control
the casting characteristics of the slip employed in our investi
YAG powder doped with Ce was obtained by co-deposi
tion from nitric acid solutions with the use of NH
precipitating agent. The deposit was calcined at 1000°C for
2 h. The raw materials were 99.99% pure yttrium oxide and
analytically pure nitrates of aluminum and cerium. The
method used to obtain YAG:Ce powder was described in
more detail in . A total of 100 g of the calcined powder
was charged into the drum of a ball mill lined with corundum
tiles. The mill contained spheres of dense-sintered aluminum
oxide (the weight of the spheres was 450 g). We also added
Refractories and Industrial Ceramics Vol. 57, No. 1, May, 2016
1083-4877/16/05701-0081 © 2016 Springer Science+Business Media New York
”IREA” Company, Moscow, Russia.
Moscow State University of Mechanical Engineering, Moscow,
”Bakor” Scientific-Technical Center, Shcherbinka District, Mos