Nomenclature
CAS number: 10101-52-7
Zirconium orthosilicate.
O
4SiZr; mol wt 183.31.
O 34.91%, Si 15.32%, Zr 49.76%.
ZrSiO
4.
Description and references
Occurs in nature as the mineral zircon. Widely scattered in all kinds of rocks and in beach sand
(South Carolina, Northeast Florida). Usually separated from sand
by electrostatic and electromagnetic elutriation, yielding 99% pure
ZrSiO4. Prepn from SiO2 and ZrO2 in an arc furnace: Curtis, Sowman, J. Am.
Ceram. Soc. 36, 195 (1953); can also be made
from solns of zirconium salts and sodium silicate.
Properties
Tetragonal, bipyramidal crystals. Should be colorless.
Colors are from impurities and radioactive bombardment, often removable
by calcination. Dissociates to ZrO2 and SiO2 when heated above 1540°. Recombines when cooled slowly, but forms
a mixture of monoclinic ZrO2 and vitreous SiO2 when rapidly quenched. Undissociated (α-form) ZrSiO4 has a high sp gr, 4.7, and a high birefringence; the dissociated, γ-form
has a lower sp gr, 3.9-4.0, and a low birefringence. Hardness of α-form
about the same as that of quartz (6-7.5). Very inert chemically.
Unaffected by aq reagents.Use
In refractories, ceramics, glazes, cements, coatings
for casting molds, polishing materials, gem stones, catalyst in alkyl
and alkenyl hydrocarbon manuf, in fritted glass filters, as stabilizer
in silicone rubbers. In Europe in cosmetic creams and powders.