Zirconium silicate, also zirconium orthosilicate, ZrSiO
4, is a
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
, a
silicate
In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is al ...
of
zirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'', ...
. It occurs in nature as
zircon
Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of the r ...
, a
silicate mineral
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust.
In mineralogy, silica (silicon dioxide, ) is usually consid ...
. Powdered zirconium silicate is also known as zircon flour.
Zirconium silicate is usually colorless, but impurities induce various colorations. It is insoluble in water, acids, alkali and
aqua regia. Hardness is 7.5 on the
Mohs scale
The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material.
The scale was introduced in 1812 by th ...
.
Structure and bonding
Zircon consists of 8-coordinated Zr
4+ centers linked to tetrahedral orthosilicate SiO
44- sites. The oxygen atoms are all triply bridging, each with the environment OZr
2Si. Given its highly crosslinked structure, the material is hard, and hence prized as gemstone and abrasive.
Zr(IV) is a d
0 ion. Consequently the material is colorless and diamagnetic.
Production
Zirconium silicate occurs in nature as mineral
zircon
Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of the r ...
. Concentrated sources of zircon are rare. It is mined from sand deposits and separated by gravity. Some sands contain a few percent of zircon.
It can also be synthesized by fusion of
SiO2 and
ZrO2 in an arc furnace, or by reacting a zirconium salt with
sodium silicate
Sodium silicate is a generic name for chemical compounds with the formula or ·, such as sodium metasilicate , sodium orthosilicate , and sodium pyrosilicate . The anions are often polymeric. These compounds are generally colorless transparent ...
in an aqueous solution.
Uses
As of 1995, the annual consumption of zirconium silicate was nearly 1M tons. The major applications exploit its refractory nature and resistance to
corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
by
alkali
In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...
materials.
[ Two end-uses are for enamels, and ]ceramic glaze
Ceramic glaze is an impervious layer or coating of a vitreous substance which has been fused to a pottery body through firing. Glaze can serve to color, decorate or waterproof an item. Glazing renders earthenware vessels suitable for holding ...
s. In enamels and glazes it serves as an opacifier
An opacifier is a substance added to a material in order to make the ensuing system opaque. An example of a chemical opacifier is titanium dioxide (TiO2), which is used as an opacifier in paints, in paper, and in plastics. It has very high refracti ...
. It can be also present in some cement
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mix ...
s.
Another use of zirconium silicate is as beads for milling and grinding
Grind is the cross-sectional shape of a blade.
Grind, grinds, or grinding may also refer to:
Grinding action
* Grinding (abrasive cutting), a method of crafting
* Grinding (dance), suggestive club dancing
* Grinding (video gaming), repetitive and ...
.
Thin film
A thin film is a layer of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in many ap ...
s of zirconium silicate and hafnium silicate
Hafnium silicate is the hafnium(IV) salt of silicic acid with the chemical formula of HfSiO4.
Thin films of hafnium silicate and zirconium silicate grown by atomic layer deposition, chemical vapor deposition or MOCVD, can be used as a high-k diel ...
produced by chemical vapor deposition
Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films.
In typical CVD, the wafer (substra ...
, most often MOCVD
Metalorganic vapour-phase epitaxy (MOVPE), also known as organometallic vapour-phase epitaxy (OMVPE) or metalorganic chemical vapour deposition (MOCVD), is a chemical vapour deposition method used to produce single- or polycrystalline thin films. ...
, can be used as a high-k dielectric as a replacement for silicon dioxide
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...
in semiconductors.[
]
Zirconium silicates have also been studied for potential use in medical applications. For example, ZS-9
Sodium zirconium cyclosilicate (ZS-9), sold under the brand name Lokelma, is a medication used to treat high blood potassium. Onset of effects occurs in one to six hours. It is taken by mouth.
Common side effects include swelling and low blood ...
is a zirconium silicate that was designed specifically to trap potassium ions
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
over other ions throughout the gastrointestinal tract.
Toxicity
Zirconium silicate is an abrasive irritant for skin and eyes. Chronic exposure to dust can cause pulmonary granuloma
A granuloma is an aggregation of macrophages that forms in response to chronic inflammation. This occurs when the immune system attempts to isolate foreign substances that it is otherwise unable to eliminate. Such substances include infectious ...
s, skin inflammation, and skin granuloma. However, there are no known adverse effects for normal, incidental ingestion.
References
{{Zirconium compounds
Silicates
Zirconium compounds
Refractory materials
High-κ dielectrics