Zirconium silicate, also zirconium orthosilicate, ZrSiO₄, 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 a ...

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 t ...

, 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 ...

Structure and bonding

Zircon consists of 8-coordinated Zr⁴⁺ centers linked to tetrahedral orthosilicate SiO₄^4- sites. The oxygen atoms are all triply bridging, each with the environment OZr₂Si. Given its highly crosslinked structure, the material is hard, and hence prized as gemstone and abrasive. Zr(IV) is a d⁰ ion. Consequently the material is colorless and diamagnetic.

Production

Zirconium silicate occurs in nature as mineral

. 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 engi ...

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 refract ...

. 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 mixe ...

s. Another use of zirconium silicate is as beads for milling and grinding.

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 ...

s of zirconium silicate and hafnium silicate 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 (subst ...

, most often MOCVD, 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 o ...

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