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 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 also used ...

zirconium Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyis ...

. 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 th ...

, 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, the crystalline forms of silica (silicon dio ...

. 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 Aqua regia (; from Latin, "regal water" or "royal water") is a mixture of nitric acid and hydrochloric acid, optimally in a molar concentration, molar ratio of 1:3. Aqua regia is a fuming liquid. Freshly prepared aqua regia is colorless, but i ...

. 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 minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the Ger ...

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 tra ...

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 ...

alkali In chemistry, an alkali (; from the Arabic word , ) is a basic 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 soluble base has a pH greater than 7.0. The a ...

materials. Two end-uses are for enamels, and

ceramic glaze Ceramic glaze, or simply glaze, is a glassy coating on ceramics. It is used for decoration, to ensure the item is impermeable to liquids and to minimize the adherence of pollutants. Glazing renders earthenware impermeable to water, sealing th ...

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 mi ...

s. Another use of zirconium silicate is as beads for

milling Milling may refer to: * Milling (minting), forming narrow ridges around the edge of a coin * Milling (grinding), breaking solid materials into smaller pieces by grinding, crushing, or cutting in a mill * Milling (machining), a process of using ro ...

and grinding.

Thin film A thin film is a layer of materials 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 (electro ...

, 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 , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundan ...

in semiconductors. Zirconium silicates have also been studied for potential use in medical applications. For example, ZS-9 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 convent ...

over other ions throughout the gastrointestinal tract. Zirconium silicate is also used as foundry sands due to its high thermal stability. t is also the primary source of

, which is used in various applications, including in

nuclear reactors A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction. They are used for commercial electricity, marine propulsion, weapons production and research. Fissile nuclei (primarily uranium-235 or plutonium-2 ...

, due to its high resistance to corrosion and low

neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

absorption.

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 (along with other cells) 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 sub ...

s, skin inflammation, and skin granuloma. However, there are no known adverse effects for normal, incidental ingestion.

References

{{Zirconium compounds Silicates Zirconium(IV) compounds Refractory materials High-κ dielectrics