Strontium titanate is an oxide of strontium and titanium with the chemical formula SrTiO₃. It is a centrosymmetric ferroelectric material with a perovskite structure. It was long thought to be a wholly artificial material, until 1982 when its natural counterpart—discovered in Siberia and named tausonite—was recognised by the IMA. Tausonite remains an extremely rare mineral in nature, occurring as very tiny crystals. Its most important application has been in its synthesized form wherein it is occasionally encountered as a diamond simulant, in precision optics, in varistors, and in advanced ceramics. This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... Rose des Sables (Sand Rose), formed of gypsum crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... In crystallography, the cubic crystal system (or isometric crystal system) is the most symmetric of the 7 crystal systems. ... Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types: Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes. ... For fractures in bones, see Fracture (bone). ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... The refractive index of a material is the factor by which the phase velocity of electromagnetic radiation is slowed relative to vacuum. ... Pleochroism is an optical phenomenon where due to double refraction of light by a colored gem or crystal, the light is divided into two paths which are polarized at a 90° angle to each other. ... The term streak is used in several ways: Streaking, the act of running around nude in public places. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... Fusibility is the ease with which a material will melt. ... A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ... An oxide is a chemical compound of oxygen with other chemical elements. ... General Name, Symbol, Number strontium, Sr, 38 Chemical series alkaline earth metals Group, Period, Block 2, 5, s Appearance silvery white metallic Atomic mass 87. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... In physics, the ferroelectric effect is an electrical phenomenon whereby certain ionic crystals may exhibit a spontaneous dipole moment. ... Perovskite (calcium titanium oxide, CaTiO3) is a relatively rare mineral occurring in orthorhombic (pseudocubic) crystals. ... 1982 (MCMLXXXII) is a common year starting on Friday of the Gregorian calendar. ... Siberia Siberia (Russian: , common English transliterations: Sibir’, Sibir; from the Tatar for “sleeping land”) is a vast region of Russia and northern Kazakhstan constituting almost all of northern Asia. ... The International Mineralogical Association (IMA) is an international group of 38 national societies. ... Quartz crystal A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. ... This article addresses the many imitations of diamond. ... See also: List of optical topics Optics (appearance or look in ancient Greek) is a branch of physics that describes the behavior and properties of light and the interaction of light with matter. ... A varistor is an electronic component with a significant non-ohmic current-voltage characteristic. ... The word ceramic is derived from the Greek word Κεραμεικος (the name of a suburb of Athens), and in its strictest sense refers to clay in all its forms. ...

The name tausonite was given in honour of Lev Vladimirovich Tauson (1917-1989), a Russian geochemist. Disused trade names for the synthetic product include strontium mesotitanate, Fabulite, Diagem, and Marvelite. The field of geochemistry involves study of the chemical composition of the Earth and other planets, chemical processes and reactions that govern the composition of rocks and soils, and the cycles of matter and energy that transport the Earths chemical components in time and space, and their interaction with...

Other than its type locality of the Murun Massif in the Sakha Republic, natural tausonite is also found in: Cerro Sarambi, Concepción department, Paraguay; and along the Kotaki River of Honshu Island, Japan. The Sakha (Yakutia) Republic (Yakut: Саха Республиката; Russian: ) is a federal subject of the Russian Federation (a republic). ... Concepción is a department of Paraguay. ... HonshÅ«   listen? (本州) is the largest island of Japan, called the Mainland; it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait. ...

Properties

Strontium titanate is both much denser (specific gravity 4.88 for natural, 5.13 for synthetic) and much softer (Mohs hardness 6–6.5 for natural, 5.5 for synthetic) than diamond. Its crystal system is cubic and its refractive index (2.41—as measured by sodium light, 589.3 nm) is nearly identical to that of diamond, but the dispersion (the optical property responsible for the "fire" of the cut stones) of strontium titanate is over four times higher, at 0.19 (B–G interval). This results in an excess of fire when compared to diamond. Relative density (also known as specific gravity) is a measure of the density of a material. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... A scattering of round-brilliant cut diamonds shows off the many reflecting facets. ... In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... In crystallography, the cubic crystal system (or isometric crystal system) is the most symmetric of the 7 crystal systems. ... The refractive index of a material is the factor by which the phase velocity of electromagnetic radiation is slowed relative to vacuum. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... In optics, dispersion is a phenomenon that causes the separation of a wave into spectral components with different frequencies, due to a dependence of the waves speed on its frequency. ...

Synthetics are usually transparent and colourless, but can be doped with certain rare earth or transition elements to give reds, yellows, browns, and blues. Natural tausonite is usually translucent to opaque, in shades of reddish brown, dark red, or grey. Both have an adamantine (diamond-like) lustre. Strontium titanate is considered extremely brittle with a conchoidal fracture; natural material is cubic or octahedral in habit and streaks brown. Through a hand-held (direct vision) spectroscope, doped synthetics will exhibit a rich absorption spectrum typical of doped stones. Synthetic material has a melting point of ca. 2080°C (3776°F) and is readily attacked by hydrofluoric acid. A dopant is an impurity element added to a semiconductor lattice in quite low concentrations in order to alter the optical/electrical properties of the semiconductor. ... A rare earth is an oxide of a rare earth element. ... This article is in need of attention. ... Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock or mineral. ... Conchoidal fracture describes the way that brittle materials break when they do not follow any natural planes of separation. ... In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. ... The term streak is used in several ways: Streaking, the act of running around nude in public places. ... A spectroscope is a device which measures the spectrum of light. ... An absorption spectrum is a diagram depicting the wavelengths of electromagnetic radiation absorbed by a material. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... R-phrases , S-phrases , , , , Flash point non flammable RTECS number MW7875000 Supplementary data page Structure & properties n, εr, etc. ...

Also possessed by synthetic material is a very large dielectric constant (300), and at very low temperatures, piezoelectric and superconductive properties. The dielectric constant εr (represented as or K in some cases) is defined as the ratio: where εs is the static permittivity of the material in question, and ε0 is the vacuum permittivity. ... Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress. ... A magnet levitating above a high-temperature superconductor (with boiling liquid nitrogen underneath) demonstrates the Meissner effect. ...

At temperatures lower than 105 K, its cubic structure transforms to tetragonal. It is an excellent substrate for epitaxial growth of high-temperature superconductors and many oxide-based thin films. Its monocrystals can be used as optical windows and high-quality sputtering targets. In crystallography, the tetragonal crystal system is one of the 7 lattice point groups. ... Unsolved problems in physics: Why do certain materials exhibit superconductivity at temperatures much higher than 50 kelvins? The term high-temperature superconductor was initially employed to designate the new family of cuprate-perovskite ceramic materials discovered by J.G. Bednorz and K.A. Müller in 1986. ... Thin-film optics is the branch of optics which deals with very thin structured layers of different materials. ... Sputtering is a physical process whereby atoms in a solid target material are ejected into the gas phase due to bombardment of the material by energetic ions. ...

Nb:SrTiO₃, niobium doped strontium titanate, is electrically conductive. General Name, Symbol, Number niobium, Nb, 41 Chemical series transition metals Group, Period, Block 5, 5, d Appearance gray metallic Atomic mass 92. ...

Synthesis

Synthetic strontium titanate was one of several titanates patented during the late 1940s and early 1950s; other titanates included barium titanate and calcium titanate. Research was conducted primarily at the National Lead Company (later renamed N. L. Industries, Inc.) in the United States, by Leon Merker and Langtry E. Lynd. Merker and Lynd first patented the growth process on February 10, 1953; a number of refinements were subsequently patented over the next four years, such as modifications to the feed powder and additions of colouring dopants. The chemical compound Titanic acid, Ti(OH)4, is a white weak acid that is a hydrated form of titanium dioxide. ... A patent is a set of exclusive rights granted by a state to a person for a fixed period of time in exchange for the regulated, public disclosure of certain details of a device, method, process or composition of matter (substance) (known as an invention) which is new, inventive and... 1940 (MCMXL) was a leap year starting on Monday (link will take you to calendar). ... 1950 (MCML) was a common year starting on Sunday (link will take you to calendar). ... Barium titanate is an oxide of barium and titanium with the chemical formula BaTiO3. ... February 10 is the 41st day of the year in the Gregorian Calendar. ... 1953 (MCMLIII) is a common year starting on Thursday. ...

A modification to the basic Verneuil process (also known as flame-fusion) is the favoured method of growth. An inverted oxy-hydrogen blowpipe is used, with feed powder mixed with oxygen carefully fed through the blowpipe in the typical fashion, but with the addition of a third pipe to deliver oxygen—creating a tricone burner. The extra oxygen is required for successful formation of strontium titanate, which would otherwise fail to oxidize completely due to the titanium component. The ratio is ca. 1.5 volumes of hydrogen for each volume of oxygen. The highly purified feed powder is derived by first producing titanyl double oxalate salt (SrTiO(C₂O₄)₂.2H₂O) by reacting strontium chloride (SrCl₂) and oxalic acid ((COOH)₂.2H₂O) with titanium tetrachloride (TiCl₄). The salt is washed to completely eliminate chloride, heated to 1000°C in order to produce a free-flowing granular powder of the required composition, and is then ground and seived to ensure all particles are between 0.2–0.5 micrometres in size. A blowgun or blowpipe is a simple weapon consisting of a small tube for firing light projectiles, or darts. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Chalcogens Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Salt Crystals (http://www. ... Strontium chloride (SrCl2) is a salt of strontium and chlorine. ... Oxalic acid (IUPAC name: ethanedioic acid, formula H2C2O4) is a dicarboxylic acid with structure (HOOC)-(COOH). ... Titanium tetrachloride (TiCl4) is used for commercial production of pure titanium metal. ... The chloride ion is formed when the element chlorine picks up one electron to form the anion (negatively charged ion) Cl−. The salts of hydrochloric acid HCl contain chloride ions and are also called chlorides. ... A micrometre (American spelling: micrometer), symbol µm, is an SI unit of length. ...

The feed powder falls through the oxyhydrogen flame, melts, and lands on a rotating and slowly descending pedestal below. The height of the pedestal is constantly adjusted to keep its top at the optimal position below the flame, and over a number of hours the molten powder cools and crystallises to form a single pedunculated pear or boule crystal. This boule is usually no larger than 2.5 centimetres in diameter and 10 centimetres long; it is an opaque black to begin with, requiring further annealing in an oxidizing atmosphere in order to make the crystal colourless and to relieve strain. This is done at over 1000°C for 12 hours. An oxyhydrogen flame is the flame attending the combustion of hydrogen and oxygen, and is characterized by a very high temperature. ... A boule is a term used to describe a single crystal ingot produced by synthetic means. ... The word anneal has several meanings: In metallurgy and materials science annealing is a heat treatment wherein the microstructure of a material is altered, causing changes in its properties such as strength and hardness. ... In any branch of science dealing with materials and their behaviour, strain is the geometrical expression of deformation caused by the action of stress on a physical body. ...

Use as a diamond simulant

Its cubic structure and high dispersion once made synthetic strontium titanate a prime candidate for simulating diamond. Beginning ca. 1955, large quantities of strontium titanate were manufactured for this sole purpose. Strontium titanate was in competition with synthetic rutile ("titania") at the time, and had the advantage of lacking the unfortunate yellow tinge and strong birefringence inherent to the latter material. While it was softer, it was significantly closer to diamond in likeness. Eventually, however, both would fall into disuse, being eclipsed by the creation of "better" simulants: first by yttrium aluminium garnet (YAG) and followed shortly after by gadolinium gallium garnet (GGG); and finally by the (to date) ultimate simulant in terms of diamond-likeness and cost-effectiveness, cubic zirconia. 1955 (MCMLV) was a common year starting on Saturday of the Gregorian calendar. ... Rutile in trellis texture characteristic of secondary rutile. ... A calcite crystal laid upon a paper with some letters showing the double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays (the ordinary ray and the extraordinary ray) when it passes through certain types of material, such as calcite crystals, depending on... YAG Yttrium Aluminum Garnet YAG is used in various lasers, doped with e. ... Gallium Gadolinium Garnet (GGG, Gd3Ga5O12) is a material with good mechanical, thermal, and optical properties. ... A round brilliant-cut cubic zirconia Cubic Zirconia (or CZ) is zirconium oxide (ZrO2), a mineral that is extremely rare in nature but is widely synthesized for use as a diamond simulant. ...

Despite being outmoded, strontium titanate is still manufactured and periodically encountered in jewellery. It is one of the most costly of diamond simulants, and due to its rarity collectors may pay a premium for large i.e. >2 carat (400 mg) specimens. As a diamond simulant, strontium titanate is most deceptive when mingled with melée i.e. <0.20 carat (40 mg) stones and when it is used as the base material for a composite or doublet stone (with, e.g., synthetic corundum as the crown or top of the stone). Under the microscope, gemmologists distinguish strontium titanate from diamond by the former's softness—manifested by surface abrasions—and excess dispersion (to the trained eye), and occasional gas bubbles which are remnants of synthesis. Doublets can be detected by a join line at the girdle ("waist" of the stone) and flattened air bubbles or glue visible within the stone at the point of bonding. The carat is a unit of mass used for gems, and equals 200 milligrams. ... Corundum is the crystalline form of aluminium oxide and one of the rock-forming minerals. ... 1852 microscope Compound microscope made by John Cuff in 1750 A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. ... Gemology (gemmology outside the United States) is the science, art and profession of identifying and evaluating gemstones. ...

References

• Nassau, K. (1980). Gems made by man, pp. 214–221. Gemological Institute of America; Santa Monica, California. ISBN 087330161
• O'Donoghue, M. (2002). Synthetic, imitation & treated gemstones, p. 34, 65. Elsevier Butterworth-Heinemann, Great Britain. ISBN 0705631732
• Read, P. G. (1999). Gemmology, second edition; p. 173, 176, 177, 293. Butterworth-Heinemann, Great Britain. ISBN 0750644117
• Webmineral. Tausonite. Retrieved February 19, 2005 from http://webmineral.com/data/Tausonite.shtml

External links

• An electron micrograph of strontium titanate, as artwork entitled "Strontium" at the DeYoung Museum in San Francisco