Tellurium dioxide

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Tellurium dioxide
TeO2powder.jpg
Cryst struct teo2.png
α-TeO2, paratellurite
Names
Other names
Tellurium(IV) oxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.357 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/O2Te/c1-3-2 Yes check.svgY
    Key: LAJZODKXOMJMPK-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/O2Te/c1-3-2
    Key: LAJZODKXOMJMPK-UHFFFAOYAO
  • O=[Te]=O
Properties
TeO2
Molar mass 159.60 g/mol
Appearancewhite solid
Density 5.670 g/cm3(orthorhombic)
6.04 g/cm3 (tetragonal) [1]
Melting point 732 °C (1,350 °F; 1,005 K)
Boiling point 1,245 °C (2,273 °F; 1,518 K)
negligible
Solubility soluble in acid and alkali
2.24
Hazards
Flash point Non-flammable
Related compounds
Other cations
Sulfur dioxide
Selenium dioxide
Related tellurium oxides
Tellurium trioxide
Tellurium monoxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Tellurium dioxide (TeO2) is a solid oxide of tellurium. It is encountered in two different forms, the yellow orthorhombic mineral tellurite, β-TeO2, and the synthetic, colourless tetragonal (paratellurite), α-TeO2. [2] Most of the information regarding reaction chemistry has been obtained in studies involving paratellurite, α-TeO2. [3]

Preparation

Paratellurite, α-TeO2, is produced by reacting tellurium with O2: [2]

Te + O2 → TeO2

An alternative preparation is to dehydrate tellurous acid, H2TeO3, or to thermally decompose basic tellurium nitrate, Te2O4·HNO3, above 400 °C. [2]

Physical properties

The longitudinal speed of sound in Tellurium dioxide is 4,260 metres per second (14,000 ft/s) at around room temperature. [4]

Chemical properties

TeO2 is barely soluble in water and soluble in strong acids and alkali metal hydroxides. [5] It is an amphoteric substance and therefore can act both as an acid or as a base depending on the solution it is in. [6] It reacts with acids to make tellurium salts and bases to make tellurites. It can be oxidized to telluric acid or tellurates.

The tellurite ion is kinetically inert, but TeO2 equivalents will oxidize thioates in acid to the diacyl disulfide. [7]

Structure

Paratellurite, α-TeO2, converts at high pressure into the β-, tellurite form. [8] Both the α-, (paratellurite) and β- (tellurite forms) contain four coordinate Te with the oxygen atoms at four of the corners of a trigonal bipyramid. In paratellurite all vertices are shared to give a rutile-like structure, where the O-Te-O bond angle are 140°. α-TeO2 In tellurite pairs of trigonal pyramidal, TeO4 units, sharing an edge, share vertices to then form a layer. [8] The shortest Te-Te distance in tellurite is 317 pm, compared to 374 pm in paratellurite. [8] Similar Te2O6 units are found in the mineral denningite. [8]

TeO
2 melts at 732.6 °C, forming a red liquid. [9] The structure of the liquid, as well as the glass which can be formed from it with sufficiently rapid cooling, are also based on approximately four coordinate Te. However, compared to the crystalline forms, the liquid and glass appear to incorporate short-range disorder (a variety of coordination geometries) which marks TeO2 glass as distinct from the canonical single-oxide glass-formers such as SiO2, which share the same short-range order with their parent liquids. [10]

Uses

It is used as an acousto-optic material. [4]

Tellurium dioxide is also a reluctant glass former, it will form a glass under suitable cooling conditions, [11] or with additions of a small molar fraction of a second compound such as an oxide or halide. TeO2 glasses have high refractive indices and transmit into the mid-infrared part of the electromagnetic spectrum, therefore they are of technological interest for optical waveguides. Tellurite glasses have also been shown to exhibit Raman gain up to 30 times that of silica, useful in optical fibre amplification. [12]

Safety

TeO2 is a possible teratogen. [13]

Exposure to tellurium compounds produces a garlic-like odour on the breath, caused by the formation of diethyl telluride. [14]

Related Research Articles

<span class="mw-page-title-main">Tellurium</span> Chemical element with atomic number 52 (Te)

Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally found in its native form as elemental crystals. Tellurium is far more common in the Universe as a whole than on Earth. Its extreme rarity in the Earth's crust, comparable to that of platinum, is due partly to its formation of a volatile hydride that caused tellurium to be lost to space as a gas during the hot nebular formation of Earth.

<span class="mw-page-title-main">Silicon dioxide</span> Oxide of silicon

Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO2, 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 abundant families of materials, existing as a compound of several minerals and as a synthetic product. Examples include fused quartz, fumed silica, opal, and aerogels. It is used in structural materials, microelectronics, and as components in the food and pharmaceutical industries. All forms are white or colorless, although impure samples can be colored.

A metalloid is a chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals. The word metalloid comes from the Latin metallum ("metal") and the Greek oeides. There is no standard definition of a metalloid and no complete agreement on which elements are metalloids. Despite the lack of specificity, the term remains in use in the literature.

Sulfur trioxide (alternative spelling sulphur trioxide) is the chemical compound with the formula SO3. It has been described as "unquestionably the most [economically] important sulfur oxide". It is prepared on an industrial scale as a precursor to sulfuric acid.

<span class="mw-page-title-main">Tellurate</span> Compound containing an oxyanion of tellurium

In chemistry, tellurate is a compound containing an oxyanion of tellurium where tellurium has an oxidation number of +6. In the naming of inorganic compounds it is a suffix that indicates a polyatomic anion with a central tellurium atom.

<span class="mw-page-title-main">Telluric acid</span> Chemical compound (Te(OH)6)

Telluric acid, or more accurately orthotelluric acid, is a chemical compound with the formula Te(OH)6, often written as H6TeO6. It is a white crystalline solid made up of octahedral Te(OH)6 molecules which persist in aqueous solution. In the solid state, there are two forms, rhombohedral and monoclinic, and both contain octahedral Te(OH)6 molecules, containing one hexavalent tellurium (Te) atom in the +6 oxidation state, attached to six hydroxyl (–OH) groups, thus, it can be called tellurium(VI) hydroxide. Telluric acid is a weak acid which is dibasic, forming tellurate salts with strong bases and hydrogen tellurate salts with weaker bases or upon hydrolysis of tellurates in water. It is used as tellurium-source in the synthesis of oxidation catalysts.

<span class="mw-page-title-main">Selenium dioxide</span> Chemical compound

Selenium dioxide is the chemical compound with the formula SeO2. This colorless solid is one of the most frequently encountered compounds of selenium. It is used in making specialized glasses as well as a reagent in organic chemistry.

<span class="mw-page-title-main">Tellurite</span> Ion

The tellurite ion is TeO2−
3. A tellurite (compound), for example sodium tellurite, is a compound that contains this ion. They are typically colorless or white salts, which in some ways are comparable to sulfite. A mineral with the formula TeO2 is called tellurite.

<span class="mw-page-title-main">Tellurous acid</span> Chemical compound

Tellurous acid is an inorganic compound with the formula H2TeO3. It is the oxoacid of tellurium(IV). This compound is not well characterized. An alternative way of writing its formula is (HO)2TeO. In principle, tellurous acid would form by treatment of tellurium dioxide with water, that is by hydrolysis. The related conjugate base is well known in the form of several salts such as potassium hydrogen tellurite, KHTeO3.

<span class="mw-page-title-main">Sodium tellurite</span> Chemical compound

Sodium tellurite is an inorganic tellurium compound with formula Na2TeO3. It is a water-soluble white solid and a weak reducing agent. Sodium tellurite is an intermediate in the extraction of the element, tellurium; it is a product obtained from anode slimes and is a precursor to tellurium.

<span class="mw-page-title-main">Tellurium tetrafluoride</span> Chemical compound

Tellurium tetrafluoride, TeF4, is a stable, white, hygroscopic crystalline solid and is one of two fluorides of tellurium. The other binary fluoride is tellurium hexafluoride. The widely reported Te2F10 has been shown to be F5TeOTeF5 There are other tellurium compounds that contain fluorine, but only the two mentioned contain solely tellurium and fluorine. Tellurium difluoride, TeF2, and ditellurium difluoride, Te2F2 are not known.

<span class="mw-page-title-main">Manganese heptoxide</span> Chemical compound

Manganese(VII) oxide (manganese heptoxide) is an inorganic compound with the formula Mn2O7. Manganese heptoxide is a volatile liquid with an oily consistency. It is a highly reactive and powerful oxidizer that reacts explosively with nearly any organic compound. It was first described in 1860. It is the acid anhydride of permanganic acid.

<span class="mw-page-title-main">Tellurium tetraiodide</span> Chemical compound

Tellurium tetraiodide (TeI4) is an inorganic chemical compound. It has a tetrameric structure which is different from the tetrameric solid forms of TeCl4 and TeBr4. In TeI4 the Te atoms are octahedrally coordinated and edges of the octahedra are shared.

Tellurium trioxide (TeO3) is an inorganic chemical compound of tellurium and oxygen. In this compound, tellurium is in the +6 oxidation state.

Selenium trioxide is the inorganic compound with the formula SeO3. It is white, hygroscopic solid. It is also an oxidizing agent and a Lewis acid. It is of academic interest as a precursor to Se(VI) compounds.

Germanium dioxide, also called germanium(IV) oxide, germania, and salt of germanium, is an inorganic compound with the chemical formula GeO2. It is the main commercial source of germanium. It also forms as a passivation layer on pure germanium in contact with atmospheric oxygen.

<span class="mw-page-title-main">Selenium compounds</span> Chemical compounds containing selenium

Selenium compounds are compounds containing the element selenium (Se). Among these compounds, selenium has various oxidation states, the most common ones being −2, +4, and +6. Selenium compounds exist in nature in the form of various minerals, such as clausthalite, guanajuatite, tiemannite, crookesite etc., and can also coexist with sulfide minerals such as pyrite and chalcopyrite. For many mammals, selenium compounds are essential. For example, selenomethionine and selenocysteine are selenium-containing amino acids present in the human body. Selenomethionine participates in the synthesis of selenoproteins. The reduction potential and pKa (5.47) of selenocysteine are lower than those of cysteine, making some proteins have antioxidant activity. Selenium compounds have important applications in semiconductors, glass and ceramic industries, medicine, metallurgy and other fields.

Ammonium fluorosilicate (also known as ammonium hexafluorosilicate, ammonium fluosilicate or ammonium silicofluoride) has the formula (NH4)2SiF6. It is a toxic chemical, like all salts of fluorosilicic acid. It is made of white crystals, which have at least three polymorphs and appears in nature as rare minerals cryptohalite or bararite.

<span class="mw-page-title-main">Polonium dioxide</span> Chemical compound

Polonium dioxide (also known as polonium(IV) oxide) is a chemical compound with the formula PoO2. It is one of three oxides of polonium, the other two being polonium monoxide (PoO) and polonium trioxide (PoO3). It is a pale yellow crystalline solid at room temperature. Under lowered pressure (such as a vacuum), it decomposes into elemental polonium and oxygen at 500 °C. It is the most stable oxide of polonium and is an interchalcogen.

Tellurium compounds are compounds containing the element tellurium (Te). Tellurium belongs to the chalcogen family of elements on the periodic table, which also includes oxygen, sulfur, selenium and polonium: Tellurium and selenium compounds are similar. Tellurium exhibits the oxidation states −2, +2, +4 and +6, with +4 being most common.

References

  1. ↑ Pradyot Patnaik (2002). Handbook of Inorganic Chemicals. McGraw-Hill. ISBN   0-07-049439-8.
  2. 1 2 3 Greenwood NN, Earnshaw A (1984). Chemistry of the Elements. Oxford: Pergamon Press. p. 911. ISBN   978-0-08-022057-4.
  3. ↑ W.R.McWhinnie (1995) Tellurium - Inorganic chemistry Encyclopedia of Inorganic Chemistry Ed. R. Bruce King (1994) John Wiley & Sons ISBN   978-0-471-93620-6
  4. 1 2 "MODEL ATM SERIES ACOUSTO-OPTIC MODULATOR" (PDF). Intraaction.com. Retrieved 14 March 2022.
  5. ↑ Mary Eagleson (1994). Concise Encyclopedia Chemistry . Berlin: Walter de Gruyter. p. 1081. ISBN   3-11-011451-8.
  6. ↑ K. W. Bagnall (1966). The Chemistry of Selenium, Tellurium and Polonium. London: Elsevier. pp.  59–60. ISBN   0-08-018855-9.
  7. ↑ Subrahmanyan T, Aravamudan G, Rout GC, Seshasayee M (1984) [18 March 1983]. "Synthesis, properties, and molecular structure of bis(thiobenzoato-S)tellurium(II), C14H10O2S2Te(II)". Journal of Crystallographic and Spectroscopic Research. 14 (3). Plenum: 242–243. Bibcode:1984JCCry..14..239S. doi:10.1007/BF01161161.
  8. 1 2 3 4 Wells, A. F. (1984), Structural Inorganic Chemistry (5th ed.), Oxford: Clarendon Press, ISBN   0-19-855370-6
  9. ↑ Egon Wiberg, Nils Wiberg, Arnold Frederick Holleman (2001). Inorganic chemistry. Academic Press. pp. 592–593. ISBN   0-12-352651-5.
  10. ↑ Alderman O, Benmore C, Feller S, Kamitsos E, Simandiras E, Liakos D, Jesuit M, Boyd M, Packard M, Weber R (2020). "Short-Range Disorder in TeO2 Melt and Glass". J. Phys. Chem. Lett. 11 (2): 427–431. doi:10.1021/acs.jpclett.9b03231. OSTI   1591765. PMID   31867975. S2CID   209446093.
  11. ↑ Tagiara NS, Palles D, Simandiras E, Psycharis V, Kyritsis A, Kamitsos EI (2017). "Synthesis, thermal and structural properties of pure TeO2 glass and zinc-tellurite glasses". Journal of Non-Crystalline Solids. 457: 116–125. doi:10.1016/j.jnoncrysol.2016.11.033.
  12. ↑ Stegeman R, Jankovic L, Kim H, Rivero C, Stegeman G, Richardson K, Delfyett P, Guo Y, Schulte A, Cardinal T (2003). "Tellurite glasses with peak absolute Raman gain coefficients up to 30 times that of fused silica". Optics Letters. 28 (13): 1126–8. Bibcode:2003OptL...28.1126S. doi:10.1364/OL.28.001126. PMID   12879929.
  13. ↑ Perez-D'Gregorio RE, Miller RK, Baggs RB (1988). "Maternal toxicity and teratogenicity of tellurium dioxide in the Wistar rat: relationship to pair-feeding". Reprod. Toxicol. 2 (1): 55–61. Bibcode:1988RepTx...2...55P. doi:10.1016/S0890-6238(88)80009-1. PMID   2980402.
  14. ↑ Atta-ur-Rahman (2008). Studies in Natural Products Chemistry, Volume 35. Elsevier. p. 905. ISBN   978-0-444-53181-0.
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