Tungsten trioxide

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Tungsten trioxide
Tungsten trioxide.png
Kristallstruktur Wolfram(VI)-oxid.png
Names
IUPAC name
Tungsten trioxide
Other names
Tungstic anhydride
Tungsten(VI) oxide
Tungstic oxide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.013.848 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
RTECS number
  • YO7760000
UNII
  • InChI=1S/3O.W
  • O=[W](=O)=O
Properties
WO3
Molar mass 231.84 g/mol
AppearanceCanary yellow powder
Density 7.16 g/cm3
Melting point 1,473 °C (2,683 °F; 1,746 K)
Boiling point 1,700 °C (3,090 °F; 1,970 K) approximation
insoluble
Solubility slightly soluble in HF
−15.8·10−6 cm3/mol
Structure
Monoclinic, mP32
P121/n1, No. 14
Octahedral (WVI)
Trigonal planar (O2– )
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Irritant
Flash point Non-flammable
Safety data sheet (SDS) External MSDS
Related compounds
Other anions
Tungsten trisulfide
Other cations
Chromium trioxide
Molybdenum trioxide
Related tungsten oxides
Tungsten(III) oxide
Tungsten(IV) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Tungsten(VI) oxide, also known as tungsten trioxide is a chemical compound of oxygen and the transition metal tungsten, with formula WO3. The compound is also called tungstic anhydride, reflecting its relation to tungstic acid H2WO4. It is a light yellow crystalline solid. [1]

Contents

Tungsten(VI) oxide occurs naturally in the form of hydrates, which include minerals: tungstite WO3·H2O, meymacite WO3·2H2O and hydrotungstite (of the same composition as meymacite, however sometimes written as H2WO4). These minerals are rare to very rare secondary tungsten minerals.

History

In 1841, a chemist named Robert Oxland gave the first procedures for preparing tungsten trioxide and sodium tungstate. [2] He was granted patents for his work soon after, and is considered to be the founder of systematic tungsten chemistry. [2]

Structure and properties

The crystal structure of tungsten trioxide is temperature dependent. It is tetragonal at temperatures above 740 °C, orthorhombic from 330 to 740 °C, monoclinic from 17 to 330 °C, triclinic from −50 to 17 °C, and monoclinic again at temperatures below −50 °C. [3] The most common structure of WO3 is monoclinic with space group P21/n. [2]

The pure compound is an electric insulator, but oxygen-deficient varieties, such as WO2.90 = W20O58, are dark blue to purple in color and conduct electricity. They can be prepared by combining the trioxide and the dioxide WO2 at 1000 °C in vacuum. [4] [1]

Possible signs of superconductivity with critical temperatures Tc = 80–90 K were claimed in sodium-doped and oxygen-deficient WO3 crystals. If confirmed, these would be the first superconducting materials containing no copper, with Tc higher than the boiling point of liquid nitrogen at normal pressure. [5] [4]

Preparation

Industrial

Tungsten trioxide is obtained as an intermediate in the recovery of tungsten from its minerals. [6] Tungsten ores can be treated with alkalis to produce soluble tungstates. Alternatively, CaWO4, or scheelite, is allowed to react with HCl to produce tungstic acid, which decomposes to WO3 and water at high temperatures. [6]

CaWO4 + 2 HCl → CaCl2 + H2WO4
H2WO4 H2O + WO3

Laboratory

Another common way to synthesize WO3 is by calcination of ammonium paratungstate (APT) under oxidizing conditions: [2]

(NH4)10[H2W12O42] · 4 H2O → 12 WO3 + 10 NH3 + 10 H2O

Reactions

Tungsten trioxide can be reduced with carbon or hydrogen gas yielding the pure metal.[ citation needed ]

2 WO3 + 3 C → 2 W + 3 CO2 (high temperature)
WO3 + 3 H2 → W + 3 H2O (550–850 °C)

Uses

Tungsten trioxide is a starting material for the synthesis of tungstates. Barium tungstate BaWO4 is used as a x-ray screen phosphors. Alkali metal tungstates, such as lithium tungstate Li2WO4 and cesium tungstate Cs2WO4, give dense solutions that can be used to separate minerals. [1] Other applications, actual or potential, include:

Related Research Articles

<span class="mw-page-title-main">Oxide</span> Chemical compound where oxygen atoms are combined with atoms of other elements

An oxide is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al2O3 that protects the foil from further oxidation.

<span class="mw-page-title-main">Tungsten</span> Chemical element, symbol W and atomic number 74

Tungsten is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternate name.

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

Zirconium dioxide is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the mineral baddeleyite. A dopant stabilized cubic structured zirconia, cubic zirconia, is synthesized in various colours for use as a gemstone and a diamond simulant.

<span class="mw-page-title-main">Wolframite</span> Iron manganese tungstate mineral

Wolframite is an iron, manganese, and tungstate mineral with a chemical formula of (Fe,Mn)WO4 that is the intermediate mineral between ferberite (Fe2+ rich) and hübnerite (Mn2+ rich). Along with scheelite, the wolframite series are the most important tungsten ore minerals. Wolframite is found in quartz veins and pegmatites associated with granitic intrusives. Associated minerals include cassiterite, scheelite, bismuth, quartz, pyrite, galena, sphalerite, and arsenopyrite.

<span class="mw-page-title-main">Tungsten hexafluoride</span> Chemical compound

Tungsten(VI) fluoride, also known as tungsten hexafluoride, is an inorganic compound with the formula WF6. It is a toxic, corrosive, colorless gas, with a density of about 13 kg/m3 (22 lb/cu yd). It is one of the densest known gases under standard conditions. WF6 ls commonly used by the semiconductor industry to form tungsten films, through the process of chemical vapor deposition. This layer is used in a low-resistivity metallic "interconnect". It is one of seventeen known binary hexafluorides.

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

Hübnerite or hubnerite is a mineral consisting of manganese tungsten oxide (chemical formula MnWO4). It is the manganese endmember of the manganese–iron wolframite solid solution series. It forms reddish brown to black monoclinic prismatic submetallic crystals. The crystals are typically flattened and occur with fine striations. It has a high specific gravity of 7.15 and a Mohs hardness of 4.5. It is transparent to translucent with perfect cleavage. Refractive index values are nα = 2.170 - 2.200, nβ = 2.220, and nγ = 2.300 - 2.320.

<span class="mw-page-title-main">Zirconium tungstate</span> Chemical compound

Zirconium tungstate (ZrWO4) is the zirconium salt of tungstic acid and has unusual properties. The phase formed at ambient pressure by reaction of ZrO2 and WO3 is a metastable cubic phase, which has negative thermal expansion characteristics, namely it shrinks over a wide range of temperatures when heated. In contrast to most other ceramics exhibiting negative CTE (coefficient of thermal expansion), the CTE of ZrW2O8 is isotropic and has a large negative magnitude (average CTE of -7.2x10−6K−1) over a wide range of temperature (-273 °C to 777 °C). A number of other phases are formed at high pressures.

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

Electrochromism is a phenomenon in which a material displays changes in color or opacity in response to an electrical stimulus. In this way, a smart window made of an electrochromic material can block specific wavelengths of ultraviolet, visible or (near) infrared light. The ability to control the transmittance of near-infrared light can increase the energy efficiency of a building, reducing the amount of energy needed to cool during summer and heat during winter.

Molybdenum trioxide describes a family of inorganic compounds with the formula MoO3(H2O)n where n = 0, 1, 2. These compounds are produced on the largest scale of any molybdenum compound. The anhydrous oxide is a precursor to molybdenum metal, an important alloying agent. It is also an important industrial catalyst. It is a yellow solid, although impure samples can appear blue or green.

<span class="mw-page-title-main">Tungstate</span> Chemical compound containing an oxyanion or mixed oxide of tungsten

In chemistry, a tungstate is a compound that contains an oxyanion of tungsten or is a mixed oxide containing tungsten. The simplest tungstate ion is WO2−4, "orthotungstate". Many other tungstates belong to a large group of polyatomic ions that are termed polyoxometalates, ("POMs"), and specifically termed isopolyoxometalates as they contain, along with oxygen and maybe hydrogen, only one other element. Almost all useful tungsten ores are tungstates.

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

Tungstic acid refers to hydrated forms of tungsten trioxide, WO3. Both a monohydrate (WO3·H2O) and hemihydrate (WO3·1/2 H2O) are known. Molecular species akin to sulfuric acid, i.e. (HO)2WO2 are not observed.

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

Sodium tungstate is the inorganic compound with the formula Na2WO4. This white, water-soluble solid is the sodium salt of tungstic acid. It is useful as a source of tungsten for chemical synthesis. It is an intermediate in the conversion of tungsten ores to the metal.

<span class="mw-page-title-main">Curium(III) oxide</span> Chemical compound

Curium(III) oxide is a compound composed of curium and oxygen with the chemical formula Cm2O3. It is a crystalline solid with a unit cell that contains two curium atoms and three oxygen atoms. The simplest synthesis equation involves the reaction of curium(III) metal with O2−: 2 Cm3+ + 3 O2− ---> Cm2O3. Curium trioxide can exist as five polymorphic forms. Two of the forms exist at extremely high temperatures, making it difficult for experimental studies to be done on the formation of their structures. The three other possible forms which curium sesquioxide can take are the body-centered cubic form, the monoclinic form, and the hexagonal form. Curium(III) oxide is either white or light tan in color and, while insoluble in water, is soluble in inorganic and mineral acids. Its synthesis was first recognized in 1955.

<span class="mw-page-title-main">Non-stoichiometric compound</span> Chemical compounds that cannot be represented by an empirical formula

Non-stoichiometric compounds are chemical compounds, almost always solid inorganic compounds, having elemental composition whose proportions cannot be represented by a ratio of small natural numbers ; most often, in such materials, some small percentage of atoms are missing or too many atoms are packed into an otherwise perfect lattice work.

<span class="mw-page-title-main">Tungsten(IV) oxide</span> Chemical compound

Tungsten(IV) oxide is the chemical compound with the formula WO2. The bronze-colored solid crystallizes in a monoclinic cell. The rutile-like structure features distorted octahedral WO6 centers with alternate short W–W bonds (248 pm). Each tungsten center has the d2 configuration, which gives the material a high electrical conductivity.

<span class="mw-page-title-main">Tungsten oxytetrafluoride</span> Chemical compound

Tungsten oxytetrafluoride is an inorganic compound with the formula WOF4. It is a colorless diamagnetic solid. The compound is one of many oxides of tungsten. It is usually encountered as product of the partial hydrolysis of tungsten hexafluoride.

<span class="mw-page-title-main">Ammonium paratungstate</span> Chemical compound

Ammonium paratungstate (or APT) is a white crystalline salt with the chemical formula (NH4)10(H2W12O42)·4H2O. It is described as "the most important raw material for all other tungsten products."

Molybdenum dioxide is the chemical compound with the formula MoO2. It is a violet-colored solid and is a metallic conductor. The mineralogical form of this compound is called tugarinovite, and is only very rarely found.

<span class="mw-page-title-main">Nickel tungstate</span> Chemical compound

Nickel tungstate is an inorganic compound of nickel, tungsten and oxygen, with the chemical formula of NiWO4.

Neodymium tungstate is an inorganic compound, a salt of neodymium and tungstic acid with the chemical formula Nd2(WO4)3. It forms hydrated light purple crystals that are slightly soluble in water.

References

  1. 1 2 3 4 5 6 J. Christian, R.P. Singh Gaur, T. Wolfe and J. R. L. Trasorras (2011): Tungsten Chemicals and their Applications . Brochure by International Tungsten Industry Association.
  2. 1 2 3 4 Lassner, Erik and Wolf-Dieter Schubert (1999). Tungsten: Properties, Chemistry, Technology of the Element, Alloys, and Chemical Compounds. New York: Kluwer Academic. ISBN   978-0-306-45053-2.
  3. H. A. Wriedt (1898): "The O-W (oxygen-tungsten) system". Bulletin of Alloy Phase Diagrams., volume 10, pages 368–384. doi : 10.1007/BF02877593
  4. 1 2 A. Shengelaya, K. Conder, and K. A. Müller (2020): "Signatures of Filamentary Superconductivity up to 94 K in Tungsten Oxide WO2.90". Journal of Superconductivity and Novel Magnetism, volume 33, pages 301–306. doi : 10.1007/s10948-019-05329-9
  5. S. Reich and Y. Tsabba (1999): "Possible nucleation of a 2D superconducting phase on WO single crystals surface doped with Na". European Physical Journal B, volume 9, pages = 1–4. doi : 10.1007/s100510050735 S2CID   121476634
  6. 1 2 3 Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. ISBN   978-0-07-049439-8 . Retrieved 2009-06-06.
  7. Merck (2006): "Tungsten trioxide." The Merck Index, volume 14.
  8. David E Williams, Simon R Aliwell, Keith F. E. Pratt, Daren J. Caruana, Roderic L. Jones, R. Anthony Cox, Graeme M. Hansford. and John Halsall (2002): "Modelling the response of a tungsten oxide semiconductor as a gas sensor for the measurement of ozone". Measurement Science and Technology. volume 13. pages 923–931. doi : 10.1088/0957-0233/13/6/314
  9. Lee, W. J.; Fang, Y. K.; Ho, Jyh-Jier; Hsieh, W. T.; Ting, S. F.; Huang, Daoyang; Ho, Fang C. (2000). "Effects of surface porosity on tungsten trioxide(WO3) films' electrochromic performance". Journal of Electronic Materials. 29 (2): 183–187. Bibcode:2000JEMat..29..183L. doi:10.1007/s11664-000-0139-8. S2CID   98302697.
  10. K. J. Patel, M. S. Desai, C. J. Panchal, H. N. Deota, and U. B. Trivedi (2013): "All-Solid-Thin Film Electrochromic Devices Consisting of Layers ITO / NiO / ZrO2 / WO3 / ITO". Journal of Nano-Electronics and Physics, volume 5, issue 2, article 02023.
  11. Yugo Miseki, Hitoshi Kusama, Hideki Sugihara, and Kazuhiro Sayama (2010): "Cs-Modified WO3 Photocatalyst Showing Efficient Solar Energy Conversion for O2 Production and Fe (III) Ion Reduction under Visible Light". Journal of Physical Chemistry Letters, volume 1, issue 8, pages 1196–1200. doi : 10.1021/jz100233w
  12. É. Karácsonyi, L. Baia, A. Dombi, V. Danciu, K. Mogyorósi, L. C. Pop, G. Kovács, V. Coşoveanu, A. Vulpoi, S. Simon, Zs. Pap (2013): "The photocatalytic activity of TiO2/WO3/noble metal (Au or Pt) nanoarchitectures obtained by selective photodeposition". Catalysis Today, volume 208, pages 19-27. doi : 10.1016/j.cattod.2012.09.038
  13. István Székely, Gábor Kovács, Lucian Baia, Virginia Danciu, Zsolt Pap (2016): "Synthesis of Shape-Tailored WO3 Micro-/Nanocrystals and the Photocatalytic Activity of WO3/TiO2 Composites". Materials, volume 9, issue 4, pages 258-271. doi : 10.3390/ma9040258
  14. Lucian Baia, Eszter Orbán, Szilvia Fodor, Boglárka Hampel, Endre Zsolt Kedves, Kata Saszet, István Székely, Éva Karácsonyi, Balázs Réti, Péter Berki, Adriana Vulpoi, Klára Magyari, Alexandra Csavdári, Csaba Bolla, Veronica Coșoveanu, Klára Hernádi, Monica Baia, András Dombi, Virginia Danciu, Gábor Kovácz, Zsolt Pap (2016): "Preparation of TiO2/WO3 composite photocatalysts by the adjustment of the semiconductors' surface charge". Materials Science in Semiconductor Processing, volume 42, part 1, pages 66-71. doi : 10.1016/j.mssp.2015.08.042
  15. G. Ou (2018). "Tuning Defects in Oxides at Room Temperature by Lithium Reduction". Nature Communications. 9 (1302): 1302. Bibcode:2018NatCo...9.1302O. doi:10.1038/s41467-018-03765-0. PMC   5882908 . PMID   29615620.
  16. S. Hurst (2011). "Utilizing Chemical Raman Enhancement: A Route for Metal Oxide Support Based Biodetection". The Journal of Physical Chemistry C. 115 (3): 620–630. doi:10.1021/jp1096162.
  17. W. Liu (2018). "Improved Surface-Enhanced Raman Spectroscopy Sensitivity on Metallic Tungsten Oxide by the Synergistic Effect of Surface Plasmon Resonance Coupling and Charge Transfer". The Journal of Physical Chemistry Letters. 9 (14): 4096–4100. doi:10.1021/acs.jpclett.8b01624. PMID   29979872. S2CID   49716355.
  18. C. Zhou (2019). "Electrical tuning of the SERS enhancement by precise defect density control" (PDF). ACS Applied Materials & Interfaces. 11 (37): 34091–34099. doi:10.1021/acsami.9b10856. PMID   31433618. S2CID   201278374.