Tellurium dioxide

Source: Wikipedia, the free encyclopedia.
Tellurium dioxide

α-TeO2, paratellurite
Names
Other names
Tellurium(IV) oxide
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.028.357 Edit this at Wikidata
UNII
  • InChI=1S/O2Te/c1-3-2 checkY
    Key: LAJZODKXOMJMPK-UHFFFAOYSA-N checkY
  • InChI=1/O2Te/c1-3-2
    Key: LAJZODKXOMJMPK-UHFFFAOYAO
  • O=[Te]=O
Properties
TeO2
Molar mass 159.60 g/mol
Appearance white solid
Density 5.670 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
Tellurium trioxide
Tellurium monoxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

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

tellurites. It can be oxidized to telluric acid or tellurates
.

Structure

Paratellurite, α-TeO2, converts at high pressure into the β-, tellurite form.[7] 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.[7] The shortest Te-Te distance in tellurite is 317 pm, compared to 374 pm in paratellurite.[7] Similar Te2O6 units are found in the mineral denningite.[7]

TeO
2 melts at 732.6 °C, forming a red liquid.[8] 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.[9]

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,

optical fibre amplification.[11]

Safety

TeO2 is a possible

teratogen.[12]

Exposure to tellurium compounds produces a garlic-like odour on the breath, caused by the formation of diethyl telluride.[13]

References

  1. ISBN 0-07-049439-8
    .
  2. ^
    ISBN 978-0-08-022057-4
    .
  3. ISBN 978-0-471-93620-6
  4. ^ a b "MODEL ATM SERIES ACOUSTO-OPTIC MODULATOR" (PDF). Intraaction.com. Retrieved 14 March 2022.
  5. ISBN 3-11-011451-8
    .
  6. ISBN 0-08-018855-9
    .
  7. ^
    ISBN 0-19-855370-6
  8. ISBN 0-12-352651-5
    .
  9. S2CID 209446093
    .
  10. doi:10.1016/j.jnoncrysol.2016.11.033
    .
  11. PMID 12879929
    .
  12. PMID 2980402
    .
  13. ISBN 978-0-444-53181-0
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Tellurium_dioxide&oldid=1212663680"