Oxypnictide

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In chemistry, oxypnictides are a class of materials including oxygen, a pnictogen (group-V, especially phosphorus and arsenic) and one or more other elements.

The interest in this group of compounds results from the superconducting properties which were discovered 2006 [1] and 2008 [2] [3].

Oxypnictides have been patented as magnetic semiconductors in early 2006[4].

[edit] Structure

For example LaOFeP has a layered structure with layers of La3+02- and Fe2+P3-.[1]

Most articles refer to the oxypnictides as having a ZrCuSiAs structure.

[edit] Superconductor

The first superconducting iron oxypnictide was discovered in 2006, based on phosphorus.[1] A drastic increase in the critical temperature was achieved when phosphorus was substituted by arsenic[2]. This discovery boosted the search for similar compounds, like the search for cuprate-based superconductors after their discovery in 1986.

Some found in 2008 to be high temperature superconductors (at 43 K) of composition ReOTmPn where Re is a rare earth, Tm is a transition metal and Pn is from group-V eg As.[5]

Tests at up to 45 Tesla[6] [7]suggest the upper critical field of LaFeAsO0.89F0.11 may be around 64 Tesla.

[edit] References

  1. ^ a b c Yoichi Kamihara, Hidenori Hiramatsu, Masahiro Hirano, Ryuto Kawamura, Hiroshi Yanagi, Toshio Kamiya, and Hideo Hosono (2006). "Iron-Based Layered Superconductor: LaOFeP". J. Am. Chem. Soc. 128 (31): 10012 -10013. doi:10.1021/ja063355c S0002-7863(06)03355-5. 
  2. ^ a b Hiroki Takahashi, Kazumi Igawa, Kazunobu Arii, Yoichi Kamihara, Masahiro Hirano, Hideo Hosono (2008). "Superconductivity at 43 K in an iron-based layered compound LaO1-xFxFeAs". Nature 453: 376-378. doi:10.1038/nature06972. 
  3. ^ Charles Day (2008). "New family of quaternary iron-based compounds superconducts at tens of kelvin". Physics Today 61 (5): 11–12. doi:10.1063/1.2930719. 
  4. ^ http://www.freepatentsonline.com/EP1868215.html
  5. ^ Samarium based SmFeAsO1−xFx.
  6. ^ http://www.planetanalog.com/news/showArticle.jhtml?articleID=208401297
  7. ^ http://www.nature.com/nature/journal/v453/n7197/abs/nature07058.html