In chemistry, oxypnictides are a class of materials composed of oxygen, a pnictogen (group-V, especially phosphorus and arsenic) and one or more other elements. Although this group of compounds has been recognized since 1995, interest in these compounds increased dramatically after the publication of the superconducting properties of LaOFeP and LaOFeAs which were discovered in 2006 and 2008.  In these experiments the oxide was partly replaced by fluoride.
These and related compounds (e.g. the 122 iron arsenides) form a new group of iron-based superconductors known as iron pnictides or ferropnictides since the oxygen is not essential but the iron seems to be.
Many of the oxypnictides show a layered structure. For example, LaFePO with layers of La3+O2− and Fe2+P3−. This structure is similar to that of ZrCuSiAs, which is now the parent structure for most of the oxypnictide.
The first superconducting iron oxypnictide was discovered in 2006, based on phosphorus. A drastic increase in the critical temperature was achieved when phosphorus was substituted by arsenic. This discovery boosted the search for similar compounds, like the search for cuprate-based superconductors after their discovery in 1986.
The superconductivity of the oxypnictides seems to depend on the iron-pnictogen layers.
Tests in magnetic fields up to 45 teslas suggest the upper critical field of LaFeAsO0.89F0.11 may be around 64 T. A different lanthanum-based material tested at 6 K predicts an upper critical field of 122 T in La0.8K0.2FeAsO0.8F0.2.
- Andreev reflection – Scattering process at the normal-metal-superconductor interface
- Charge-transfer complex
- Color superconductivity – Predicted phenomenon in quark matter in quarks
- Composite reaction texturing
- Conventional superconductor – Materials that display superconductivity as described by BCS theory or its extensions
- Covalent superconductor – Superconducting materials where the atoms are linked by covalent bonds
- Iron-based superconductor
- High-temperature superconductivity – Superconductive behavior at temperatures much higher than absolute zero
- Homes's law
- Kondo effect – Physical phenomenon due to impurities
- Little–Parks effect
- Magnetic sail – Spacecraft propulsion method that takes advantage of solar wind.
- National Superconducting Cyclotron Laboratory – Building in Michigan, United States
- Proximity effect – Phenomena that occur when a superconductor is in contact with a non-superconductor
- Room-temperature superconductor – Material which exhibits superconductivity above 0 °C
- Rutherford cable – Type of superconducting electrical cable
- Spallation Neutron Source
- Superconducting radio frequency – Technique used to attain a high quality factor in resonant cavities
- Superconductor classification – Different types of superconductors
- Superfluid film – Thin layer of liquid in a superfluid state
- Technological applications of superconductivity
- Timeline of low-temperature technology – Aspect of history
- Type-I superconductor – Type of superconductor with a single critical magnetic field
- Type-II superconductor – Superconductor characterized by the formation of magnetic vortices in an applied magnetic field
- Unconventional superconductor – Superconductive materials not explained by existing established theories
- Zimmer, Barbara I.; Jeitschko, Wolfgang; Albering, Jörg H.; Glaum, Robert; Reehuis, Manfred (1995). "The rate earth transition metal phosphide oxides LnFePO, LnRuPO and LnCoPO with ZrCuSiAs type structure". Journal of Alloys and Compounds. 229 (2): 238–242. doi:10.1016/0925-8388(95)01672-4.
- Kamihara, Y; Hiramatsu, H; Hirano, M; Kawamura, R; Yanagi, H; Kamiya, T; Hosono, H (2006). "Iron-Based Layered Superconductor: LaOFeP". J. Am. Chem. Soc. 128 (31): 10012–10013. doi:10.1021/ja063355c. PMID 16881620.
- Takahashi, H; Igawa, K; Arii, K; Kamihara, Y; Hirano, M; Hosono, H (2008). "Superconductivity at 43 K in an iron-based layered compound LaO1−xFxFeAs". Nature. 453 (7193): 376–378. Bibcode:2008Natur.453..376T. doi:10.1038/nature06972. PMID 18432191.
- Day, Charles (2008). "New family of quaternary iron-based compounds superconducts at tens of kelvin". Physics Today. 61 (5): 11–12. Bibcode:2008PhT....61e..11D. doi:10.1063/1.2930719.
- H. Hosono et al. (2006) Magnetic semiconductor material European Patent Application EP1868215
- Ozawa, T. C.; Kauzlarich, S. M. (2008). "Chemistry of layered d-metal pnictide oxides and their potential as candidates for new superconductors". Sci. Technol. Adv. Mater. 9 (3): 033003. arXiv:0808.1158. Bibcode:2008STAdM...9c3003O. doi:10.1088/1468-6996/9/3/033003. PMC 5099654. PMID 27877997.
- Tegel, Marcus; Bichler, Daniel; Johrendt, Dirk (2008). "Synthesis, crystal structure and superconductivity of LaNiPO". Solid State Sciences. 10 (2): 193–197. Bibcode:2008SSSci..10..193T. doi:10.1016/j.solidstatesciences.2007.08.016.
- Ren, Z. A.; Yang, J.; Lu, W.; Yi, W.; Che, G. C.; Dong, X. L.; Sun, L. L.; Zhao, Z. X. (2008). "Samarium based SmFeAsO1−xFx". Materials Research Innovations. 12 (3): 105. arXiv:0803.4283. doi:10.1179/143307508X333686.
- Ishida, Kenji; Nakai, Yusuke; Hosono, Hideo (2009). "To What Extent Iron-Pnictide New Superconductors Have Been Clarified: A Progress Report". J. Phys. Soc. Jpn. 78 (6): 062001. arXiv:0906.2045. Bibcode:2009JPSJ...78f2001I. doi:10.1143/JPSJ.78.062001.
- Prakash, J.; Singh, S. J.; Samal, S. L.; Patnaik, S.; Ganguli, A. K. (2008). "Potassium fluoride doped LaOFeAs multi-band superconductor: Evidence of extremely high upper critical field". EPL. 84 (5): 57003. Bibcode:2008EL.....8457003P. doi:10.1209/0295-5075/84/57003.
- Shirage, Parasharam M.; Miyazawa, Kiichi; Kito, Hijiri; Eisaki, Hiroshi; Iyo, Akira (2008). "Superconductivity at 43 K at ambient pressure in the iron-based layered compound La1‑xYxFeAsOy". Physical Review B. 78 (17): 172503. Bibcode:2008PhRvB..78q2503S. doi:10.1103/PhysRevB.78.172503.
- Ren, Z. A.; Yang, J.; Lu, W.; Yi, W.; Che, G. C.; Dong, X. L.; Sun, L. L.; Zhao, Z. X. (2008). "Superconductivity at 52 K in iron based F doped layered quaternary compound Pr[O1–xFx]FeAs". Materials Research Innovations. 12 (3): 105. arXiv:0803.4283. doi:10.1179/143307508X333686.
- Yang, Jie; Li, Zheng-Cai; Lu, Wei; Yi, Wei; Shen, Xiao-Li; Ren, Zhi-An; Che, Guang-Can; Dong, Xiao-Li; Sun, Li-Ling; et al. (2008). "Superconductivity at 53.5 K in GdFeAsO1−δ". Superconductor Science and Technology. 21 (8): 082001. arXiv:0804.3727. Bibcode:2008SuScT..21h2001Y. doi:10.1088/0953-2048/21/8/082001.
- Ren, Zhi-An; Che, Guang-Can; Dong, Xiao-Li; Yang, Jie; Lu, Wei; Yi, Wei; Shen, Xiao-Li; Li, Zheng-Cai; Sun, Li-Ling; Zhou, Fang; Zhao, Zhong-Xian (2008). "Superconductivity and phase diagram in iron-based arsenic-oxides ReFeAsO1−δ (Re = rare-earth metal) without fluorine doping". EPL. 83: 17002. arXiv:0804.2582. Bibcode:2008EL.....8317002R. doi:10.1209/0295-5075/83/17002.
- "High-temp superconductors pave way for 'supermagnets'". planetanalog. May 29, 2008.[permanent dead link]
- Hunte, F; Jaroszynski, J; Gurevich, A; Larbalestier, D. C.; Jin, R; Sefat, A. S.; McGuire, M. A.; Sales, B. C.; Christen, D. K.; Mandrus, D (2008). "Two-band superconductivity in LaFeAsO0.89F0.11 at very high magnetic fields". Nature. 453 (7197): 903–905. arXiv:0804.0485. Bibcode:2008Natur.453..903H. doi:10.1038/nature07058. PMID 18509332.
- Gao, Zhaoshun; Wang, Lei; Qi, Yanpeng; Wang, Dongliang; Zhang, Xianping; Ma, Yanwei (2008). "Preparation of LaFeAsO0.9F0.1 wires by the powder-in-tube method". Superconductor Science and Technology. 21 (10): 105024. Bibcode:2008SuScT..21j5024G. doi:10.1088/0953-2048/21/10/105024.
- Hosono at JST Has diagram of LaO & FeAs layers in LaOFeAs