Class of materials containing oxygen and a group-V element
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,[1]
interest in these compounds increased dramatically after the publication of the superconducting properties of LaOFeP and LaOFeAs which were discovered in 2006[2]
and 2008.[3][4]
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.
Oxypnictides have been patented as magnetic semiconductors in early 2006.[5]
Many of the oxypnictides show a layered structure.[6] For example, LaFePO with layers of La3+O2− and Fe2+P3−.[2] This structure is similar to that of ZrCuSiAs, which is now the parent structure for most of the oxypnictide.[7]
Superconductivity
The first superconducting iron oxypnictide was discovered in 2006, based on phosphorus.[2] A drastic increase in the critical temperature was achieved when phosphorus was substituted by arsenic.[3] 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.
^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.
^ abcKamihara, 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. PMID16881620.
^ abPrakash, 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. S2CID119254951.
^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. Bibcode:2008MatRI..12..105R. doi:10.1179/143307508X333686. S2CID55488705.
^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. PMID18509332. S2CID115211939.
^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. S2CID122471407.
External links
Hosono at JST Has diagram of LaO & FeAs layers in LaOFeAs