Chemistry:Lanthanum manganite
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3D model (JSmol)
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| Properties | |
| LaMnO3 | |
| Molar mass | 241.84 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Lanthanum manganite is an inorganic compound with the formula LaMnO3, often abbreviated as LMO. Lanthanum manganite is formed in the perovskite structure, consisting of oxygen octahedra with a central Mn atom. The cubic perovskite structure is distorted into an orthorhombic structure by a strong Jahn–Teller distortion of the oxygen octahedra.[2]
LaMnO3 often has lanthanum vacancies as evidenced by neutron scattering. For this reason, this material is usually referred as LaMnO3+ẟ. These vacancies generate a structure with a rhombohedral unit cell in this perovskite. A temperatures below 140 K, this LaMnO3+ẟ semiconductor exhibit a ferromagnetic order.[3]
Synthesis
Lanthanum manganite can be prepared via solid-state reactions at high temperatures, using their oxides or carbonates.[4] An alternative method is to use lanthanum nitrate and manganese nitrate as raw materials. The reaction occurs at high temperature after the solvents are vaporized.[5]
Lanthanum manganite alloys
Lanthanum manganite is an electrical insulator and an A-type antiferromagnet. It is the parent compound of several important alloys, often termed rare-earth manganites or colossal magnetoresistance oxides. These families include lanthanum strontium manganite, lanthanum calcium manganite and others.
In lanthanum manganite, both the La and the Mn are in the +3 oxidation state. Substitution of some of the La atoms by divalent atoms such as Sr or Ca induces a similar amount of tetravalent Mn4+ ions. Such substitution, or doping can induce various electronic effects, which form the basis of a rich and complex electron correlation phenomena that yield diverse electronic phase diagrams in these alloys.[6]
See also
- Super exchange
- Double exchange
- Jahn–Teller effect
- Electron correlation
References
- ↑ Macintyre, Jane E. (1992) (in en). Dictionary of Inorganic Compounds. CRC Press. p. 3546. ISBN 9780412301209. https://books.google.com/books?id=9eJvoNCSCRMC&pg=PA3546.
- ↑ S. Satpathy (1996). "Electronic Structure of the Perovskite Oxides: La1−xCaxMnO3". Physical Review Letters 76 (6): 960–963. doi:10.1103/PhysRevLett.76.960. PMID 10061595. Bibcode: 1996PhRvL..76..960S. http://vinar.vin.bg.ac.rs//bitstream/id/12220/1956.pdf.
- ↑ J. Ortiz, L. Gracia, F. Cancino, U. Pal (2020). "Particle dispersion and lattice distortion induced magnetic behavior of La1−xSrxMnO3 perovskite nanoparticles grown by salt-assisted solid-state synthesis". Materials Chemistry and Physics 246: 122834. doi:10.1016/j.matchemphys.2020.122834.
- ↑ Bockris, John O'M.; Otagawa, Takaaki (1983). "Mechanism of oxygen evolution on perovskites". The Journal of Physical Chemistry 87 (15): 2960–2971. doi:10.1021/j100238a048. ISSN 0022-3654.
- ↑ Liu, Yuxi; Dai, Hongxing; Du, Yucheng; Deng, Jiguang; Zhang, Lei; Zhao, Zhenxuan; Au, Chak Tong (2012). "Controlled preparation and high catalytic performance of three-dimensionally ordered macroporous LaMnO3 with nanovoid skeletons for the combustion of toluene". Journal of Catalysis 287: 149–160. doi:10.1016/j.jcat.2011.12.015. ISSN 0021-9517.
- ↑ Dagotto, E. (14 March 2013). Nanoscale Phase Separation and Colossal Magnetoresistance. Springer. ISBN 978-3-662-05244-0. https://www.springer.com/materials/book/978-3-540-43245-6.
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