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DFT Calculation For Ru-Mn Active Oxide Electrode Materials

Posted on:2016-08-08Degree:MasterType:Thesis
Country:ChinaCandidate:F LuoFull Text:PDF
GTID:2321330512475892Subject:Materials science
Abstract/Summary:PDF Full Text Request
RuO2-MnO2 active oxide system has been discussed in this paper by ab initio density functional theory method.?1?The structures of rutile type Ru02 and MnO2 are calculated by density functional theory method.?2?The structure of rutile Mn1-xRuxO2 is optimized and the micro structure data is obtained.The influence of doping amount on electronic structures of Mn1-xRuxO2 has been discussed.?3?The structure of a-MnO2 Mn1-xRuxO2 is optimized and the microstructure data is obtained.The influence of doping amount on electronic structures of Mn1-xRuxO2 has been discussed.The results indicated that:Unit cell parameters of rutile type Ru02 and MnO2 are calculated by GGA are better than LDA and more closely related to JCPDS cards.The band structures show that pure rutile type RuO2 has metallic properties while pure rutile type MnO2 is direct band gap semiconductor.The two peaks of density of states of rutile type Ru02 at the Fermi level are mainly composed of O 2p electronic states and Ru 5S electronic states,while those of rutile type MnO2 are mainly composed of O 2p electronic states and Mn 3d electronic states.The volume of the rutile Mn1-xRuxO2 unit cell increases with the doping amount of Ru when calculated with GGA.The average bond length LO-O average and LaMe-O aberage of rutile type Mn1-xRuxO2 increase with the doping amount of Ru.So it is considered that the bond length of O-O and Me-O are important to structure parameters of Mn1-xRuxO2.The band structures of rutile type Mn1-xRuxO2 show impurity bands after doped Ru,which improves the conductivity of rutile type Mn1-xRuxO2.The density of states of rutile type Mn1-xRuxO2 show strong local characteristics of Ru 4d electronic states after doped with Ru.The volume of the rutile Mn1-xRuxO2 unit cell increases with the doping amount of Ru when calculated with GGA+U.The average bond length LaO-O average and LMe-O abergae of a-MnO2 type Mn1-xRuxO2 increased with the doping amount of Ru.So it is considered that the bond of O-O and Me-O are important to structure parameters of ?-MnO2 type Mn1-xRuxO2.The band structures of ?-MnO2 type Mn1-xRuxO2 show that after doped with Ru,there come impurity band then improve the conductivity of ?-MnO2 type Mn1-xRuxO2.The density of states of ?-MnO2 type Mn1-xRuxO2 show strong local characteristics by Ru 4d electronic states and O 2p electronic states after doped with Ru.By comparison of the complex oxides of rutile MnO2,rutile Mn1-xRuxO2 and?-MnO2,?-MnO2 type Mn1-xRuxO2,the fitting curves of Mn1-xRuxO2 ?-MnO2 are found to have larger deviation.The lattice distortion of ?-MnO2 is obviously larger than rutile type MnO2.The conductivity of Mn1-xRuxO2 and ?-MnO2 type Mn1-xRuxO2 are both improved after doped with Ru.But density of states show that a-MnO2 type Mn0.825Ru0.125O2 is more likely to be affected by local characteristics after doped with Ru.The crystal structure of ?-MnO2 is more likely to be affected after doped with Ru than rutile type MnO2.
Keywords/Search Tags:RuO2-MnO2, Density Functional Theory, First Principle, Electronic Structure
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