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非水溶胶-凝胶法合成的新型含氧锰矿VO1.52（OH）0.77纳米棒的表征与性能Characterization and Properties of Novel Oxygen Contained Hollandite VO1.52(OH)0.77 Nanorods Synthesized by Nonaqueous Sol-Gel Route |
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| 课程网址: | http://videolectures.net/slonano07_djerdj_cpn/ |
| 主讲教师: | Igor Djerdj |
| 开课单位: | 约瑟夫·斯特凡学院 |
| 开课时间: | 2008-01-18 |
| 课程语种: | 英语 |
| 中文简介: |  |
| 课程简介: | Using the nonaqueous sol-gel route based on benzyl alcohol pathway, a new compound VO1.52(OH)0.77 in the form of nanorods has been synthesized. Comprehensive structural investigations have been carried out using complementary neutron and synchrotron powder X-ray diffraction as well as different electron microscopy techniques: SEM, (HR)TEM, EDX, SAED, EELS for determination of material's morphology, crystallinity and oxidation state of vanadium. The data show that the structure can be described as hollandite-type containing only oxygen in the 2×2 channels along the c-axis, with hydrogen attached to the one octahedral-coordinating oxygen, forming thus OH− group. The nanorods are single-crystalline, up to 500 nm long and 105 nm in diameter with the growth direction along the axis. The shape of OK edge and L3/L2 white-line ratio confirmed that the vanadium oxidation state is between 3+ and 4+ which is also deduced from the charge neutrality analysis being +3.81. Temperature dependent DC conductivity measurement evidenced Arrhenius behavior and semiconducting ground state with a band gap of 0.64 eV (cooling mode). Ab initio density-functional calculations with local spin density approximation including orbital potential (LSDA+U) predicts a direct band gap of 0.64 eV and a high degree of hybridization between O 2p and V 3d orbitals. The temperature dependence of magnetic susceptibility follows the Curie-Weiss law above 150 K. The extracted effective magnetic moment per vanadium of 1.95 B is consistent with the mixture of 3+ and 4+ oxidation states with predominant fraction of 4+. |
| 关 键 词: | 非水溶胶凝胶途径; 苄醇; 半导体基态 |
| 课程来源: | 视频讲座网 |
| 最后编审: | 2019-09-25：yuh |
| 阅读次数: | 86 |