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介孔CeO2负载的Co3O4催化剂催化富氢气体中的CO优先氧化反应 总被引:2,自引:0,他引:2
采用溶胶-凝胶法制备出介孔氧化铈(meso-CeO2)及其负载的氧化钴(Co3O4/meso-CeO2)催化剂,并将其应用于富氢气体中CO的优先氧化反应.通过N2物理吸附及X射线衍射表征考察了meso-CeO2和Co3O4/meso-CeO2的结构性质.活性评价结果表明,在高空速下,Co3O4/meso-CeO2催化剂上的CO优先氧化性能很好,但水和CO2对CO的氧化有一定的负作用.Co3O4/meso-CeO2催化剂的CO完全氧化温度窗口远大于沉淀法制备CeO2负载的氧化钴催化剂. 相似文献
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一般地,钛矿结构锰氧化物的电脉冲诱导电阻转变(EPIR) 效应源于非内禀界面处的肖特基势垒. 本文采用固相烧结法制备了La0.5Ca0.5MnO3 (LCMO)陶瓷样品, 用四线测量模式对样品电输运性质, 特别对其内禀EPIR效应和忆阻器行为进行了研究. 室温下, 尽管样品在四线测量模式下的I-V特性曲线呈欧姆线性规律, 但在适当的脉冲电压刺激下, 仍能诱导产生明显、稳定的EPIR效应. 通过与二线模式的界面EPIR比较, 发现LCMO内禀EPIR效应具有更小的脉冲临界电压、更好的稳定性和抗疲劳特性, 是稀土掺杂锰氧化物中观察到的一类新颖的EPIR效应.
关键词:
钙钛矿结构锰氧化物
电致电阻效应
电脉冲诱导电阻转变效应
肖特基势垒 相似文献
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采用固相烧结方法制备了Pr1-xCaxMnO3(x=0.3)钙态矿结构锰氧化物陶瓷样品,对其在磁场和电场下的直、交流输运性质做了系统研究.通过测量加磁场和零场下的Ⅰ-Ⅴ曲线,得到其居里温度为150K,与VSM测试结果一致.通过测量加磁场与零场下交流的阻抗频谱,发现加磁场后样品的晶界电阻明显减小,而晶粒电阻几乎保持不变,表明Pr1-xCaxMnO3陶瓷多晶样品的CMR效应源于样品的晶界.为确定晶界处的势垒高度,测量了样品在不同频率下的阻抗温谱,根据Arrhenius定律拟合得出势垒高度为117 meV,与用直流R-T数据拟合得出的激活能一致. 相似文献
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Large reversible magnetocaloric effect induced by metamagnetic transition in antiferromagnetic HoNiGa compound 下载免费PDF全文
The magnetic properties and magnetocaloric effects(MCE) of Ho Ni Ga compound are investigated systematically.The Ho Ni Ga exhibits a weak antiferromagnetic(AFM) ground state below the Neel temperature TNof 10 K, and the AFM ordering could be converted into ferromagnetic(FM) ordering by external magnetic field. Moreover, the field-induced FM phase exhibits a high saturation magnetic moment and a large change of magnetization around the transition temperature,which then result in a large MCE. A large-?S_M of 22.0 J/kg K and a high RC value of 279 J/kg without magnetic hysteresis are obtained for a magnetic field change of 5 T, which are comparable to or even larger than those of some other magnetic refrigerant materials in the same temperature range. Besides, the μ_0H~(2/3)dependence of |?S_M~(pk)| well follows the linear fitting according to the mean-field approximation, suggesting the nature of second-order FM–PM magnetic transition under high magnetic fields. The large reversible MCE induced by metamagnetic transition suggests that Ho Ni Ga compound could be a promising material for magnetic refrigeration in low temperature range. 相似文献
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