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Effect of C doping on the structural and electronic properties of LiFePO<sub>4</sub>:A first-principles investigation 下载免费PDF全文
Using first-principles calculations within the generalized gradient approximation (GGA) +U framework, we investigate the effect of C doping on the structural and electronic properties of LiFePO 4 . The calculated formation energies indicate that C doped at O sites is energetically favoured, and that C dopants prefer to occupy O 3 sites. The band gap of the C doped material is much narrow than that of the undoped one, indicating better electro- conductive properties. To maintain charge balance, the valence of the Fe nearest to C appears as Fe 3+ , and it will be helpful to the hopping of electrons. 相似文献
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针对声纹识别领域不匹配,且目标领域缺少标注数据的难题,提出在对抗学习基础上融合分布对齐的无监督领域自适应方法,通过训练过程中统计分布的对齐,以减小领域差异,从而提取声音中更有声纹鉴别性的特征,取得了稳定的性能提升。在文本相关的声纹识别任务中,对抗学习和分布对齐的方法能协同发挥作用,等错率相对降低11%;在文本无关的任务中,对抗学习效果不稳定,而分布对齐的方法依然有相对8%的性能提升。实验结果证明该方法在领域不匹配且目标领域缺少标注数据时,能有效提取语音中声纹鉴别信息,稳定提升识别性能。 相似文献
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采用基于密度泛函理论(DFT)广义梯度近似(GGA)下的第一性原理方法系统地研究了不同覆盖度下O在Ni(111)表面的吸附特性.计算结果表明,O在Ni(111)表面的稳定吸附位为三重面心立方(fcc)洞位,吸附能随着覆盖度的增加而减小,O诱导Ni(111)表面功函数的变化量与覆盖度成近线性关系,并随着覆盖度的增加而增大.同时,通过对电子密度和分波态密度的分析发现:O在Ni(111)表面的吸附使得Ni表面电子向O原子转移,形成表面偶极矩,导致功函数增加;表面Ni原子的3d轨道和O的2p轨道通过耦合、杂化作用形成成键态和反键态,而反键态几乎不被占据,因而O—Ni键相互作用比较强,吸附能较大.
关键词:
表面吸附
密度泛函理论
吸附能
功函数 相似文献
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用固相反应法制备了La2/3(CaxBa1-x)1/3MnO3(x=0.00, 0.40, 0.45, 0.55, 0.60, 1.00) 6种多晶CMR材料, 测量了材料在77~350 K范围内零磁场和0.4 T外磁场下的电阻率.在不同的温度区域呈现不同的电阻率以及磁电阻随温度的变化行为, 说明存在不同的磁电阻效应的机制.证实了高温下的电阻率峰为I-M转变.研究发现掺杂量x=0.55, 0.60两种材料在室温有较大的磁电阻, 表明掺杂量大小影响材料特性. 相似文献
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Monte carlo simulation of magnetization and coercivity of free magnetic clusters 总被引:4,自引:0,他引:4 下载免费PDF全文
Based on Monte Carlo method, the oscillatory behaviour of the
average magnetic moment as a function of the cluster sizes and the
temperature dependences of magnetic moment with different sizes have
been studied. It is found that the oscillations superimposed on the
decreasing moment are associated with not only the geometrical
structure effects but also the thermal fluctuation. The hystereses
and thermal coercivities for free clusters with zero and finite
uniaxial anisotropies have been calculated. The simulated thermal
dependence of the coercivity is consistent with the experimental
result, but does not fit the Tα law in the whole temperature
range. It is evident that an easy magnetization direction and an
anisotropy resulting from the spin configurations exist in the free
clusters with the pure exchange interaction, which is also proved by
the natural angle and energy distribution of clusters. A systematic
theoretical analysis is also made to establish the relationship
between natural angle and coercivity. 相似文献
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本文考察了一个随机延滞的时序模型:x(n+ 1) =∑η( n+ 1)l=0al| xn+ 1| s+ εn-1,n 0 ,0 相似文献
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