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Solid-state resonant tunneling thermoelectric refrigeration in the cylindrical double-barrier nanostructure
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A solid-state thermoelectric refrigerator with a cylindrical InP/InAs/InP double-barrier heterostructure is proposed.Based on the ballistic electron transport and the asymmetrical transmission, we derive the expressions of the performance parameters of this refrigerator. The cooling rate rather than the coefficient of performance is affected by the area of the inner cylinder. Then through the numerical simulation, a triangular cooling rate region is found with respect to the chemical potential and bias voltage; further, that it is because of the small full width at half maximum of the transmission resonance and the linear relationship between the energy position of resonance and the bias voltage. These tunable results might supply some guide to the cooling in tiny components or devices. 相似文献
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通过应变调控二维材料的电学性质和光学性质是设计新型二维电子和光电子器件的重要环节,也是后摩尔时代薄膜器件设计中的关键技术.薄膜CrI3具有铁磁和层间反铁磁的独特性质,但是关于应变调制其电学性质和光学性质的研究未见报道.本文采用高精度杂化密度泛函理论研究了面内单双轴应变对单层CrI3载流子迁移率和介电函数的调控规律,研究结果与已有的实验和理论值符合较好.计算发现:单层CrI3载流子迁移率非常小,均在10 cm2·V-1·s-1以内;与拉伸应变相比,双轴压缩应变可以显著提升迁移率;当双轴压缩应变量增至8%时,沿锯齿方向电子迁移率增至174 cm2·V-1·s-1,达到了MoS2水平.可见光区介电函数虚部x (y)方向Ⅰ号吸收峰强度随双轴拉伸应变量增加明显增强,而z方向几乎没有变化;可见光区x (y)和z方向的介电函数虚部曲线开始攀升的起点对应的光子能量均随双轴压缩应变量增加... 相似文献
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在N2环境下,离子强度为0.1 mol/L的NaClO4溶液中,考察了不同pH值(3.0~11.0)对Eu(Ⅲ)在氧化铝上吸附行为的影响,用荧光时间衰减光谱法研究了Eu(Ⅲ)在氧化铝表面上的化学形态.结果表明,Eu(Ⅲ)在氧化铝上的吸附随pH值的升高而增强,在较低pH值(<4.0)溶液中,绝大部分Eu以自由的Eu3 存在于溶液中;在较高pH值(>6.9)溶液中,Eu(Ⅲ)在氧化铝上的吸附形态会失去大部分水,形成化学吸附,吸附形态为≡(Al-O)-Eu2 .(H2O)4. 相似文献
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Surface effect of nanocrystals doped with rare earth ions enriched on surface and its application in upconversion luminescence
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By employing a certain proportion of hydrogen peroxide, ammonia, ammonium fluoride, and ethylene diamine tetraacetic acid (EDTA) as precipitator, well-crystallized LaOF:Eu3+ and LaOF:Yb3+, Er3+ nanocrystals are synthe- sized by using the chemical co-precipitation method. The structural properties of these samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) spectra. The results show that all the samples have an average size below 70 nm, which decreases gradually with the increase of the EDTA content, and a certain number of EDTA molecules are coupled with doped ions on the surfaces of nanocrystals. Most of the doped ions are proved to be enriched on the surfaces of nanocrystals and surrounded by the high energy vibration groups and bonds in EDTA molecules. The observed differences in upconversion emission spectrum among the different LaOF:Yb3+, Er3+ nanocrystals are explained by the different two-photon upconversion mechanisms. Especially, in the LaOF:Yb3+, Er3+ nanocrystals with EDTA, the two-photon processes that contain several special cross-relaxation processes are introduced to analyse the corresponding upconversion mechanisms. 相似文献
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在Lü系统的基础上提出了一个新的三维自治混沌系统,并对系统的基本动力学特性进行了深入的分析,利用数值分析软件MATLAB给出了系统的相轨迹图、分岔图、Lyapunov指数谱等.结果研究表明,系统具有丰富的非线性动力学行为.根据非线性电路的基本理论,把新的三维自治混沌系统的数学模型转化为电路方程,构造出符合新混沌系统的非线性电路.利用电路仿真软件Multisim对非线性电路进行了仿真实验,仿真结果证实了该非线性混沌系统电路在物理上的可实现性. 相似文献
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