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The structure-property relation is a key outstanding problem in the study of nanocomposite materials. Here we elucidate the fundamental physics of nanodopants in thermoelectric nanocomposites XPb(m)YTe(2+m) (X = Ag, Na; Y = Sb, Bi). First-principles calculations unveil a sizable band-gap widening driven by nanodopant-induced lattice strain and a band split-off mainly caused by the spin-orbit interaction in nanodopant. Boltzmann transport calculations on PbTe with modified band mimicking nanodopant-induced modulations show significant but competing effects on high-temperature electron transport behavior. These results offer insights for understanding experimental findings and optimizing thermoelectric properties of narrow band-gap semiconductor nanocomposites. 相似文献
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蔡灵仓 《光谱学与光谱分析》1998,18(3):273-278
本文对类镓等电子序列GaI-XeXXIV离子4s^24p、4s^24p、4s^24d、4s4p^2、4p^3和4s^25s组态组级结果和组态相互作用了理论分析,找出沿等电子序列的变化规律。 相似文献
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采用密度泛函理论(DFT)中的B3LYP方法得到了(AlB2)m团簇的平衡几何结构. 计算并分析了基态掺杂团簇的平均结合能、电离势、能隙和前线分子轨道. 结果表明:掺杂团簇(AlB2)m (m=1~6)整体上具有较高化学活性,(AlB2)5团簇具有金属特征. Al原子总是向团簇外围扩散并且以配位数较少的方式与主团簇结合,团簇表现出以AlB2分子为基元生长的迹象. B-Al键长大于B-B键长. 电荷总是从Al原子转移到B原子. (AlB2)m团簇中B原子的2p轨道在成键中起主要作用,并使(AlB2)m团簇趋于形成离域π键. 相似文献
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利用密度泛函理论,通过几何优化和态密度计算了AunAgm-(n+m=2~4)团簇的光电子光谱,结果显示只有Au2Ag2-团簇的第一个峰发生了0.5eV的红移,而其它团簇的峰位置符合的很好,因此理论计算给出的团簇结构是合理的. 相似文献
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利用密度泛函理论,通过几何优化和态密度计算了AunAgm- (n+m=2~4)团簇的光电子光谱,结果显示只有Au2Ag2-团簇的第一个峰发生了0.5eV的红移,而其它团簇的峰位置符合的很好,因此理论计算给出的团簇结构是合理的。 相似文献
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Roberto Floreanini Vyacheslav P. Spiridonov Luc Vinet 《Communications in Mathematical Physics》1991,137(1):149-160
Realizations of the quantum superalgebras corresponding to theA(m, n), B(m, n), C(n+1), andD(m, n) series are given in terms of the creation and annihilation operators ofq-deformed Bose and Fermi oscillators. 相似文献
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Y. J. Chen Y. F. Lin X. H. Gong H. M. Zhu Z. D. Luo Y. D. Huang 《Applied physics. B, Lasers and optics》2010,98(1):55-60
End-pumped by a single-stripe 805-nm diode laser, a maximum continuous-wave output power of 290 mW with slope efficiency of
42% and 90 mW with slope efficiency of 44% around 2 μm were achieved in a 1.6-mm-thickness, unprocessed 7.2 at.% Tm3+:BaGd2(MoO4)4 cleavage plate in a hemispherical and plano–plano cavities, respectively, when the absorbed pump power was 830 mW. The dependence
of the polarization of output laser on the output coupler transmission was investigated. The influence of upconversion on
the laser performance was analyzed. The results show that the unprocessed Tm3+:BaGd2(MoO4)4 cleavage plate is a promising 2-μm laser gain medium pumped by diode laser around 808 nm. 相似文献
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S. Hüfner P. Steiner M. Weirich R. Courths 《Zeitschrift für Physik B Condensed Matter》1991,85(1):43-48
The electronic structure of (LaSr)2CuO4 and (NdCe)2CuO4 are compared. It is concluded that in both materials after doping by holes and electrons respectively the Fermi energy is at the top of the valence band. This explains many symmetrical properties and in particular the photoemission experiments.Dedicated to Prof. P. Kienle on the occasion of his 60th birthday 相似文献
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Optical observations of growth twins and ferroelastic domains and measurements of the rotation of the optical indicatrix were carried out for Rb3H(SeO4)2 and (NH4)3H(SO4)2 using an optical microscope. Taking into account the symmetry reduction from the rhombohedral (Rm) to the monoclinic phase (B2/a) the occurrence of domains and growth twins can be well described. The orientations of oblique ferroelastic walls are well determined by the spontaneous strains s e 11 and s e 23 at room temperature. 相似文献
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W.G. Schmidt 《Applied Physics A: Materials Science & Processing》1997,65(6):581-586
Received: 21 March 1997/Accepted: 12 August 1997 相似文献
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Physics of the Solid State - Simulation of the solid solutions in the system of double sodium–gadolinium and sodium–europium molybdates, which are promising matrices for solid state... 相似文献
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ENDOR measurements at 25 K have been used to determine the hyperfine coupling tensors for all ten protons in the VO(H2O)5 2+ ion in single crystals of Mg(NH4)2(SO4)26H2O. The traceless components of all the tensors are close to axial and their use in a point dipole treatment enables a very plausible geometrical model of the complex ion to be constructed. Six of the protons in the equatorial water molecules have substantial positive isotropic couplings and it is suggested that these reflect the direct admixture of hydrogen 1s components into the singly occupied orbital. 相似文献
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采用二项式方案构建了FenOm+(n+m=4)团簇的大量可能初始结构.运用广义梯度近似(GGA)密度泛函理论中的PW91交换关联泛函对这些初始结构进行优化和频率分析,得到12个稳定的异构体.在此基础上计算和分析了它们的结合能、对称性、键长、磁矩,最高占据轨道与最低未占据轨道的能隙.发现Fe—O键在FenOm+(n+m=4)团簇的稳定中具有重要作用,团簇的总磁矩主要取决于铁原子的磁矩和各个原子磁矩排布情况. 相似文献
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为了验证KTiOAsO4(KTA)晶体用于光参变振荡产生2μm激光的可行性,设计了脉冲式2μm KTA光参变振荡器,采用θ=49°切割的KTA晶体作为光参变振荡晶体,实现了2μm激光的输出;计算了该系统在双谐振情况下的起振阈值,在实验中测得输出的信号光、闲频光波长在2.16μm和2.09μm附近,与理论计算基本吻合,并测量了脉冲宽度。同时选用了对信闲光透过率分别为60%、70%、90%的镜片作为光参变振荡器(OPO)输出镜,测得了三种情况下的输出能量及电光效率的数值;测得了在380 V电压下,输出镜透过率一定时输出能量与光参变振荡器腔长之间的关系曲线,从而验证了KTA晶体用于光参变振荡产生2μm激光的可行性,为下一步的研究工作打下了基础。 相似文献