共查询到20条相似文献,搜索用时 125 毫秒
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2004年以来,以石墨烯为代表的新型二维纳米材料引起了全球范围内的研究热潮,在光电子、生物、能源等领域展现出了巨大的应用潜力。过渡金属硫族化合物因平面内结合力较强、平面外结合力较弱以致可以将其剥离成单个细胞厚度的二维层状纳米材料,且该材料具备类石墨烯物理化学性质而被誉为"无机石墨烯"。关于二维过渡金属硫族化合物纳米材料的研究已有多年,众多研究表明,因其具有独特的结构和特性,在光电器件、催化及能源存储领域有着广阔的应用前景。基于该领域研究的最新进展,综述了二维过渡金属硫族化合物纳米材料在能源领域中的应用,并对目前相关研究领域的发展趋势进行了总结和展望。 相似文献
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按照K2Se:K2Te2:MnCl2@4H2O:SnCl2 2H2O:Se:乙二胺(en)=3.8:1:2:2:6:270的摩尔比配料,采用溶剂热法使原料混合物在180℃反应7 d,得到黑色块状晶体[Mn(en)3]2@Sn2Se4Te2.属于三斜晶系,空间群为P-1,晶胞参数a=0.91428(7)nm,b=1.02781(7)nm,c=1.15745(8)nm,α=94.632(2)°,β=100.944(2)°,γ=115.918(1)°,V=0.94382(12)nm3,Z=1.晶体由[Mn(en)3]2+和(Sn2Se4Te2)4-堆积而成.具有Zintl结构的特征半导体[Mn(en)3]2@Sn2Se4Te2的光学能隙(Eg)为2.2 eV.当温度低于190℃时,[Mn(en)3]2@Sn2Se4Te2晶体是稳定的.详细讨论了这类化合物的组成对晶体结构和光吸收性能的影响. 相似文献
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以乙二胺为修饰剂,采用水热法合成了不同掺杂比例的Zn_(1-x)Mn_xS(x=0,0.02,0.05,0.07)稀磁半导体材料,并通过XRD、FESEM、HRTEM、XEDS、光致发光光谱(PL)和振动样品磁强计(VSM)对样品的晶体结构、形貌、光学性能和磁学性能进行表征。实验结果表明:本方法制备的所有样品具有结晶良好的纤锌矿结构,没有杂峰出现;样品形貌为一维的纳米棒状,分散性良好;掺杂的Mn2+以替代Zn2+的形式进入到ZnS晶格中,随着Mn掺杂量的增加晶格常数呈现收缩趋势;样品的PL光谱存在明显的紫外发光峰、蓝光发光峰和绿光发光峰,而且峰位发生蓝移;同时一定量的Mn掺杂ZnS纳米晶在室温条件下具有铁磁性。 相似文献
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K. C. Ku S. H. Chun W. H. Wang W. Fadgen D. A. Issadore N. Samarth R. J. Epstein D. D. Awschalom 《Journal of Superconductivity》2005,18(2):185-188
We describe the growth of modulation-doped ZnSe/(Zn,Cd)Se quantum wells on (110) GaAs substrates. Unlike the well-known protocol for the epitaxy of ZnSe-based quantum structures on (001) GaAs, we find that the fabrication of quantum well structures on (110) GaAs requires significantly different growth conditions and sample architecture. We use magnetotransport measurements to confirm the formation of a two-dimensional electron gas in these samples, and then measure transverse electron spin relaxation times using time-resolved Faraday rotation. In contrast to expectations based upon known spin relaxation mechanisms, we find surprisingly little difference between the spin lifetimes in these (110)-oriented samples in comparison with (100)-oriented control samples. 相似文献
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The electronic band-edges of lead chalcogenides PbY and tin chalcogenides SnY (where Y = S, Se, and Te) are investigated by the means of a full-potential linearized augmented plane wave (FPLAPW) method and the local density approximation (LDA). All six chalcogenide binaries have similar electronic structures and density-of-states, but there are differences in the symmetry of the band-edge states at and near the Brillouin zone L-point. These differences give the characteristic composition, pressure, and temperature dependences of the energy gap in Pb1−xSnxY alloys.We find that: (1) SnY are zero-gap semiconductors Eg = 0 if the spin–orbit (SO) interaction is excluded. The reason for this is that the conduction band (CB) and the valence band (VB) cross along the Q ≡ LW line. (2) Including the SO interaction splits this crossing and creates a direct gap along the Q-line, thus away from the L symmetry point. Hence, the fundamental band gap Eg in SnY is induced by the SO interaction and the energy gap is rather small Eg ≈ 0.2–0.3 eV. At the L-point, the CB state has symmetric and the VB state is antisymmetric thereby the L-point pressure coefficient ∂Eg(L)/∂p is a positive quantity. (3) PbY have a direct band gap at the L-point both when SO coupling is excluded and included. In contrast to SnY, the SO interaction decreases the gap energy in PbY. (4) Including the SO interaction, the LDA yields incorrect symmetries of the band-edge states at the L-point; the CB state has and the VB state has symmetry. However, a small increase of the cell volume corrects this LDA failure, producing an antisymmetric CB state and a symmetric VB state, and thereby also yields the characteristic negative pressure coefficient ∂Eg(L)/∂p in agreement with experimental findings. (5) Although PbY and SnY have different band-edge physics at their respective equilibrium lattice constants, the change of the band-edges with respect to cell volume is qualitatively the same for all six chalcogenides. (6) Finally, in the discussion of the symmetry of the band edges, it is important to clearly state the chosen unit cell origin; a shift by (a/2,0,0) changes the labeling of the irreducible representations. 相似文献
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We describe the growth of modulation-doped ZnSe/(Zn,Cd)Se quantum wells on (110) GaAs substrates. Unlike the well-known protocol for the epitaxy of ZnSe-based quantum structures on (001) GaAs, we find that the fabrication of quantum well structures on (110) GaAs requires significantly different growth conditions and sample architecture. We use magnetotransport measurements to confirm the formation of a two-dimensional electron gas in these samples, and then measure transverse electron spin relaxation times using time-resolved Faraday rotation. In contrast to expectations based upon known spin relaxation mechanisms, we find surprisingly little difference between the spin lifetimes in these (110)-oriented samples in comparison with (100)-oriented control samples. 相似文献
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Optical and EPR characterization of Cr and Fe doped ZnSe crystals annealed in Zn vapor revealed a strong bleaching of the divalent state of transition metal ions. Photo induced EPR kinetics were studied in 20–80 K temperature range. Analysis of time-dependent data reveals Cr1+ signal rise time decreases with increasing temperature. The non-exponential decay of Cr1+ concentration were analyzed using Auger-type recombination process. The photoluminescence quantum yield of Cr2+ ions at 5E(D) → 5T2(D) mid-IR transition excited via chromium ionization process was measured to be close to 100%. 相似文献
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A. Manzoli 《Thin solid films》2007,515(17):6860-6866
The negative potential sweep of a polycrystalline Au electrode in a solution containing 5 × 10− 4 mol L− 1 SeO2, 0.2 mol L− 1 Zn(ClO4)2 and 0.5 mol L− 1 HClO4 was analyzed at 0.05 V s− 1. The simultaneously collected voltammetric and nanogravimetric responses allowed to analyze the several electrochemical processes occurring in the studied range of potential, finishing with the formation of a thin film of ZnSe. The association of results obtained using both techniques was applied to identify the species involved in the AuO reduction as (AuO)2H2SeO3, which was desorbed during the oxide reduction with a mass variation much larger than that one observed in the supporting electrolyte. Initially, the Se(IV) reduction results in Seads coverage, followed by a further reduction to H2Se, which is a gas and desorbs from the electrode surface. Finally, the Zn(II) reduction inhibits the H2Se formation and generates a thin film of ZnSe, as the final coating. The strong dependence of the nature of reacting compound and the mass as well as the charge variations allowed to postulate a reaction mechanism. 相似文献
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《Journal of Experimental Nanoscience》2013,8(14):1082-1092
White light generation is achieved by single-step co-doping of copper and manganese into the robust ZnSe quantum dots (QDs) which were synthesised using a wet chemical route. Photoluminescence (PL) emission spectra revealed three peaks related to blue (ZnSe), green (copper related) and orange (manganese related). The PL spectra indicated no surface and/or trap state related emission. Photoluminescence excitation (PLE) measurements confirmed co-doping of copper and manganese in the same QD. PLE spectra recorded with emission wavelength fixed at copper and manganese showed a band edge at the same position, indicating the incorporation of both copper and manganese in the same QD. Time-resolved PL measurements suggest an atomic like nature of Mn and Cu in ZnSe QDs. 相似文献
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Andrea Ravagli Christopher Craig Ghada A. Alzaidy Paul Bastock Daniel W. Hewak 《Advanced materials (Deerfield Beach, Fla.)》2017,29(27)
Gallium lanthanum sulfide glass (GLS) has been widely studied in the last 40 years for middle‐infrared applications. In this work, the results of the substitution of selenium for sulphur in GLS glass are described. The samples are prepared via melt‐quench method in an argon‐purged atmosphere. A wide range of compositional substitutions are studied to define the glass‐forming region of the modified material. The complete substitution of Ga2S3 by Ga2Se3 is achieved by involving new higher quenching rate techniques compared to those containing only sulfides. The samples exhibiting glassy characteristics are further characterized. In particular, the optical and thermal properties of the sample are investigated in order to understand the role of selenium in the formation of the glass. The addition of selenium to GLS glass generally results in a lower glass transition temperature and an extended transmission window. Particularly, the IR edge is found to be extended from about 9 µm for GLS glass to about 15 µm for Se‐added GLS glass defined by the 50% transmission point. Furthermore, the addition of selenium does not affect the UV edge dramatically. The role of selenium is hypothesized in the glass formation to explain these changes. 相似文献
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Kedir Ebrahim Ahmed Dong-Hau Kuo Worku Lakew Kebede 《Advanced Powder Technology》2019,30(8):1664-1671
Heterojunction construction with low band gap materials is an effective way of utilizing UV light active materials under visible light irradiation. Here, we report the synthesis of Bi2(O,S)3/Zn(O,S) heterostructure using simple solvothermal method without surfactant. The catalysts were investigated with different characterization techniques. All the composite catalysts showed high light absorption capacity in the whole visible light spectrum. The catalytic activity of the catalysts was evaluated by Cr(VI) reduction. While pure Zn(O,S) catalyst showed no significant Cr(VI) reduction, higher photocatalytic activity than individual components were exhibited after heterojunction construction with Bi2(O,S)3. 20-BiZnOS catalyst with Bi/Zn molar percentage of 20% showed the best photocatalytic activity among the composites with 99.5% Cr(VI) reduction within 12 min under visible light irradiation. Heterojunction formation between Bi2(O,S)3 and Zn(O,S) nanoparticle, and selective adsorption of Cr(VI) and desorption of Cr(III) on the surface of 20-BiZnOS composite catalyst were ascribed to the enhanced photocatalytic activity of the composite catalyst. 相似文献