Sb2S3 quantum dots: diffusion‐controlled growth and characterization

The quantum dots of antimony trisulphide, a potential semiconductor for various applications, are grown in glass matrix for the first time and are characterized by various techniques. The dependence of the average dot size on growth parameters like growth temperature and time is systematically studied for the dot size range of 5–80 nm. The linear blue shift of band gap of dots with inverse square of dot size clearly indicates the typical behavior of quantum dots in a strong quantum confinement regime. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dielectric Measurements on Rare Earth-Substituted Bi6Fe2Ti3O18 Ceramic

Polycrystalline materials of rare earth-substituted (La, Sm, Gd and Dy) 5-layered compound of Bi₆Fe₂Ti₃O₁₈ were prepared by solid state sintering method. Dielectric measurements were made on these samples, which reveal the occurrence of diffuse phase transitions. The Curie temperatures of these materials have been found to be strongly dependent on the size of the rare earth ion. Pyroelectric and P vs. E measurements at room temperature confirm their ferroelectric nature.     

基于Sb_2O_3/Ag/Sb_2O_3叠层透明导电薄膜的自组装沟道透明薄膜晶体管

首次利用Sb2O3/Ag/Sb2O3(SAS)叠层透明导电薄膜作为透明电极,并采用衍射自组装沟道的方法研制了一种透明薄膜晶体管。通过一次掩模工艺,在电子束热蒸发过程中的SAS源漏电极之间制作沟道层。SAS透明导电薄膜具有优异的光电性能。研制的透明薄膜晶体管具有良好的器件性能,其迁移率高达11.36cm2/(V·s)。整个器件在可见光范围内的平均透过率为80%。结果表明,这种透明薄膜晶体管有希望应用于低成本透明光电子产品中。     

Low-Temperature Phase Transitions in the Trigonal Modification of Cs 3 Bi 2 Br 9 and Cs 3 Sb 2 I 9

The trigonal (P-3 m1) modification of Cs 3 Bi 2 Br 9 and Cs 3 Sb 2 I 9 have been studied using NQR, X-ray single crystal and powder pattern methods. Moreover, the heat capacity was measured in a wide temperature interval: 4-300 K. In Cs 3 Bi 2 Br 9 a second-order phase transition was found at T C = 96 K. The low-temperature phase is monoclinic (C12/c1), with the unit cell doubled along the [001] direction. Cs 3 Sb 2 I 9 has a sequence of phase transitions at T C = 85 K, T i = 78 K and T L = 72.1 K. The monoclinic structure below 85 K is isomorphic with the low-temperature structure of Cs 3 Bi 2 Br 9 . According to calorimetric data the lock-in transition at 72.1 K is discontinuous.     

A Structural Study of Some Metal Diethyldithiocarbamate Chelates by X-ray Photoelectron Spectroscopy

The diethyldithiocarbamate chelates of copper (II), lead (II) and tin (IV) have been prepared and characterized. Pure or nearly pure metal diethyldithiocarbamate (DEDTC) chelates could be prepared through recrystallization. The x-ray photoelectron spectra (XPS) for the recrystallized samples were obtained. Three different carbons (C Is) in the diethyldithiocarbamate molecule can be recognized through a computer deconvolution system. Sulfer 2p showed two peaks of spin doublet S 2p_1/2 and S 2p_3/2. Based on the XPS results we may conclude that the diethyldithiocarbamate ligand forms an unusual 4-membered chelate ring structure with the metal ion, both sulfur having bonding with the metal. The N in the DEDTC may also bind with the metal.     

Effect of Mo doping on phase change performance of Sb2Te3

Mo, as a dopant, is doped into SbTe to improve its thermal stability. It is shown in this paper that the Mo-doped Sb₂Te₃ (Mo_0.26Sb₂Te₃, MST) material possesses phase change memory (PCM) applications. MST has better thermal stability than Sb₂Te₃(ST) and will crystallize only when the annealing temperature is higher than 250 ℃. With the good thermal stability, MST-based PCM cells have a fast crystallization time of 6 ns. Furthermore, endurance up to 4×10⁵ cycles with a resistance ratio of more than one order of magnitude makes MST a promising candidate for PCM applications.     

Proximity-Effect-Induced Superconductivity in Nb/Sb2Te3-Nanoribbon/Nb Junctions

Nanohybrid superconducting junctions using antimony telluride (Sb₂Te₃) topological insulator nanoribbons and Nb superconducting electrodes are fabricated using electron beam lithography and magnetron sputtering. The effects of bias current, temperature, and magnetic field on the transport properties of the junctions in a four-terminal measurement configuration are investigated. Two features are observed. First, the formation of a Josephson weak-link junction. The junction is formed by proximity-induced areas in the nanoribbon right underneath the inner Nb electrodes which are connected by the few tens of nanometers short Sb₂Te₃ bridge. At 0.5 K a critical current of 0.15 µA is observed. The decrease of the supercurrent with temperature is explained in the framework of a diffusive junction. Furthermore, the Josephson supercurrent is found to decrease monotonously with the magnetic field indicating that the structure is in the small-junction limit. As a second feature, a transition is also observed in the differential resistance at larger bias currents and larger magnetic fields, which is attributed to the suppression of the proximity-induced superconductive state in the nanoribbon area underneath the Nb electrodes.     

Sb2O3掺杂对提高PbWO4晶体光学及闪烁性能的作用

采用改进的布里奇曼（Ｂｒｉｄｇｍａｎ）法生长了掺杂Ｓｂ２Ｏ３的ＰｂＷＯ４晶体。基于透射光谱、紫外激发及其发射谱、Ｘ射线激发的发射谱、光输出和辐照损伤待方面的测试,讨论了Ｓｂ２Ｏ３掺杂对提高ＰｂＷＯ４晶体光学及闪烁性能的作用。     

高温高压下掺杂N型PbTe的热电性能

 以Sb₂Te₃作为掺杂剂,利用高温高压技术,成功合成出N型PbTe。在常温下对其热电性能的测试结果表明：掺杂微量的Sb₂Te₃后,PbTe的赛贝克系数绝对值和电阻率大幅度下降,热导率随掺杂浓度的增加缓慢升高。掺杂后PbTe的品质因子先大幅度增加,后逐渐降低,最高达到8.7×10^-4 K^-1,它比常压合成的PbTe掺杂PbI₂高一倍以上。结果表明,将高温高压方法与掺杂相结合,能有效地改善PbTe的热电性能。     

Au_nAg_m~-(n+m=2～4)负离子团簇光脱附电子谱计算

利用密度泛函理论,通过几何优化和态密度计算了Au_nAg_m^-（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.     

AunAgm- (n+m=2～4)负离子团簇光脱附电子谱计算

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。     

Photoelectron Spectroscopic Study on Photo-Induced Phase Transition of Spin-Crossover Complex

Valence band structures in various phases of an organometal spin-crossover complex [Fe(2-pic) 3 ]Cl 2 - EtOH have been measured by means of photoelectron spectroscopy based on the combination of synchrotron radiation and laser light. The valence band structure showed the remarkable change due to the photo-induced (PI) phase transition (PIPT) at low-temperatures (LTs) as well as the thermally induced phase transition (TIPT), but the structure of the PI phase was very different from that of the high-temperature (HT) phase. The DV-X f calculation based on the [Fe-(NH 3 ) 6 ] octahedron was also carried out for comparison, indicating that the electronic structure originating from Fe and N ions is closely related to the PIPT.     

A density-wave-like transition in the polycrystalline V3Sb2 sample with bilayer kagome lattice

Recently,transition-metal-based kagome metals have aroused much research interest as a novel platform to explore exotic topological quantum phenomena.Here we report on the synthesis,structure,and physical properties of a bilayer kagome lattice compound V₃Sb₂.The polycrystalline V₃Sb₂ samples were synthesized by conventional solid-state-reaction method in a sealed quartz tube at temperatures below 850℃.Measurements of magnetic susceptibility and resistivity revealed consistently a density-wave-like transition at Tdw≈160 K with a large thermal hysteresis,even though some sample-dependent behaviors were observed presumably due to the different preparation conditions.Upon cooling through Tdw,no strong anomaly in lattice parameters and no indication of symmetry lowering were detected in powder x-ray diffraction measurements.This transition can be suppressed completely by applying hydrostatic pressures of about 1.8 GPa,around which no sign of superconductivity was observed down to 1.5 K.Specific-heat measurements revealed a relatively large Sommerfeld coefficientγ=18.5 mJ·mol^-1·K^-2,confirming the metallic ground state with moderate electronic correlations.Density functional theory calculations indicate that V₃Sb₂ shows a non-trivial topological crystalline property.Thus,our study makes V₃Sb₂ a new candidate of metallic kagome compound to study the interplay between density-wave-order,nontrivial band topology,and possible superconductivity.     

高压下稳态六方Ge2Sb2Te5结构、电子和光学性质的第一性原理研究

采用基于密度泛函理论的广义梯度近似方法研究了稳态六方petrov原子序列结构Ge2Sb2Te5的结构、电子和光学性质。计算所得的平衡态晶格参数与实验数据和先前的理论结果吻合很好。基态的能带结构和态密度表明了稳态六方petrov原子序列结构的Ge2Sb2Te5持有金属性。从压强影响下体积的变化趋势发现稳态六方Ge2Sb2Te5在17 GPa和34 GPa 出现不稳定,暗示在此压强下的相变发生,这与2009年Krbal等人的实验结果相吻合。同时,还系统地研究了稳态六方petrov原子序列结构的Ge2Sb2Te5高压下的光学性质,得到了高压下介电函数、吸收率、光反射率、折射率、消光系数和电子能量损失谱在20 eV内的变化情况。     

First principles study of isostructural phase transition in Sb2Te3 under high pressure

The structural properties, electronic band structure and Bader charge of Sb₂Te₃ under hydrostatic pressure were simulated using density functional theory in order to study isostructural phase transitions (IPT) in Sb₂Te₃. The theoretical results showed that the axial ratio c /a did not exhibit any anomaly below 6 GPa. The variations of bond lengths were discontinuous at 2.5 GPa, which suggested considerable changes in interatomic interactions and provided sound support to the IPT. The effective charges of Sb and Te atoms showed significant discontinuous variations at 2.5 GPa, which revealed a strong redistribution of the electronic charge density and considerably changed interactions among bonding atoms. Thus, the IPT is originated from the considerable variation in the electronic charge density. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Growth behavior of Bi2Te3 and Sb2Te3 thin films on graphene substrate grown by plasma‐enhanced chemical vapor deposition

A comparative study of the substrate effect on the growth mechanism of chalcogenide Bi₂Te₃ and Sb₂Te₃ thin films was carried out. Obvious microstructural discrepancy in both the as‐deposited Bi₂Te₃ and Sb₂Te₃ thin films was observed when grown on graphene or SiO₂/Si substrate. Bi₂Te₃ and Sb₂Te₃ thin films deposited on the graphene substrate were observed to be grown epitaxially along c‐axis and show very smooth surface compared to that on SiO₂/Si substrate. Based on the experimental results of this study, the initial adsorption sites on graphene substrate during deposition process, which had been discussed theoretically, could be demonstrated empirically.     

Ga3S2-和Ga4S3-团簇结构及性质的密度泛函理论研究

采用密度泛函理论（DFT）中的B3LYP方法和BP86方法,对Ga₃S₂^-团簇和Ga₄S₃^-团簇进行结构优化,并计算和分析了最稳定结构的成键性质及振动特性.计算结果表明,Ga₃S₂^-团簇和Ga₄S₃^-团簇的最稳定结构是由"Ga-S-Ga"结构单元和处于端位的"Ga-S"结构单元组成的.键级分析表明上述两结构单元都具有较强的稳定性.此外,通过分析红外振动光谱数据也发现在"Ga-S-Ga"单元和"Ga-S"单元处有红外强峰出现.