Stability of Thin-Film Cu–As2S3 and Ag–As2S3 Structures

Technical Physics - Thin-film Cu–As2S3 and Ag–As2S3 structures obtained by successively evaporating Cu(Ag) and As2S3 in vacuum on glass substrates have been studied. Samples of these...     

Tunable electronic properties and carrier mobility in binary pnictogen nanosheets,PX (X = As,Sb, and Bi)

Catalytic graphitization of kraft lignin to nano-materials was investigated over four transitional metal catalysts (Ni, Cu, Fe, and Mo) through a thermal treatment process under an argon flow at 1000 °C. The catalytic thermal process was examined using thermal gravimetric analysis (TGA) and temperature-programmed decomposition (TPD) experiments. The crystal structure and morphology of the thermal-treated metal-lignin samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. Catalytic graphitization of kraft lignin to nano-materials was investigated over four transitional metal catalysts (Ni, Cu, Fe, and Mo) through a catalytic thermal treatment process. It was observed that multi-layer graphene-encapsulated metal nanoparticles were the main products, beside along with some graphene sheets/flakes. The particle sizes and graphene shell layers were significantly affected by the promoted metals. BET surface areas of samples obtained from different metal precursors were in the range of 88–115 m²/g within the order of Ni-?>?Fe-?>?Mo-?>?Cu-. Thermal gravimetric analysis (TGA) and temperature-programmed decomposition (TPD) experimental results showed that adding transitional metals could promote the decomposition and carbonization of kraft lignin. The catalytic activity increased with an order of Mo?Cu?<?Ni?Fe. XRD results show that face-centered cubic (fcc) Cu crystals is formed in the thermal-treated Cu-lignin sample, fcc nickel phase for the Ni-lignin sample, β-Mo₂C hexagonal phase for the Mo-lignin sample and α-Fe, γ-iron, and cementite(Fe₃C) for the Fe-lignin sample. Average particle sizes of these crystal phases calculated using the Scherrer formula are 52.4 nm, 56.2 nm, 21.0 nm, 23.3 nm, 11.3 nm, and 32.8 nm for Ni, Cu, β-Mo₂C, α-Fe, γ-iron, and Fe₃C, respectively. Raman results prove that the graphitization activity of these four metals is in the order of Cu?<?Mo?<?Ni?<?Fe. Metal properties such as catalytic activity, carbon solubility, and tendency of metal carbide formation were related to the graphene-based structure formation during catalytic graphitization of kraft lignin process.

     

Phase transitions of YbX (X = P,As and Sb) with a NaCl-type structure at high pressures

The powder X-ray diffraction of YbX (X?=?P, As and Sb) with a NaCl-type structure has been studied with synchrotron radiation up to 63?GPa at room temperature. YbSb undergoes the first-order structural phase transition from the NaCl-type (B1) to the CsCl-type (B2) structure at around 13?GPa. The structural change to the B2 structure occurs with the volume collapse of about 1% at 13?GPa. The transition pressure of YbSb is surprisingly lower than that of any other heavier LnSb (Ln?=?Dy, Ho, Er, Tm and Lu). The pressure-induced phase transitions in YbP and YbAs are observed at around 51?GPa and 52?GPa respectively. The transition pressure of both compounds is much higher than that of YbSb. The high-pressure structural behaviour of YbX (X?=?P, As and Sb) is discussed. The volume versus pressure curve for YbX with the NaCl-type structure is fitted by a Birch equation of state. The bulk moduli of these compounds with the NaCl-type structure are 104?GPa for YbP, 85?GPa for YbAs and 52?GPa for YbSb.     

ICP-AES法测定蒿甲醚中 Cu、Pb、Zn、As、Sb和Cd

本文有用硝酸－高氯酸消解蒿甲醚样品，ICP－AES法同时测定其中痕量的Cu、Pb、Zn、As、Sb和Cd等。研究了样品处理方法及高氯酸残余量对测定的干扰，选择了仪器最佳工作条件，考查了方法准确度和精密度，6种元素加标回收率在91％－110％范围内，RSD（n=7)为4．2％－6．5％。     

Spectromicroscopic investigation of (NH4)2S treated polycrystalline Cu(In1−xGax)Se2

Device-grade polycrystalline thin-film Cu(In_1−xGa_x)Se₂ was treated with (NH₄)₂S at 60°C to determine the resulting microscopic surface composition/morphology. Scanning electron microscopy was used to evaluate the resultant macroscopic surface morphology. Modification of the surface and grain boundary chemistry of the Cu(In_1−xGa_x)Se₂ polycrystalline films was investigated with scanning photoemission spectromicroscopy. The submicrometer lateral resolution of this technique allows us to directly characterize not only the surface chemistry of the treated films on the submicron scale, but also to probe the grain boundary chemistry. Chemical maps depicting the distribution of chemical species on the surface and at grain boundaries were obtained by monitoring the S 2p, Se 3d, In 4d/Ga 3d and Cu 3d (valence band) photoelectrons while scanning the sample. Background maps were also acquired of each of the peak energies to separate chemical contrast from topographic contrast. Results show that S has been incorporated at the surface, possibly creating a wider bandgap Cu(In_1−xGa_x)(Se_1−yS_y)₂ surface layer, and along the grain boundaries. The purpose of this investigation is to find an environmentally safe replacement for the toxic CdS overlayer commonly used for heterojunction devices without sacrificing overall device performance and reliability.     

Effect of replacement of Se by S on structural and physical properties of Ge–Sb–As–Se–S chalcogenide glasses

In the present study, the structural and opto-mechanical properties of Ge–Sb–As–Se–S chalcogenide glasses have been investigated. For this purpose, different bulk glasses of Ge₂₀Sb₅As₁₅Se_60?xS_x (0 ≤ x≤50) were prepared by conventional melt quenching technique in quartz ampoule and different characteristics of prepared glasses such as glass transition temperature, density, hardness, transmittance, optical band gap energy and refractive index were determined. The value of hardness and glass transition temperature of prepared glasses were found to increase with increasing the sulfur content as a result of formation of GeS₄ tetrahedral units and increasing the network connectivity and average bonding energy. The optical energy gap (according to Tauc’s relation), transmittance and refractive index of prepared glasses are in direct relation with sulfur content. In this study, the highest value of transmittance (about 70%) and lowest value of refractive index (2–2.3) was achieved in Ge₂₀Sb₅As₁₅Se₄₀S₂₀ and Ge₂₀Sb₅As₁₅Se₁₀S₅₀ glasses, respectively.     

(e,e′), (γ, π+ and (π−, γ) on12C and13C

A detailed theoretical analysis of spin degrees of freedom in carbon isotopes is performed, probing them by electron scattering, pion photoproduction and radiative pion capture from the mesoatomic orbits.Dedicated by the co-authors to the memory of J. Gmitro.The present paper is one of the last works made together with our colleague Marian Gmitro. We had to complete it without him. We mourn for his sudden death and we will always keep alive the memory of his bright personality.     

LiNdP_4O_(12)的晶体结构

对于盐熔法合成的LiNdP_4O_(12)单晶进行了X射线衍射分析,该晶体属于单斜晶系,空间群为C2/c,z=4,晶胞参数为:α=16.486A,b=7.073A,c=9.775A,β=126.23°,全矩阵最小二乘法修正给出1251个独立反射的R=0.054,R_ω=0.050,经吸收和次级消光校正后,R=0.048,R_ω=0.043,基本的结构单位是(PO_3)_n的螺旋带,它们由共角的四面体构成,十二面体NdO_8不共有任何O原子,从这意义来说是相互分立的。     

LiErP_4O_(12)的晶体结构

对于盐熔法合成的LiErP_4O_(12)单晶进行了X射线衍射分析。该晶体属于单斜晶系,空间群为C2/c,z=4,晶胞参数为:a=16.229A,b=7.009A,c= 9.524A,β=125.92°。包括把二次消光作为晶体结构参数的全矩阵最小二乘法修正给出1282个独立反射的R=0.058。基本的结构单位为(PO_3)_n的螺旋带,它们由共角的四面体构成。十二面体ErO_8不共有任何O原子,从这意义来说是相互分立的。     

(φ4As) CuCl3晶体中Cu2+-Cu2+离子对的EPR研究

本文在晶场理论的基础上,考虑了Cu²⁺-Cu²⁺离子间的交换作用后,得到了(φ₄As) CuCl₃晶体中Cu^2--Cu^2-离子对的跃迁能级,g-因子和零场分裂,计算结果与实验符合较好。     

Band gap tunable and improved microstructure characteristics of Cu2ZnSn(S1−x,Sex)4 thin films by annealing under atmosphere containing S and Se

Cu₂ZnSn(S_xS_1?x)₄ (CZTSSe) thin films were prepared by annealing a stacked precursor prepared on Mo coated glass substrates by the sputtering technique. The stacked precursor thin films were prepared from Cu, SnS₂, and ZnS targets at room temperature with stacking orders of Cu/SnS₂/ZnS. The stacked precursor thin films were annealed using a tubular two zone furnace system under a mixed N₂ (95%) + H₂S (5%) + Se vaporization atmosphere at 580 °C for 2 h. The effects of different Se vaporization temperature from 250 °C to 500 °C on the structural, morphological, chemical, and optical properties of the CZTSSe thin films were investigated. X-ray diffraction patterns, Raman spectroscopy, and X-ray photoelectron spectroscopy results showed that the annealed thin films had a single kesterite crystal structure without a secondary phase. The 2θ angle position for the peaks from the (112) plane in the annealed thin films decreased with increasing Se vaporization temperature. Energy dispersive X-ray results showed that the presence of Se in annealed thin films increased from 0 at% to 42.7 at% with increasing Se vaporization temperatures. UV–VIS spectroscopy results showed that the absorption coefficient of all the annealed thin films was over 10⁴ cm^?1 and that the optical band gap energy decreased from 1.5 eV to 1.05 eV with increasing Se vaporization temperature.     

Spectroscopic Properties of Cu(L-met)2, Cu(DL-met)2, Cu(L-ala)2 and Cu(DL-ala)2˙H2O and Qualitative Explanations to the Magnetism and Relative Ordering of the One-Electron Energy Levels.

Electronic absorption spectra and photoacoustic spectra of four copper(II)-amino acid complexes of formulas Cu(L-met)˙(1). Cu(DL-met)˙(2). Cu(L-ala)x(3) and Cu(DL-ala)˙-H₂O(4)(L-met=L-methioninato;DL-met=DL-methioninato;L-ala=L-alaninato DL-ala=DL-alaninato) were recorded and the results are discussed quantitatively with respect to llgand field theory and the radical wave function of a non-free copper(II) ion. The relationship between the maximum absorption peak in PAS and magnetic properties is also discussed. Lastly, a qualitative explanation on the senquence of splitting energy in going from regular octahedral to strongly elongately and slightly tetragonally distorted octahedral around each copper(II) center is proposed.     

混合团簇Cu13-nAgn(n≤13)基态结构的遗传算法研究

在混合团簇基态结构优化的遗传算法方案中增加了交换算子,结合Gupta紧束缚模型势研究了Cu13-nAgn团簇的最低能量结构,选择合适的交换和杂交概率,可有效地提高优化效率,优化结果表明,Cu13和Ag13是全对称的二十面体,n=1～10的混合团簇能形成稳定结构,其构型是在二十面体基础上发生畸变,Cu原子趋于处在团簇中心,随着Ag原子数目的增加,原子间的平均距离单调增加,团簇的结合能单调减小,Cu2Ag11和CuAg12只存在亚稳结构.     

Synthesis and excess conductivity analysis of TlBa2(Ca3−y Be y )Cu4O12−δ superconductors

TlBa₂(Ca_3?y Be _y )Cu₄O_12?δ (y = 0, 0.5, 1.0, 1.5, 2) samples are synthesized at normal pressure and the influence of doped Be-atoms on the superconductivity parameters at the microscopic level is investigated by carrying out excess conductivity analyses of conductivity data. The samples have shown tetragonal structure and the unit cell volume decreases with increased Be-doping. The onset temperature of superconductivity [T _c(onset)] and zero resistivity critical temperature [T _c(R = 0)] decrease with increased Be, however, the magnitude of diamagnetism is enhanced with Be (except for Be-doping of y = 1.0). The apical oxygen mode of the type Tl–O_A–Cu(2) and CuO₂ planar oxygen mode are softened as observed in FTIR absorption measurements. The FIC analyses of conductivity data have shown an increase in the coherence length along the c-axis and inter-plane coupling. The values of B _c0(T), B _c1(T), J _c(0), τ _φ are improved with the doping of Be. These observations suggested that due to the proximity effect there is less suppression in the value of the order parameter of the Cooper pairs from |ψ|² = 1 value in the CuO₂ planes in Be-doped samples that maintains the density of carriers in the conducting CuO₂ planes [since the |ψ|² = n/2] which promotes enhancement in the magnitude of superconductivity.     

Cu(111),Cu(110)和Cu(100)表面的振动弛豫

用能带理论研究了Cu(111)、Cu(110)和Cu(100)表面的振动弛豫。结果表明,第一内层间距为2.073±0.008(收缩0.53％±0.008)[对Cu(111)],1.25±0.01(收缩2.2％±0.01[对Cu(110)],1.815±0.001(膨胀0.55％±0.001)[对Cu(100)];而第二内层间距为2.15±0.01(膨胀2.2％±0.01[对Cu(111)],1.32±0.01(膨胀3.6％±0.01)[对Cu(110)],2.084±0.001(膨胀15.5％±0.001)[对Cu(100)];而第三内层间距为2.24±0.01(膨胀7.3％±0.01时Cu(111)]。     

Na(4D)+Na(3S)Na(4F)+Na(3S)碰撞能量转移截面

利用双光子吸收,将Na(3S)原子激发到4D态,测量了Na(4D)+Na(3S)Na(4F)+Na(3S)碰撞能量转移截面,因为直接由4F→3D的荧光不能探测,所以检测3D→3P级联荧光讯号。结合基态钠原子密度的测量,给出了截面值σ_4D→4F=1.3 x 10~(-14)±28％(cm~2)。     

APDC-MIBK萃取石墨炉原子吸收光谱法测定As(Ⅲ、Ⅴ)、Se(Ⅲ、Ⅵ)和Sb(Ⅲ、Ⅴ)

环境和生物样品中As、Se和Sb的测定具有重要意义。它们的毒性和生理行为与其价态有密切关系。Kamada和Yamamoto等分别以石墨炉和氢化物发生法对上述元素的不同价态进行了报导。Subramanian在柠檬酸铵缓冲溶液及HCl介质中,以硫氰酸盐还原可选择测定不同价态。Chanhuan Chung在醋酸缓冲溶液中,以TiCl_3还原可以区分高、低价态,用CHCl_3和CCl_4混合溶剂萃取,选择测定As、Se、