A thermally resistant and air-stable n-type organic semiconductor: Naphthalene diimide of 3,5-bis-trifluoromethyl aniline

We report a thermally resistant and air-stable n-type semiconductor based on our study of naphthalene diimide (NTCDI) derivatives (N1, N2, and N3) with various numbers of electron-withdrawing CF₃ groups. The device using N3, which contains aromatic NTCDI, was found to exhibit an electron mobility (μ_e) of 0.15 (±0.04) cm²/V s (the maximum μ_e observed was 0.24 cm²/V s) and an I_on/I_off (at V_d = 80 V) of approximately 2 × 10⁵. Moreover, the N3 device exhibits excellent air stability, even when exposed to the open air for 42 days, and significantly better thermal resistance than the previously reported benzylic imide derivative R1.     

Perylenetetracarboxylic di-imide-based bottom-contact devices: A study on two kinds of source/drain electrodes,ITO and MoW

High-performance bottom-contact devices based on an air-stable n-type organic semiconductor N,N-bis(4-trifluoromethoxybenzyl)-perylene-3,4,9,10-tetracarboxylic di-imide, were fabricated, and the effects of crystal packing on indium tin oxide and molybdenum–tungsten alloy were shown in two different electric characteristics. The estimated work function of indium tin oxide and molybdenum–tungsten alloy were 4.7 and 5.0 eV. The calculated lowest unoccupied molecular orbital energy level of the organic material was 3.7 eV. Transistors with indium tin oxide bottom electrodes exhibited a high mobility of 3.37 × 10^?2 cm² V^?1 s^?1, an on/off current ratio of 6.5 × 10⁵ and threshold voltage of ?4.0 V.     

The current–voltage and capacitance–voltage characteristics of molecularly modified β-carotene/n-type Si junction structure with fluorescein sodium salt

β-Carotene–FSS organic semiconductor/n-type Si structure has been characterized by current–voltage and capacitance–voltage methods. A deviation in I–V characteristic of the diode is observed due to effect of series resistance and interfacial layer. Cheung's functions were used to calculate diode parameters. The ideality factor, series resistance and barrier height values of the diode are n = 1.77, R_s = 10.32 (10.39) kΩ and 0.78 eV. The obtained ideality factor suggests that Au/β-carotene–FSS/n-Si Schottky diode has a metal–SiO₂ oxide layer plus organic layer–semiconductor (MIOS) configuration. The capacitance–voltage characterizations of Au/β-carotene–FSS/n-Si diode at different temperatures were performed. The capacitance of the diode changes with temperature. The barrier height and ideality factor obtained from C–V curves are 0.67 eV and 1.68. The interface density properties of the diode are analyzed and the shape of the density distribution of the interface states is in the range of E_c −0.49 to −0.62 eV. It is evaluated that the FSS organic layer controls electrical charge transport properties of Au/β-carotene/n-Si diode by excluding effects of the β-carotene and SiO₂ residual oxides on the hybrid diode.     

成分配比对Ti/IrO2-Ta2O5电极电容性能影响

摘要：采用低温热分解法制备了Ti基IrO2-Ta2O5氧化物涂层电极。通过X射线衍射(XRD),循环伏安曲线,交流阻抗谱,恒流充放电等测试方法分析了Ta含量对IrO2-Ta2O5氧化物涂层组织结构及电容性能的影响。结果表明,Ta2O5可抑制IrO2的晶化程度。随涂层中Ta含量增加,晶化度降低。当Ta含量为60mol%时,IrO2-Ta2O5电极的结晶度为6.4%,具有较小的电荷转移电阻和最高的比电容（239.2F/g）,比IrO2电极比电容(54.1F/g)提高了近4倍。     

A series of stable salts of the oxidized donors TTF, o-Me2TTF,TMTTF, and TTF(SCH2CH2CN)4

Reactions of the organic donors tetrathiafulvalene (TTF), o-dimethyltetrathiafulvalene (o-Me₂TTF), tetramethyltetrathiafulvalene (TMTTF), and tetrathiafulvalene tetrathiolate [TTF(SCH₂CH₂CN)₄] with oxidizing agents of suitable potential resulted in the formation of stable salts in which the donors are present in their monocationic radical forms. The salts presented herein represent a series of reagents containing oxidized chalcofulvalene donors that can be used as starting materials for metathesis reactions with other cations. All of the salts were characterized by X-ray crystallography and UV–vis–NIR spectroscopy.     

Effect of nitrogen-incorporation on structure, properties and performance of magnetron sputtered CrB2

Transition metal (TM) boron nitrides are promising candidates for protective coatings with self-lubricating abilities as they can combine properties of TM diborides with the lubricity of hexagonal boron nitride (h-BN). Here, we report on Cr-B-N coatings prepared by unbalanced DC magnetron sputtering of a CrB₂ target in argon/nitrogen atmosphere at 450 °C. By varying the nitrogen partial pressure (p_N2) between 0 and 64% of the total pressure (p_Ar + p_N2), the N-content in our coatings could be increased from 0 to 47 at.%. The results obtained from X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy show that for p_N2 ≤ 11% a CrB₂-based structure type develops, whereas with increasing p_N2 the microstructure becomes then X-ray amorphous and finally CrN is detected as the sole crystalline constituent. With increasing p_N2 from 0 to 11%, the hardness and indentation modulus rapidly decrease from 40.6 and 397 GPa for CrB₂ to 13.4 and 108 GPa for CrB_2.0N_0.5. All coatings investigated yield only a moderate friction coefficients between 0.5 and 0.7. Based on detailed high-resolution TEM studies, we can conclude that the missing h-BN based lubricity is due to a lack of a significant long-range order.     

Effects of growth temperature on structure and electrical properties of dielectric (Ba,Sr)TiO3 capacitors with transparent conducting oxide electrodes

200 nm-thick BST thin films were grown on Zr-doped In₂O₃/SrTiO₃ (1 0 0) substrates at 550-750 °C. X-ray diffraction results show that the as-deposited BST films were polycrystalline with random crystallographic orientations. X-ray diffraction patterns reveal that the BST film grown at 650 °C had the best crystalline quality of all the deposition temperatures. Atomic force microscopy and secondary ion mass spectrometry showed that the surface and interface structures of the BST films became rough as the growth temperature increased. The BST film grown at 650 °C showed the best electrical properties, with a dielectric constant of 420 at 1 MHz, dielectric tunability of 32.1%, dielectric loss of 0.015 at 300 kV/cm, and a mean optical transmittance in visible wavelength of 71.3%.     

First principles study on the phase stability and mechanical properties of MoSi2 alloyed with Al,Mg and Ge

The phase stability, mechanical properties and electronic structure of C11_b and C40 MoSi₂ with alloying elements Al, Mg and Ge were systematically investigated using first principles methods. The calculated lattice constants and elastic constants of C11_b and C40 MoSi₂ are in good agreement with the previous results. It is found that there is a phase transition from C11_b to C40 when the concentrations of Al and Mg reach ∼7 at.% and ∼6 at.%, respectively. Based on the elastic constants, the anisotropy, ductility, hardness and melting temperatures are presented for MoSi₂ with alloying elements. For C11_b, the ductility will be enhanced by increasing the concentrations of Al or Mg. Simultaneously, hardness will be reduced by the increasing of Al or Mg. Ge have a reverse effects. For C40, the ductility is reduced weakly by Al or Mg. In addition, the effects of substitution of Mo by Nb with Si substitution of Si by Al, Mg and Ge are also investigated. Nb and Mg codoping can improve the ductility of MoSi₂. Finally, the density of states is used to analysis the effects of alloying elements on the mechanical properties, and the results are in consistent with the predictions based on elastic constants.     

On the relationship between the structure and the barrier performance of plasma deposited silicon dioxide-like films

Silicon dioxide-like barrier films were deposited by plasma enhanced chemical vapor deposition from different siloxane and silane precursors. The variation of the precursor was investigated as a route to obtain silicon dioxide-like films with different structures, densities and hence barrier performances.Although the films were characterized by the same elemental composition, some differences in film density and porosity were evidenced from optical properties measurements and from the shift of the SiOSi infrared absorption band position. These differences were correlated with film microstructure and in turn with barrier performances. The results confirmed that films with high density and low porosity performed better as single inorganic barrier layers for food-packaging.     

Synthesis, crystal structure and properties of the new semiconductor (EVT)4·[Pt(CN)4]

A novel radical cation salt based on of the donor (4,5-ethylenedithio-4′,5′-vinylenedithio)tetrathiafulvalene (EVT) with the square planar anion Pt(CN)₄²⁻ has been synthesized: (EVT)₄·[Pt(CN)₄] (1). According to the X-ray analysis its crystal structure includes EVT cation layers alternating with anion layers along the a-axis of the unit cell. The radical cation layer is formed by EVT stacks with β-packing type, the donors in stacks are tetramerized. The EPR spectra of a plate-like crystal of (EVT)₄·[Pt(CN)₄] salt shows a very weak signal with typical parameters of TTF derivative. The room temperature conductivity of salt 1 is 8×10⁻² Ω⁻¹ cm⁻¹ and the temperature dependence of the conductivity exhibits semiconducting character.     

SPS制备多级孔结构钨骨架压缩性能及致密化行为研究

以粒径分布为15～106μm多孔球形团聚W粉为原料,采用放电等离子体烧结(SPS)在不同烧结温度(1450、1500、1550℃),轴向恒压40 MPa,保温5 min下分别制备出高强度(347.8±10.6 MPa、407.4±14.2 MPa、543.9±8.7 MPa)、多级孔结构(3～10μm/200～500 nm)W骨架。结合XRD、SEM、万能试验机等检测技术,对SPS烧结过程中粉末致密化行为、显微组织变化及力学性能进行了系统研究。结果表明:SPS可制得烧结前后物相无明显变化、孔隙率介于30%～40%、烧结颈发育完全多级孔结构钨骨架。该多级孔W骨架SPS烧结致密化过程可分为4个阶段,第1阶段为升压阶段,烧结试样相对密度随压力升高而迅速升高;第2阶段为典型的颗粒重排阶段;第3阶段烧结温度高于1000℃,烧结试样相对密度随温度的升高而增加,属于典型的烧结中期;第4阶段为烧结末期,烧结体内部高温蠕变引起致密化程度进一步提高。利用高温蠕变模型研究了该多孔球形W粉的致密化机理为纯扩散致密化,通过颈长方程确定该多孔球形钨粉在整个SPS烧结过程中的致密化机理是以体积扩散为主,晶界扩散为辅。     

Effect of partial substitution of Co with Fe on the properties of LaNi3.55Mn0.4Al0.3Co0.75−xFex (x=0, 0.15, 0.55) alloys electrodes

The effect of iron substitution on the electrochemical behaviour of LaNi_3.55Mn_0.4Al_0.3Co_0.75−xFe_x compounds (x=0, 0.15, 0.55) has been studied by chronopotentiometry and cyclic voltammetry techniques. The maximum capacity decreases linearly from 308 to 239 mAhg⁻¹ when the iron content increases from 0 to 7.3 wt.% (x=0.55). This decrease can be explained by the corrosion of the alloy in the aqueous KOH electrolyte. In spite of this decrease and of the long time needed for the activation, a good stability of discharge capacity was observed in LaNi_3.55Mn_0.4Al_0.3Co_0.75−xFe_x compounds. The reversibility of the electrochemical redox reaction of LaNi_3.55Mn_0.4Al_0.3Co_0.75−xFe_x alloy electrodes has been observed in the alloys least rich in iron. The hydrogen diffusivity in LaNi_3.55Mn_0.4Al_0.3Co_0.75−xFe_x alloy electrodes decreases when increasing the iron content. The obtained values of the hydrogen diffusion coefficient D_H, varies between 2.1×10⁻⁷ and 8.2×10⁻⁹ cm² s⁻¹ depending on the iron content of the electrode.     

Structural characterization of layered LiNi0.85−xMnxCo0.15O2 with x = 0, 0.1, 0.2 and 0.4 oxide electrodes for Li batteries

We report the synthesis of LiNi_0.85−xCo_0.15Mn_xO₂ positive electrode materials from Ni_0.85−xCo_0.15Mn_x(OH)₂ and Li₂CO₃. XRD and XPS are used to study the effect of Mn-doping on the microstructures and oxidation states of the LiNi_0.85−xCo_0.15Mn_xO₂ materials. The analysis shows that Mn-doping promotes the formation of a single phase. With increasing substitution of Mn ions for Ni ions, the lattice parameter a decreases, while the lattice parameters c and c/a increase. XPS revealed that the oxidation states of Ni, Co and Mn in LiNi_0.85−xCo_0.15Mn_xO₂ compounds (where x = 0.1, 0.2 and 0.4) were +2/+3, +3 and +4. The substitution of Mn ions for Ni ions induces a decrease in the average oxidation state of Ni. Because the substitution of Mn for Ni ions is complex, the extent of the changes between the lattice parameter and L_M-O differ. The occupation of Ni in Li sites is affected by the ordering of Mn⁴⁺ with Ni²⁺ and Mn⁴⁺ with Li⁺.     

Single crystal preparation and crystal structure of the Cu2Zn/Cd,Hg/SnSe4 compounds

Single crystals of Cu₂Zn/Cd/SnSe₄ were grown using a solution-fusion method. The crystal structure of the Cu₂Zn/Cd,Hg/SnSe₄ compounds were investigated using X-ray powder diffraction. These compounds crystallize in the stannite structure (space group I 2m) with the lattice parameters: a=0.56882(9), c=1.13378(9) nm, c/a=1.993 (Cu₂ZnSnSe₄), a=0.58337(2), c=1.14039(4) nm, c/a=1.955 (Cu₂CdSnSe₄) and a=0.58288(1), c=1.14179(2) nm, c/a=1.959 (Cu₂HgSnSe₄). Atomic parameters were refined in the isotropic approximation (R_I=0.0517, R_I=0.0511 and R_I=0.0695 for Cu₂ZnSnSe₄, Cu₂CdSnSe₄ and Cu₂HgSnSe₄, respectively).     

Discrepancy of the magnetic behaviors and crystalline structure on the Co/FeMn and FeMn/Co interfaces with ultrathin Pt spacer

The exchange coupling at the ferromagnetic/antiferromagnetic (FM/AFM) interface is influenced by both the magnetic structure and the crystalline micro-structure. Co/FeMn/Co thin films with 0.4 nm Pt spacer layer inserted into the Co/FeMn and FeMn/Co interface respectively were deposited by means of magnetron sputtering. The two interfaces upon and beneath the FeMn layer show distinct behaviors before and after the Pt spacer inserted. There is a remarkable shrink of the interfacial uncompensated spins within the FeMn bottom interfacial monolayers, whereas a relaxation of the pinning strength of the FeMn interfacial spins along the out-of-plane direction occurs at the top interface. XRD analysis indicates the Pt layer upon the FeMn layer forms an fcc (002) texture, implying the magnetic discrepancy between the top and bottom FeMn interfaces has crystalline structural origins.     

Synthesis, characterization, magnetic and electrical properties of the novel conductive and magnetic Polyaniline/MgFe2O4 nanocomposite having the core-shell structure

Conductive and magnetic Polyaniline/MgFe₂O₄ nanocomposite was successfully synthesized in the form of core-shell via in situ chemical polymerization of aniline in the presence of MgFe₂O₄ nano-particles. X-ray powder diffraction of ferrites indicated that the structure of the core material is having the spinel structure, and demonstrated the formation of PAni/MgFe₂O₄ nanocomposite. XRD and TEM photographs showed that the particle's size of the MgFe₂O₄ core-material were around 30-35 nm before coating with Polyaniline, and grown up to 45 nm in the core-shell nanocomposite after coating. Although PAni has a relatively smaller electrical field coefficient than the core-shell nanocomposite, the resistivity of the core-shell material decreased, and hence its conductivity increased after a certain threshold voltage of 0.98 V equivalent to threshold electric field value equals 5.5 V cm⁻¹. The magnetic hysteresis loops investigated with VSM indicated that coating MgFe₂O₄ with Polyaniline has an healing effect which covers the ferrite surface defects, thus decreasing the magnetic surface anisotropy of ferrite particles leading to a decrease of the saturated magnetization (Ms) from 21.33 emu/g to 5.905 emu/g and a decrease of the coercivity (Hc) from 88.66 Oe to 81.6 Oe for MgFe₂O₄ and the core-shell nanocomposite respectively due to the amount of Polyaniline added. TGA and DTA revealed improved thermal stability of the core-shell nanocomposite with respect to that of Polyaniline due to the incorporation of ferrites. Raman spectroscopy confirmed TGA, DTA and XRD studies, and revealed that pure PAni is less stable than the corresponding core-shell nanocomposite with respect to molecular changes which might occur during heating at elevated temperatures. Moreover, Raman study confirmed the interfacial interaction between the core and the shell materials, and lead to an assumption about the presence of different conjugation chain lengths and types, such as the presence of the semi-quinones aside the quinone rings in the polymer chain, which showed different response upon heating the sample.     

Preparation, structure and electrical conductivity of the pyrochlore-type phase Sm2Zr2O7 codoped with bivalent magnesium and trivalent dysprosium cations

The pyrochlore-type phases with the compositions of SmDy_1−xMg_xZr₂O_7−x/2 (0 ≤ x ≤ 0.20) have been prepared by pressureless-sintering method for the first time as possible solid electrolytes. The structure and electrical conductivity of SmDy_1−xMg_xZr₂O_7−x/2 ceramics have been studied by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and impedance spectroscopy measurements. SmDy_1−xMg_xZr₂O_7−x/2 (x = 0, 0.05, 0.10) ceramics exhibit a single phase of pyrochlore-type structure, and SmDy_1−xMg_xZr₂O_7−x/2 (x = 0.15, 0.20) ceramics consist of pyrochlore phase and a small amount of the second phase magnesia. The total conductivity of SmDy_1−xMg_xZr₂O_7−x/2 ceramics obeys the Arrhenius relation, and the total conductivity of each composition increases with increasing temperature from 673 to 1173 K. SmDy_1−xMg_xZr₂O_7−x/2 ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 × 10⁻⁴ to 1.0 atm at all test temperature levels. The highest total conductivity value is about 8 × 10⁻³ S cm⁻¹ at 1173 K for SmDy_1−xMg_xZr₂O_7−x/2 ceramics.     

Ce(Au,Sb)2 with UHg2 structure type, a new member of the AlB2 family

A new ternary compound Ce(Au,Sb)₂, with a homogeneity range has been observed from X-ray powder diffraction of as cast alloys, a = 4.743–4.712 Å, c = 3.567–3.768 Å. Its crystal structure was investigated by X-ray diffraction from Ce(Au_1−xSb_x)₂ (x = 0.266) single crystal: CAD-4 automatic diffractometer, Mo K radiation, a = 4.7256(6) Å, c = 3.6711(6) Å, P6/mmm space group, V = 70.997(17) Å³, Z = 1, ρ = 10.732 Mg/m³, μ = 76.369 mm⁻¹, R₁ = 0.0415, wR₂ = 0.0793 for 99 reflections with I > 2σ(I₀). The coordination polyhedron of X (X = 0.734Au + 0.266Sb) atom is a full-capped trigonal prism [XCe₆X₃X₂]. Ce atom is coordinated by 14 atoms: [CeX₁₂Ce₂]. The compound is isotypic with UHg₂ structure, a deformation derivative of AlB₂ structure type. It forms isostructural compounds with La and Pr.