Spatial Distribution of EL2 Defect in Semi-insulating GaAs

ＳｐａｔｉａｌＤｉｓｔｒｉｂｕｔｉｏｎｏｆＥＬ２ＤｅｆｅｃｔｉｎＳｅｍｉ－ｉｎｓｕｌａｔｉｎｇＧａＡｓＲｕＱｉｏｎｇｎａ；ＬｉＧｕａｎｇｐｉｎｇａｎｄＨｅＸｉｕｋｕｎ（汝琼娜）（李光平）（何秀坤）（ＴｉａｎｊｎｇＥｌｅｃｔｒｏｎｉｃＭａｔｅｒｉａｌｓ...     

Correlation between the Concentrations of Ionized EL2 and Carbon Acceptor in Undoped Semi－insulating LEC GaAs

ＣｏｒｒｅｌａｔｉｏｎｂｅｔｗｅｅｎｔｈｅＣｏｎｃｅｎｔｒａｔｉｏｎｓｏｆｌｏｎｉｚｅｄＥＬ２ａｎｄＣａｒｂｏｎＡｃｃｅｐｔｏｒｉｎＵｎｄｏｐｅｄＳｅｍｉ－ｉｎｓｕｌａｔｉｎｇＬＥＣＧａＡｓＹａｎｇＲｕｉｘｉａ（杨瑞霞）（ＨｅｂｅｉＩｎｓｔｉｔｕｔｅ...     

热处理对大直径半绝缘砷化镓中EL2缺陷的影响

利用金相显微镜和微区红外测量技术分析热处理对液封直拉法生长的大直径半绝缘砷化镓(LEC SI-GaAs)单晶中深施主缺陷EL2的影响。结果表明,原生大直径SI-GaAs样品中EL2缺陷浓度沿直径方向的分布呈现中心区域较高、近中心区域最低、边缘区域最高的特点。500℃退火EL2缺陷浓度稳定,真空闭管并快速冷却条件下850℃以上退火时,EL2缺陷浓度随温度升高而下降。并分析了热处理对EL2缺陷的影响机理。     

Investigation of EL2 Defect in 10 MeV Electron Irradiated Undoped Semi－insulating LEC GaAs

ＩｎｖｅｓｔｉｇａｔｉｏｎｏｆＥＬ２Ｄｅｆｅｃｔｉｎ１０ＭｅＶＥｌｅｃｔｒｏｎＩｒｒａｄｉａｔｅｄＵｎｄｏｐｅｄＳｅｍｉ－ｉｎｓｕｌａｔｉｎｇＬＥＣＧａＡｓＷｕＦｅｎｇｍｅｉ，ＳｈｉＹｉ，ＣｈｅｎＷｕｍｉｎｇ，ＷｕＨｏｎｇｗｅｉａｎｄＬａｉＱｉｊｉ（...     

Double Donor Behavior of EL2 Defect in Photoquenching Experiment

ＤｏｕｂｌｅＤｏｎｏｒＢｅｈａｖｉｏｒｏｆＥＬ２ＤｅｆｅｃｔｉｎＰｈｏｔｏｑｕｅｎｃｈｉｎｇＥｘｐｅｒｉｍｅｎｔＺｈｏｕＢｉｎ１，２，ＹａｎｇＸｉｑｕａｎ１ａｎｄＷａｎｇＺｈａｎｇｕｏ１（周滨）（杨锡权）（王占国）１．ＬａｂｏｒａｔｏｒｙｏｆＳｅｍｉ...     

Effect of Substrate Temperature on Electroluminescence of SrS:HoF3 Thin Film

The SrS:HoF3 Electroluminescent (EL) thin films are prepared at the different substrate temperature by electron beam evaporation. The crystallinity and EL characteristics of the samples are analyzed. It is found that the main diffraction peak is (200) at the higher substrate temperature and the main diffraction peak is (111) at the lower substrate temperature. The blue emission intensity and EL brightness of the SrS∶HoF3 thin films increase with the increase of the substrate temperature. Annealing the samples can change the cyrstal phase and strengthen the blue emission of EL thin film.     

EL4B-2400A多连杆压力机平衡器设计与计算

平衡器可以保证滑块运行的平稳性,保持压力机精度稳定,是压力机不可或缺的组成部分。文章介绍了平衡器结构,重点研究了平衡器设计计算。实际应用表明计算可靠,可用于指导生产。     

Effects of casting solvents on characteristics of organic EL devices containing poly(l-glutamate) as hole-transport material

The characteristics of EL devices containing α-helical poly(l-glutamate) and having a carbazole side chain (PCELG) were found to strongly depend on the casting solvents. Among EL devices fabricated using chlorine-containing casting solvents such as 1,2-dichloroethane (DCE), 1,1,2,2-tetrachloroethane (TCE), chloroform (CHCl₃), and monochlorobenzene (?-Cl), the EL device fabricated using the DCE solvent exhibited the maximum luminance (65.8 cd/m²). The difference between the threshold voltages of the devices ranged up to 6.0 V, despite their fabrication by using solutions with the same composition ratio. The maximal efficiency of the devices fabricated using the DCE solvent was found to be 20 times greater than that of the devices fabricated using TCE solvents. A comparison of the current densities and voltages among devices fabricated using different casting solvents at their maximal efficiencies showed that the maximal efficiencies tended to significantly increase in the order TCE < CHCl₃ < DCE solvents at similar voltages (～15 V), despite a lowering of the current density. The current density was considered to be directly related to the number of carriers injected into the device. The above-mentioned observations suggested that the maximal efficiency in these devices was not the hole and electron injection efficiencies, but the values of some parameters subsequent to carrier injection, such as the recombination rate, amount of excitons generated, and the diffusion length.     

New blue emitting indenopyrazine derivatives for OLEDs: Improving the EL properties through substitution effects by using terphenyl side group

Two new blue emitting materials of o,p-TP-EPY (6,6,12,12-tetraethyl-2,8-bis-[1,1′;3′,1″]terphenyl-4′-yl-6,12-dihydro-diindeno[1,2-b;1′,2′-e]pyrazine) and m,m-TP-EPY (6,6,12,12-tetraethyl-2,8-bis-[1,1′;3′,1″]terphenyl-5′-yl-6,12-dihydro-diindeno[1,2-b;1′,2′-e]pyrazine) were synthesized using two bulky m-terphenyl side groups with different substitution positions in the new core system of indenopyrazine (IPY). The o,p-TP-EPY more effectively prevented intermolecular interactions compared to m,m-TP-EPY, resulting in more blue-shifted emission in the thin film state. When the synthesized compounds were used as emitting layers in non-doped OLED devices, an identical trend in electroluminescent spectra was observed. EL spectrum of o,p-TP-EPY (λ_max,EL = 440 nm) was more blue shifted than that of m,m-TP-EPY (λ_max,EL = 452 nm), and external quantum efficiency (E.Q.E.) of o,p-TP-EPY (2.68%) was also showed large improvement of about 60% compared to efficiency of m,m-TP-EPY (1.61%).     

Effects of annealing of poly(3-hexylthiophene) film on the performance of double-layered EL devices of ITO/polymer/Alq3/Mg–Ag

Double layer devices with a structure of ITO/pHT/Alq3/Mg–Ag (ITO = indium tin oxide, pHT = regio-regular or random poly(3-hexylthiophene), Alq3 = tris(8-hydroxyquinoline)aluminium) were fabricated. The device with a random pHT film emitted a green-yellow light in all voltage region, while that having a regio-regular pHT film exhibited a color change from green to red by applying the bias voltage higher than 15 V. Annealing the pHT films prepared on ITO at 200 °C for 1 h in nitrogen, prior to vapor-deposition of the Alq3 layer, improved the device performance with lowering the onset bias voltage by 2–3 V. The EL colors and spectra were also affected by annealing. X-ray reflectivity measurements before and after annealing the pHT film on ITO indicated increased density of the pHT layer and structural changes in the pHT/ITO interface by annealing, which seems to be responsible for the improved EL device performance.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.