Tin oxide as a transparent electrode material for light-emitting diodes fabricated with poly (p-phenylene vinylene)

We have fabricated light emitting diodes (LED) with poly (p-phenylene vinylene) (PPV) as the emissive layer and tin oxide (TO) as the transparent conducting positive electrode and aluminium as the negative electrode. The fabrication conditions are optimized for visible light emission in these TO/PPV/Al LEDs. The threshold voltage for substantial charge injection for visible light emission in these LEDs lies below 10V. The device fabrication and electrical characterization of TO/PPV/Al LEDs are discussed in this communication.     

Theory of te precipitation and related effects in CdTe Crystals

A thermodynamic calculation is presented which explains the origin of often reported large stress fields in and around Te precipitates and associated punching of dislocation loops in star like patterns. The calculation is based on the consideration that the stoichiometric deviation in Te saturated crystals are accommodated by Te interstitials, Cd multivacancy complexes and Te antisites; the Te interstitials are most mobile of them, and dominate the precipitation process; and the precipitates when they appear first are in droplet form. The droplet state is modelled on the basis of the Lennard-Jones 6-12 interaction potential. The droplet growth is envisaged to occur via the following two processes operating in tandem: first, capture of excess Te interstitials to cause droplet overpressurization, and then, punching of interstitial dislocation loops whenever the pressure exceeds a threshold value. The flow of Te interstitials into the droplets is driven by the difference between their formation energies in the lattice and the free energy change of the droplets per Te atom added. It is shown that the achievable droplet pressures far exceed that required for the loop punching and sustaining the growth cycle. The occurrence of varying precipitate morphologies are explained, and the possibility of nucleating high presssure Te phases is examined. Some experimental evidence is also presented which corroborate the theoretical arguments involved.     

Experimental study and parameter design of electro-discharge diamond grinding

Electrical discharge diamond grinding (EDDG), which integrates diamond grinding and electro-discharge machining (EDM), is a new hybrid machining process for shaping electrically conductive very hard materials. The process employs synergetic interactive effect of electro-discharge action and abrasion action to increase machining performance. This paper presents an investigation on the experimental study and machining parameter design of electro-discharge diamond grinding (EDDG). The EDDG setup was designed and fabricated, and experiments were conducted on high speed steel (HSS) workpiece under varying current, pulse-ontime, duty factor and wheel speed. The settings of machining parameters were determined by using the Taguchi experimental design method. The level of the machining parameters on the MRR is determined by using analysis of variance (ANOVA). The optimum machining parameter combination was obtained by using the evaluated S/N ratio.     

Viscosities of binary mixtures of ethanenitrile with benzene and several substituted benzenes

Viscosities (η) and densities (?) of five binary mixtures of ethanenitrile with benzene and several substituted benzenes viz methylbenzene, 1,4-dimethylbenzene, chlorobenzene and 1,2-dichlorobenzene have been experimentally determined at 308.15 K. Viscosity deviations (Δη) from the linear blending rule have been evaluated for all the mixtures studied. These are small with a maximum negative deviation of about 6% for binary mixture with benzene and maximum positive deviation of about 3% for mixture with 1,4-dimethylbenzene. Δη Values are fitted into Redlich - Kister equation and standard deviations in Δη values, σ (Δη) have been evaluated. The correlating performance of several viscosity models such as Grunberg - Nissan, Katti and Chaudhari, Hind-McLaughlin - Ubbelohde and Sedgwick has been evaluated. Grunberg-Nissan viscosity model is suitable for viscosities of several binary systems studied. The results are discussed in terms of molecular interactions between the components of binary mixtures.     

Effect of Temper Condition on Stress Relaxation Behavior of an Aluminum Copper Lithium Alloy

Deformation behavior of an Al-Cu-Li alloy in different temper conditions (solutionized and T8) is investigated using stress relaxation tests. Fundamental parameters such as the apparent and physical activation volume, strain rate sensitivity, effective stress, and exhaustion rate of mobile dislocation density are determined from single and multiple relaxation tests. It was found that dislocation–dislocation interaction controls the kinetics of plastic deformation in the solutionized sample, whereas dislocation–precipitate interaction is the overriding factor in the presence of T₁ precipitates. The apparent activation volume was found to be significantly lower in the presence of T₁ precipitates compared with solutionized samples. Strain rate sensitivity and effective stress were found to be higher in the presence of T₁ precipitates. In addition, multiple relaxation tests showed that irrespective of microstructural features (solutes, semi-coherent precipitates), the mobile dislocation density reduces during the relaxation period. Further evidence regarding reduction in mobile dislocation density is obtained from uniaxial tensile tests carried out after stress relaxation tests, where both solutionized and T8 samples show an increase in strength. Additional discussion on relaxation strain is included to provide a complete overview regarding the time-dependent deformation behavior of the Al-Cu-Li alloy in different temper conditions.     

Analysis of EEG signals and its application to neuromarketing

Multimedia Tools and Applications - Marketing and promotions of various consumer products through advertisement campaign is a well known practice to increase the sales and awareness amongst the...     

Slotted-electrical discharge diamond cut-off grinding of Al/SiC/B4C hybrid metal matrix composite

Advanced manufacturing industries need materials with high strength and low weight in the fields of advanced engineering, such as automobiles and aeronautics. Metal matrix composites (MMCs) are one of the advanced engineering materials that meet the above requirements. To enhance the properties of MMCs, researchers added an additional phase of reinforcements into single reinforced MMCs; such developed MMCs are known as hybrid MMCs. The additional phase of reinforcements enhances the properties of MMCs, but simultaneously leads to rapid tool wear and poor machinability. This study developed an innovative hybrid machining process (HMP) consisting of electrical discharge grinding and diamond grinding in such a way that both the processes occur alternately with equal intervals due to the rotation of a slotted abrasive grinding wheel. The performance of the hybrid process was tested on an Al/SiC_p/B₄C_p work-piece in cut-off grinding mode. The experiments were conducted on an electrical discharge machining machine, which consists of a separate attachment on a vertical column to rotate the wheel. Pulse current, pulse on-time, pulse off-time, wheel RPM, and abrasive grit number were taken as input parameters while material removal rate (MRR) and average surface roughness were taken as output parameters. Result were shown that the HMP gives higher MRR with better surface finish as compared to the constituent processes. Pulse current ranging from 3 A to 21 A, pulse on-time ranging from 30 μs to 200 μs, and pulse off-time ranging from 15 μs to 90 μs were also found to be more suitable for higher MRR, and a wheel RPM at 1300 RPM was more suitable for higher MRR with better surface finish.     

On the electrical transport in nickel telluride

Journal of Materials Science Letters -