IOP Conference Series Materials Science and Engineering

Published by IOP Publishing
Online ISSN: 1757-899X
Publications
Basic settings for the X-ray microtomography measurements
CT reconstruction of the dendritic phase 
Conference Paper
A central parameter to describe the formation of porosity and macrosegregation during casting processes is the permeability of the dendritic mushy zone. To determine this specific feature for a binary Al-18wt.%Cu alloy, flow simulations based on the Lattice Boltzmann (LB) method were performed. The LB method allows an efficient solving of fluid flow problems dealing with complex shapes within an acceptable period of time. The 3D structure required as input for the simulations was captured with X-ray microtomography, which enables the generation of representative geometries for permeability investigations. Removing the eutectic phase from the measured dataset generated a remaining network of solid primary dendrites. In the simulations, a pressure gradient was applied to force the liquid through the free interdendritic channels. The permeability of the structure was then calculated from the resulting flow velocity pattern using Darcy’s law. To examine the influence of different boundary conditions on the results obtained, several simulations were conducted.
 
Article
We have recently described a novel method for the construction of a solid-state optical frequency reference based on doping $^{229}$Th into high energy band-gap crystals. Since nuclear transitions are far less sensitive to environmental conditions than atomic transitions, we have argued that the $^{229}$Th optical nuclear transition may be driven inside a host crystal resulting in an optical frequency reference with a short-term stability of $3\times10^{-17}<\Delta f/f <1\times10^{-15}$ at 1 s and a systematic-limited repeatability of $\Delta f/f \sim 2 \times 10^{-16}$. Improvement by $10^2-10^3$ of the constraints on the variability of several important fundamental constants also appears possible. Here we present the results of the first phase of these experiments. Specifically, we have evaluated several high energy band-gap crystals (Th:NaYF, Th:YLF, Th:LiCAF, Na$_2$ThF$_6$, LiSAF) for their suitability as a crystal host by a combination of electron beam microprobe measurements, Rutherford Backscattering, and synchrotron excitation/fluorescence measurements. These measurements have shown LiCAF to be the most promising host crystal, and using a $^{232}$Th doped LiCAF crystal, we have performed a mock run of the actual experiment that will be used to search for the isomeric transition in $^{229}$Th. This data indicates that a measurement of the transition energy with a signal to noise ratio (SNR) greater than 30:1 can be achieved at the lowest expected fluorescence rate. Comment: Eurodim Conference Proceedings
 
Article
The uranium mononitride (UN) is a material considered as a promising candidate for Generation-IV nuclear reactor fuels. Unfortunately, oxygen in air affects UN fuel performance and stability. Therefore, it is necessary to understand the mechanism of oxygen adsorption and further UN oxidation in the bulk and at surface. Recently, we performed a detailed study on oxygen interaction with UN surface using density functional theory (DFT) calculations. We were able to identify an atomistic mechanism of UN surface oxidation consisting of several important steps, starting with the oxygen molecule dissociation and finishing with oxygen atom incorporation into vacancies on the surface. However, in reality most of processes occur at the interfaces and on UN grain boundaries. In this study, we present the results of first DFT calculations on O behaviour inside UN grain boundaries performed using GGA exchange-correlation functional PW91 as implemented into the VASP computer code. We consider a simple interface (310)[001](36.8{\deg}) tilt grain boundary. The N vacancy formation energies and energies of O incorporation into pre-existing vacancies in the grain boundaries as well as O solution energies were compared with those obtained for the UN (001) and (110) surfaces.
 
Liquidus surface of the ternary phase diagram showing the three-phase eutectic at E 1 [7].
Conference Paper
Ternary eutectics provide a unique opportunity for studying the eects of complex microstructure formation, as three distinct phases must be formed simultaneously from the melt. In order to produce fully coupled three-phase growth, Al-Ag-Cu at the ternary eutectic composition was directionally solidied in a constant temperature gradient of 3 K/mm at velocities between 0.2 and 5.0 m/sec. Under these conditions, the two intermetallic phases appear to grow as closely coupled rods in an (Al) matrix, with the solidication velocity aecting the specic morphologies chosen by the rods and the general degree of alignment of the structure. Crystal orientations were examined by EBSD to determine if variations in morphology within a single sample are due to specic orientation relationships. Although no conclusive connection to morphology has yet been found, two dierent sets of orientation relationships between the three phases have thus far been identied.
 
Intensity over time of one pixel ( top left ); smoothed derivative of intensity with fit peak ( top right ); peak times for all pixels, gauged from pix/s to mm/s ( bottom ) 
Furnace setup (from figure 1) and prism inside the TMF heat sink and coil bearings. The camera (not shown) is mounted above the setup, looking down onto the prism.
Positions of the examined transversal and longitudinal cross sections (in mm)
Primary DAS for different velocities. The transition from columnar to dendritic growth is clearly recognisable.
Secondary DAS shows no apparent effect of the TMF, while the velocity dependence seems to follow a λ 2 ∝ v −1/2 law.
Conference Paper
The precipitation of Mn-rich intermetallics in AlSiMn alloys during solidification ahead of the mushy zone affects the solidification microstructure, especially if fluid flow is present. Recently Steinbach and Ratke reported a barrier effect of -AlMnSi, meaning these intermetallics prevent fluid flow to enter the mush. To investigate this effect further we studied the solidification of AlSi7Mn1 with a fluid flow field induced by a traveling magnetic field (TMF). Samples were molten and directionally solidified within a silica aerogel crucible at various constant solidification velocities between 0.03 and 0.24 mm/s. The application of two separate heaters allowed the fixation of constant temperature gradients in the solid and liquid parts of the samples, the use of a transparent aerogel as crucible material permitted direct optical verification of the desired solidification velocity using an infrared line camera. Three collinear coils induced a TMF of approximately 5 mT strength, traveling either up or downward in the direction of the sample axis. The microstructures of the processed samples were studied using light microscopy and SEM-EDX and characterised by the primary and secondary dendrite arm spacing, the distribution of intermetallic phases as well as the radial segregation of primary phase and eutectic. Results are presented which show differences between samples with and without TMF-induced fluid flow. We noticed a radial macro-segregation dependent on the orientation of the TMF and the effects of the induced fluid flow on the primary and secondary dendrite arm spacing are examined.
 
Conference Paper
Rapid slurry formation is a semi-solid metal forming technique, which is based on a so-called solid enthalpy exchange material (EEM). It is a fascinating technology offering the opportunity to manufacture net-shaped metal components of complex geometry in a single forming operation. At the same time, high mechanical properties can be achieved due to the unique microstructure and flow behaviour. The major process parameters used in the RSF process are rotation speed of the EEM, melt superheat, amount of EEM added (determining fs), and holding time. The process parameters can be well controlled with clear effects on the microstructure. There is a lack of theoretical modelling of the morphological evolution in these two-phase slurries.
 
Phase diagram for the examined system Al–Pb after Yu[4] with calculated spinodal line (dashed line). The composition used in this work is marked.  
Size distribution of the lead precipitates acquired from SEM data.  
Aluminum rich corner of the Al-Ti phase diagram by Sigworth [7]. The used concentrations of titanium are marked.  
Conference Paper
Simple casting experiments were set up to solve the question, if heterogeneous nucleation of the liquid-liquid decomposition in monotectic systems is possible. Al{Pb alloys with dierent inoculants were solidied, and the resulting microstructure was analysed by SEM and X-ray microtomography. Pronounced changes in the distribution of the lead precipitations indicate that it is possible to trigger the nucleation.
 
Primary Dendrite Spacing PDS [µm]
Secondary Dendrite Arm Spacing SDAS [µm]
The averaged value L β-avg from all investigated alloys (Al-5/7/9 wt. % Si-0.2/0.5/1.0 wt. % Fe) for the L β of β-Al 5 FeSi on the cross section of specimens solidified without (B = 0 mT) and with RMF (B = 6 mT) in areas A, B, C, and D (figure 1).
Conference Paper
In secondary AlSi alloys, the presence of small amounts of Fe causes the formation of intermetallic phases, which have a negative effect on mechanical and physical properties of castings. To understand the effect of fluid flow on the microstructure and intermetallic phases, Al-5/7/9 wt pct Si 0.2/0.5/1.0 wt pct Fe alloys have been directionally solidified under defined thermal (gradient 3 K/mm, solidification velocity 0.04 mm/s) and fluid flow (rotating magnetic field 6 mT) conditions. The primary α-Al phase and intermetallic phases were studied using light microscopy and SEM with EDX. The influence of fluid flow and intermetallic phases (β- Al5FeSi) on microstructure was characterized by changes of primary and secondary dendrite arm spacing and specific surface area of the dendrites. We observe a pronounced effect of flow on the length of the intermetallic precipitates, a macro-segregation Fe and Si and even small amounts of iron and thus intermetallics reduce possible effects of flow on microstructural parameters.
 
Applying cognitive computing to large astronomical surveys could have a huge impact in terms of serendipitous discovery - areas that might specifically benefit include those like SETI where human bias and other pre-conceptions may limit current efforts. 
Article
The days of the lone astronomer with his optical telescope and photographic plates are long gone: Astronomy in 2025 will not only be multi-wavelength, but multi-messenger, and dominated by huge data sets and matching data rates. Catalogues listing detailed properties of billions of objects will in themselves require a new industrial-scale approach to scientific discovery, requiring the latest techniques of advanced data analytics and an early engagement with the first generation of cognitive computing systems. Astronomers have the opportunity to be early adopters of these new technologies and methodologies: the impact can be profound and highly beneficial to effecting rapid progress in the field. Areas such as SETI research might favourably benefit from cognitive intelligence that does not rely on human bias and preconceptions.
 
The value of temperature dependent fitting parameter obtained from the fit with equation (3).
Article
We report here the magnetic properties of electron-doped Sm1-xCaxMnO3 manganites with the doping level of x=0.91. Exchange bias effect has been observed in Sm0.09Ca0.91MnO3 nanomanagnites system and can be tuned by the strength of cooling magnetic field (Hcool). The values of exchange bias parameter i.e. exchange bias fields (HE), coercivity (HC), remanence asymmetry (ME) and magnetic coercivity (MC) are found to strongly depend on Hcool. The larger effective magnetic moments and deviation of inverse susceptibility (\c{hi}-1) from Curie-Weiss law indicate the possible existence of Griffiths phase (GP). A rigorous measurement of linear and nonlinear ac and dc magnetic susceptibility in nanomanganites proves the existence of Griffiths phase (GP) in the temperature range TC<T<TG (Griffiths temperature). The effect of size reduction on exchange bias effect and GP is addressed here. The enhancement of exchange bias effect and GP has been argued to be due to the modification of the phase separated state on size reduction.
 
Article
We discuss the consistency of the D=11 supermembranes with non zero central charge arising from a nontrivial winding CSNW. The spectrum of its regularized Hamiltonian is discrete and its heat kernel in terms of a Feynman formula may be rigorously constructed. The $N\to\infty$ limit is discussed. Since CSNW is equivalent to a noncommutative supersymmetric gauge theory on a general Riemann surface, its consistency provides a proof that all of them are well defined quantum theories. We interpret the supermembrane with central charge $n$, in the type IIA picture, as a bundle of D2 branes with $n$ units of D0 charge induced by a nonconstant magnetic flux.
 
(a). Distributed query resolution [12]. (b). Corresponding speedup [12].
The block diagram of the GPU and CPU [4]. 
Graph of presented solutions for short time OLAP answers. 
Article
The overwhelmingly increasing amount of stored data has spurred researchers seeking different methods in order to optimally take advantage of it which mostly have faced a response time problem as a result of this enormous size of data. Most of solutions have suggested materialization as a favourite solution. However, such a solution cannot attain Real- Time answers anyhow. In this paper we propose a framework illustrating the barriers and suggested solutions in the way of achieving Real-Time OLAP answers that are significantly used in decision support systems and data warehouses.
 
Article
We propose a framework for indexing of grain and sub-grain structures in electron backscatter diffraction (EBSD) images of polycrystalline materials. The framework is based on a previously introduced physics-based forward model by Callahan and De Graef (2013) relating measured patterns to grain orientations (Euler angle). The forward model is tuned to the microscope and the sample symmetry group. We discretize the domain of the forward model onto a dense grid of Euler angles and for each measured pattern we identify the most similar patterns in the dictionary. These patterns are used to identify boundaries, detect anomalies, and index crystal orientations. The statistical distribution of these closest matches is used in an unsupervised binary decision tree (DT) classifier to identify grain boundaries and anomalous regions. The DT classifies a pattern as an anomaly if it has an abnormally low similarity to any pattern in the dictionary. It classifies a pixel as being near a grain boundary if the highly ranked patterns in the dictionary differ significantly over the pixels 3x3 neighborhood. Indexing is accomplished by computing the mean orientation of the closest dictionary matches to each pattern. The mean orientation is estimated using a maximum likelihood approach that models the orientation distribution as a mixture of Von Mises-Fisher distributions over the quaternionic 3-sphere. The proposed dictionary matching approach permits segmentation, anomaly detection, and indexing to be performed in a unified manner with the additional benefit of uncertainty quantification. We demonstrate the proposed dictionary-based approach on a Ni-base IN100 alloy.
 
Inelastic light scattering in a GHz range from a PZN-0.045PT single crystal on ZFC and FC (E= 500 V/cm). (a) Inelastic light scattering spectra at three different temperatures. The peak around 42 GHz denotes the scattering from the LA phonon. Note that LA phonon propagates perpendicular to E. (b) Contour map of inelastic light scattering intensity versus temperature and frequency shift in x z y z x ) (  scattering geometry (Free Spectral Range = 75 GHz, scan range = 70.5 GHz). (c) Frequency shift,  B , and FWHM, , of the LA phonon under 0, 100, and 500 V/cm, which are determined by fitting the spectra. 
Temperature dependence of the real and imaginary parts of complex dielectric constant, = '-j'', obtained in a PZN-0.045PT single crystal on ZFC and FC under E= 500V/cm along [100]-direction. 
Schematic of free energies predicted for PZN-0.045PT around the phase transition temperatures to explain the observed difference between the data on ZFC and FC. The energies of the three phases are so close that supercooling can easily occur. On the other hand, the application of the electric field stabilizes each phase. 
Article
Effect of an electric field along [100] direction on diffuse phase transitions in a relaxor ferroelectric 0.955Pb(Zn1/3Nb2/3)O3-0.045PbTiO3 (PZN-0.045PT) crystal is studied through dielectric properties and a longitudinal acoustic (LA) phonon. Compared with the diffuse phase transition observed in zero-field cooling in PZN-0.045PT, it shows two sharp phase transitions under field cooling. This result indicates that inhomogeneity is reduced by the electric field in the way that electric field grows the static polar nanoregions and microdomains into larger ferroelectric domains. From a thermodynamic point of view, the electric field enhances the relaxation from the nonequilibrium polymorphic states to the equilibrium homogeneous state. At the same time, ferroelectric tetragonal phase is stabilized with increasing an electric field along [100].
 
Projection along the fourfold axis with an anti-ferrorotative displacement of the [TeCl 4 Br 2 ] 2-octahedral: Show the Hydrogen bond in compound [Rb 0.92 (NH 4 ) 0.08 ] 2 TeCl 4 Br 2 .
DSC thermogram of [Rb 0.92 (NH 4 ) 0.08 ] 2 TeCl 4 Br 2 in the temperature range 120 to 320K.
Article
The structure of [Rb0.92(NH4)0.08]2TeCl4Br2 has been determined from conventional X-ray powder diffraction data, by Rietveld method, in P4/mnc tetragonal space group (a = 7.315 (2) Å, c = 10.354(4) Å, Z = 2). The refinement of the structure led to final factor χ2 = 4.20%. The structure is considered as isolated octahedred TeCl4Br22-. These anions show a 4° rotation around the fourfold axis against the cubic arrangement of the K2PtCl6 type structure. The monovalent cations (Rb+/NH4+) are located between the octahedra ensuring the stability of the structure by ionic and hydrogen bonding contacts: Rb....Cl/Br and N-H...Cl/Br. At low temperature a second order transition phase was detected at 213K by DSC.
 
Observed (open circles), calculated and difference X-ray diffraction profiles of BDF-PFW at 295 K.
57 Fe Mössbauer effect spectrum of BDF-PFW sinter at 77 K.
Observed (open circles), calculated and difference X-ray diffraction profiles of BDF-PFW at 295 K. In general rule ABO 3 -type perovskites crystallise in cubic Pm-3m system. Nevertheless, the ferroelectric  
a) Temperature evolution of the selected Mössbauer spectra: close to T N in magnetic state (575 K) and above T N (700 K and 800 K); b) temperature dependence of a half width of Lorentzian line.  
Article
Multiferroics which are simultaneously ferroelectric and magnetically ordered are of great importance both for fundamental solid state physics and for modern technology. The polycrystalline sample of 0.1Bi0.95Dy0.05FeO3 – 0.9Pb(Fe2/3W1/3)O3 were synthesized using standard sintering procedure. Crystal phase purity and crystal structure were determined using XRD method. The obtained crystal structure of the compound is a tetragonally distorted perovskite like structure (P4mm) with lattice parameters a = b = 3.987 Å, c = 3.990 Å. Mössbauer Effect (ME) studies were performed on 57Fe nuclei at 77K. The obtained spectra are composed of three Zeeman sextets. In the middle part of the obtained spectra there is observed paramagnetic dublet, which could be designated to impurity phase, which wasn't reveled on XRD pattern. The hyperfine interaction parameters for the all subspectra components confirm existence iron Fe3+ only in the investigated material.
 
Magnetization curves M(H) taken at 4.2 K.  
Magnetoelectric voltage coefficient (ME) vs. frequency for 0.3Bi 0.95 Dy 0.05 FeO 3 –0.7Pb(Fe 2/3 W 1/3 )O 3 .  
Frequency dependence of the magnetoelectric coefficient.  
Article
Pb-based complex perovskites with Fe3+ like Pb(Fe2/3W1/3)O3 (PFW) were found to be interesting because of their unique properties such as relaxor and magnetoelectric behavior. PFW is ferroelectric with ferroelectric Curie temperature TC between 150 and 200 K and at the same time is antiferromagnetic with magnetic Neel temperature about 400 K. BiFeO3 is a well known perovskite compound which exhibits ferroelectric (TC = 1103 K) and antiferromagnetic (TN = 643 K) ordering simultaneously. The polycrystalline sample of 0.1Bi0.95Dy0.05FeO3 – 0.9Pb(Fe2/3W1/3)O3 were synthesized using standard sintering procedure. Magnetization vs. magnetic field (at 4.2 K) curves was measured. Magnetoelectric properties of the sample were obtained.
 
Article
We present here a comparative study of sol-gel-derived 0.9Pb(Mg1/3Nb2/3)O3−0.1PbTiO3 (PMNT) thin films about 120 nm in thickness that were, respectively, deposited directly on a platinized Si substrate and on a Pb(Zr,Ti)O3 (PZT)-buffered one, but were both annealed at 750 °C in ambient air. It was found that the PZT buffer layer plays an important role in the enhancement of crystallographic and electrical properties of PMNT thin films. The PMNT film grown on PZT-buffered platinized Si substrate showed a nearly pure perovskite structure, while the film without buffer layer contained a big amount of pyrochlore phase. Also, the PZT buffer layer changed the preferred orientation of PMNT thin films from (111) to mainly (110) orientation, and helped to improve the films' densification and microstructural evolution. Coherent with what was observed comparatively in structural characterization, enhanced dielectric and leakage current characteristics were observed in the film with buffer layer. For the PMNT film grown directly on Pt-coated Si substrate, the dielectric permittivity is as low as 570, whereas the value is enhanced to 1200 for the PMNT film with PZT buffer layer. Moreover, the leakage current density of PMNT thin films is reduced remarkably, roughly 4-5 orders of magnitude lower, by introducing the PZT buffer layer.
 
Article
PET foils have a high potential as a material for biomedical and electrical industries. PET foils were irradiated by ions for variable irradiation time. The effects of low (2.5, 0.2 keV) energy argon ion flux irradiation on the surfaces of polyethylene terephthalate thin foils (PET) were studied. The source of ions was an ECR Ion Gun with settable acceleration voltages. The modified foils were investigated by in-situ X-ray Photoelectron Spectroscopy (XPS) and ex-situ Fourier transform infrared spectroscopy (FTIR). The significant changes in the chemical composition of the surface layer were quantitatively studied by XPS. The scission of the chains in the surface layer of PET foil was induced by ion flux interaction with PET surface. The strong selective sputtering of oxygen atoms in PET film was observed. The atomic ratio O/C was decreased by 0.2keV and 2.5keV argon ion flux from 0.40 to 0.25 and 0.04 respectively. The oxygen atoms in ester bonds are detached first. This phenomenon is responsible for the creation of carbon-rich surface layer. The FTIR analyses identified changes in chemical composition but with no obvious correlation to surface changes. PET volume changes in the spectra were probably results of photons from the ion source influence on PET foils.
 
(a) Schematic presentation of orientations with respect to the sample axes of the active {111} slip planes. (b) Stereographic projections on ( 1 01) plane showing configuration of the most active slip systems in ideal brass ( 1 01)[1 2 1] orientation.
Typical TEM bright field images of microstructures observed in longitudinal section for sample deformed at strains of: (a) 0.15, (b) 0.5 6 and (c) 1.5. 
TEM bright field images of microstructures observed in: (a) ED-TD and (b) ND-TD section for sample deformed 0.56.
TEM orientation maps presenting the acquisition planes: (a) ND-ED, (b) ND-TD and (c) ED-TD planes, and (d) - (f) corresponding {111} pole figures, respectively. TEM local orientation measurements with step size of 30 nm after strain of 0.56. 
(a) SEM-FEG/EBSD orientation map of the deformation microstructure showing cyclic orientation changes along line scan. (b) {111} pole figure showing the orientation groups within neighbouring grains (‘a’ and ‘b’). (c) Inverse pole figures showing two tendencies of scattering of initial orientation: cyclic orientation changes between neighbouring bands (white points) covered by general tendency of crystal lattice rotation (red arrows) of {110}<112>->{112}<110> type. Sample deformed up to a strain of 0.56. 
Article
A systematic study of the deformation microstructures over 3 perpendicular surfaces was carried out in the present work in order to correlate better the substructure with slip patterns, initial and final crystal orientation, and the macroscopic coordinate system. The microstructure and texture evolution of high purity Al-0.3 wt% Mn alloy of initial near brass {110}<112> (or Bs) orientation, channel-die compressed to the strain level of 1.5, were studied by TEM (including TEM orientation mapping) and high-resolution FEG-SEM/EBSD techniques to observe crystal subdivision deformation patterns at the microscopic scale. The grain orientation dependent structures were analyzed in terms of active slip systems focussing on the crystallography of extended planar boundaries. It was concluded that the type of dislocation structure (one or two sets of microbands) in {110}<112> oriented crystallites, at moderate strains (< 1.5) depended strongly on the crystallographic grain orientation. In this non-ideal initial crystal orientation the applied deformation mode activates a double slip, of which one system predominates and leads to further rotation away from Bs. A general rotation combined with a wide orientation spread is observed after a strain up to 1.5. The microband boundary alignment corresponds very well to the traces of crystallographic {111} planes, on which most of the slip occurs.
 
Article
We have investigated nanoscale domain structures of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 ((1-x)PMN-xPT) single crystal with x~0.32 around a morphotropic phase boundary (MPB) by a transmission electron microscopy (TEM). We found domain structures with multiple inhomogeneities in the so-called monoclinic phase near the MPB region around x~0.32 at room temperature. In addition to the large banded domains with the 100~200 nm width, there exist nanoscale lamella-type domain structures with ~10 nm width inside the large banded domains. In-situ TEM observation revealed that these nanoscale domain structures are inherent to the monoclinic phase. These domain structures with multiple inhomogeneities in the monoclinic phase should be responsible for the giant piezoelectric response to the external electric field.
 
In plane cross-section of a FS plate with a broken pin embedded, taken along the plane ~ 4 mm from the surface. L signifies leading, R retreating, T trailing and A advancing sides of the pin. 
X-Y coordinates and illustration of various object tracings drawn on the micrograph taken from location L in Figure 1: Curve 1 with solid circles for tracing the dendrite trunk, Curve 2 being a portion of Curve 1 (for Y from 0 to 22 units) moved to the right, Object 1 representing an imaginary dendrite trunk and Object 2 representing Object 1 after shear deformation. 
Shear deformation estimated as illustrated in Figure 2: location after deformation represented by the solid circles extended to X = 127 units and the best fit curve. 
Article
The maximum strain and strain rate experienced during friction stir welding/processing (FSW/P) has remained quite unclear, despite various efforts. Knowledge of strain and strain rate is important for understanding the subsequent evolution of grain structure, and serves as a basis for verification of various models as well. In the present study, we facilitated the breaking and embedding of the pin into the workpiece of cast Al-Si-Mg alloy during FS to obtain "frozen" samples for analysis. Metallographic evidence has indicated that in the leading transitional zone the strain gradient increased rapidly before entering into the thread space. Analysis of the deformed dendrites has suggested that the strain was ~ 3.5 and the strain rate was ~ 85 s-1 when the deforming material entered the thread space. The heavily deformed material then formed a rotational zone confined within thread spaces rotating largely with the pin, depositing a large part on the trailing side of the pin. Thus, once into the thread spaces, further strain is low and strain rate should decrease considerably.
 
Article
Polycrystalline samples of the delafossite Cr oxide Cu1−xAgxCrO2 were investigated to clarify its transport properties. The synthetized phases are found to contain a slight oxygen excess (δ = 0.06). The valence state of the Cr ions in the Cu1−xAgxCrO2 samples was identified as >3+ by analysing their TGA spectra, their lattice parameters and their electrical properties. The temperature dependence of zerofield-cooling magnetization was measured. All samples exhibits paramagnetic behaviour at high temperature. At low temperature they exhibit a clear ferromagnetic (FM) transition around 130 K. For x = 0.10 the samples exhibit an AFM transition at 25K. Clear hysteresis loops indicate that FM order exists in the Ag-doped samples at 2 K. All samples behave like semiconductors.
 
Configuration of solder joint.
Effect of pore size and soldering temperature on IMC thickness.  
Elemental analysis of the IMC layer for sample joined with P25 of porous.
Conference Paper
The morphology and growth of interfacial intermetallic compound (IMC) between Sn-3.0Ag-0.5Cu solder alloy and Cu substrate metal of solder joint is reported. The IMC morphology and IMC thickness layer were observed at three different porosities of porous Cu interlayer. The results revealed that during soldering process, Cu6Sn5 compound with scallop like morphology was formed at the interface of both the solder alloy and Cu substrate and at solder alloy and porous Cu interlayer. By adding porous Cu interlayer at the solder joint, the IMC thickness increased with increasing soldering temperature and the number of pores in porous Cu interlayer. The effect of porosity on increasing the IMC layer was also due to the slower cooling rate during solidification of molten solder.
 
XRD patterns of Nd 2 O 3doped (1-x)BT-xBiNKT powders calcined at 600 o C for 1 h.
Frequency dependence of impedance |Z| and phase of (a) undoped and (b) Nd 2 O 3 -doped 0.94BT-0.06BiNKT.  
Article
High purity Nd2O3-doped (1−x)BaTiO3-xBi0.5(Na, K)0.5TiO3 (x = 0.00-0.08) were synthesized by a composite-hydroxide-mediated approach at 200°C using a hydrothermal reaction apparatus with a rolling system. The powders with an average size of 100 nm in diameter were produced and were sintered to almost full theoretical density at low temperature such as 1200°C for 2 h. Although (1−-x)BaTiO3-xBi0.5(Na, K)0.5TiO3 could not be poled, Nd2O3 additive was useful to proceed the polarization of (1−x)BaTiO3-xBi0.5(Na, K)0.5TiO3 ceramics.
 
Article
Cubic-phase AlN thin films were fabricated on sapphire(0001) substrates by pulsed laser deposition at an extremely high-pressure ambient nitrogen. The crystallographic properties of the films were evaluated using X-ray diffraction techniques. The θ-2θ measurements showed diffraction peaks originating from different c-AlN structure between the films grown in the nitrogen atmosphere at 30 Torr and 80 Torr, which implied that the structural phase of c-AlN films was sensitive to the pressure of the ambient nitrogen. We investigated the details of the AlN 11 diffraction spots from the films at 80 Torr and revealed that the films were epitaxially grown on the substrates with the relationship of c-AlN(111)[11]//Al2O3(0001)[110].
 
Article
We report the growth of epitaxial Pb(Zr0.54Ti0.46)O3 (PZT) thin films on yttria-stabilized zirconia buffered silicon substrates by pulsed laser deposition. We demonstrate a full in plane epitaxy of the buffer layer, showing a RMS roughness of less than 0.3 nm for a 120 nm thick layer. This buffer layer allows the growth of fully (110) textured oxide conducting SrRuO3 and subsequent functional oxide layers. Here the Pb(Zr,Ti)O3 oxide was chosen to demonstrate its possible integration in piezoelectric microelectromechanical systems on silicon.
 
SEM top view of Si NWs on Si(100) substrate with FFT of the image.  
STEM images of Si NWs with diameter larger than 100nm (a) and less than 100 nm (b).  
Plan view SEM images of Si NWs grown from Au droplets of which the average sizes are 60 nm (a) and 100nm (b).
Article
In this paper, we have investigated an alternative method to obtain well-organized silicon nanowires grown by vapor-liquid-solid process. We have studied the influence of the droplet size on the growth direction of nanowires on plain wafers. By using self-organized Au droplets grown by molecular beam epitaxy on vicinal Si(111) surface with a 2° miscut towards the [11-2] crystallographic direction, we have obtained well organized gold droplets along the steps with small size dispersion. The growth of Si nanowires from these droplets allows defining a critical diameter for changing the Si nanowires growth direction. When the gold droplet diameter is larger than 100 nm, Si nanowires exhibit a <111> orientation and remain free of structural defects. The localisation of Si nanowires was performed in nanoscale silicon seeds formed by modified local oxidation of silicon process. This approach, based on a simple and reliable method, enable the organisation of Si nanowires with <111> orientation on Si(001) substrates.
 
Article
By means of a metal-organic deposition process, the anatase TiO2 thin films with and without (010)-oriented RbLaNb2O7 seed layer prepared by an excimer laser assisted metal-organic deposition process were crystallized on silica glass substrates. The anatase TiO2 thin film on the substrate with the seed layer showed high (001)-orientation because of the small lattice mismatch between the (001)-TiO2 and (010)-RbLaNb2O7 planes, while the anatase TiO2 thin film without the seed layer was crystallized without any specific orientations. The Lotgering factor F(001) of the obtained (001)-oriented anatase TiO2 thin film was evaluated to be about 0.92. The (001)-orientation degree seems to be further improved by some surface modifications of the seed layer to stimulate the chemical bonding for the edge shared TiO6 octahedra along the c-axis.
 
Material properties of CaF 2 single crystal for the residual stress analysis (Unit of T : K).
Article
We developed an analysis system for simulating birefringence of an annealed ingot of CaF2 single crystal caused by the residual stress after annealing process. The analysis system comprises the heat conduction analysis that provides the temperature distribution during the ingot annealing, the stress analysis to calculate the residual stress after ingot annealing, and the birefringence analysis of an annealed ingot induced by the residual stress. The finite element method was applied to the heat conduction analysis and the stress analysis. In these analyses, the temperature dependence of material properties and the crystal anisotropy were taken into account. In the residual stress calculation, we considered the time-dependent nonlinear deformation behavior of a material called creep. In the birefringence analysis, the distributions of optical path difference were calculated by using average stress method with consideration of the crystal anisotropy. We can perform the birefringence analysis of an ingot of CaF2 single crystal with any growth direction, using this analysis system, and we performed the analyses of the crystals with the <001> and <111> growth directions. From these analyses, we obtained reasonable results of optical path difference in comparison with the experimental results.
 
Article
MSWT-01, Mobile Surface Water Treatment, producing 1m3 per hour, is an alternative for providing clean water in flood disaster areas, and was developed at Bandung State Polytechnic for Manufacturing (Polman) as a part of institution research project. The combination of cartridge or membrane technology such as carbon block, MF, UF and filtration media is used for this machine, instead of coagulation-flocculation with chemical addition, due to emergency purposes related with its treatment processing time. The idea is that MSWT could be combined with Production Based Education (PBE) concept in Polman as a vocational education institution and students 'CSR', students social activities. With the number of implementation trials in real flood area condition, MSWT will be developed further based on the technical output result. The manufacturing process for improving or adding necessary features could be implemented as a student's project in PBE system. This might be an ideal combination alternative for such vocational institution that students get the product media for their PBE program and implement their work as a defined social activity. They will learn and experience related technical matters and more social interactions with the people and other disaster stakeholder as well.
 
General stage in water treatment technology selection 
WWT-01 Block Diagram 
RWT-05 Block Diagram 
MSWT-01 for Disaster Mitigation Block Diagram 
Article
Indonesia has a lot of potential flood disaster places with clean water problems faced. Various solution programs always initiated by Government, companies CSR, and people sporadical actions to provide clean water; with their advantages and disadvantages respectively. One solution is easy to operate for instance, but didn't provide adequate capacity, whereas the other had ideal performance but more costly. This situation inspired to develop a water treatment machine that could be an alternative favor. There are many methods could be choosed; whether in simple, middle or high technology, depends on water source input and output result quality. MSWT, Mobile Surface Water Treatment, is an idea for raw water in flood area, basically made for 1m3 per hour. This water treatment design adopted from combined existing technologies and related literatures. Using common ideas, the highlight is how to make such modular process put in compact design elegantly, and would be equipped with mobile feature due to make easier in operational. Through prototype level experiment trials, the machine is capable for producing clean water that suitable for sanitation and cooking/drinking purposes although using contaminated water input source. From the investment point of view, such machine could be also treated as an asset that will be used from time to time when needed, instead of made for project approach only.
 
EDS spectrum of surface-hardened nodular iron
Evaluation percentage of Anisotropy.
Models to evaluate Kc
Article
This paper studies the effect of anisotropy in the propagation of surface cracks to identify areas of potential failure, and thus implement methods that increase the resistance of the phases created in the surface hardened cast iron ductile boride by the process. On the other hand assesses the influence of residual stresses using the fracture toughness microindentación by Palmqvist cracks regime taking the perpendicular and parallel cracks generated in the hard surface, with samples of 6 h and 8 h, 900 °C treatment of boriding, with loads of 1.9 and 2.9 N. Where the value of at (kc) > (kc) > (kc) (θ) a constant distance of 30 microns. Also the phases present were determined by X-ray diffraction (XRD) and scanning electron microscopy (EDS), finally adherence is determined by the indentation technique HRC.
 
PL excitation spectra at 1.9 eV emission, in KU1 neutron irradiated silica up to 10 21 n/m 2 fluence, measured at temperatures: 10K(•), 50K(x), 150K (◊) and 300K(▲).
Article
The photoluminescence emission around 1.9 eV, excited from the ultraviolet to vacuum ultraviolet was investigated in neutron irradiated silica (at 1021 and 1022 n/m2 fluences) with different OH and impurity content: KU1 and KS-4V high purity silica and Infrasil 301. The measurements were made at different temperatures from 300K to 10K. The three irradiated silica grades show similar excitation spectra shape, although the band intensities are different depending on silica grade and temperature. Neutron irradiated KU1, with the highest OH content, shows the highest red emission attributed to nonbridging oxygen hole centers (NBOHCs). The excitation profile, from 4.0 to 8.8 eV, has two bands, which are centered around 4.85 eV and 6.5 eV. The band intensities increase with decreasing temperature from 300 to 10K for the three types of silica.
 
Schematic representation of a directionally solidified turbine blade showing spatial location of scale (dark region) with photographic insert.  
Article
There is a continuing demand to raise the operating temperature of jet engine turbine blades to meet the need for higher turbine entry temperatures (TET) in order to increase thermal efficiency and thrust. Modern, high-pressure turbine blades are made from Ni-based superalloys in single-crystal form via the investment casting process. One important post-cast surface defect, known as 'surface scale', has been investigated on the alloy CMSX-10N. This is an area of distinct discolouration of the aerofoil seen after casting. Auger electron and X-ray photoelectron spectroscopy analysis were carried out on both scaled and un-scaled areas. In the scaled region, a thin layer (~800nm) of Ni oxide is evident. In the un-scaled regions there is a thicker Al2O3 layer. It is shown that, as the blade cools during casting, differential thermal contraction of mould and alloy causes the solid blade to 'detach' from the mould in these scaled areas. The formation of Ni Oxides is facilitated by this separation.
 
Article
Density functional theory calculations have been performed to investigate the structural and electronic properties for both unrelaxed and relaxed cases of oxygen-doped c-BN(110) surface. Oxygen atom has been substituted in a neutral charge state on both the B site (OB) and the N site (ON). Defect formation energies, [unrelaxed (E°f) and relaxed (Ef)], and relaxation energies, Er, have been calculated. It has been found that substitution ON is more probable, moreover the ON causes an inward relaxation of the first neighbor surface B atom.
 
Article
Incremental sheet forming by the method of single point incremental forming Dieless-SPIF, is a widely studied process, experimented and developed in countries with high manufacturing technologies, with friendly costs when the productive configuration in a productivity system is based in small production batches. United states, United kingdom and France lead this type of studies and cases, developing various proof with experimental geometries, different from the national environment such as Colombia, Bolivia, Chile, Ecuador and Peru where this process where discretely studied. Previously mentioned, it pretends develop an experimental case of a particular geometry, identifying the maximum formability angle of material permissible for the forming of a piece in one pass, the analysis of forming limit curve (FLC), with the objective to emphasizes in this innovative method based in CAD-CAM technologies, compare with other analogous process of deformation sheet metal like embossing, take correct decisions about the viability and applicability of this process (Dieless) in a particular industrial piece, which responses to the necessities of productive configurations mentioned and be highly taken like a manufacturing alternative to the other conventional process of forming sheet metal like embossing, for systems with slow batches production.
 
RHEED oscillatio ns during Co/Ni lattice growth on the left hand side. RHEEDimages of Co (111) and Ni(111)-layers on the right.  
Typical hysteresis-loops for Co/Ni-samples for OOP and IP measurements. On the right hand side K eff D as a function of the Co-thickness. Lines are guides to the eye.  
Structure of [Co/Ni ]-superlattices  
Article
This paper is dedicated to the preparation of thin film with a strong perpendicular to the film plane magnetic anisotropy, behaviour of great interest for spintronics. Single-crystalline [Co/Ni] (111) superlattices have been grown by molecular beam epitaxy. The epitaxial growth of Co and Ni was controlled by using reflection high energy diffraction (RHEED), allowing us to get an accurate control of the thicknesses . The superlattices magnetic properties were studied using magnetometry. All of them exhibit strong perpendicular to the plane magnetic anisotropy. The maximum of magneto-crystalline anisotropy is obtained for one cobalt mo nolayer. A simple model which takes into account surface and volume anisotropy explains the evolution of perpendicular anisotropy in these layers.
 
Typical XRD pattern of MBE grown SiC FTIR in transmission mode has been performed to confirm crystallinity of the grown film and spectrum is shown in figure 2. FTIR (%transmission mode) shows SiC (TO) mode at 794cm -1 and in addition, we can see CO2 and CO modes at 467 cm -1 and 1097 cm -1 respectively. The observation of C-O complexes yields the coexistence of C-O and Si-C on the Si substrate Peak at 796 cm -1 clearly indicates the presence of SiC crystals [12]. The observation of C-O can be attributed to the unpaired C60 on Si surface.  
Raman scattering data of 3C-SiC grown by single source MBE  
Article
3C-SiC thin films have been grown by Molecular Beam Epitaxial (MBE) technique on a Si (111) substrate at 1050°C using a single solid source fullerene (C60). Fullerene molecules adsorb on the tissue like surface of substrate and then thermally decompose into amorphous carbon and produce 3C-SiC. The grown films were characterized by SEM/EDX, XRD, FTIR and Raman spectroscopy. XRD data confirmed the growth of thick, highly crystalline and epitaxial SiC. The grown film has amorphous surface but the inner core consists of nearly perfect crystalline lattice structure indicated by SEM. FTIR and Micro-Raman also confirmed the high crystalline growth of 3C-SiC . The method proves to be a milestone for low temperature and high crystalline growth of 3C-SiC.
 
Article
GaN and related structures attracted a great interest in the recent years for electronic and optoelectronic applications due to their promising properties. GaN is grown popularly on foreign substrates like sapphire and SiC. However, silicon due to its favourable properties attended the great attention of material scientists and researchers to utilize as substrate for heteroepitaxy of GaN based structures and devices. Silicon substrates are low cost, available in large diameters and have well characterized thermal and electrical properties. In this study, GaN/AlN/Si(111) heterostructures were grown by molecular beam epitaxy. We performed x-ray diffraction spectroscopy and spectroscopic ellipsometry on these samples to study their structural and optical properties. XRD measurements performed on these samples revealed the presence of high quality GaN films as well as the presence of AlN buffer layer with the following miller indices: GaN (002), GaN (004), GaN (006) and GaN (110) along with Si peak of phase (111). The ellipsometric data obtained were used to characterize the GaN/Si samples as a function of film thickness. Refractive index, extinction coefficient and dielectric constant were calculated by the measured data.
 
Article
The interest of piezoelectric materials for Radio Frequency and Microwave applications is presented. Simulation and characterization results of RF band pass filter formed by five piezoelectric Film Bulk Acoustic Resonators for UMTS wireless communication applications are carried out and showed in this work.
 
Article
Semiconductor nanocrystals are intriguing because of their electronic, optical, and chemical characteristics. Silicon nanocrystals (Si-NCs) of sub-5 nm dimension are of particular interest due to their intense photoluminescent response and the promise of linking silicon photonics and electronics. Other related nanomaterials of technological importance include SiC and Ge. The following contribution describes key experimental findings pertaining to synthetic methodology, investigation of nanodomain formation and growth, as determined by X-ray powder diffraction (XRD) and photoluminescence (PL) spectroscopy for a series of sol-gel derived prepolymers suitable for preparing Group 14 based nanocrystal containing composites.
 
Average temperature and oxygen concentration variations along the combustion chamber height
Article
In this paper pulverized combustion of insufficiently investigated low-grade Pavlovskiy coal is simulated using the modern engineering software FIRE 3D. The object of study is a widespread in Russia BKZ–210–140 steam boiler. The results of computer simulation are represented with average temperatures in horizontal sections and oxygen concentration. Curves are plotted for three steam generating capacity loads of the boiler: 100%, 70% and 50%.
 
Article
The light lithophile (Li, Be and B) and halogen (F, Cl) elements are powerful tracers of fluid transfer due to their mobility during high temperature hydrothermal processes and metamorphic devolatilisation. Moreover, although a great deal of studies have been carried out on these elements in whole rock and minerals of altered rocks from divergent and convergent plate margins, an inventory for mineral phases from the altered Icelandic oceanic crust is still incomplete. In the present paper we report the results of in situ EPMA and SIMS investigations on variously altered magmatic (plagioclase and clinopyroxene) and hydrothermal phases (amphibole and epidote) from selected cuttings drilled at different depths (400 – 3000 m) of the well RN-17, Reykjanes geothermal system (SW Iceland). Our study has benefited from the use of high-magnification SEM investigations; from ICP-MS on Li, P-TIMS determinations of boron isotope composition (δ¹¹B) and ID analyses of B contents on the whole rock. Particularly, SIMS data on epidote have shown that alteration beneath Reykjanes has been more efficient in the shallow and intermediate cuttings, while whole rock data on boron isotope composition have revealed that the alteration has been caused firstly by δ¹¹B-poor fluids and successively by δ¹¹B-rich seawater-hydrothermal fluids.
 
Article
Thermally sprayed coatings developed by use of high velocity oxy-fuel (HVOF) process are known for their superior wear characteristics. In many industrial applications, new parts as well as repaired and refurbished parts coated with WC-Co microstructured coatings have shown enhanced erosion-corrosion and abrasive resistant properties when compared with other surface modification technologies such as chrome replacement, fusion welding, and cladding. This research has been further directed towards the development of HVOF technique to deposit dense nanostructured ceramic-metallic composites. The mechanism of plastic deformation, which determines the strength and ductility of materials, in nanostructured materials are different, thereby leading to novel mechanical properties. Various parameters can influence these properties, but the substrate surface preparation by grit blasting before thermal spraying is one critical parameter. The grit blasting process generates a surface roughness, which ensures mechanical anchoring between the coating and the substrate surface. In this work, the sliding wear behavior and microhardness of WC-17wt.%Ni(80/20)Cr cermet coatings deposited onto carbon steel substrates are examined as a function of three different surface roughness values under different loads. The results show that as-prepared surface with different blasting profiles have a direct influence on the surface roughness and wear performance of the coatings. The sliding wear resistance of the coatings increased as the substrate surface roughness increased. The wear depth decreased with increasing surface roughness.
 
Article
Titanium dioxide is one of the most important oxides for applications in energy and environment, such as solar cells, photocatalysis, lithium-ion batteries. In recent years, new forms of titanium dioxide with unusual structure and/or morphology have been developed, including nanocrystals, nanotubes or nanowires. We have studied in detail the point defect chemistry in nanocrystalline TiO2 powders and ceramics. There can be a change from predominant Frenkel to Schottky disorder, depending on the experimental conditions, e.g. temperature and oxygen partial pressure. We have also studied the local environment of various dopants with similar ion radius, but different ion charge (Zn²⁺, Y³⁺, Sn⁴⁺, Zr⁴⁺, Nb⁵⁺) in TiO2 nanopowders and nanoceramics by Extended X-Ray Absorption Fine Structure (EXAFS) Spectroscopy. Interfacial segregation of acceptors was demonstrated, but donors and isovalent ions do not segregate. An electrostatic "space charge" segregation model is applied, which explains well the observed phenomena.
 
Article
Nylon 6,6 electrospun nanocomposites were prepared and reinforced with 0.1, 0.5 and 1wt.% of 1D and 2D carbon. Both carbon nanotubes and graphene were functionalised with amino groups (f-CNT and f-Ge respectively). The morphology and graphitization changes of carbon nanomaterials were evaluated by transmission electron microscopy (TEM) and Raman spectroscopy; functional groups of modified nanomaterials was analysed by infrared spectroscopy. The mechanical response and the crystallinity of the fibres were measured by dynamical mechanical analysis, differential scanning calorimetry and wide angle x-ray diffraction. The morphology and dispersion of the nanomaterials in the nanofibres was studied by scanning electron microscopy and TEM. The storage modulus was improved by 118% for f-CNT and 116% for f-Ge. The mechanical response of the nanocomposites exhibited different behaviour upon loading of 1D and 2D carbon. This trend is consistent with the crystallinity of the nanofibres. This study showed f-CNT resulted in better mechanical properties at the lowest loading. On the other hand f-Ge showed improved reinforcing effect by increasing the filler loading. The two-dimensional structure of graphene was an important factor for the higher crystallinity in the electrospun nanofibres.
 
Article
For stress corrosion cracking (SCC) study of 2.25Cr-1Mo steel, specimens were initially austenitized at 925°C for 2 hours and quenched in ice brine solution. With this process of heat treatment martensite was formed and banded morphology in the microstructure developed during previous processing was also removed. Tempering at 575°C for 1h was employed to introduce ductility in the quenched martensite of the specimens. The effects of temperature variations on SCC behavior showed a successive decrease in strength and ductility of the steel. Theses variations in tensile properties were correlated with scanning electron microscopic (SEM) examinations. The SEM results clearly revealed that mostly transgranular cracks initiated at the edges of the tensile specimens grown perpendicular to loading axes, and their intensity is increased with the testing temperatures.
 
Article
Solid Metal Induced Embrittlement (SMIE) is caused by a specific combination of two solid metals in intimate contact. Cadmium, gold, silver and copper are known to cause SMIE in certain titanium alloys. Solid copper is used in welding electrodes and fixtures in various manufacturing processes for titanium parts within the aerospace industry. In the case of resistance welding, titanium alloys are in intimate contact with solid copper, since the electrodes resistively heat the titanium part under pressure during the welding process. No previous published work that investigates the risk of using copper electrodes for welding of titanium alloys is available in the literature, but an initial study using U-bend testing indicates that solid copper in contact with Ti-8Al-1V-1Mo and Ti-6Al-2Sn-4Zr-2Mo could lead to SMIE. Therefore, in the present study, resistance welded Ti-8Al-1V-1Mo and Ti-6Al-2Sn-4Zr-2Mo have been evaluated to investigate the influence of copper electrodes on these alloys. Furthermore, resistance welded specimens sputtered with copper and gold to promote SMIE have also been evaluated. No SMIE was found in the resistance welded specimens, which may be explained by the short interaction time that the copper electrodes are in intimate contact with the titanium alloy, and/or the magnitude of residual stresses after welding, which may be too low to initiate SMIE.
 
Structures of pyrrole-based conjugated polymers.
Blue emission colors (CIE (x, y)) of OLED devices embedded P1 (7 V), P2 (10 V), P3 (10 V), P4 (7 V), and P5 (8 V) on the 1931 CIE chromaticity diagram with reference points of NTSC primary blue in1953: B (0.14, 0.08) and achromatic point: W (0.33, 0.33). 
Scheme 1. Reaction pathway for synthesis of monomers and polymers.
Article
Recent remarkable development of poly(2,7-carbazole)s and copolymers including a carbazolyl unit have demonstrated that they are one of key conjugated polymer materials for optoelectronic applications. This short review reports recent progress made in synthesis and characterization of poly(N-aryl-2,7-carbazole)s for application of light emitting diode. Main strategy and remaining challenges in the development of reliable emitting materials for devices of organic light emitting diodes are discussed.
 
Top-cited authors
Patryk Kot
  • Liverpool John Moores University
Rafid M Alkhaddar
  • Liverpool John Moores University
K. Mahender
  • Sumathi Reddy institute of technology for women
Andrea Ehrmann
  • Fachhochschule Bielefeld
Salah L. Zubaidi
  • Liverpool John Moores University