Competitive effects of film thickness and growth rate in spray pyrolytically deposited fluorine-doped tin dioxide films

Here we report efforts to understand the competitive roles of film thickness (up to ∼ 650 nm) and growth rate (up to ∼ 190 nm/min) in spray pyrolytically deposited fluorine-doped tin dioxide films. This was achieved by varying the time of deposition and/or the precursor concentration. Film properties were investigated using X-ray diffraction technique and Hall effect measurements. The thickness evolution involved textured growth along [200] orientation followed by a secondary prominence of [110] and [101] orientations. The growth rate induced effects accelerated this change. The carrier concentration and carrier mobility showed that the [200] oriented growth is technologically advantageous and can be obtained using a wider growth rate range ∼ 50-130 nm/min.     

A First Principle Study of Co2CrZ (Z=In, Sn, Sb) Based on FP-LAPW Method

The structural and electronic properties of Heusler alloys Co₂CrZ (Z=In, Sn, Sb) have been studied using the generalized gradient approximation (GGA) and local spin density approximation (LSDA), respectively. Among the systems under investigation, Co₂CrSb gives 100 % spin polarization at E _F . Co₂CrSb is the most stable Half-Metallic Ferromagnets (HMFs) with an energy gap 0.25 eV at the Fermi level in the spin-down channel. We have also found that the increase in the total magnetic moment as Z goes from In to Sb. The calculated density of states (DOS) and band structures shows the half-metallic ferromagnets (HMF) character of Co₂CrSb.     

Preparation and characterization of poly(chlorotrifluoroethylene‐co‐ethylvinyl ether)/poly(styrene acrylate) core–shells and SiO2 nanocomposite films via a solution mixing method

Nanocomposite particles of poly(chlorotrifluoroethylene‐co‐ethylvinyl ether) [poly(CTFE‐co‐EVE)]/poly(styrene acrylate) (PSA)/SiO₂ were prepared with poly(CTFE‐co‐EVE)/PSA [CS(FS); core–shell (CS) fluoro surfactant (FS)] and hydrophilic SiO₂ nanoparticles by a solution mixing method. This method yielded a homogeneous dispersion of hydrophilic SiO₂ nanoparticles in the CS(FS) matrix. The nanocomposite particle composition was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. A slight improvement in the thermal stability was observed and the glass‐transition temperature of the nanocomposite particles increased compared with the CS(FS) matrix. A remarkable enhancement was observed in the mechanical properties with an increase in the tensile strength from 1.1 to 6.2 MPa and with an increase in the elongation at break from 209.6 to 350.1% for the films with 15 wt % SiO₂. The presence of a wettable PSA shell on the fluorocore made interaction possible with SiO₂; this made it more hygroscopic with a decent water uptake capacity and an enhanced water contact angle. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

Structural,electronic,magnetic and optical properties of neodymium chalcogenides using LSDA+U method

正We have studied the electronic,magnetic and optical properties of neodymium chalcogenides by performing LSDA+U and full potential linearized augmented plane wave(FP-LAPW) method.The electronic structure calculation shows that the electronic states in Nd-chalcogenides were mainly contributed by Nd-4f electrons near Fermi energy and 3p,4p and 5p state electrons of X(S,Se and Te),respectively.We have also studied the absorption of light via the imaginary parts of the dielectric function of Nd-chalcogenides.     

Structural, electronic, magnetic and optical properties of neodymium chalcogenides using LSDA+U method

We have studied the electronic,magnetic and optical properties of neodymium chalcogenides by performing LSDA+U and full potential linearized augmented plane wave (FP-LAPW) method.The electronic structu...     

The formation of MgZnO luminescent ceramics

Mg_xZn_1−xO is a promising alloy system with UV-tunable bandgap. The alloy can have the hexagonal or cubic structure depending on the composition x and growth conditions. We present studies of the optical and material properties of Mg_0.1Zn_0.9O and Mg_0.6Zn_0.4O sintered ceramics. The rationale for choosing these compositions is that alloys of both the wurtzite and the cubic phases, respectively, can be investigated. To study the alloying dynamics for the optimization of light emission, the properties as a function of annealing temperature in the range of 600–1,100 °C were investigated via micro-photoluminescence, X-ray diffraction, and imaging techniques. For the Mg_0.1Zn_0.9O it was found that a threshold temperature of ~900 °C is required in order to initiate the formation of the solid solution with the wurtzite structure. At the elevated temperature regime, the photoluminescence energy for this ceramic sample shifted from 3.25 to 3.5 eV, while the ceramic retained the wurtzite structure. The Mg_0.6Zn_0.4O was found to have a sequence of phases: initially the alloy formed with the wurtzite structure, and then a transition into the NaCl cubic structure took place. Similar to the Mg_0.1Zn_0.9O, a threshold temperature of ~900 °C was required in order to initiate the alloying process. At that temperature regime an alloy was formed with the wurtzite structure, and its photoluminescence energy was ~3.25 eV. At ~1,100 °C the alloy was found to undergo a phase transition from wurtzite to cubic structure. The photoluminescence energy at that temperature was considerably shifted into the UV-range of 4 eV.     

From symmetric AC/AC to asymmetric AC/graphite,a progress in electrochemical capacitors

Graphitic carbon instead of activated carbon has been employed as the positive electrode material in the activated carbon (AC)/carbon capacitors using organic electrolytes. The advantageous electrochemical performance of the AC/graphite capacitors has been investigated as compared with the AC/AC capacitors. The charge storage mechanism of anions on the graphite positive electrodes in the AC/graphite capacitors has been studied by in situ XRD measurements.     

An efficient frontier for sum deviation JIT sequencing problem in mixed-model systems via apportionment

In this paper, the sum deviation just-in-time (JIT) sequencing problem in mixed-model production systems is studied relating with the discrete apportionment problem together with their respective mathematical formulations. The assignment formulation for the first problem is brieffy discussed followed by the existence of JIT cyclic sequences. Presenting the concise discussion on divisor methods for the discrete apportionment problem, we have proposed two mean-based divisor functions for this problem claiming that they are better than the existing divisors; hence, we found a better bound for the JIT sequencing problem. The linkage of both the problems is characterized in terms of similar type of objective functions. The problems are shown equivalent via suitable transformations and similar properties. The joint approaches for the two problems are discussed in terms of global and local deviations proposing equitably efficient solution.     

One-pot solvothermal synthesis of Co2P nanoparticles: An efficient HER and OER electrocatalysts

Development of an inexpensive electrocatalyst for hydrogen evolution (HER) and oxygen evolution reactions (OER) receives much traction recently. Herein, we report a facile one-pot ethyleneglycol (EG) mediated solvothermal synthesis of orthorhombic Co₂P with particle size ~20–30 nm as an efficient HER and OER catalysts. Synthesis parameters like various solvents, temperatures, precursors ratios, and reaction time influences the formation of phase pure Co₂P. Investigation of Co₂P as an electrocatalyst for HER in acidic (0.5 M H₂SO₄) and alkaline medium (1.0 M KOH), furnishes low overpotential of 178 mV and 190 mV, respectively to achieve a 10 mA cm^?2 current density with a long term stability and durability. As an OER catalyst in 1.0 M KOH, Co₂P shows an overpotential of 364 mV at 10 mA cm^?2 current density. Investigation of Co₂P NP by XPS analysis after OER stability test under alkaline medium confirms the formation of amorphous cobalt oxyhydroxide (CoOOH) as an intermediate during OER process.