Volume 5, Issue 6, June 2014


Editorial

International Conference On Smart Materials And Surfaces (SMS), Bangkok

Ashutosh Tiwari

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 297-298
DOI: 10.5185/amlett.2014.6001

We are pleased to announce International Conference on Smart Materials and Surfaces (SMS). It will be organised jointly by SETCOR, IAAM and VBRI Press during 26-28 August 2014 at Sheraton Grande Sukhumvit Hotel, Bangkok, Thailand. Smart Materials and Surfaces (SMS), Bangkok is a three-day event targeting researchers interested in the design, modification, characterisation and applications of Novel Smart & Active Surfaces and Materials. The goal of conference is to provide a global platform for researchers and engineers coming from academia and industry to present their research results and activities in the field of Intelligent Materials science and engineering. The conference will provide opportunities for the delegates to exchange face-to-face their novel ideas and experiences with the international experts during plenary & invited talks, oral presentations and poster sessions. We will set up sessions with keynote forum, panel discussion, project negotiation along with welcome cocktail and gala dinner

Conductive Polymer Composites And Coated Metals As Alternative Bipolar Plate Materials For All-vanadium Redox-flow Batteries

Burak Caglar; Justin Richards; Peter Fischer; Jens Tuebke

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 299-308
DOI: 10.5185/amlett.2014.amwc.1023

In this study polypropylene (PP) based conductive composites and metal doped diamond like carbon (DLC) coated metallic substrates are studied as alternative bipolar materials for all-vanadium redox flow battery (VRFB). Graphite and carbon nanotube (CNT) filled PP based bipolar plates were produced via twin-screw co-rotating extruder and injection molding. Addition of 3 wt. % CNTs into highly filled graphite-PP matrix increased in-plane and through-plane electrical conductivities from 10 S/cm to 50 S/cm and from 2 S/cm to 10 S/cm respectively. PP composites with 78 wt. % graphite and 2 wt. % CNT filling ratio showed flexural strength value of 48,01 MPa. Produced bipolar plates were examined with galvanostatic charge-discharge test in a single-cell VRFB. Energy efficiency of 85,43 % at 25 mA/cm2 and discharge power density of 78,48 mW/cm 2 at 75 mA/cm 2 were achieved and those values were found to be comparable with commercial bipolar plates. Titanium, vanadium, chromoium and tungsten doped diamond-like coating (DLC) films were coated on metallic substrates (e.g. stainless steel 1.4301 and titanium alloy 3.7165) by a physical vapor deposition. The metallic dopant is necessary to achieve high conductivities in the order of ~100 S/cm. The values range from 0.5 to 35 S/cm for in-plane and from 10 to 110 S/cm for through-plane. The hydrogen evolution reaction (HER) and the anodic corrosions stability in 2 molar sulfuric acid constituted the main focus area for our investigations on metallic bipolar plates. An interesting material for coated metallic bipolar plate is the 10 µm Ti-DLC on 1.4301 which exhibits the highest hydrogen evolution overpotential of all investigated materials (710 mV µA/cm²). It also showed improved corrosion stability for anodic potentials.

Electrical And Microstructural Properties Of (Cu, Al, In)-doped SnO2 Films Deposited By Spray Pyrolysis

Sibel Gurakar; Tulay Serin; Necmi Serin

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 309-314
DOI: 10.5185/amlett.2014.amwc.1016

The effect of Cu, Al and In doping on the microstructural and the electrical properties of the SnO2 films were studied. The undoped, Cu, Al and In (2 at. %) doped SnO2 films were deposited on the glass substrate by spray pyrolysis from 0.8 M SnCl2–ethanol solution at substrate temperature 400 °C. The microstructural properties of films were investigated by X-ray diffraction (XRD) method. It was determined that the films formed at polycrystalline structure in tetragonal phase and structure was not changed by dopant species. The lattice parameters (a), (c) and crystallite size (D) were determined and obtained in the range of 4.90-4.92 Å, 3.26-3.31 Å and 34-167 Å, respectively. The optical transmittance of thin films was measured and the optical band gap Eg values of the films were obtained in the range of 3.96-4.00 eV, using the Tauc relation. The electrical transport properties of undoped, Cu, Al and In-doped SnO2 films were investigated by means of conductivity measurements in a temperature range of 120-400 K. The electrical transport mechanism of the undoped, Cu, Al and In-doped SnO2 films was determined by means of the tunneling model through the back-to-back Schottky barrier and the thermionic field emission model in the temperature range of 120-300 K and 300-400 K, respectively.

Thermodynamics And Electrochemical Characterization Of Core-shell Type Gold-coated Superparamagnetic Iron Oxide Nanoparticles

Faruq Mohammad; Tanvir Arfin

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 315-324
DOI: 10.5185/amlett.2014.amwc.1030

In continuation to our previous work, the superparamagnetic Fe3O4@Au core-shell type nanoparticles (NPs) were further characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), electrical conductivity, impedance and cyclic voltammetry measurements. From the analysis of DSC and TGA results with our Fe3O4@Au NPs of about 6.25 ± 0.6 nm size, we observed a clear endothermic peak at 310°C due to the decomposition of the oleic acid/oleylamine surface ligands and the particles found to contain more than 80% of the metallic content from the mixed compositions of gold and iron oxide were observed. Because of the conduction through the Fe3O4@Au grain, the impedance profile of the pellet exhibited a well-resolved semi-circle and an inclined spike in a far low-frequency region. The electrical conductivity of the Fe3O4@Au material found to be increased with an increase of temperature. The standard Gibbs free energy (ΔG) of the reaction provided a criterion for spontaneous changes in the equilibrium of the material. From the analysis of the results of ΔG, it appears that at 25°C temperature, ΔS found to be negative. The calculated enthalpy, ΔH = -0.635 kJ/mol, at the corresponding entropy of ΔS = -0.132 kJ/mol. Finally, the activation energy in temperature range of 25-200°C for the Fe3O4@Au core-shell material was calculated using Line fitting and the surface characterization by using cyclic voltammetry. The electrochemical redox property of the Fe3O4@Au shows quasi-reversible wave corresponding to Au 3+ /Au 2+ .In addition, the electrochemical parameters for Fe3O4@Au NPs of E c p < /sub>, E a p < /sub>, E o 1/2 and were also obtained. Since the Fe3O4@Au material has low activation energy at low temperature range which makes it a good candidate as an ion conductor and even has the potential uses in many solid state devices and also in the future prospects of electrochemistry applications.

Stability Of ZnO Nanorods Coated On The Channel Wall Under Continuous Flow Conditions

Berrin Ikizler; Sumer Peker

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 325-332
DOI: 10.5185/amlett.2014.amwc.1020

The damage given to the ZnO nanorod coating immobilized at the bottom of a rectangular channel by water flow is assessed in this work. The experiments were conducted in complete darkness to determine the inherent stability of the nanorod coating without the interfering effect of UV radiation. The quality and morphology of the nanorod arrays before and after use were determined by x-ray diffraction, scanning electron microscopy; rod breakage, by dynamic light scattering; and the extent of erosion, by concentration and weight measurements. The effect of pH of the flowing water in the range 4£pH10, and the effect of the volumetric flow rate in the range, 3.3-33 cm 3 /s are investigated in this work as parameters. ZnO erosion reaches a low-level plateau in the pH range of 6£pH£10. Within this range, water velocity and alignment of the nanorods control the extent of dissolution. Dissolution of ZnO nanorods essentially takes place on the polar (0001)-Zn plane of ZnO, resulting in the formation of serrated surfaces. Furthermore, inclined rods joining at the top surface is subjected to further dissolution through pit formation originating at the junction interface, and extending outwards. ZnO nanorod arrays could be used as a photocatalyst in the photocatalytic water treatment processes, where the dissolution from nanorods is in the range of 2.0−2.5 wt% after 24 h of operation under a flow rate of 3.30 cm 3 /s (≈12 L/h), well under the requirements of World Health Organization.

Synthesis, Characterization And Mesomorphic Properties of Side Chain Liquid Crystalline Oligomer Having Schiff Base Type Mesogenic Group

H. E. Gulbas; D. G. Coskun; Y. H. Gursel; B. Bilgin-Eran

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 333-338
DOI: 10.5185/amlett.2014.amwc.1022

A new liquid crystalline oligomer OLC was synthesized from its monomer having Schiff-base type mesogenic group MLC via free radical polymerization. The chemical structures of all compounds were confirmed using UV, FTIR, 1 H NMR, 13 C NMR and MS spectroscopy. Schiff-base type thermotropic system based on side chain oligomer containing long aliphatic branching was studied to determine the change in mesophase behaviour of the Schiff-base type mesogenic groups. A combination of differantial scanning calorimetry (DSC) and polarize optical microscopy (POM) demonstrated that the oligomer behaves similar to its monomer and both of them exhibit enantiotropic SmC and monotropic SmX mesophases. The oligomerization of the liquid crystal monomer gives rise to decreased transition temperatures whereas it has no influence on the type and stability of the mesophase formed. Namely, simply through oligomerization, we can greatly vary transition temperatures of the mesogenic groups.

Nanocrystalline Nickel Ferrite Reinforced Conducting Polyaniline Nanocomposites

Subhash B. Kondawar; Arti I. Nandapure; Bharti I. Nandapure

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 339-344
DOI: 10.5185/amlett.2014.amwc.1035

Nanocrystalline nickel ferrite (NiFe2O4) powder of crystallite size ~20 nm was synthesized by refluxing method. Electrically conductive polyaniline-nickel ferrite (PANI/NiFe2O4) nanocomposites have been synthesized by an in-situ polymerization of aniline monomer in the presence of as-prepared NiFe2O4 in different weight percentage (5%, 10%, and 15%). These nanocomposites were subsequently characterized for morphological, crystalline, structural, electrical and magnetic properties by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Four Probe Resistivity (FPR) and Vibrating Sample Magnetometer (VSM). Existence of NiFe2O4 in the nanocomposites was confirmed by XRD, FTIR and TEM analysis. The change in morphology with crystallite size ? 50 nm was observed for the nanocomposites clearly indicate the coating of PANI on  NiFe2O4 . Nanocomposites showed increase in saturation magnetization as compared to that of PANI and increase in electrical conductivity as compared to that of  NiFe2O4  indicating the synergistic effect of individual components. The saturation magnetization drastically increased as nickel ferrite content changed from 5 to 15% in nanocomposites. The conductivity of nanocomposites increased with temperature, exhibiting typical semiconductor behavior. The nanocomposites show semiconducting and ferromagnetic behaviour. The electrical conductivity of nanocomposites decreased from 1.089 to 0.268 S/cm, but saturation magnetization increased from 0.97 to 2.803 emu/g, when ferrite content changed from 5 to 15 wt%, indicates such nanocomposites are good for electromagnetic devices.

Abrasion Resistance Of Reactive Powder Concrete: The Influence Of Water-to-cement Ratio And Steel Micro-fibers

Caglar Yalcinkaya; Jedrzej Sznajder; Ahsanollah Beglarigale; Orkut Sancakoglu; Halit Yazici

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 345-351
DOI: 10.5185/amlett.2014.amwc.1021

Reactive Powder Concrete (RPC) is characterized by high cementitious material content, very low water to cement ratio and steel micro-fiber reinforcement. This type of cementitious composite has greater ductility, durability and mechanical properties compared to traditional concrete. Abrasion resistance of the composite material is still not well understood,although it has a variety of applications, including bridge deck construction and floor covering. In the scope of this study, three water-to-cement ratios and various micro-fiber volume fractions were investigated. Mechanical properties under steam curing were determined. Cubic specimens with a 71 mm side were prepared for the surface abrasion test by means of Böhme apparatus. In addition, the flexural toughness and Charpy impact tests were performed on unnotched prismatic specimens. A relationship between loss of mass by the Böhme abrasion test and mechanical properties was investigated. Test results indicated that abrasion resistance and mechanical properties can be improved by incorporating steel micro-fiber. The positive effect of fibers can be enhanced by reducing W/C ratio. It seems that RPC has a great potential to use in civil engineering structures subjected to abrasion.

Metal Decontamination From Chemically Modified Rice Husk Film

S. K. Shukla; Anand Bharadvaja;G. C. Dubey

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 352-355
DOI: 10.5185/amlett.2014.1018

Finely grinded rice husk (RH) has been treated with different alkalis (NaOH, KOH, Na2CO3 and KCO3)   and a film was casted   from obtained semi liquid product. The effect of various alkalis on physical properties like water absorption, swelling behavior, bulk density husk has been investigated. The morphology and chemical structure were studied by Infrared spectroscopy (FT-IR), Optical microscopy and thermogravimetry (TG) techniques. The results   revealed the formation of homogenous film with partial crystalline nature with better thermal stability than RH and approx half bulk density. Further, the developed film was found suitable for metal (Cu(II) and As (III) decontamination from  prepared aqueous sample upto 90 and 93 % with removal capacity 2gm per sq cm.

Solidification Sequences In The Ternary Fe-V-Nb System

Samir Mansour; Naima Boutarek; Sif Eddine Amara

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 356-359
DOI: 10.5185/amlett.2014.amwc.1111

The present work is a continuation of research on alloys based on iron, with the aim to understanding the solidification behaviour of Fe-V-Nb alloys. Solidification sequences are proposed in relation to the observed microstructures for Fe-V-Nb synthesis alloys. Fe-V-Nb binary alloys with different concentrations are arc melted and characterized systematically by means of differential thermal analysis, optical and scanning electron microscopy coupled to an energy dispersive X-Ray microprobe analysis, quantitative XRF spectrometry and X-Ray diffraction. In the present work, the thermal and microsructural behavior of Fe–V –Nb alloys with different concentrations have been studied with the aim of answering some questions and especially paying attention to the microstructures and temperature transition. Two primary surfaces are identified: a(Fe) and Fe2Nb. Moreover, one invariant line is also identified as a binary eutectic reaction (L « a + Fe2Nb), which is clearly shown according to the observed microstructure. In perspective, other shades of this ternary alloy will be studied for a path projection of liquidus surface.

Thermal And Frequency Dependance Dielectric Properties Of Conducting Polymer/ Fly Ash Composites

Subhash B. Kondawar; A. D. Dahegaonkar; V. A. Tabhane; D. V. Nandanwar

Advanced Materials Letters, 2014, Volume 5, Issue 6, Pages 360-365
DOI: 10.5185/amlett.2014.amwc.1036

With more than 100 million tonnes of fly ash produced in India, use of fly ash for the preparation of polyaniline – fly ash composites will in no way help in its bulk utilization. Still the authors have made an effort towards the better utility of fly ash by synthesizing polyaniline –fly ash composites for electronic devices where the requirement of dielectric materials with good electrical conductivity. There is great challenge to use the waste of thermal power stations in the form of fly ash as reinforcement for the conducting polymers to be good dielectric materials. In this paper, we report the use of fly ash to prepare conducting polymer composite materials. In-situ polymerization of aniline was carried out in the presence of fly ash (FA) to synthesize conducting polyaniline–fly ash composites (PANI-FA) by chemical oxidation method.   The PANI-FA composites have been synthesized with various compositions (10, 20, 30, 40 and 50 wt %) of fly ash in conducting polymer matrix. The surface morphology of these composites was studied by scanning electron microscopy (SEM). These composites were characterized by Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD), Fourier Transform Infra-Red (FTIR) Spectroscopy to investigate surface morphology and structure of the composites. Thermal and frequency dependence dielectric properties of all the synthesized composites have been studied with the help of impedance analyzer. By incorporating fly ash into conducting polymers, dielectric constant of the composites was found to be improved as compared to that of pure conducting polymers. It was also noticed that the dielectric constant of all the composites found to be decreased with increasing frequency but increased with increasing temperature. The results obtained for these composites are of greater scientific and technological interest for good quality capacitors.