• Issue front cover thumbnail

      Volume 37, Issue 5

      August 2014,   pages  953-1190

    • Size-dependent magnetic properties in Cu0.25Co0.25Zn0.5Fe2O4

      Hina Bhargava V D Sudheesh J Nehra Varkey Sebastian N Lakshmi K Venugopalan V R Reddy Ajay Gupta

      More Details Abstract Fulltext PDF

      Cu0.25Co0.25Zn0.5Fe2O4 nanoparticles were prepared by a co-precipitation method and the size was varied by varying annealing temperatures. The cation distribution, estimated using Mössbauer spectroscopy, shows that it is the same for all samples, irrespective of the size. The variation of Curie temperature and saturation magnetization as a function of particle size, studied using d.c. magnetization, clearly indicates that these are a result of finite size scaling effects. The superparamagnetic size limit is estimated to be 8 nm.

    • High-temperature thermoelectric properties of Ag𝑥Y𝑦Ca2.8Co4O9 + 𝛿 ceramics

      Youjin Zheng Hui Zhou Tengzhou Ma Guihong Zuo Hongtao Li Taichao Su Chunlei Wu Hailiang Huang Dan Wang Longcheng Yin

      More Details Abstract Fulltext PDF

      Thermoelectric ceramics, Ag𝑥Y𝑦Ca2.8Co4O9 + 𝛿 (0 ≤ 𝑥, 𝑦 ≤ 0.15), have been prepared using a sol–gel method, followed by pressureless sintering. The phase structures and microstructures of oxides were investigated at room temperature. Thermoelectric properties including Seebeck coefficient, electrical conductivity and thermal conductivity were measured from 303 to 973 K. It was found that the samples contain nanostructured Ag phase with grain size of 100 nm. The Ag0.05Y0.15Ca2.8Co4O9 + 𝛿 sample has the maximum figure of merit (ZT ∼ 0.14 @ 973 K), which is about 27% higher than that of Ca3Co4O9 + 𝛿.

    • Large-scale synthesis of YSZ nanopowder by Pechini method

      Morteza Hajizadeh-Oghaz Reza Shoja Razavi Mohammadreza Loghman Estarki

      More Details Abstract Fulltext PDF

      Yttria–stabilized zirconia nanopowders were synthesized on a relatively large scale using Pechini method. In the present paper, nearly spherical yttria-stabilized zirconia nanopowders with tetragonal structure were synthesized by Pechini process from zirconium oxynitrate hexahydrate, yttrium nitrate, citric acid and ethylene glycol. The phase and structural analyses were accomplished by X-ray diffraction; morphological analysis was carried out by field emission scanning electron microscopy and transmission electron microscopy. The results revealed nearly spherical yttria–stabilized zirconia powder with tetragonal crystal structure and chemical purity of 99.1% by inductively coupled plasma optical emission spectroscopy on a large scale.

    • Effect of electrolytes on electrochromic properties and morphology of poly(2,5-dimethoxy aniline) films

      Bureerat Suephatthima Nophawan Paradee Anuvat Sirivat Datchanee Pattavarakorn

      More Details Abstract Fulltext PDF

      Poly(2,5-dimethoxyaniline) (PDMA) was electrochemically synthesized in oxalic (H2C2O4) nitric (HNO3) and hydrochloric (HCl) acids and deposited onto flexible indium tin oxide at various synthesis times and deposition potentials as electrochromic materials. The PDMA films were characterized by FT–IRspectrometry, scanning electron microscopy, UV–Vis spectrophotometry and cyclic voltammetry. All PDMA films show reversible colour changes from yellow to green corresponding to the transition from the fully reduced state to the fully oxidized state under potential switching. The surface morphology and thickness of PDMA films depend critically on the type of acids used in the electrochemical polymerization process. The morphology of PDMA are highly porous microfibres (H2C2O4 and HNO3), tiny granular aggregate (HCl) and particle agglomerate depending on the polymerization time. The fastest response time observed via colour changing of 3.7 s is obtained from the HCl–PDMA film at 3.5 volt and at the synthesis time of 6 min, as primarily due to the thickness of the film. The flexible PDMA film is demonstrated here as a potential candidate to be used in electrochromic devices.

    • Influence of annealing temperature on ZnO thin films grown by dual ion beam sputtering

      Sushil Kumar Pandey Saurabh Kumar Pandey Vishnu Awasthi Ashish Kumar Uday P Deshpande Mukul Gupta Shaibal Mukherjee

      More Details Abstract Fulltext PDF

      We have investigated the influence of in situ annealing on the optical, electrical, structural and morphological properties of ZnO thin films prepared on 𝑝-type Si(100) substrates by dual ion beam sputtering deposition (DIBSD) system. X-ray diffraction (XRD) measurements showed that all ZnO films have (002) preferred orientation. Full-width at half-maximum (FWHM) of XRD from the (002) crystal plane was observed to reach to a minimum value of 0.139° from ZnO film, annealed at 600 °C. Photoluminescence (PL) measurements demonstrated sharp near-band-edge emission (NBE) at ∼ 380 nm along with broad deep level emissions (DLEs) at room temperature. Moreover, when the annealing temperature was increased from 400 to 600 °C, the ratio of NBE peak intensity to DLE peak intensity initially increased, however, it reduced at further increase in annealing temperature. In electrical characterization as well, when annealing temperature was increased from 400 to 600 °C, room temperature electron mobility enhanced from 6.534 to 13.326 cm2/V s, and then reduced with subsequent increase in temperature. Therefore, 600 °C annealing temperature produced good-quality ZnO film, suitable for optoelectronic devices fabrication. X-ray photoelectron spectroscopy (XPS) study revealed the presence of oxygen interstitials and vacancies point defects in ZnO film annealed at 400 °C.

    • Optical properties on thermally evaporated and heat-treated disodium phthalocyanine derivative thin films

      M E Sánchez-Vergara M Rivera R A Torres-García C O Perez-Baeza E A Loza-Neri

      More Details Abstract Fulltext PDF

      Thin films were grown on quartz substrates and crystalline silicon wafers using disodium phthalocyanine and the organic ligands 2,6-diaminoanthraquinone, 2,6-dihydroxianthraquinone and its potassium derivative salt. The surface morphology of these films was analysed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). IR spectroscopy was employed in order to investigate possible changes of the intra-molecular bonds between the powder compounds and thin films. The optical parameters have been investigated using spectrophotometric measurements of absorbance in the wavelength range of 200–1100 nm and the effects of post-deposition heat treatment were analysed. The absorption spectra recorded in the UV–Vis region for the deposited samples showed two bands, namely the Q and Soret bands. The absorption coefficient in the absorption region reveals non-direct transitions. In addition, the optical gap dependence upon the thickness of these thin films was evaluated.

    • Metal–polyaniline nanofibre composite for supercapacitor applications

      S H Kazemi M A Kiani R Mohamadi L Eskandarian

      More Details Abstract Fulltext PDF

      The aim of the present work is to increase the electrical conductivity and specific capacitance of the polyaniline (PANi) nanofibres by introducing the metallic nanostructures. Herein, metal nanoparticleincorporated PANi nanofibres were prepared from interfacially synthesized PANi nanofibres as seeds. In the main step of aniline polymerization, the seeds were employed to produce a large amount of PANi nanofibres in the next steps. Also, metal–PANi nanofibres were chemically prepared by adding inorganic salts (nickel and copper salts) which incorporated PANi nanofibres via the self-assembly process. Increased conductivity and good electrochemical behaviour were observed for these metal–PANi nanofibres at room temperature compared with the single PANi nanofibres, which was previously reported. SEM, FT–IR and UV–Vis techniques were applied for characterization of the products. Finally, the potential application of the composites to use as electrode materials for supercapacitor was examined. Elevated specific capacitance in addition to good cycle stability was observed for the metal–PANi nanofibres. Also, electrochemical impedance spectroscopy and charge/discharge experiments show that these metal–PANi nanofibres possess the high conductivity and low charge transfer resistance, which make them suitable candidates for high-performance supercapacitors.

    • Thermoelectric properties of rare earth-doped 𝑛-type Bi2Se0.3Te2.7 nanocomposites

      Fang Wu Hongzhang Song Jianfeng Jia Xing Hu

      More Details Abstract Fulltext PDF

      𝑛-Type R0.2Bi1.8Se0.3Te2.7 (R = Ce, Y and Sm) nanopowders were synthesized by hydrothermal method and the thermoelectric properties of the bulk samples made by hot-pressing these nanopowders were investigated. The Ce, Y and Sm doping have significant effects on the morphologies of the synthesized nanopowders. The thermoelectric property results show that Ce, Y and Sm doping not only help to decrease the electrical resistivity, but also help to reduce the thermal conductivity. Among rare earth elements–doped samples, it seems that the Y0.2Bi1.8Se0.3Te2.7 bulk has a suitable microstructure, which scatters phonons effectively but does not scatter electronic carriers as much. As a result, the ZT values of Y0.2Bi1.8Se0.3Te2.7 can reach 1.21 at 413 K, which is higher than those of Bi2Se0.3Te2.7 ingots made by zone-melting method.

    • Excellent bonding behaviour of novel surface-tailored fibre composite rods with cementitious matrix

      Fernando Cunha Sohel Rana Raul Fangueiro Graça Vasconcelos

      More Details Abstract Fulltext PDF

      Novel composite rods were produced by a special braiding technique that involves braiding of polyester yarns around a core of resin-impregnated carbon fibres and subsequent curing. The surface roughness of these braided rods was tailored by replacing one or two simple yarns in the outer-braided layer with braided yarns (produced from 8 simple yarns) and adjusting the take-up velocity. Pull-out tests were carried out to characterize the bond behaviour of these composite rods with cementitious matrix. It was observed that the rod produced with two braided yarns in the outer cover and highest take-up speed was ruptured completely before pull-out, leading to full utilization of its tensile strength, and exhibited 134% higher pull-out force as compared to the rods produced using only simple braiding yarns.

    • Effects of geometry and temperature on mode I interlaminar fracture of filled polypropylene–elastomer nanocomposite

      Bishnu P Panda Smita Mohanty S K Nayak

      More Details Abstract Fulltext PDF

      In this study, organically modified Na-MMT clay was used for the preparation of blend nanocomposites containing different ratios of polypropylene (PP) and ethylene propylene diene monomer (EPDM) elastomer in a twin screw extruder. Maleic-grafted PP (MAPP) was used as compatibilizer for making PP hydrophilic. Surface modification of Na–MMT was made by using amino propyl trimethoxy silane (APS) and trimethyl amine as coupling agent with surface grafting catalyst, respectively. A fracture mechanics approach has been adopted by mode I test and the effects of specimen geometry have been investigated. Increase in interlaminar fracture energy value, 𝐺c, was observed as the crack propagated through the composite, i.e. a rising ‘R-curve’ for both blend and nanocomposites. Deep fracture studies were carried out at different temperatures (–60 °C to 60 °C) using Izod impact and SENT tests. Fracture energy, fracture stress and brittle ductile transition were determined from crack initiation and propagation process, which showed significant improvement in impact and fracture energy at positive temperature. The wide-angle X-ray diffraction (XRD) patterns showed increased 𝑑-spacing of clay layers, indicating enhanced compatibility between PP and clay with the addition of maleated polypropylene (MAPP). Morphology/impact property relationships and an explanation of the toughening mechanisms were made by comparing the impact properties with scanning electron micrographs (SEMs) of fracture surfaces. The transmission electron microscopy (TEM) photomicrographs illustrated the intercalated and partially exfoliated structures of the hybrids with clay, MAPP and elastomer.

    • A novel method for fabrication of Fe catalyst used for the synthesis of carbon nanotubes

      E Z Karimi J Vahdati-Khaki S M Zebarjad I A Bataev A G Bannov

      More Details Abstract Fulltext PDF

      Carbon nanotubes (CNTs) have been grown by decomposition of propane over a nanocamposite catalyst by chemical vapour deposition (CVD). The catalyst was prepared from an aluminum/iron oxide/graphite mixture milled in a high-energy ball-milling equipment. Scanning and transmission electron microscopies, Raman spectroscopy and X-ray diffraction measurements have been carried out in order to investigate the catalyst and synthesized CNTs. The results show that iron nanoparticles are produced in an alumina and ball-milled graphite matrix. This produced nanocomposite is used as a catalyst to synthesize CNTs via CVD successfully. The yield of CNTs formation was greatly influenced by the milling time and deposition temperature.

    • Electrophoretic deposition of titania nanoparticles: Wet density of deposits during EPD

      Morteza Farrokhi-Rad Taghi Shahrabi Shirin Khanmohammadi

      More Details Abstract Fulltext PDF

      Electrophoretic deposition (EPD) of titania nanoparticles was performed at different voltages and times. The wet density of deposits was calculated according to the Archimedes’ principle. The wet density as well as the electric field over the deposits increased with time and attained the plateau at longer times. The velocity at which particles attach to the deposit, strongly influences its wet density at initial times. However, the effect of electro-osmotic flow is dominant at longer times. The coating with higher wet density had the higher corrosion resistance in Ringer’s solution at 37.5 °C due to its closely packed and crack free microstructure.

    • Electrical conductivity of metal–carbon nanotube structures: Effect of length and doping

      R Nigam S Habeeb A Priyadarshi N Jaggi

      More Details Abstract Fulltext PDF

      The electrical properties of asymmetric metal–carbon nanotube (CNT) structures have been studied using density functional theory and non-equilibrium Green’s function method with Atomistix tool kit. The models with asymmetric metal contacts and carbon nanotube bear resemblance to experimental set-ups. The study shows the effect of varying length of carbon nanotube on electronic transmission and conductance of various structures. The effects of silicon doping on CNT-based structures have also been studied. The conductance of structure with longer CNT is more compared with shorter CNT. Silicon doping increases the conductivity of carbon nanotube-based structure.

    • Electrodeposition and characterization of Ni–W/ZrO2 nanocomposite coatings

      Chunmei Zhao Yingwu Yao Liang He

      More Details Abstract Fulltext PDF

      Ni–W/ZrO2 nanocomposite coatings were prepared by electrodeposition in Ni–W plating bath containing ZrO2 nanoparticles. The influences of preparation parameter, such as ZrO2 nanoparticles concentration, current density and stirring rate, on weight percentage of codeposited ZrO2 nanoparticles in the nanocomposite coatings were investigated. The surface morphology of Ni–W/ZrO2 nanocomposite coating was characterized by scanning electron microscopy (SEM). The microhardness, wear resistance and corrosion resistance properties of Ni–W/ZrO2 nanocomposite coatings were studied. The results indicated that the addition of ZrO2 nanoparticles leads to an increase in microhardness and wear resistance of the nanocomposite coatings and a reduction in the wear weight loss. The corrosion behaviour of Ni–W/ZrO2 nanocomposite coatings was evaluated by the anodic polarization curves and weight loss measurements. The results revealed that Ni–W/ZrO2 nanocomposite coating has better corrosion resistance than the Ni–W alloy coating.

    • Effects of fibre orientation on mechanical properties of hybrid bamboo/glass fibre polymer composites

      B Stanly Jones Retnam M Sivapragash P Pradeep

      More Details Abstract Fulltext PDF

      The usage of natural fibre as reinforcement in polymer composites have widely increased because of its enhanced properties. The usage of plant fibre cannot alone satisfy all the needs of the composites. Hence, introduction of hybrid plays a vital role in enhancing the mechanical properties of the FRP composites. Fibre orientation contributes significant role in improving the mechanical properties of the FRP composites. In this proposal, hybrid bamboo/glass fibre woven in different orientations such as 0°/90° and ± 45° was used and its effect on mechanical properties were studied. Composites containing hybrid fibres found to possess better mechanical properties, when compared to pure bamboo. In order to justify this, the following mechanical properties such as tensile, flexural, impact and hardness were investigated. SEM analysis shows the bonding between the matrix and reinforcement. All the above test results indicate that the introduction of natural bamboo fibre in glass reduces the overall cost of the composites with no compromise in strength and also attracted several studies covering green technologies.

    • Effect of amino acid-functionalized multi-walled carbon nanotubes on the properties of dopamine-based poly(amide–imide) composites: An experimental study

      Shadpour Mallakpour Amin Zadehnazari

      More Details Abstract Fulltext PDF

      In a single-step, rapid microwave-assisted process, multi-walled carbon nanotubes were functionalized by 𝑆-valine amino acid. Formation of amino acid on nanotube surface was confirmed by Fourier transform-infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, field emission scanning and transmission electron microscopy techniques. The surface-modified nanotubes showed better chemical stability in common solvents such as 𝑁,𝑁-dimethylacetamide. The effects of amino acid functionalization of multiwalled carbon nanotubes on the properties of nanotube/poly(amide–imide) nanocomposites were investigated. The functionalized carbon nanotubes (5–15 wt%) were dispersed homogeneously in the poly(amide–imide) matrix, while the structure of the polymer and the nanotubes structure were stable in the preparation process as revealed by microscopic observations. The properties of nanocomposites were characterized extensively using the aforementioned techniques. The composite films have been prepared by casting a solution of precursor polymer containing 𝑆-valine-functionalized carbon nanotubes into a thin film and its tensile properties were examined. The Young’s modulus (elastic modulus) and tensile strength of the composite films were greatly improved by the incorporation of modified nanotubes.

    • A new sonochemical method for preparation of different morphologies of CuInS2 nanostructures

      Omid Amiri Masoud Salavati-Niasari Mehdi Mousavi-Kamazani Davood Ghanbari Mohammad Sabet Kamal Saberyan

      More Details Abstract Fulltext PDF

      CuInS2 nanostructures were synthesized by sonochemical route using (bis(salicylate)copper(II)) as a new copper precursor. The effects of different parameters such as sulphur source, solvent, power of irradiation and reaction time on the morphology of the products were investigated. Nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) and Fourier transform infrared (FT–IR) spectroscopy. CuInS2 nanostructures paste was prepared by doctor’s blade technique on the transparent conductive oxide (TCO). The fill factor (FF), open circuit voltage (𝑉oc), and short circuit current (𝐼sc) were obtained by I–V characterization.

    • Effect of treatment time on characterization and properties of nanocrystalline surface layer in copper induced by surface mechanical attrition treatment

      Farzad Kargar M Laleh T Shahrabi A Sabour Rouhaghdam

      More Details Abstract Fulltext PDF

      Nanocrystalline surface layers were synthesized on pure copper by means of surface mechanical attrition treatment (SMAT) at various treatment times. The microstructural features of the surface layers produced by SMAT were systematically characterized by optical microscopy (OM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. Hardness and surface roughness measurements were also carried out. It is found that the thickness of the deformed layer increased from 50 to 500 𝜇m with increasing treatment time from 10 to 300 min, while the average grain size of the top surface layer decreased from 20 to 7 nm. Hardness of the all SMATed samples decreased with depth. Furthermore, the hardness of the top surface layer of the SMATed samples was at least two times higher than that of the un-treated counterpart. Surface roughness results showed different trend with treatment time. Amounts of PV and 𝑅a values first sharply increased and then decreased.

    • Spin fluctuation and small polaron conduction dominated electrical resistivity in La0.875Sr0.125MnO3 manganite nanostructures

      K K Choudhary N Gupta N Kaurav S Katiyal S K Ghosh

      More Details Abstract Fulltext PDF

      The anomalous temperature-dependent electrical resistivity ρ(𝑇) of La0.875Sr0.125MnO3 manganite nanoparticles (particle size 18 nm) is theoretically analysed. ρ(𝑇) exhibits semiconducting phase in lowtemperature regime (20 𝐾 < 𝑇 < 53 K), shows a minima near 53 K and increases with 𝑇 at high temperatures (53 𝐾 < 𝑇 < 170 K). The resistivity in metallic phase (𝑇 > 53 K) is theoretically analysed by considering the strong spin-fluctuation effect, which is modelled using Drude–Lorentz type function. In addition to the spin fluctuation-induced contribution, the electron–phonon and electron–electron $ ρe–e(𝑇) = 𝐵𝑇2 contributions are also incorporated for complete understanding of experimental data. The contributions to the resistivity by inherent acoustic phonons ( ρac) as well as high-frequency optical phonons ( ρop) were estimated using Bloch–Gruneisen (BG) model of resistivity. It is observed that the resistivity contribution due to electron–electron interaction shows typical quadratic temperature dependence. Spin fluctuation-induced resistivity is dominant over electron–electron and electron–phonon contributions in overall temperature range in the manganite nanoparticles. Resistivity in the semiconducting phase is discussed with small polaron conduction (SPC) model. SPC model consistently retraces the low-temperature resistivity behaviour (𝑇 < 53 K). Finally, the theoretically calculated resistivity compared with experimental data is found to be consistent in wide range of temperature.

    • Preparation and characterization of monosubstituted porphyrins immobilized on nanosilica

      Ebrahim Ahmadi Ali Ramazani Asemeh Mashhadi-Malekzadeh Zahra Hamdi Zahra Mohamadnia

      More Details Abstract Fulltext PDF

      Three kinds of heteroaldehydes, 𝑁-(3-triethoxysilylpropyl)-4-formyl benzamide (TPHA/SiO2), were prepared by the reaction of terephthalaldehydic acid with different silica supports such as hexagonal SBA-15, spherical SBA-15 and amorphous SiO2 for comparison purposes. Anchoring of this aldehyde to different supports allows the synthesis of mono-substituted porphyrins without the production of di-, tri- and tetra-substituted porphyrin side products. The exclusion of the aforementioned side products during the synthesis of monosubstituted porphyrins greatly reduced the complexity during purification of the product. Absorption spectrophotometry was performed on silica gel immobilizing porphyrin (CPTTP), free base tetraphenylporphyrin (H2TPP) and heteroaldehydes (TPHA/SiO2) using UV–Visible instrument and confirmed the presence of porphyrin on the structure of CPTTP.

    • Non-isothermal crystallization kinetics of polyethylene–clay nanocomposites prepared by high-energy ball milling

      Maryam Abareshi Seyed Mojtaba Zebarjad Elaheh K Goharshadi

      More Details Abstract Fulltext PDF

      Non-isothermal crystallization kinetics of pure medium density polyethylene (MDPE) and MDPE–clay nanocomposites have been investigated by differential scanning calorimeter. The modified Avrami, Ozawa, Liu and Ziabicki equations have been applied to describe non-isothermal crystallization process. The results of Avrami analysis showed a very complicated crystallization mechanism. Although, Ozawa equation failed to provide an adequate description for non-isothermal crystallization process, Liu equation could describe it well. The data showed the crystallization rate of MDPE and nanocomposites raises with increasing cooling rate and the crystallization rate of nanocomposite is faster than that of MDPE at a given cooling rate. Ziabicki’s kinetic crystallizability index showed that clay can increase the ability of MDPE to crystallize, when it is cooled at unit cooling rate. The activation energy of samples has been evaluated by Kissinger method. The results showed that the activation energy of nanocomposite was lower than that of MDPE.

    • Influence of chelation ratio of metal alkoxides on aging of PZT 53/47 sol–gel-based precursors

      A Suárez-Gómez M Sanchez-Tizapa R Castañeda-Valderrama M A Carreón-Álvarez

      More Details Abstract Fulltext PDF

      The high reactivity of metal alkoxides, common starting reagents in sol–gel-based synthesis routes, generally demands the use of chelating agents in order to avoid fast hydrolysis and also to allow an easier manipulation of intermediates as well as final solutions. Under these conditions, stability issues sometimes can be linked to chelation issues that, therefore, should deserve a proper study suited to the material system of interest and, more specially, when considering the use of sol–gel-based precursors in research, small-scale applications and industry. In this work, we explore the sol–gel-based synthesis route of lead zirconate titanate (Pb(Zr0.53Ti0.47)O3 or PZT 53/47) using acetylacetone-chelated propoxides as intermediate reactants. Our main purpose here is to analyse the influence of the alkoxides:acetylacetone chelation ratio on the time evolution of mean particle size in the resultant organic colloidal dispersion used as PZT precursor. Purposely, we explored three different scenarios for chelation:

      1. defective chelation,

      2. optimal chelation and

      3. excessive chelation.

      The time dependence of mean particle size was recorded by dynamic light scattering (DLS) measurements and aggregation kinetics was then explored by considering a diffusion-limited colloidal aggregations (DLCA) model.

    • Synthesis and characterization of electroactive novel poly-2-cynoaniline

      Umesh S Waware Mohd Rashid Afidah A Rahim S S Umare

      More Details Abstract Fulltext PDF

      Uniform needle-like structures of poly-2-cynoaniline are formed without the use of any template by electrochemical oxidative polymerization method on copper electrode in acidic medium. The structural characterizations are performed by FT–IR, UV–Visible spectroscopy and X-ray diffraction studies. The morphology of the polymer is demonstrated by scanning electron microscopy (SEM). The framework of the needle-like structure, which is seen at low and high magnifications appeared as nanorods of 50–80 nm diameter and of length up to a few micrometres to form a scaffold of interconnected nanorods. Thermogravimetic analysis (TGA) indicates that poly-2-cynoaniline is thermally more stable than polyaniline. The conductivity of pressed pellet of the as-synthesized polymer measured at room temperature of 25 °C by four-probe measurement method was found to be 9.1824 × 10-5 S/cm. The polymer is easily dispersed in some organic solvents and shows high solubility.

    • Effect of ethyl vanillin on ZnNi alloy electrodeposition and its properties

      K O Nayana T V Venkatesha

      More Details Abstract Fulltext PDF

      The bright ZnNi alloy coating on steel surface was prepared by elctrodepostion technique using brightener ethyl vanillin (EV). To know the influence of brightener on deposition and dissolution behaviour of ZnNi alloy, cyclic voltammetric studies were carried out. FT–IR spectroscopic evidence was given to confirm selective adsorption of brightener on steel surface. The brightener enhances current efficiency and throwing power of plating bath during coating. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses in presence of brightener confirmed the change in surface morphology, phase composition and preferred orientation of ZnNi coating. In presence of brightener, nickel content of the coating was reduced at higher current density and thickness. In addition, deposit properties like appearances, hardness, adherence, ductility and corrosion resistance of ZnNi alloy deposits were also improved in bright deposit. Simultaneously, effect of deposition current density and thickness on corrosion behaviour of coating was examined.

    • X-ray peak broadening analysis of Fe50Ni50 nanocrystalline alloys prepared under different milling times and BPR using size strain plot (SSP) method

      L Hosseinzadeh J Baedi A Khorsand Zak

      More Details Abstract Fulltext PDF

      Fe50Ni50 nanocrystalline alloys were prepared by mechanical alloying method at different milling times of 2, 5, 10, 30, 50 and 70 h and ball powder ratios (BPR) of 10 : 1, 20 : 1 and 30 : 1. The structures of prepared powders were studied by X-ray diffraction (XRD). The broadening of the diffraction peaks were analysed using size strain plot (SSP) method and the lattice strain and crystallite size of the nanocrystals were calculated. In addition, the typical morphological studies were performed by scanning electron and transmission electron microscopies (SEM and TEM). The results showed that the crystallite size of the nanocrystals decreased with the milling time and BPR increases; whereas, the lattice constant (𝑎) increased. Vibrating sample magnetometer (VSM) study of the powder prepared at 50 h and BPR 30 : 1 showed that the sample exhibits both the superparamagnetic and ferromagnetic properties in nanocrystallite size range.

    • Microstructural evolution and mechanical properties of hypereutectic Al–Si alloy processed by liquid die forging

      F F Wu S T Li G A Zhang F Jiang

      More Details Abstract Fulltext PDF

      The microstructural evolution and mechanical properties of a hypereutectic Al–Si alloy processed by liquid die forging were investigated. It is found that the grain size of the primary Si was significantly reduced by liquid die forging with increased pressure. The volume fraction of eutectic silicon was decreased with increased pressure. By liquid die forging with pressure up to 180 MPa, the average size of the primary Si was reduced to about 18 𝜇m, which results in the remarkable increase in the fracture strength and hardness of the hypereutectic Al–Si alloy.

    • First principles calculations of structural, electronic and thermal properties of lead chalcogenides PbS, PbSe and PbTe compounds

      N Boukhris H Meradji S Amara Korba S Drablia S Ghemid F El Haj Hassan

      More Details Abstract Fulltext PDF

      The structural, electronic and thermal properties of lead chalcogenides PbS, PbSe and BeTe using full-potential linear augmented plane wave (FP-LAPW) method are investigated. The exchange–correlation energy within the local density approximation (LDA) and the generalized gradient approximation (GGA) are described. The calculated structural parameters are in reasonable agreement with the available experimental and theoretical data. The electronic band structure shows that the fundamental energy gap is direct (L–L) for all the compounds. Thermal effects on some macroscopic properties of these compounds are predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account. The variations of the lattice constant, bulk modulus, heat capacity, volume expansion coefficient and Debye temperature with temperature and pressure are obtained successfully. The effect of spin–orbit interaction is found to be negligible in determining the thermal properties and leads to a richer electronic structure.

    • Magnetic-supported cucurbituril: A recyclable adsorbent for the removal of humic acid from simulated water

      Qin Yang Ying Jiang Xiaoli Li Yongli Yang Liyun Hu

      More Details Abstract Fulltext PDF

      Magnetic cucurbituril (MQ[𝑛]), a new functional material compound, was prepared via chemical co-precipitation method as a high-capacity adsorbent for humic acid (HA). The material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT–IR) and thermal gravimetric analysis (TGA), respectively, indicating that Q[𝑛] has been grafted on the surface of Fe3O4. Its adsorption–desorption behaviour towards HA from aqueous solution have been investigated. MQ[𝑛] demonstrated good adsorption capacity at pH 7 in adsorption experiments. Adsorption isotherm could be well interpreted by the Freundlich isotherm model. Adsorption kinetic followed pseudosecond-order kinetics, which indicated that the limit factor of adsorption HA was adsorption mechanism. The negative value of thermodynamic parameters showed that adsorption process was spontaneous and exothermic. Moreover, the capacity of MQ[𝑛] was also above 80% after being used for four times, so it may have potential industrial applications.

    • Determination of gamma ray attenuation coefficients of Al–4% Cu/B4C metal matrix composites at 662, 1173 and 1332 keV

      I Akkurt K Günoğlu A Çalik M S Karakas

      More Details Abstract Fulltext PDF

      Gamma ray attenuation coefficients of metal matrix composites have been investigated. For this purpose, the linear attenuation coefficients of composites containing boron carbide (B4C) at different rates have been measured using a gamma spectrometer that contains a NaI(Tl) detector and MCA at 662, 1173 and 1332 keV, which are obtained from 137Cs and 60Co sources. The measured results were compared with the calculation obtained using computer code of XCOM for 1 keV–1 GeV gamma energies.

    • Synthesis, characterization, thermal and electrical properties of composite of polyaniline with cobaltmonoethanolamine complex

      Rehana Rasool Kowsar Majid

      More Details Abstract Fulltext PDF

      The present paper involves the synthesis of polyaniline (PANI) composite with cobaltmonoethanolamine [Co(mea)2(H2O)2Cl2] complex via in situ oxidative polymerization by ammonium persulphate. The complex has been synthesized by refluxing method. The composite has been subjected to UV–Visible spectra, FT–IR, X-ray diffraction, SEM and electrical conductivity characterization techniques. Thermal analysis has been done by using TG and DSC techniques. FT–IR absorption peaks confirm the insertion of complex in the backbone of PANI. SEM of the composite also supports its successful synthesis. The XRD of composite also shows crystalline structure hence, proving the successful synthesis of PANI. Thermal analysis shows enhanced thermal stability of polyaniline. In the present composite system, the polymerization of PANI with [Co(mea)2(H2O)2Cl2] complex causes strong interfacial interactions between PANI and [Co(mea)2(H2O)2Cl2] complex crystallites, also suggested by the FT–IR and XRD studies, thereby changing the molecular conformation of PANI from compact coil structure to an expanded coil-like structure. As a consequence, there is an enhancement in the conductivity of composite of PANI up to certain dopant concentration. The anticorrosive property of a coating of PANI/[Co(mea)2(H2O)2Cl2] composite on mild steel coupon in 3 M HNO3 was evaluated using weight loss measurement and compared with pure polyaniline coating. The said composite has shown anticorrosive property and can thus, act as a potent dopant for enhancing corrosion resistance of PANI coatings.

  • Bulletin of Materials Science | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.