• Issue front cover thumbnail

      Volume 37, Issue 4

      June 2014,   pages  743-951

    • Porous copper template from partially spark plasma-sintered Cu–Zn aggregate via dezincification

      M Mandal D Singh Gouthama B S Murty S Sangal K Mondal

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      Present work deals with the preparation of spark plasma-sintered Cu–Zn aggregate (5, 10 and 20 wt% Zn) with interfacial bonding only starting from elemental powders of Cu and Zn (99.9% purity) and subsequently making of porous template of Cu by dezincification. Sintering is done so as to achieve only interfacial bonding with the aim to maintain maximum potential difference between the Cu and Zn particles during dezincification process in various solutions, viz. 1 N HCl and 3.5 wt% NaCl solutions. X-ray diffraction, optical microscopy and SEM–EDS are carried out to examine microstructural evolution and subsequent changes in hardness with sintering temperatures and different Zn percentages. Dezincification and pore formation are conducted on sintered 0.5 mm thick 12 mm diameter disc samples. The size, distribution and nature of pores in porous templates of Cu are then investigated using optical microscopy and SEM–EDS analysis.

    • Synthesis and characterization of PbTe micro/nanostructures through hydrothermal method by using a novel capping agent

      Shahla Ahmadian-Fard-Fini Masoud Salavati-Niasari Fatemeh Mohandes

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      For the first time, a Schiff base compound derived from 1,8-diamino-3,6-dioxaoctane and 2-hydroxybenzophenone marked as (2-HBP)-(DaDo) was synthesized, characterized and then used as capping agent for the preparation of PbTe micro/nanostructures. Besides the as-synthesized Schiff base compound, Pb(NO3)2 and Te powders were applied as lead and telluride precursors. In addition, effect of preparation parameters like reaction time and temperature in hydrothermal synthesis on the morphology of the final products was tested. The products were analysed with the aid of SEM, XRD, FT–IR and EDS. Based on the obtained results, it was found that pure cubic phased PbTe has been obtained by this method. According to SEM images, it was found that uniform PbTe micro/nanocubes have been obtained at 180°C for 12 h. On the other hand, by increasing the reaction temperature from 3 to 24 h, the production of cubic-like shapes increased.

    • Synthesis and influence of alkaline concentration on 𝛼-FeOOH nanorods shapes

      Zhang Enlei Wang Guosheng Long Xiaozhu Wang Zhumin

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      𝛼-FeOOH nanorods having uniform morphology were synthesized by water bath process. X-ray diffraction and transmission electron microscopy revealed that the single-crystalline orthorhombic 𝛼-FeOOH nanorods are about 10 nm in diameter and hundreds of nanometer in length. The effect of concentration of KOH on morphology of 𝛼-FeOOH nanorods was investigated. pH values of solution play an important role in the process of transformation of ferrihydrite into goethite. The inconsistent growth rate along different facets can be effected by pH values of the solution. The influence and growth mechanism of 𝛼-FeOOH nanorods were discussed in detail. This method may be widely used as reference to fabricate other inorganic one-dimensional nanostructured materials and easily realized in industrial-scale synthesis.

    • A facile route to synthesis of AgInS2 nanostructures

      Mehdi Ranjbar Mohammad Ali Taher Mohammad Sadeghinia

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      AgInS2 nanoparticles have been synthesized via a facile one-step process using AgNO3, thiosemicarbazid (TSC) and InCl3.4H2O as starting reagents from propylene glycol solution. The effects of concentration of precursors, reaction time and type of sulfur sources on the morphology and particle size were also studied. X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), scanning electron microscope (SEM), transmission electron microscope (TEM), ultraviolet–visible spectroscopy (UV–Vis) and photoluminescence (PL) spectroscopy were used to characterize the obtained products.

    • Effect of particle size and lattice strain on Debye–Waller factors of Fe3C nanoparticles

      E Purushotham N Gopi Krishna

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      Fe3C nanoparticle powders have been prepared by a high energized ball mill. The resulting nano-particle powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. The high-energy ball milling of Fe3C after 10 h resulted in crystalline size of about 5 nm. The Debye temperature, mean-square amplitudes of vibration, Debye–Waller factor, lattice parameters, particle size, lattice strain and vacancy formation of energies of Fe3C nanoparticles prepared by ball mill have been obtained from X-ray integrated intensities. The integrated intensities have been measured with a Philips CWU 3710 X-ray powder diffractometer fitted with a scintillation counter using filtered CuK𝛼 radiation at room temperature and have been corrected for thermal diffuse scattering. The X-ray Debye temperatures obtained in the present investigation has been used to estimate the vacancy formation energies for Fe3C nanoparticles.

    • Grain growth kinetics of textured-BaTiO3 ceramics

      Fang Fu Jiwei Zhai Zhengkui Xu Bo Shen Xi Yao

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      Textured BaTiO3 (BT) ceramics were fabricated by templated grain growth method. Effects of sintering conditions on the grain growth process of textured-BT ceramics were investigated. Orientation degree increased initially and then decreased with increasing soaking time. The ceramics were composed of equiaxed matrix grains and brick-like template particles. The brick-like particles aligned parallel to the casting direction by observing from SEM images. A (ℎ00)-preferred orientation was confirmed by SAED and XRD patterns. Mechanism of grain growth in textured-BT ceramics was studied. Both consumption of matrix by templates and grain growth of templates determined the orientation degree of ceramics. The kinetic mechanism for grain orientation was also discussed by the simplified phenomenological kinetic equation. The average activation energies were 364 kJ/mol for matrix grain and 918 kJ/mol for template particle, respectively. Finally, a dense ceramic with 85% grain orientation was obtained after sintering at 1400°C for 2 h.

    • Rapid hydrothermal route to synthesize cubic-phase gadolinium oxide nanorods

      Samiran Hazarika Nibedita Paul Dambarudhar Mohanta

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      An inexpensive fabrication route and growth mechanism is being reported for obtaining quality gadolinium oxide (Gd2O3) nanoscale rods. The elongated nanoscale systems, as produced via a hydrothermal process, were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), optical absorption spectroscopy, photoluminescence (PL) spectroscopy, Raman spectroscopy and magnetic hysteresis measurements. XRD patterns of the nanorods, as-prepared from independent precursors of different pH, depict a cubic crystal phase and an average crystallite size of 5-6.5 nm. As revealed from HRTEM micrographs, diameter of the nanorods prepared at pH = 13.3 (∼ 7nm) was much smaller than the rods prepared at pH = 10.8 (∼ 19nm). However, the aspect ratio was more than double in the former case than the latter case. PL response was found to be dominated by defect mediated emissions, whereas Raman spectrum of a given specimen (pH = 10.8) has revealed characteristic 𝐹g + 𝐴g modes of cubic phase of Gd2O3 nanorods, apart from other independent modes. Furthermore, 𝑀 ∼ 𝐻 plot of the nanorod system (pH = 10.8) exhibited slight departure from the ideal superparamagnetic behaviour, with low remanence and coercive field values. The exploitation of one-dimensional Gd2O3 nanorods have immense potential in the production of advanced contrast agents, smart drives and also in making novel ferrofluids of technological relevance.

    • Facile synthesis and catalytic properties of silver colloidal nanoparticles stabilized by SDBS

      Wen Wang Yinmin Song Quansheng Liu Keli Yang

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      A facile method was explored to prepare stable silver colloidal nanoparticles (AgCNPs) in water. Sodium dodecyl benzene sulfonate (SDBS) was used as the stabilizing agent, without addition of any co-surfactant. The reaction was rapid and the product prepared at different conditions was measured by transmission electron microscopy (TEM) and UV-Vis spectroscopy. The results showed that AgCNPs stabilized by SDBS was stable in water with narrow size distribution (1-5 nm). The amount of surfactant has great influence on the products. When the molar ratio of Ag+ to SDBS increased to 1 : 4, AgCNPs can be obtained with high dispersion (2-3 nm), which has high catalytic activity on reduction of 4-nitrobenzoic acid to 4-aminobenzoic acid.

    • Study of Cu-doping effects on magnetic properties of Fe-doped ZnO by first principle calculations

      A El Amiri H Lassri M Abid E K Hlil

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      Using ab initio calculations on Zn0.975–𝑥Fe0.025Cu𝑥O (𝑥 = 0, 0.01, 0.02, 0.05), we study the variations of magnetic moments vs Cu concentration. The electronic structure is calculated by using the Korringa–Kohn–Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that the total magnetic moment and magnetic moment of Fe increase on increasing Cu content. From the density of state (DOS) analysis, we show that Cu-induced impurity bands can assure, by two mechanisms, the enhancement of Fe magnetic moment in Zn0.975–𝑥Fe0.025Cu𝑥O.

    • Magnetization reversal and ferrimagnetism in Pr,1–𝑥Nd𝑥MnO3

      Sanjay Biswas Momin Hossain Khan Sudipta Pal

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      Detailed magnetic properties of Pr1–𝑥Nd𝑥MnO3 (𝑥 = 0.3, 0.5 and 0.7) have been reported. All the samples crystallize in orthorhombic perovskite structure with Pnma space group. Magnetization measurements under field cooled (FC) protocal reveal magnetization reversal at low temperatures and low magnetic field. This indicates clear evidence of two magnetic sublattices aligned opposite to each other. There is a well-defined maximum around 48 K in the 𝑥 = 0.7 sample (i.e. Pr0.3Nd0.7MnO3) in the 𝜒' value which is identified as paramagnetic to ferrimagnetic transition. The peak value shifts to higher temperature with decrease of 𝑥 and width of the maximum broadened. It is also observable that with decrease of Nd, both the value of 𝜒' and 𝜒" decrease. An attempt is made to explain the magnetization reversal within the framework of available models

    • Synthesis of Fe–Si–B–Mn-based nanocrystalline magnetic alloys with large coercivity by high energy ball milling

      P D Reddi N K Mukhopadhyay B Majumdar A K Singh S S Meena S M Yusuf N K Prasad

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      Alloys of Fe–Si–B with varying compositions of Mn were prepared using high energy planetary ball mill for maximum duration of 120 h. X-ray diffraction (XRD) analysis suggests that Si gets mostly dissolved into Fe after 80 h of milling for all compositions. The residual Si was found to form an intermetallic Fe3Si. The dissolution was further confirmed from the field emission scanning electron microscopy/energy dispersive X-ray analysis (FE-SEM/EDX). With increased milling time, the lattice parameter and lattice strain are found to increase. However, the crystallite size decreases from micrometer (75–95 𝜇m) to nanometer (10–20 nm). Mössbauer spectra analysis suggests the presence of essentially ferromagnetic phases with small percentage of super paramagnetic phase in the system. The saturation magnetization (𝑀s), remanance (𝑀r) and coercivity (𝐻c) values for Fe–0Mn sample after 120 h of milling were 96.4 Am2/kg, 11.5 Am2/kg and 12.42 k Am-1, respectively. However, for Fe–10Mn–5Cu sample the 𝑀s, 𝐻c and 𝑀r values were found to be 101.9 Am2/kg, 10.98 kA/m and 12.4 Am2/kg, respectively. The higher value of magnetization could be attributed to the favourable coupling between Mn and Cu.

    • Analysis of Ostwald ripening in Ni-rich Ni–Ti alloys by diffusion couples

      C G Garay-Reyes F Hernández-Santiago N Cayetano-Castro R Martínez-Sánchez J L Hernández-Rivera H J Dorantes-Rosales J J Cruz-Rivera

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      The coarsening kinetics of 𝛾' precipitates in Ni-rich Ni–Ti alloys are studied using a Ni–11.5 wt% Ti and pure Ni diffusion couple. The formed concentration gradient allowed to study the aging process at 1023 K (750 °C) in Ni-rich Ni–Ti alloys with Ti content from 8.62 to 11.15 wt% Ti. In general, during the coarsening of 𝛾' precipitates, the experimental coarsening kinetics do not fit well to the LSW or TIDC theoretical models and anomalous behaviour of coarsening rate constant (𝑘r) associated with 𝛾' volume-fraction is confirmed at high values.

    • Comparison of hydrogen storage properties of pure Mg and milled pure Mg

      Myoung Youp Song Young Jun Kwak Seong Ho Lee Hye Ryoung Park

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      Hydrogen storage properties of pure Mg were studied at 593 K under 12 bar H2. In order to increase the hydriding and dehydriding rates, pure Mg was ground under hydrogen atmosphere (reactive mechanical grinding, RMG) and its hydrogen storage properties were subsequently investigated. Pure Mg absorbed hydrogen very slowly. At the number of cycles (𝑛) of 1, pure Mg absorbed 0.05 wt% H for 5 min, 0.08 wt% H for 10 min and 0.29 wt% H for 60 min at 593 K under 12 bar H2. Activation was completed at the fifth cycle. At 𝑛 = 6, pure Mg absorbed 1.76 wt% H for 5 min, 2.17 wt% H for 10 min and 3.40 wt% H for 60 min. The activation of pure Mg after RMG was completed at the sixth cycle. At 𝑛 = 7, pure Mg after RMG absorbed 2.57 wt% H for 5 min, 3.21 wt% H for 10 min and 4.15 wt% H for 60 min.

    • CO impurities effect on LaNi4.7Al0.3 hydrogen storage alloy hydrogenation/dehydrogenation properties

      Qi Wan Ping Li Yunlong Li Fuqiang Zhai Weina Zhang Liqun Cui Alex A Volinsky Xuanhui Qu

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      LaNi4.7Al0.3 alloy was prepared by vacuum induction melting in high purity helium atmosphere, and the ingot was pulverized into 200–400 mesh powder after annealing. X-ray diffraction (XRD) and scanning electron microscopies (SEM) were utilized to study the alloy morphology and phase structure. X-ray photoelectron spectroscopy (XPS) was used for surface analysis. The poisoned alloy was tested at 30 °C in the mixture gas by thermogravimetric and differential thermal analyses (TG + DTA). The hydrogen storage properties were studied by the pressure–composition–temperature test. The activated sample was completely deactivated after only 3 hydriding/dehydriding cycles in hydrogen containing 300 ppm CO at 30 °C, but hydrogen storage capacity did not degrade when tested at 80 °C. Additionally, two different steps appeared in the absorption processes. Combined with XRD, XPS and TG + DTA results, an explanation for this phenomenon is given.

    • Synthesis and characterization of 𝛾-Bi2O3 based solid electrolyte doped with Nb2O5

      Handan Ozlu Soner Cakar Caner Bilir Ersay Ersoy Orhan Turkoglu

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      𝛾-phase bismuth oxide is a well known high oxygen ion conductor and can be used as an electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). This study aims to determine new phases of Bi2O3–Nb2O5 binary system and the temperature dependence of the electrical transport properties. The reaction products obtained in open air atmosphere were characterized by X-ray powder diffractions (XRD). The unit cell parameters were defined from the indexes of the powder diffraction patterns. The 𝛾-Bi2O3 crystal system were obtained by doping 0.01 < mole% Nb2O5 < 0.04 at 750 °C for 48 and 96 h. Thermal behaviour and thermal stability of the phases were investigated by thermal analysis techniques. Surface and grain properties of the related phases were determined by SEM analysis. The temperature dependence of the electrical properties of 𝛾-Bi2O3 solid solution was measured by four-point probe d.c. conductivity method. In the investigated system, the highest value of conductivity was observed for $\sigma_{T}$ = 0.016 ohm-1 cm-1 at 650 °C on 4 mole% Nb2O5 addition. The electrical conductivity curves of studied materials revealed regular increase with temperature in the form of the Arrhenius type conductivity behaviour.

    • Study of magnetocaloric effect in LaFe11.5Si1.5 alloys prepared by different cooling methods

      Xiang Chen Yungui Chen Yongbo Tang

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      LaFe11.5Si1.5 alloys are annealed at 1503 K for 5 h and cooled down to room temperature by furnace cooling, air cooling and quenching in ice water, respectively. The main phases are 1:13 phases in those alloys. The impurity phases are 𝛼-Fe and the amount of LaFeSi phase is so small that it is hard to observe in their XRD patterns. The powder X-ray diffraction patterns and SEM show that the three cooling methods have little influence on the phase relation and microstructure of those LaFe11.5Si1.5 alloys. But the lattice constant of LaFe11.5Si1.5 alloy prepared by quenching in ice water is lesser than those of the other two alloys, respectively. For studying the influence of different cooling processes on magnetic properties, the Curie temperature, thermal and magnetic hysteresis, magnetocaloric effect and relative cooling power are investigated. The result shows that the Curie temperature of LaFe11.5Si1.5 prepared by quenching in ice water is 197.6 K, about 4 K lesser than those of the other two LaFe11.5Si1.5 alloys. The maximum 𝛥 𝑆M (𝑇, 𝐻) of LaFe11.5Si1.5 prepared by furnace cooling and quenching in ice water is the most and the least under the field of 0–2 𝑇, respectively.

    • Effect of iron content on permeability and power loss characteristics of Li0.35Cd0.3Fe2.35O4 and Li0.35Zn0.3Fe2.35O4

      Vivek Verma Prachi Sharma Adarsh Singh

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      Substituted lithium ferrites having the chemical formula, Li0.35Cd0.3Fe2.35O4 and Li0.35Zn0.3Fe2.35O4, with different iron (metal) contents (2, 4, 6, 8 and 10) in wt% have been prepared by solid-state technique. Complex permeability and power loss of all samples have been measured by network analyser in the frequency range of 50–5000 kHz. Magnetic properties like saturation magnetization, coercivity, retentivity have been measured by vibrating sample magnetometer (VSM). The permeability of cadmium doped lithium ferrites exhibited higher values than zinc doped lithium ferrites. The power loss of cadmium doped lithium ferrites is lesser as compared to zinc doped lithium ferrites in the frequency range of 50–5000 kHz and at flux density of 10 mT. The behaviour of power loss with flux density has been found near about same for both series. Magnetic and power loss behaviour of the samples suggest that a small amount of Fe content can improve the properties of ferrite samples for microwave devices.

    • Interfacially synthesized PAni–PMo12 hybrid material for supercapacitor applications

      Arumugam Manivel Abdullah M Asiri Khalid Ahmad Alamry Teresa Lana-Villarreal Sambandam Anandan

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      The concept of interfacial polymerization is utilized for the synthesis of polyaniline–phosphomolybdate (PAni–PMo12) molecular hybrids and it is well characterized. The electrical conductivity of the synthesized hybrid materials increases with increase in PMo12 wt%. The synthesized hybrid materials are evaluated as the active electrode materials for supercapacitor application. Cyclic voltammetric studies of the hybrid-modified electrode shows broad parallelogram-shaped peak as an evidence for pseudo-capacitive behaviour. The galvanostatic charge–discharge studies enlighten that interfacially synthesized hybrid materials loaded with PMo12 show relatively enhanced specific capacitance values than PMo12 free samples.

    • Synthesis of aluminium nanoparticles by arc evaporation of an aluminium cathode surface

      M Gazanfari M Karimzadeh S Ghorbani M R Sadeghi G Azizi H Karimi N Fattahi Z Karimzadeh

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      Aluminium nanoparticles (Al Nps) are synthesized using arc discharge method by applying direct current between aluminium electrodes in liquid environment without any use of vacuum equipment, heat exchangers, high temperatures furnaces and inert gases. After synthesis of Al Nps, in situ coating process on the nanoparticles was performed immediately. The effects of media on the yield and morphology of aluminium nanoparticles were investigated. Analysis result of the samples indicated that particle size was less than 30 nm, when 120 A/cm2 arc current was used. In addition, coating agent can affect arc velocity, arc stability, morphology and composition of the nanoparticles. Resultant nanoparticles were identified using X-ray powder diffraction (XRD), also their surface morphology was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and finally the accuracy of coating was assessed with infrared (IR) spectroscopy.

    • 3-Methyltrimethylammonium poly(2,6-dimethyl-1,4-phenylene oxide) based anion exchange membrane for alkaline polymer electrolyte fuel cells

      K Hari Gopi S Gouse Peera S D Bhat P Sridhar S Pitchumani

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      Hydroxyl ion (OH) conducting anion exchange membranes based on modified poly (phenylene oxide) are fabricated for their application in alkaline polymer electrolyte fuel cells (APEFCs). In the present study, chloromethylation of poly(phenylene oxide) (PPO) is performed by aryl substitution rather than benzyl substitution and homogeneously quaternized to form an anion exchange membrane (AEM). 1H NMR and FT–IR studies reveal successful incorporation of the above groups in the polymer backbone. The membrane is characterized for its ion exchange capacity and water uptake. The membrane formed by these processes show good ionic conductivity and when used in fuel cell exhibited an enhanced performance in comparison with the state-of-the-art commercial AHA membrane. A peak power density of 111 mW/cm2 at a load current density of 250 mA/cm2 is obtained for PPO based membrane in APEFCs at 30 °C.

    • Structural, spectroscopic and electrochemical study of V5+ substituted LiTi2(PO4)3 solid electrolyte for lithium-ion batteries

      A Venkateswara Rao V Veeraiah A V Prasada Rao B Kishore Babu B Swarna Latha K Rama Rao

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      Vanadium substituted LiTi2(PO4)3 (LTP) samples of composition of Li1–𝑥[Ti2–𝑥V𝑥](PO4)3 (𝑥 = 0.0, 0.05, 0.10 and 0.15) have been prepared by solid-state reaction method. XRD data for these compositions indicated the formation of phase pure materials of rhombohedral structure with space group 𝑅$\bar{3}$𝑐 (167). Microstructural studies by scanning electron microscope indicated particle size in the range of 0.5–1 𝜇m. Electrochemical impedance studies showed that ionic conductivity is high for 𝑥 = 0.10 composition. a.c. and d.c. conductivity results up to 573 K are in accordance with the Jonscher’s power law. Cyclic voltammetry study showed its electrochemical stability in the voltage range from 0.5 to 3.5 V.

    • Synthesis of copper–ferrous (CuFe) nanowires via electrochemical method and its investigations as a fluid sensor

      Saleem Khan Sandeep Arya Parveen Lehana Suresh Kumar

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      The special behaviour of nanowires with respect to electrical conductivity makes them suitable for sensing application. In this paper, we present a copper–ferrous (CuFe) nanowires based sensor for detection of chemicals. CuFe nanowires were synthesized by template-assisted electrochemical method. By optimizing the deposition parameters, continuous nanowires on a copper substrate were synthesized. The morphological and structural studies of the synthesized CuFe nanowires were carried out using scanning electron microscope (SEM) and X-ray diffraction (XRD). Substrates containing CuFe nanowires were moulded to form a capacitor. Different chemicals were used as dielectric in the capacitor which showed that the capacitance was a nonlinear function of the dielectric constant of fluid unlike the linear relation shown by conventional capacitors. This unique property of the nanowires based capacitors may be utilized for developing fluid sensors with improved sensitivity.

    • Structural evolution, electrical and optical properties of AZO films deposited by sputtering ultra-high density target

      Jiwen Xu Zupei Yang Hua Wang Xiaowen Zhang

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      Aluminum-doped zinc oxide (AZO) target was fabricated using AZO nanopowders synthesized by co-precipitation method and then the AZO films with different thicknesses were deposited on glass by d.c. magnetron sputtering at room temperature. AZO target is nodules free and shows homogeneous microstructure, ultra-high density and low resistivity. ZnAl2O4 phase appears in AZO target and disappears in AZO films. All AZO films show c-axis preferred orientation and hexagonal structure. With increasing film thickness from 153 to 1404 nm, the crystallinity was improved and the angle of (002) peak was close to 34.45°. The increase in grain size and surface roughness is due to the increase in film thickness. The decrease of resistivity is ascribed to the increases of carrier concentration and Hall mobility. The lowest resistivity is 9.6 × 10-4 𝛺.cm. The average transmittance of AZO films exceeds 80%, and a sharp fundamental absorption edge with red-shifting is observed in the visible range. The bandgap decreases from 3.26 to 3.02 eV.

    • Distinction between SnO2 nanoparticles synthesized using co-precipitation and solvothermal methods for the photovoltaic efficiency of dye-sensitized solar cells

      M M Rashad I A Ibrahim I Osama A E Shalan

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      Nanocrystalline SnO2 powders prepared by solvothermal and co-precipitation pathways have been characterized using XRD, TEM, UV–Visible absorption, BET specific surface area (𝑆BET) method, EIS and 𝐽–𝑉 measurements. The obtained powders have a surface area and size of 38.59 m2/g and 10.63 nm for the SnO2 powders synthesized solvothermally at a temperature of 200 °C for 24 h, while the values were 32.59 m2/g and 16.20 nm for the formed hydroxide precursor annealed at 1000 °C for 2 h by co-precipitation route. The microstructure of the formed powders appeared as tetragonal-like structure. Thus, the prepared SnO2 nanopowders using two pathways were applied as an electrode in dye-sensitized solar cell (DSSC). The photoelectrochemical measurements indicated that the cell presents short-circuit photocurrent (𝐽sc), open circuit voltage (𝑉oc) and fill factor (FF) were 7.017 mA/cm2, 0.690 V and 69.68%, respectively, for solvothermal route and they were 4.241 mA/cm2, 0.756 V and 66.74%, respectively, for co-precipitation method. The energy conversion efficiency of the solvothermal SnO2 powders was considerably higher than that formed by co-precipitation powders; ∼ 3.20% (solvothermal) and 2.01% (co-precipitation) with the N719 dye under 100 mW/cm2 of simulated sunlight, respectively. These results were in agreement with EIS study showing that the electrons were transferred rapidly to the surface of the solvothermal-modified SnO2 nanoparticles, compared with that of a co-precipitation-modified SnO2 nanoparticles.

    • Photocatalytic hydrogen generation with Ag-loaded LiNbO3

      Beata Zielińska

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      In this contribiution LiNbO3 and Ag-loaded LiNbO3 photocatalysts were tested in the reaction of hydrogen evolution. The silver modified samples contained different loading of co-catalyst in the range of 0.5–4 wt%. It was essential to optimize the sample composition to achieve an efficient hydrogen evolution. The optimal sample contained 2 wt% of silver. The detailed analysis indicated that silver was deposited on the surface of LiNbO3 in the form of Ag2O. Therefore, it is supposed that Ag2O was responsible for the enhanced photocatalytic activity in the studied reaction. The crystallographic phases and optical and vibronic properties were examined by X-ray diffraction (XRD) and diffuse reflectance (DR) UV–Vis and resonance Raman spectroscopic methods, respectively. Morphology of the produced samples were studied using a highresolution transmission electron microscope (HRTEM).

    • Design, synthesis and physical properties of poly(styrene–butadiene–styrene)/poly(thiourea-azo-sulfone) blends

      Ayesha Kausar

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      A new aromatic azo-polymer, poly(thiourea-azo-sulfone), has been synthesized using 1-(4-thiocarbamoylaminophenylsulfonylphenyl)thiourea and diazonium salt solution. Conducting and thermally stable rubbery blends of poly(styrene-block-butadiene-block-styrene) (SBS) triblock copolymer and poly(thiourea-azo-sulfone) (PTAS) were produced by solution blending technique. PTAS possessed fine solubility in polar solvents and high molar mass 63 × 103 g moL-1. Microscopic analysis on SBS/PTAS blends revealed good adhesion between the two polymers without macro phase separation. Electrical conductivity measurement recommended that blending of SBS with 60% PTAS was sufficiently conducting 1.43 S cm-1. A relationship between PTAS loading and thermal stability of blends was observed. With the increasing PTAS content, 10% gravimetric loss was increased from 481 to 497 °C, while glass transition improved from 123 to 136 °C (better than neat SBS but lower than PTAS). The blends also established higher tensile strength (52.40–59.96 MPa) relative to SBS. Fine balance of properties renders new SBS/PTAS, potential engineering plastics for a number of aerospace relevance.

    • Photoluminescence, trap states and thermoluminescence decay process study of Ca2MgSi2O7 : Eu2+, Dy3+ phosphor

      Ravi Shrivastava Jagjeet Kaur Vikas Dubey Beena Jaykumar

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      Europium and dysprosium-doped calcium magnesium silicate powder with different concentrations of dysprosium were synthesized using solid-state reaction. The Fourier transform infrared (FT–IR) spectra confirmed the proper preparation of the sample. The prepared phosphors were characterized using photoluminescence excitation and emission spectra. Prominent green colour emission was obtained under ultraviolet excitation. The thermoluminescence glow curves of the samples were measured at various delay times. With increased delay time, the intensity of the thermoluminescence peak decays and the position of the thermoluminescence peak shifts towards higher temperature, indicating the considerable retrapping associated with general order kinetics.

    • Synthesis, characterization, photocatalytic and reusability studies of capped ZnS nanoparticles

      Jagdeep Kaur Manoj Sharma O P Pandey

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      This paper presents results of a study on the structural and morphological properties of 2-mercaptoethanol (2-ME) capped ZnS nanoparticles (NPs). The photocatalytic and reusability study of the synthesized NPs to degrade dyes was also done. ZnS semiconductor NPs were synthesized via chemical precipitation route using 2-ME as a stabilizing agent. The as-prepared NPs were characterized by X-ray diffraction (XRD) technique to confirm the nanometer sized particle formation. Morphological features of capped ZnS NPs were determined by transmission electron microscopy (TEM). Dynamic light scattering (DLS) technique was used to determine the hydrodynamic size of capped ZnS NPs. UV–Vis studies were done to determine the absorption edge and bandgap of the capped ZnS NPs. Fourier transform infrared spectroscopy (FT–IR) studies were done to confirm the presence of 2-ME on the surface of NPs. Photocatalytic studies of the as-prepared ZnS NPs were done by taking Ponceau S and crystal violet dyes as model pollutants. Their comparative degradation behaviour has been discussed. Reusability study of ZnS NPs was done to ensure its applicability as recycled catalyst in photocatalysis. The result showed photocatalytic enhancement of reused catalyst. Possible reason has been discussed in this work.

    • Study of as-synthesized and calcined hydrocalumites as possible antacid agents

      Carlos F Linares Freddy Ocanto Pablo Bretto Maricela Monsalve

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      A hydrocalumite-type solid was synthesized by the homogeneous co-precipitation method by using Ca and Al nitrate solutions in a basic medium (NaOH). This solid was calcined at 700 and 900 °C, respectively. Then, solids were characterized by X-ray diffraction, FT–IR spectroscopy and BET surface area measurements. Finally, these solids were tested as antacids by using a synthetic gastric juice. Results showed that calcined samples were able to neutralize the synthetic gastric juice in more extension as an as-synthesized hydrocalumite; however, the last solid showed better conditions as a potential antacid.

    • Methotrexate-loaded biodegradable nanoparticles: preparation, characterization and evaluation of its cytotoxic potential against U-343 MGa human neuronal glioblastoma cells

      Kranti P Musmade Praful B Deshpande Prashant B Musmade M Naseer Maliyakkal A Ranjith Kumar M Sreenivasa Reddy N Udupa

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      Nanoparticles represent one of the attractive alternatives in the effective treatment of cancer chemotherapy. In the present work, formulation and development of a novel methotrexate (MTX)-loaded biodegradable nanoparticles using poly(D,L-lactide-co-glycolide) (PLGA) was carried out. The prepared nanoparticles were evaluated for physicochemical properties such as particle size, zeta potential, release studies, etc and also evaluated for its in vitro cytotoxic potential against U-343 MGa human neuronal glioblastoma cells. Particle size of optimized formulation was < 200 nm. There was a considerable decrease in cell viability and enhancement in cytotoxic activity of MTX-loaded nanoparticles compared to MTX alone when tested against U-343 MGa human neuronal glioblastoma cells.

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