Volume 6, Issue 7, July 2015


Amazing Growth Of “Energy Materials Research” Over The Last Five Years

Lokman Uzun

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 566-567
DOI: 10.5185/amlett.2015.7001

We celebrate 5 th  anniversary of the  Advanced  Materials Letters in this year.  At the beginning, we had comprehensively discussed scope and readership of the journal.  Tremendous improvements have been made from the last five years to improve the quality of the journal.  Journal aims to join the list of pioneer material's journals in the near future. In this respect, we reorganized our editorial team, as well as web portal, the monthly cover page of journal, online submission, and review system.  In addition to these managerial remodeling, we have decided to compile a series of "Editorials on the recent developments of Advanced  Materials".  In this issue, we publish statistics to describe amazing growth of energy materials research with the listing of top ten countries with numbers of documents, citations and h-index as well as top five authors/affiliations, etc.  Although we are mainly interested in the advanced materials research and technology, it is hard for us to realize how much-advanced materials world enlarged. Two-thirds of documents in respect to advanced materials have been published within last five years.  These documents were related to top seven subject areas including materials science,  engineering,  chemistry, physics and astronomy, biomedical, energy and computer science. Energy research is one of incredibly growing subject area of advanced materials.

Ferroelectrics And Multiferroics For Next Generation Photovoltaics

M. A. Jalaja; Soma Dutta

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 568-584
DOI: 10.5185/amlett.2015.5878

Growing energy crisis and environmental issues demand alternative source of green energy. In recent years ferroelectrics and multiferroics have got renewed attention for the breakthrough in photovoltaic application. Multiferroic is an appealing class of material, having two or more ferroic properties intimately coupled to each other. Energy harvesting from ferroelectrics and multiferroics is a pioneering field of research by its own, combination of other ferroic properties is a value addition to it. The coupling of ferroic and optical properties has brought a revolution in the field of photovoltaics. This review highlights recent development in the field of ferroelectric-multiferroic photovoltaics and summarizes the electrical, optical and photovoltaic properties of various ferroelctric and multiferroic systems. The different mechanisms and factors that attribute to the photovoltaic phenomena in ferroelctrics and multiferroics are also described here.

Designing Of MWCNT/ Ferrofluid/ Flyash Multiphase Composite As Safeguard For Electromagnetic Radiation

Pradeep Sambyal; Avanish Pratap Singh; Meenakshi Verma; Ankit Gupta; Bhanu Pratap Singh; S.K. Dhawan

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 585-591
DOI: 10.5185/amlett.2015.5807

Utilization of flyash which is produced at large scale in coal based thermal power plant is a challenge. In this regard, our investigation provides distinctive way of utilizing flyash for designing and preparing high-performance EMI shielding materials. Herein, we report synthesis and characterization of multiwalled carbon nanotubes (MWCNT) based multiphase composites. The multiphase composites were synthesized by in-situ co-precipitation with conductive filler (MWCNT) and magnetic filler (Ferrofluid). Scanning electron microscopy results confirm the presence of fly ash particles covered with Ferrofluid nanoparticles along with MWCNTs. Multiphase composites show total shielding effectiveness of 48 dB (>99.998 % attenuation) in the Ku-band (12.4–18 GHz) frequency range. The electromagnetic attributes, dielectric and permeability parameters have been calculated from the measured scattering parameters (S11, S22, S12, S21) using the Nicolson–Ross–Weir algorithm. The synthesized multiphase composites were characterized using XRD, FTIR, VSM and SEM. The results suggested that the MPC composites showed great potential as a radar absorbing material.

Mechanisms Of Composite-hydroxide-mediated Approach For The Synthesis Of Functional ZnO Nanostructures And Morphological Dependent Optical Emissions

Taj Muhammad Khan; M. Zakria; Rana I. Shakoor; M. Raffi; Mushtaq Ahmad

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 592-599
DOI: 10.5185/amlett.2015.5876

We report synthesis of the functional ZnO nanostructures (nanowires, nanorods) by a cost-effective and efficient method; called composite-hydroxide-mediated (CHM) approach. Effect of the processing temperature on the particle size, morphology, and subsequently morphological dependent optical emissions is investigated. Needle-shaped nanowires are obtained at 200 and 220 o C, of about (500-1500) nm in length, while at 250 o C; nanorods are formed with length in the range of (200-460) nm and width (10-30) nm. Optical study reveals that ZnO nanorods show only ultra-violet (UV) emission while bent nanowires demonstrate both UV and green emissions simultaneously. The week green emission at 2.4 eV indicates no efficient trapping of the photo-generated hole in the nanostructures. Phase purity, crystalline structure, size and chemical nature of the product are probed by XRD, EDX, Raman spectroscopy and FT-IR. The particle size estimated from the spatial correlation phonon confinement model for the E2 (high) phonon mode. The applied approach is believed to be efficient, and a direct route for the synthesis of a wide range of simple and complex oxide nanostructures for novel electro-optical nanodevices.

Effect Of Diffusion Parameters On The Efficiency Of C-Si Solar Cell

Vineet Kumar Singh; Jampana Nagaraju

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 600-606
DOI: 10.5185/amlett.2015.5616

This paper presents the effect of emitter thickness and post-annealing process on the conversion efficiency of crystalline silicon (c-Si) solar cells. Diffusion parameters like pre-deposition temperature, drive-in temperature, and process duration assist to control the emitter thickness and inturn improves the conversion efficiency of the solar cells. It is observed that shallower emitter cells have higher conversion efficiency of 10.81% than deeper emitter cells of 7.62%. Post-annealing process at 700 °C for 60 minutes boosts the efficiency of shallower emitter cell from 10.81% to 12.06%. Dark current-voltage characteristics authenticate the formation of p-n junction and also elucidate the presence of recombination saturation current along with diffusion saturation current. Illuminated and dark current-voltage characteristics further provide the evidence that post-annealing process during phosphorus diffusion reduces the trap density and thus the recombination saturation current, which helps to improve the efficiency. The combination of a shallower emitter with post-annealing process provides an excellent approach to enhance the solar cell efficiency.

Cadmium (II) Removal From Aqueous Solution Using Guar Gum-silica Nanocomposite

Vandana Singh; Somit Kumar Singh

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 607-615
DOI: 10.5185/amlett.2015.5873

In present communication we report on Cd(II) adsorption using our recently reported material, the guar gum-silica nanocomposite. The equilibrium, thermodynamics and kinetics of Cd(II) adsorption onto composite from aqueous solution were investigated. Optimum experimental parameters were determined to be pH 8, contact time 2 hours, Cd(II) concentration 100 mg/L, temperature 30 o C and adsorbent dose 10 mg. The sorption equilibrium data were modeled using the Langmuir and Freundlich isotherms where the data fitted better to Langmuir model indicating unilayer sorption, the Qmax being 666 mg/g. The kinetic data indicated chemisorption in the rate-controlling step as the pseudo-second-order model was best suited (rate constant of 2.79 × 10-4 gmg -1 min -1 at 100 mg/L Cd 2+ ). The calculated thermodynamic parameters (ΔG°, ΔS°, ΔH°) showed the adsorption to be exothermic and spontaneous with decreased randomness at the solid–solution interface. The adsorbent could be recycled for six successive cycles with 31% loss in its efficiency.

Synthesis And Optical Characterization Of Ca2PO4Cl:Tb3+ And Mn2+ Phosphor For Solid State Lighting

N. S. Kokode; V. R. Panse; S. J. Dhoble

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 616-619
DOI: 10.5185/amlett.2015.SMS3

In present work we studied the luminescence properties of Tb 3+ and Mn 2+ doped Ca2PO4Cl phosphor synthesized by wet chemical method were studied with extra heat treatment, to understand the mechanism of excitation and the corresponding emission of prepared phosphor. For the green emission, Tb 3+ ion is used as an activator, the excitation and emission spectra indicate that this phosphor can be effectively excited by 380 nm, to exhibit bright green emission centered at 545 nm corresponding to the f→f transition of Tb 3+ ions. The emission spectrum of Mn 2+ ion at 405 nm excitation 4 T1(4G) -  6 A1(6S) gives an emission band at 591 nm (orange-red). The observed photoluminescence (PL) measurements of Tb 3+ and Mn 2+ activated prepared phosphor indicates that these are the outstanding green and orange-red emitting potential phosphor , suitable application for the solid state lighting. The synthesized phosphors were analyzed by X-ray diffraction (XRD) for confirmation of phase and purity. The morphology and structure were characterized by scanning electron microscopy. Thus the phosphors in this system may be chosen as the green component for the tri-color lamp and certainly applied in w-UV LEDs. In the view of the excitation band and excellent luminescent properties, Ca2PO4Cl:Tb 3+ and Mn 2+ phosphor is expected to be a potential candidate for application in n-UV white LEDs and solid-state lighting because of its cost-efficient manufacturing, mercury-free excitation and eco-friendly characteristics.

Absorption, Photoluminescence And Thermoluminescence Studies Of γ- Irradiated Pure And Eu Doped LiF phosphors

Satinder Kumar; S. P. Lochab;Ravi Kumar; Arvind K. Gathania; Ankush Vij; A. K. Sharma; R. Dogra

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 620-627
DOI: 10.5185/amlett.2015.5811

We synthesized single phase pure and Eu doped LiF having micro-cubical morphology by modified co-precipitation method. The complete solid solubility of Eu in LiF has been observed up to 0.04 mol% and afterwards phase segregation started. The absorption spectra of pure and Eu doped LiF revealed the formation of γ-irradiation induced and dose dependent F, M and F3 color centers at room temperature. The concentrations of both F and M color centers calculated by using Smakula’s formula, increased almost ten times for γ- irradiated Eu doped LiF in comparison to γ-irradiated pure LiF. Non irradiated LiF doesn’t show any photoluminescence (PL) signal. However, γ-irradiated LiF showed broad emission peak around 681 nm, which is due to the excitation of F2 color centers. The Eu doped LiF samples exhibit PL emission peaks at 577, 591, 612, 648 and 690-698 nm correspond to Eu 3+ ion transitions from 5D0 to 7 FJ (J=0,1,2,3,4). The γ-irradiated Eu doped LiF show simultaneous PL emission spectrum of Eu 3+ ions and radiation induced F2 color centers. Thermoluminescence (TL) glow curves of γ- irradiated LiF and LiF: Eu (0.03 mol %) samples were also investigated and various trapping parameters for were evaluated by using Chen’s peak shape method

Plasmonic Resonance In Spray Deposited Au Nanoparticles Grown On TiO2 Thin Film

Promod Kumar; M. M. Ahmad

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 628-632
DOI: 10.5185/amlett.2014.5745

Gold nanoclusters embedded in titania (TiO2) matrix were synthesized by thermal spray method followed by thermal annealing in an inert atmosphere. The effect of annealing temperature on the plasmonic response and optical properties of gold nanocluster in titanium dioxide matrices have been investigated by using UV-visible absorption spectroscopy. The surface plasmon resonance (SPR) at metal-dielectric interface for gold nanoparticles has been observed for as deposited samples at 561.8 nm which degrade as a function of post annealing temperature. Field emission scanning electron micrographs confirm the presence of spherical nanoparticles whose size increases with post annealing temperature. The plasmonic resonance of noble metals at nanoscale is fundamentally and technologically important for light trapping photovoltaic and other applications.

Influence Of TiC Particulate Reinforcement On The Corrosion Behaviour Of Al 6061 Metal Matrix Composites

H. C. Ananda Murthy; Somit Kumar Singh

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 633-640
DOI: 10.5185/amlett.2015.5654

Aluminum matrix composites (AMCs), reinforced with ceramic particulates, have significant applications in the field of aerospace, marine, automobiles, sports and recreation. Al-TiC particulate composite has better potential for high-temperature applications. The corrosion behaviour of Al 6061-TiC particulate composites prepared by stir casting route, has been explored in chloride medium using electroanalytical techniques such as Tafel, Cyclic polarization and Impedance measurements (EIS). SEM and EDX analysis of the microstructures obtained in both matrix alloy and reinforced composites were performed in order to know the effect of titanium carbide on the corrosion resistance of composites. The polarization studies reveal an increase in the corrosion resistance in composites compared to the matrix alloy. The observed increase in corrosion resistance of TiC particulate reinforced composites is attributed to excellent bond integrity of TiC particulates with aluminium and possible electrochemical decoupling between TiC particles and Al 6061 matrix alloy. The EIS study reveals that the polarisation resistance (Rp) increase with increase in TiC content in composites and the corrosion process is mainly charge transfer controlled. Titanium carbide is proved to be a potential reinforcement for improved corrosion resistance in Al MMCs.

Polyaniline Niobium Pentoxide Composite As Humidity Sensor At Room Temperature

S. Kotresh; Y. T. Ravikiran; S.C. Vijaya Kumari; H.G. Raj Prakash; S. Thomas

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 641-645
DOI: 10.5185/amlett.2015.5795

In this present work, Polyaniline (PANI) and Polyaniline-Niobium Pentoxide (PANI-Nb2O5) composite were synthesized separately at room temperature by chemical polymerization of aniline without/with Nb2O5. Comparative study of XRD pattern of PANI and the composite confirms superficial deposition of PANI on Nb2O5 and the average size of the composite particle was found to be 10 nm. Aggregated granular morphology of the composite as compared to pristine PANI was confirmed by SEM images. Sensitivity of PANI-Nb2O5 composite to humidity at room temperature was tested using digital LCR meter at a selected frequency of 100 Hz and the results showed consistent variation in impedance from 60 KΩ to 360 KΩ within the relative humidity (RH) range 25% - 95%. Further, the response and recovery time of the composite were measured to be 80s and 90s respectively and the composite showed stable sensing ability over a period of one month.

 Correlation Of Bulk And Surface Properties In Bi-Sn And Bi- In Liquid Alloys

I. Koirala; B. P. Singh; I. S. Jha

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 646-652
DOI: 10.5185/amlett.2015.5742

We have used simple statistical model to report the energetic and its effect on the alloying behavior of Bi-Sn and Bi-In liquid alloys. The energetic of mixing in liquid alloys has been analyzed through the study of bulk and surface properties. In the bulk, we have studied thermodynamic properties, which include Gibb’s free energy of mixing, enthalpy of mixing and entropy of mixing. The surface behavior has been analyzed by computing surface concentration and surface tension of the alloys. For the microscopic structural investigation our study includes concentration-concentration fluctuation in long wavelength limit and Warren-Cowley short range order parameter, they have been discussed in term of the energetic of the bulk as well as that of the surface part. The computed results are in good agreement with experimental data and support a weak phase-separation tendency in molten Bi-Sn system and ordering behavior in Bi-In system. In both system, temperature dependent energy parameter takes important role to explain bulk and surface properties.

 Influence Of Particle Velocities And Impact Angles On The Erosion Mechanisms Of AISI 1018 Steel

Paul C. Okonkwo; A. M. A. Mohamed; Essam Ahmed

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 653-659
DOI: 10.5185/amlett.2015.5645

Failure of oil and gas pipeline due to solid particles entrainment has been a great concern to the petroleum industry. Erosion is the gradual material removal of pipeline materials due to solid particle impingement and results in unacceptable damage to the pipeline steel material surface. Because this process is difficult to investigate during operation, laboratory simulation test provides some insight. In this study, series of erosion tests were carried out to investigate the influence of particle velocity and impact angle on the erosion mechanism of AISI 1018 steel. Sand blaster erosion machine was used as the test equipment while the particle velocity and impact angle were ranged from 20 to 80 m/s and between 30 and 90° respectively. The results showed that at 90° impact angle, ploughing mechanism was operative, while material removal through low angle cutting was the dominant mechanism at lower impact angle during the erosion of AISI 1018 steel. Mainly, embedment of aluminium oxide particles on the target steel surface, micro–cutting, low angle cutting, pitting and ploughing were observed for low impact angle tests. It was suggested that scratches, cuttings and ploughing observed on some failed oil and gas pipeline steels could be attributed to erosion mechanism.

 Amorphous Thermochromic VO2 Coatings Grown By APCVD At Low Temperatures

Dimitra Vernardou; Dimitris Louloudakis; Emmanouil Spanakis; Nikolaos Katsarakis; Emmanouil Koudoumas

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 660-663
DOI: 10.5185/amlett.2015.5810

Vanadium dioxide coatings were grown on SnO2-precoated glass substrates by atmospheric pressure chemical vapor deposition using vanadyl (V) triisopropoxide at temperatures ≤ 450 o C. X-ray diffraction indicated the presence of metastable phase for the as-grown samples at 350 and 400 o C, while well-defined monoclinic vanadium dioxide phase was shown at 450 o C as derived by Raman spectroscopy. The different phases of vanadium dioxide affected the coating’s morphology presenting long grains with irregular size and shape turning to flattened structures composed with grains of uniform dimensions as the temperature increased from 350 to 450 o C. The best reversible behavior was at 64 o C with hysteresis width of 15 o C and a change in transmittance of 21 % for the as-grown coating at 450 o C. The significance of achieving thermochromic vanadium dioxide at temperatures ≤ 450 o C by a chemical procedure without post-treatment reduction and oxidant source is highlighted.

 Hg(II) Adsorption By Alginate-guar Gum Templated Titania Spheres: Kinetic And Isotherm Studies

Vandana Singh; Angela Singh; Devendra Singh; Jadveer Singh; Arvind K Pandey; Tulika Malviya

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 664-669
DOI: 10.5185/amlett.2015.5624

In present communication we report on the kinetic and isotherm studies on Hg(II) removal using our recently reported material, the millimeter sized hollow titania spheres (TSP). The mesoporous spheres with high surface area (11.75 m 2 /g) and bimodal pore size distribution were fabricated by a facile sol-gel approach using alginate-guar gum hybrid beads as the structure directing agent. In order to investigate the utility of TSP for Hg(II) adsorption, the batch adsorption experiments were conducted at various pH values (2–7), initial Hg(II) concentrations (50–300 mg/L), and TSP doses (20-100 mg) at 150 rpm, and 30 °C temperature. The spheres exhibited good capacity to adsorb Hg(II) in wide pH range (pH 3 to pH 7). It was possible to remove >95 % Hg(II) from 100 mg/L synthetic Hg(II) solution at pH 5, and 50 mg TSP dose in 10 h. The adsorption equilibrium data were better fitted to Langmuir model at low temperatures while Freundlich model become favored as the temperature was increased to 40 ºC. Langmuir adsorption isotherm study indicated that the monolayer adsorption capacity of TSP was 62.5 mg/g 62.5 mg/g 78.7 mg/g and 100 mg/g at 10, 20, 30, and 40 ºC respectively, which suggested good Hg(II) adsorption capacity of TSP. The calculated RL values evidenced the feasibility of the adsorption. Adsorption kinetic data well accorded with pseudo-second order kinetic model with the rate constant k, equal to 2.5 x 10 -4 g/mg.min 1.99 x 10 -4 g/mg.min and 0.28 x 10 -4 g/mg.min at 100, 150 and 200 mg/mL initial Hg (II) concentrations, indicating chemisorption taking place in the rate determining step. At high initial Hg(II) concentration (200 mg/mL), the adsorption was exclusively controlled by intraparticle diffusion. The study revealed the suitability of TSP for the mercury removal from wastewater.