Volume 6, Issue 4, April 2015


Editorial

Advanced Materials World Congress, Sweden

Ashutosh Tiwari

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 278-278

Advanced Materials World Congress’ (AMWC) during 23-26 August, 2015, www.vbripress.com/amwc in Stockholm, Sweden. It is a four-day international event of the International Association of Advanced Materials (www.iaamonline.org), which regularly meets every two-year since 2010. This upcoming world congress is going to host in the city of Nobel Prize, Stockholm, Sweden. The venue of congress will be held on the Baltic Sea from Stockholm (Sweden) – Helsinki (Finland) - Stockholm (Sweden) via Mariehamn (Åland Islands) by the Viking Line. The goal of congress is to provide a global platform for researchers and engineers coming from academia and industry to present their research results and activities in the field of fundamental and interdisciplinary research of materials science. The World Congress will provide opportunities for the delegates to exchange their face-to-face novel ideas and experiences with the international experts during the plenary and invited talks, oral presentations and poster sessions. We will also set up sessions with keynote forum, panel discussion and project negotiation.

X-ray Photoelectron Spectroscopy Study Of Adsorption Of (3-mercaptopropyl)trimethoxysilane And N-propyltriethoxysilane On A Rutile TiO2(110) Surface

Shilpi Chaudhary; Ashley R. Head; Joachim Schnadt

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 279-283
DOI: 10.5185/amlett.2015.SMS1

We have studied the adsorption of two silane compounds, (3-mercaptopropyl) trimethoxysilane (MPTMS) and n-propyltriethoxysilane (PTES), on a rutile TiO2(110) surface using angle dependent X-ray photoelectron spectroscopy. The observation of the S 2p line, in the case of MPTMS, and the C 1s line for both MPTMS and PTES confirms the adsorption of the molecules. For a dose of 122 Langmuirs of MPTMS we find room temperature coverage of 0.55 monolayers, while for a 60 Langmuir dose of PTES the coverage is found to be 0.89 monolayers. Thus, MPTMS has a considerably lower sticking coefficient on the rutile TiO2(110) surface than PTES. Both PTES and MPTES are found to bind dissociatively to the surface. An analysis of angle dependent data further suggests that for MPTMS the thiol group and thus alkyl chain points away from the surface, while for a 0.5 monolayer coverage of PTES the alkyl chain is oriented towards the surface. A higher coverage, ~1 monolayer, the behavior seems to be reversed for at least a fraction of all molecules. Temperature programmed XPS measurements suggest that the oxy groups of both molecules desorb from the surface at 550 K, which is in accordance with literature. The present study thus provides information on how these silane coupling agents bind to titanium oxide and what their molecular orientation is on the surface.

Observation Of Dielectric Relaxor Behavior In Pb0.95Sr0.05(Zr0.5Ti0.5)O3 Ceramics

Nawnit Kumar; Patri Tirupathi; Bineet Kumar; Mukul Pastor; A. C. Pandey; R. N. P. Choudhary

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 284-289
DOI: 10.5185/amlett.2015.6618

We reports structural, microstructural and dielectric characteristics of Sr 2+ doped PZT (50/50) ceramic. X-ray diffraction reveals that the system exhibit coexistence of two phases (Tetragonal and rhombohedral) at room temperature. Typical relaxor behavior was observed by the dielectric studies and confirmed by Vogul-Fulcher fitting. The observed relaxor was predicted as existence of nanopolar regions due to short range ordering in presence of oxygen vacancies. The evidence for oxygen vacancies was studied by conductivity and polarization studies. Moreover, at 270 °C one more phase transition is noted which was ascribed to structural phase transition. Present study has scientific significance to distinguish the performance of oxygen vacancies in ferroelectric materials.  

 Electric Field-effect-assisted Persistent Photoconductivity In CZTS

Nadarajah Muhunthan; Om P. Singh; Vidya N. Singh; Kedar N. Sood

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 290-293
DOI: 10.5185/amlett.2015.5704

Copper zinc tin sulfide (CZTS) thin film was deposited by co-sputtering metal targets and post-deposition sulfurization in H2S. Temperature-dependent electrical conductivity and photoconductivity effects in CZTS are studied. The low temperature electrical conductivity measurement shows acceptor level energy value as 36.85 meV. A large decay time of 108 s at 300K, 99 s at 200K and 94 s at 100K after switching off the light source was observed. The decay behavior of this persistent photoconductivity (PPC) in CZTS follows the double exponential function. The results show that defects are responsible for the observed PPC in CZTS. The combined measurements of low temperature electrical conductivity and photoconductivity give account of the defect level. Control of these defects can improve the quality of material and thus the resulting device.  

Transport Properties And Electronic Structure Of Intercalated Compounds MTiS2 (M = Cr, Mn And Fe)

Yamini Sharma; Seema Shukla; Shalini Dwivedi; Ramesh Sharma

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 294-300
DOI: 10.5185/amlett.2015.5608

New material systems of intercalated compounds MTiS2 (M= Cr, Mn, Fe) have been systematically studied by ab-initio method. In order to investigate the effect of charge transfer from guest 3d transition metal atoms to host TiS2, the electronic and transport properties have been calculated using full potential linearized augmented plane wave (LAPW) + local orbitals (lo) scheme, in the framework of density functional theory (DFT) with generalized gradient approximation (GGA) for the purpose of exchange correlation energy functional. From the energy bands and density of states it is observed that the 3d-states of M atoms contribute mainly to the conduction band, which results in increase in electrical and thermal conductivity of highly intercalated TiS2. The calculated electronic component γ which is derived from specific heats of intercalated TiS2 is quite high (2-50 mJ/mol K2) and increases substantially on intercalation. The 3d-states of transition metal M and Ti atoms which split due to the exchange interaction imparts magnetic properties to the MTiS2 systems. The calculated transport properties have been analysed on the basis of the density of states and correctly explain the origin of different magnetic ordered phases.

Synthesis Of Al And Ag Nanoparticles Through Ultra-sonic Dissociation Of Thermal Evaporation Deposited Thin Films For Promising Clinical Applications As Polymer Nanocomposite

Narendra Kumar Agrawal; Ravi Agarwal; Divya Bhatia; Divya Saxena; Garima Kedawat; K.C. Swami; Y.K. Vijay

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 301-308
DOI: 10.5185/amlett.2015.5625

Nanoparticles (NPs) having well-defined shape, size and clean surface serve as ideal model system to investigate surface/interfacial reactions. Ag and Al NPs are receiving great interest due to their wide applications in bio-medical field, aerospace and space technology as combustible additives in propellants and hydrogen generation. Hence, in this study, we have synthesized Ag and Al NPs using an innovative approach of ultra-sonic dissociation of thin films. Phase and particle size distributions of the Ag and Al NPs have been determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thin film dissociation/dissolution mechanism, hence conversion into NPs has been characterized by SEM- scanning electron microscope. EDXA & ICPMS have been performed for chemical analysis of NPs. Optical properties have been characterized by UV-Vis and PL spectroscopy. These NPs have also been investigated for their anti-bacterial activity against Escherichia coli bacteria. To the best of our knowledge, this is the first time when NPs has been synthesized by ultra-sonic dissociation of thin films. As an application, these NPs were used further for synthesis of nanocomposite polymer membranes, which show excellent activity against bio film formation.  

 Study On Poly(vinylidene Fluoride)/nickel Composites With Low Percolation

R. K. Goyal; R. Sulakhe

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 309-317
DOI: 10.5185/amlett.2015.5627

The preparation, electrical and thermal properties of nickel (Ni) particles filled poly(vinylidene fluoride) (PVDF) composites were discussed in this paper. The experimental density of the composites was close to that of theoretical density. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that PVDF has primarily α-phase. The coefficient of thermal expansion of the composites decreased approximately 30 % compared to pure PVDF. The percolation threshold of the composite is about 5 vol% Ni, which is less than one-third of the value reported for metal filled polymer composites in the literature. The significantly lower percolation was attributed to the increased crystallinity and the better processing method which results in an easy formation of 3-dimensional network of Ni particles in the matrix, as confirmed by scanning electron microscopy (SEM). The electrical conductivity of these composites increased from 6.3×10 -13 S/cm to 2.6×10 -1 S/cm which is better and comparable than those of required for antistatic (10 -4 -10 -8 S/cm) and electromagnetic interference (EMI) shielding applications. The significant increase in electrical and thermal properties showed that these composites might be potential candidates for the EMI shielding and antistatic devices.

Cost Effective And Minimal Time Synthesis  of Mullite From A Mine Waste By Thermal Plasma Process

Swatirupa Pani; Rakesh Kumar Sahoo; Nilima Dash; Saroj Kumar Singh; Birendra Kumar Mohapatra

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 318-323
DOI: 10.5185/amlett.2015.5644

The synthesis of mullite from an aluminous-rich mine waste (shale) closely associated with iron/manganese mines from Bonai-Keonjhar belt, Odisha is reported. The shale constitutes major kaolinite with minor halloysite, quartz, orthoclase and plagioclase minerals and compositionally contains 36.40 % Al2O3 and 52.10% SiO2. In order to convert this mine waste to a refractory product, ‘Mullite’, alumina powder was added in 1:0.9; 1:1 and 1:1.1 weight ratios with the shale and thoroughly homogenized. Individual mixtures were fed in to the thermal plasma reactor and processed for only 5 minutes to form mullite. The phase and microstructure developed in the processed samples were investigated from their XRD patterns, Raman spectra and SEM images. Diagnostic peaks of the mullite phase are distinctly marked in the XRD pattern and Raman spectra of plasma treated products. Microstructure of mullite observed under SEM clearly exhibits a fused layered structure. The integrated results confirm the formation of high quality mullite from a mixture of 1:1 weight ratio. This low cost process can be implemented in industrial scale for processing of such mine waste to a value added refractory product.

 Shape Control Synthesis, Characterizations, Mechanisms And Optical Properties Of Larg Scaled Metal oxide Nanostructures Of ZnO And TiO2

Rajni Verma; Bhanu Mantri; Avanish Kumar Srivastava

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 324-333
DOI: 10.5185/amlett.2015.5661

In the present study, ZnO and TiO2 nanostructures of different size have been synthesized in high yield with excellent repeatability by simple, economical and environmentally benign chemical route. ZnO quantum dots and nanorods of tuned aspect ratio were evolved by optimising the reaction conditions such as by varying solvent composition, precursor concentration and by using different additives. On the other hand, the synthesis of brookite, the rare phase, anatase and rutile, the stable phases of TiO2 were also achieved by just varying the annealing temperature from 400 to 615 °C.  The obtained nanostructures were rationalized by various characterization techniques such as XRD, FTIR, Raman, SEM, HR- TEM, UV-Vis and PL. The Phase formation and structure determination were identified by using XRD, FTIR and Raman Spectra, SEM and HR-TEM were performed to determine the morphology and particle size. The aspect ratio was calculated to be in the range of 3.2-9.4 in case of ZnO NRs, and particle size was found to be 2-5 nm for ZnO QDs of wurtzite phase and ~ 10 nm for TiO2 (anatase phase) NPs, respectively. The UV-Vis optical absorption spectrum demonstrates the band gap value of 3.60, 4.02 and 3.40 eV for ZnO NRs, QDs and TiO2 NPs respectively. The UV-Vis optical absorption spectrum demonstrates the band gap and room temperature PL spectra illustrates about the various defects present in the sample. Various chemical reactions and mechanism involved in producing these nanostructures are dealt in detail. The future prospective of these metal oxide nanostructures lie in photocatalysis, sensors and biomedical applications.

Sequentially Reduced Biogenic Silver-gold Nanoparticles With Enhanced Antimicrobial Potential Over Silver And Gold Monometallic Nanoparticles

Dipali Nagaonkar; Mahendra Rai

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 334-341
DOI: 10.5185/amlett.2015.5737

Bimetallic nanoparticles have emerged up as advanced nanomaterials due to the synergism between two metallic nanoparticles in core-shell or alloy arrangement. Moreover, bioinspired synthesis of nanoparticles is an evergreen approach of nanobiosciences. In this experiment, we have fabricated silver, gold and silver (core) - gold (shell) bimetallic nanoparticles using leaf extract of Catharanthus roseus Linn. by sequential reduction technique. The sequentially reduced silver-gold nanoparticles in core-shell arrangement were detected by shift in the surface plasmon resonance of nanoparticles from 423 nm to 526 nm with the aid of UV-Visible spectrophotometer. Nanoparticle tracking analysis confirmed the mean particle size for all the nanoparticles within the range 11 to 65 nm. X-Ray diffraction analysis revealed Bragg’s reflections denoting face cubic centered crystalline nature of all the synthesized nanoparticles. Transmission electron microscopy showed that silver and silver-gold nanoparticles are quite polydispersed and spherical in shape while anisotropic Au nanoparticles were also observed. These phytofabricated Ag-Au nanoparticles have been evaluated with enhanced antibacterial and anticandidal potential over their monometallic counterparts with particular reference to some pathogenic bacteria and Candida sp. The maximum lethality of bimetallic nanoparticles was observed for Escherichia coli followed by Pseudomonas aeruginosa, while Candida parapsilosis was found to be the least susceptible organism for the silver-gold nanoparticles.

SHI Induced Thermoluminescence Properties Of  sol-gel Derived Y2O3:Er3+ Nanophosphor

N.J. Shivaramu; B.N. Lakshminarasappa; K.R. Nagabhushana; Fouran Singh

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 342-347
DOI: 10.5185/amlett.2015.5713

Nanocrystalline erbium doped yttrium oxide (Y2O3:Er 3+ ) was synthesized by the sol-gel technique using citric acid as complexing agent. The synthesized samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM) techniques for phase-purity and microstructure. Er 3+ doped Y2O3 crystallizes in cubic phase with an average crystallite size of 24.3 nm. The pellets of Y2O3:Er 3+ were irradiated with 100 MeV swift Si 8+ ions with fluence in the range of 3×10 11 - 3×10 13 ions cm -2 .  Three well resolved thermoluminescence (TL) glows with peaks at ~422, 525 and 620 K were observed in Er 3+ doped Y2O3 samples. It was observed that the TL intensity was found to increases with increasing Er 3+ concentration up to 0.4 mol% in Y2O3 and thereafter it decreases with further increase of Er 3+ concentration. Also, the intensity of low temperature TL glow peak (~422 K) increases with increasing ion fluence up to 1×10 12 ions cm -2 and decreases with further increase of ion fluences. The TL trap parameters were calculated by glow curve shape method and the deconvoluted glows were exhibit of second order kinetics.

Ag Nano-composite Glasses Synthesized By Swift Heavy Ion Irradiation

Ranjana S. Varma; D.C. Kothari; S. Santra; R.G. Thomas; R. Tewari; S. Neogy; C.S. Suchand Sandeep; Reji Philip; D. Kanjilal

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 348-353
DOI: 10.5185/amlett.2015.5715

In the present work, we have used swift heavy ions (SHI) irradiation and post irradiation annealing to synthesize Ag nanoparticles in fused silica. Fused silica samples deposited with 15 nm of Ag film were irradiated using SHI beam of 120 MeV Ag 9+ ions at different fluences and post irradiation annealing was done at 500 °C in air for 30 min. The samples were characterized using UV-vis absorption spectroscopy, Rutherford Backscattering Spectrometry (RBS), GAXRD, Transmission Electron Microscopy (TEM), and open aperture z-scan measurements. The signature of Ag nanoparticles was observed in optical absorption spectra and the average size of the Ag nanoparticles was estimated using Mie’s theory. The size of the nanoparticles (~3 nm) was also confirmed from the GAXRD and TEM measurements. RBS results for Ag/SiO2 irradiated with the fluence of 5 x10 13 ions/cm 2 shows the decrease in slope at the interface of the Ag profile, indicating a partial mixing at a fluence of 5 x10 13  ions/cm 2 . Open aperture z-scan measurement of Ag/SiO2 SHI irradiated sample after annealing shows a saturation behavior, indicating that the sample is optically non-linear. The sample shows saturation behavior but does not show optical limiting behavior, which indicates that the size and number density of nanoparticles are low. The ability to control the particle size using ion beam technique as a function of fluence and observed nonlinearity results provide concrete evidence that Ag nano composite glasses can be used in nonlinear and optical limiting application.

Study Of Chemically Synthesized SHI Irradiated CdS Nanostructured Films

P.K. Mochahari; Ananta Rajbongshi; Nava Choudhury; F. Singh; K.C. Sarma

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 354-358
DOI: 10.5185/amlett.2015.5719

Cadmium sulphide (CdS) nanostructured films were prepared by chemical bath deposition (CBD) method at room temperature. The prepared films were subjected to swift heavy ion (SHI) irradiation by using 100 MeV Si 8+ ion beams at various fluences from 1x10 11 to 1x10 13 ions/cm 2 . Structural, morphological, optical properties of the pristine and irradiated films were characterized by X-ray diffractrometer (XRD), high resolution transmission electron microscope (HRTEM), UV-Vis spectroscopy and Raman spectroscopy. XRD study confirms the formation of nanocrystalline cubic phase in all the films. The crystallite size is found to increase from 7nm to 9 nm and shift of peak positions are observed due to irradiation. The lattice strain and dislocation density of the samples are of the order of 10 -3 and 10 16 m -2 respectively and the values are found to decrease upon irradiation. HRTEM images show that the shapes of the particles are nearly spherical and the selected area electron diffraction (SAED) pattern of HRTEM have also supported the formation of cubic phase CdS. The optical absorption spectra exhibit shift in the fundamental absorption edge and the optical band gap decreases from 2.585eV to 2.513 upon SHI irradiation. Three intense Raman lines for pristine as well as irradiated CdS have been observed and all the samples show shift in Raman lines relative to bulk CdS due to phonon localization. The SHI irradiation on chemically deposited CdS films is an important tool used for modification of structural, morphological and optical properties of the films for possible applications in device fabrication.

Swift Heavy Ion Irradiation Induced Surface Sputtering And Micro Structural Modification Of Gold Thin Films

Priyadarshini Dash; Haripriya Rath; Udai B. Singh; Sunil Ojha; Devesh K. Avasthi; Naresh C. Mishra

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 359-364
DOI: 10.5185/amlett.2015.5723

Two sets of gold thin films of thickness of about 20 and 50 nm, grown by thermal evaporation method on (100) silicon wafers were irradiated by 197 MeV Au ions. Grazing incidence X-Ray diffraction (GIXRD) study has been revealed lattice expansion on decreasing the film thickness. 197 MeV Au ion irradiation was not affect either the cubic crystal structure of gold or its lattice parameter. Atomic force microscopy (AFM) study indicated that the evolution of the surface morphology with ion fluence crucially depended on the film thickness, the thinner film being more sensitive than the thicker one. Irradiation led to nanoparticles formation on the surface of the films. This observation is in contrast to the generally perceived damaging role of swift heavy ion (SHI) irradiation. Power spectral density analysis of the roughness along both the lateral and vertical directions demonstrated dominance of surface diffusion over volume diffusion induced by SHI irradiation. A comparison of the sputtering yield obtained from Rutherford back scattering (RBS) spectra of the irradiated films and transmission electron microscopy (TEM) of the particles sputtered from the films and collected by a catcher grid during irradiation indicated that more than the surface and volume diffusion processes, it is the irradiation induced sputtering that controls the overall surface morphology of the films. The surface roughness increase with ion fluence and the irradiation induced sputtering yield was found to be larger in thinner films. Film thickness dependence of the evolution of surface morphology and sputtering yield with 197 MeV Au ion irradiation clearly indicates the dominance of the electronic energy loss over the nuclear energy loss of the projectiles ions in the target medium and opens up the ways for examining the applicability of different models of ion-matter interaction in systems with reduced dimensions.

Native Defects And Optical Properties Of Ar Ion Irradiated ZnO

S. Pal; A. Sarkar; D. Sanyal; T. Rakshit; D. Kanjilal; P. Kumar; S. K. Ray; D. Jana

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 365-369
DOI: 10.5185/amlett.2015.5730

1.2 MeV Argon (Ar) ion irradiation turns white coloured ZnO to yellowish (fluence 1 × 10 14 ions/cm 2 ) and then reddish brown (1 × 10 14  ions/cm 2 ). At the same time the material becomes much more conducting and purely blue luminescent for the highest fluence of irradiation. To get insight on the defects in the irradiated samples Ultraviolet-visible (UV-vis) absorption, Raman, and photoluminescence (PL) spectroscopy and Glancing Angle X-Ray Diffraction (GAXRD) measurements have been carried out. Enhancement of overall disorder in the irradiated samples is reflected from the GAXRD peak broadening. UV-vis absorption spectra of the samples shows new absorption bands due to irradiation. Complete absorption in the blue region of the spectrum and partial absorption in the green and red region changes the sample colour from white to reddish brown. The Raman peak representing wurtzite structure of the ZnO material (~ 437 cm -1 ) has decreased monotonically with the increase of irradiation fluence. At the same time, evolution of the 575 cm -1 Raman mode in the irradiated samples shows the increase of oxygen deficient disorder like zinc interstitials (IZn) and/or oxygen vacancies (VO) in ZnO. PL spectrum of the yellow coloured sample shows large reduction of overall luminescence compared to the unirradiated one. Further increase of fluence causes an increase of luminescence in the blue region of the spectrum. The blue-violet emission can be associated with the interstitial Zn (IZn) related optical transition. The results altogether indicates IZn type defects in the highest fluence irradiated sample. Large changes in the electrical resistance and luminescent features of ZnO using Ar ion beam provides a purposeful way to tune the optoelectronic properties of ZnO based devices.