Volume 4, Issue 8, August 2013

Impact Of Nanotoxicology Towards Technologists To End Users

Chan Oeurn Chey; Wetra Yandi;Ashutosh Tiwari; Hirak K Patra; Mattias Tengdelius; Mohsen Golabi; Onur Parlak; Roghayeh Imani; Sami A. I. Elhag

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 591-597
DOI: 10.5185/amlett.2013.8002

The length scale for nanomaterial is small enough to be invisible and presume innocence for the initial avoidance of the toxicity issues. Again it was beyond the understanding of the time frame when nanotechnology just blooms that a length scale itself might be an important toxic parameter apart from its materialistic properties. We present this report to address the fundamental issues and questions related to the nanotoxicity issues from laboratory to the land of applications. We emphasize about the basic nanoscale materials that are regularly being used by the scientific community and the nanotechnology based materials that has already in the market or will come soon.

Spectroscopic Analysis Of Ag Nanoparticles Embedded In Glass

Jyoti Rozra; Isha Saini; Sanjeev Aggarwal; Annu Sharma

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 598-604
DOI: 10.5185/amlett.2013.1402

Structural and optical properties of Ag-glass nanocomposite, synthesized by the combined use of vacuum deposition method and subsequent thermal annealing have been studied using UV-Visible absorption spectroscopy, Field emission scanning electron microscopy (FE-SEM) along with Energy dispersive analysis of X-rays (EDAX), Transmission electron microscopy (TEM) and Photoluminescence spectroscopy. Ag-glass nanocomposites were synthesized by depositing Ag on glass slides and the resulting samples were annealed at various temperatures from 300°C to 550°C for 1 hour. The fingerprint feature of Ag nanoparticles formation i.e. the surface plasmon resonance peak is observed around 427 nm in absorption spectra of Ag-glass samples annealed at various temperatures, this confirms the formation of Ag nanoparticles in glass. The size of Ag nanoparticles has been found to increase with increase in annealing temperature. At an annealing temperature of 400°C the size of Ag nanoparticles comes out to be 4.6 nm which increases to a value of 10.0 nm at an annealing temperature of 550°C. TEM micrograph further confirms the formation of Ag nanoparticles of size 8 + 2 nm at an annealing temperature of 550°C. Further, analysis of UV-Visible absorption and reflection data indicates towards the increase in refractive index of Ag nanoparticles doped glasses. It has been established that with the insertion of Ag nanoparticles of size 8 + 2 in glass the refractive index of the resulting nanocomposite increases to a value of 1.96. The dispersion parameters such as single-oscillator energy Eo, and the dispersion energy Ed have been discussed in terms of the Wemple-DiDomenico single-oscillator model. Photoluminescence spectra of silver glass nanocomposite have been studied and observed spectroscopic features have been correlated with various transitions of silver ions. Such studies are vital for designing optical materials for example optical communication, photonic devices etc.

Effects Of Crystallite Grain Size On The Triboluminescent Emmision For EuD4TEA

Ross S. Fontenot; William A. Hollerman; Kamala N. Bhat; Mohan D. Aggarwal

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 605-609
DOI: 10.5185/amlett.2012.12486

One of the brightest tested triboluminescent materials is europium dibenzoylmethide triethylammonium (EuD4TEA). In 2011, the authors discovered that synthesizing EuD4TEA using europium nitrate instead of chloride significantly increased the triboluminescence yield. In 2012, the authors discovered that anhydrous ethanol is not the best solvent to be used for synthesizing EuD4TEA. The less expensive acetone increases the triboluminescence and makes the synthesis much easier. However, no study has ever been done on how increasing the crystal size of EuD4TEA changes its triboluminescence. This paper reports the effect of increasing crystal size on the triboluminescence of EuD4TEA. The results indicate that acetone can be used to successfully control the grain size of EuD4TEA and thus increase the amount of triboluminescence emitted. The normalized TL yield is seen to be directly proportional to the square of the average grain size. The fluorescence decay time remains unchanged with an average value of 534.5 ± 7.3 µs, with no change in the emission properties of EuD4TEA.

One-pot Reaction To Synthesis And Characterization Of Two-stage Zinc Oxide Hexagonal Microprism On Nickel Thin Films

Wei Wu; Shaofeng Zhang; Xiangheng Xiao; Changzhong Jiang

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 610-614
DOI: 10.5185/amlett.2012.12477

A novel two-stage zinc oxide (ZnO) hexagonal microprisms was successfully synthesis via a hydrothermal route on a nickel (Ni) thin films. The Ni thin films are deposited by using magnetron sputtering onto Si (100) substrate. The formation of the secondary structure and optical properties of ZnO microprism have been investigated and the formation mechanism has been discussed. The results illustrate the Ni substrate is a key factor to grow the two-stage ZnO, and the photoluminescence (PL) emission peak at 389 nm reveals that the high crystal quality of these nanorods. ZnO with its excellent luminescent properties and the controllable nanostructures will hold promise for the development of photonic devices.

Investigations On Sputter Deposited LiCoO2 Thin Films From Powder Target

Yellareswara Rao Kosuri; Tirupathi Rao Penki; Munichandriah Nookala; Per Morgen; Mohan Rao Gowravaram

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 615-620
DOI: 10.5185/amlett.2012.12479

LiCoO2 thin films used as cathode layers in thin-film solid-state batteries have been deposited from LiCoO2 powder target using radio frequency (rf) magnetron sputtering in a cost effective approach in terms of material consumption and processing time. X-ray diffraction (XRD) studies of the films after post deposition annealing treatment revealed (104) orientation, which is the characteristic of rf sputtered LiCoO2 films. Raman spectroscopy was used to identify the different modes of vibration of atoms in the film. The surface morphology and cross-section of the samples were characterized using field emission scanning electron microscopy (SEM). The chemical analysis of LiCoO2 thin films was examined by X-ray photoelectron spectroscopy (XPS) showed atomic ratio of Li/Co as 0.9 which is close to the ideal value 1. Electrochemical characterization such as charge – discharge and cyclic voltammetry were conducted for LiCoO2 films deposited on platinized silicon substrates in the potential range 3.0 to 4.2 V vs Li/Li + . The maximum discharge capacity of 64 µAh.µm -1 . cm -2 and 52 µAh. µm -1 .cm -2 were achieved when discharged at a current of 5 µA and 50 µA for the first discharge cycle respectively. Moreover the electrochemical investigations of LiCoO2 thin films on flexible copper substrates also investigated and achieved an initial discharge capacity of 83 mAh/g. The possible reasons for degradation in the electrochemical properties have been discussed. The present work indicates suitability of sputtering from powder targets for thin film battery fabrication.

A Convenient Noninjection One-pot Synthesis Of CdS Nanoparticles And Their Studies

M. Penchal Reddy; B.C. Jamalaiah; I.G. Kim; D.S. Yoo; R. Ramakrishna Reddy

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 621-625
DOI: 10.5185/amlett.2012.12483

Water-dispersible CdS quantum dots (QDs) were synthesized in a simple one-pot noninjection route. The X-ray diffraction (XRD) pattern of the nanoparticles shows the cubic structure with particle size of the order 5-7 nm which was in good agreement with the transmission electron microscopic (TEM) studies. Selected area electron diffraction (SAED) recognized the cubic structure of CdS. The energy dispersive X- ray spectroscopy (EDAX) analysis confirms the presence of Cd and S elements in the samples. The optical properties are characterized by Ultraviolet-Visible (UV-Vis) absorption and Photoluminescence (PL) spectra. The synthesis parameters of this simple and rapid approach, including the reaction temperature and time, the pH of the reaction solution and the molar ratio of the 3-mercaptopropionic acid (MPA) stabilizer to Cd 2+ , have considerable influence on the particle size and photoluminescence of the CdS quantum dots. The 3-mercaptopropionic acid (MPA) stabilized CdS QDs can be used in solar cells, light emitting diodes, biological imaging etc.

Synthesis And Characterization Of Cellulose Nanocrystals/PVA Based Bionanocomposite

Anuj Kumar; Y. S. Negi; N. K. Bhardwaj; V. Choudhary

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 626-631
DOI: 10.5185/amlett.2012.12482

Sugarcane bagasse based cellulose nanocrystals (CNCs) and poly (vinyl alcohol) (PVA) were used to fabricate biodegradable porous foam bionanocomposites for application in biomedical applications by thermally- induced phase separation (TIPS) (freeze drying) technique. Aqueous suspension of cellulose nanocrystals and poly (vinyl alcohol) (PVA) solution in water were mixed to prepare (20/80) (v/v) composition of these polymers. For the comparative study 3D porous PVA foam was also prepared. Samples were characterized by FE-SEM, FTIR, X-ray diffraction analysis, porosity and pore size by ImageJ software. FE-SEM showed the surface morphology of pores distribution of the foam samples. The porosity of 3D porous PVA foam and 3D porous CNCs/PVA bionanocomposite was calculated as 90.8% and 89.0% respectively. The functional groups and crystallinity of the samples were determined by FTIR and X-ray diffraction spectra, respectively. The diameter of CNCs was in the range from 29 nm to 65 nm and the average diameter was calculated as 43± 3 nm by image analysis using ImageJ software. Thus produced porous composite in the present study might find potential applications to be used in biomedical applications.

Fabrication And Characterization Of Epitaxial BaTiO3 Thin Film Employing Platinum (111) Template

Antony Jeyaseelan A.; Sruthi S.; Soma Dutta

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 632-636
DOI: 10.5185/amlett.2012.11476

Epitaxial Barium Titanate (BaTiO3) thin films were fabricated on Platinised (Pt 111) Si/SiO 2 wafer by spin coating of metalloorganic sol gel solution. A preferred directional growth was obtained for BT (BaTiO3) thin film by employing Platinum (111) coating as a template. BT film was heat-treated at 700°C for 1 hour using the direct insertion method. The film was epitaxially grown with (111) and (211) being parallel to the Pt(111). The epitaxial growth of the thin film along (111) orientation was confirmed by XRD, AFM and SEM. The cross sectional view of SEM image showed that most nuclei were formed at the interface between the film and the substrate. BT thin film was characterized for its ferroelectric, dielectric and piezoelectric properties. Ferroelectric hysteresis measurement yielded high spontaneous polarization value (12.3µC/cm 2 ) comparatively at low electric field (150kV/cm). Substantial increase in piezoelectric d33 was explained in the light of domain wall engineering.

Post-deposition Annealing Controlled Structural And Optical Properties Of RF Magnetron Sputtered MoO3 Films

S. Subbarayudu; V. Madhavi;S. Uthanna

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 637-642
DOI: 10.5185/amlett.2012.11466

MoO3 films were deposited on Corning glass and silicon substrates held at room temperature (303 K) by RF magnetron sputtering of metallic molybdenum target at a fixed oxygen partial pressure of 4x10 -4 mbar and sputter pressure of 4x10 -2 mbar. The as deposited films were annealed in air at different temperatures in the range 473 – 673 K. X-ray diffraction studies suggest that the as-deposited and the films annealed at 473 K were amorphous in nature, while those annealed at 573 and 673 K were polycrystalline with mixed phases of α- orthorhombic and β- monoclinic MoO3. Scanning electron microscope images of the films annealed at 573 and 673 K exhibited nanoflower like and nanodisk like structures due to improvement in the crystallinity. Fourier transform infrared studies showed the characteristic vibrations of MoO3 with shift in the vibrational modes of Mo = O and Mo – O – Mo with increase of annealing temperature. The optical absorption edge of the films shifted towards lower wavelengths side with increase of annealing temperature. Optical band gap of as-deposited films was 2.98 eV with refractive index 2.01, while those annealed at 673 K showed the optical band gap of 3.15 eV and refractive index of 2.08. The MoO3 films annealed at 673 K were of nanocrystalline with crystallite size of 39 nm with optical band gap of 3.15 eV and refractive index of 2.08 were favorable for electron blocking and hole-selective layers in bulk-heterojuction solar cells.

Crystal Structure And Thermal Studies Of Copper(II) And Nickel(II) Complexes Of 2-hydroxyacetophenoimine As Vapour Precursors

V. Jeseentharani; J. Selvakumar; Babu Varghese; A. Dayalan; K. S. Nagaraja

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 643-649
DOI: 10.5185/amlett.2012.11462

Schiff’s base complexes bis(2-hydroxyacetophenoimine)nickel(II) [Ni(ohapim)2] and bis(2-hydroxyacetophenoimine)copper(II) [Cu(ohapim)2] were synthesized and studied for their idealist novel vapour source for chemical vapour deposition (CVD) application. Molecular structure was determined using single crystal X-ray diffraction, FT-IR, and elemental (C, H, N, and O) studies. Upon screening these complexes by dynamic thermogravimetric (TG) analyses, [Ni(ohapim)2] was found to be completely volatile and suitable for Ni/NiO CVD application. The temperature-dependent vapour pressure of [Ni(ohapim)2] was measured by using a transpiration apparatus and gave a value of 77.4 ± 0.8 kJ/mol for the enthalpy of sublimation (ΔH°sub) in the temperature range 527.86–584.22 K.

Rapid Biosynthesis Of Platinum And Palladium Metal Nanoparticles Using Root Extract Of Asparagus Racemosus Linn.

Rajesh W Raut; Bandopant T Nikam;Sahebrao B Kashid; Ansari Sana Mohd. Haroon; Yuvraj S Malghe

Advanced Materials Letters, 2013, Volume 4, Issue 8, Pages 650-654
DOI: 10.5185/amlett.2012.11470

The fabrication of metal nanoparticles is undergoing the revolutionary changes due to their widespread applications in the areas like selective and specific catalysis such as hydrogenation, optoelectronics, semiconductor, sensing and diagnosis. Biologically, the metal nanoparticles are produced using fungi, yeasts, bacteria, algae and plant biomass. The metal nanoparticles synthesized using biological methods include mainly silver and gold. The synthesis of metals like platinum and palladium is still unexplored. In this context we have synthesized Platinum and palladium metal nanoparticles using root extract of Asparagus racemosus Linn. at room temperature. The synthesized metals were characterized using UV-visible spectroscopy, Transmission Electron Microscopy (TEM) and Cyclic Voltammetry (CV) techniques. UV-Visible study revealed that in both cases nanoparticles are produced within 5 min. TEM study shows that metal nanoparticles formed are crystalline in nature and spherical in shape. It also shows that Pt and Pd nanoparticles are nearly monodispersed and having a particle size ranging between 1 to 6nm. CV of the metal nanoparticles shows reversible redox behavior. The method reported for the synthesis of metal nanoparitcles is clean, rapid and ecofriendly.