Issue 1

An Era Of High-tech Materials

Ashutosh Tiwari

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 1-2
DOI: 10.5185/amlett.2016.1001

The design of innovative materials is one of measure for driving industry to place the sustainable basis of new technology in order to enhance the wealth and well-being of society. The last half century has realized a vital development in the area of high-tech materials ranging from various elements and composites, emerged through synthetic chemistry and often drawing motivation from the nature. The idea of an intelligent material imagines added values in terms of functionality built into the materials structure desirable to response the defined conditions. The previous two decades has emerged to understand the extraordinary behavior and properties of engineered nanostructured materials.

Fate Of Inorganic Nanoparticles In Agriculture

Navneet Phogat; Shadab Ali Khan; Shiv Shankar; Abu A. Ansary; Imran Uddin

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 3-12
DOI: 10.5185/amlett.2016.6048

In modern world, engineered nanoparticles (ENPs) are increasingly becoming an important component of daily life. They are becoming an integral part of a wide range of man-made products including electronics, paints, biomedical products, sunscreens, clothing, automobiles, etc. Rapid progress in the manufacturing of ENPs and the subsequent increase in its commercial applications always have had an impact on agriculture due to the exposure of living things to these ENPs. Also, human beings are directly dependent on the plants because of their nutritional values. Hence, the impact of nanoparticles on agricultural soil and plants is always of topical interest. It is imperative to be aware of the effects of nanoparticles on soil as well as on the soil ecosystem it supports especially the soil microbes and plants; or more specifically whether they have an influence on the agricultural yield and agri-economy. It is also important to study the effects of man-made nanomaterials on the properties of agricultural soil. This work reviews some of the key features of the impact of ENPs on the environment and the fate of ENPs in agriculture.

Nanoindentation Shows Uniform Local Mechanical Properties Across Melt Pools And Layers Produced By Selective Laser Melting Of AlSi 10Mg Alloy

Nicola M. Everitt; Nesma T. Aboulkhair; Ian Maskery; Chris J. Tuck; Ian Ashcroft

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 13-16
DOI: 10.5185/amlett.2016.6171

Single track and single layer AlSi 10Mg has been produced by selective laser melting (SLM) of alloy powder on an AlSi12 cast substrate. The SLM technique produced a cellular-dendritic ultra-fined grained microstructure. Chemical composition mapping and nanoindentation showed higher hardness in the SLM material compared to its cast counterpart.  Importantly, although there was some increase of grain size at the edge of melt pools, nanoindentation showed that the hardness (i.e. yield strength) of the material was uniform across overlapping tracks. This is attributed to the very fine grain size and homogeneous distribution of Si throughout the SLM material. 

Electronic Structure Study And Dielectric Properties Of Amorphous ZrO2 And HfO2

Aditya Sharma; Shalendra Kumar;Hyun-Joon Shin; Mayora Varshney; Sejun Kang; Jaeyoon Baik; Tae-Kyun Ha; Keun-Hwa Chae

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 17-22
DOI: 10.5185/amlett.2016.6136

ZrO2 and HfO2 powder samples were prepared by using the chemical precipitation method and subsequent annealing. Crystal structure, local electronic structure and dielectric constant of amorphous and crystalline powders of ZrO2 and HfO2 have been examined using the synchrotron X-ray diffraction, O K-edge X-ray absorption spectroscopy, Zr 3d and Hf 4f core-level X-ray photoelectron spectroscopy and temperature dependent dielectric measurements, respectively. Amorphous ZrO2 and HfO2 powders exhibit a local tetragonal structure, with mixed +3 and +4 valence states of Zr and Hf ions, and demonstrated the high dielectric performance. After the heat treatment, the tetragonal phase transforms into the monoclinic phase with dominant +4 valence state of Zr and Hf ions and the larger sized ZrO2 and HfO2 nanoparticles exhibited low dielectric constant. The manifestation of high dielectric constants in the amorphous ZrO2 and HfO2 samples is because of the hopping of electrons between the Zr +3 -Zr +4 and Hf +3 -Hf +4 networks. 

Influence Of Anodization Parameters On Morphology Of TiO2 Nanostructured Surfaces

Mukta Kulkarni; Anca Mazare; Patrik Schmuki; Ales Iglic

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 23-28
DOI: 10.5185/amlett.2016.6156

Titanium (Ti) is one of the most promising biomaterial for biomedical devices due to its high corrosion resistance and specific combination of strength and biocompatibility. Titanium dioxide (TiO2) nanostructures are obtained by electrochemical anodization of Ti foils under self-organization condition; anodization parameters such as anodization time, voltage, temperature and most important electrolyte composition are critical for the resulting morphology. Nanostructures are grown in ethylene glycol (EG) based electrolytes and we evaluated the influence of the water content, as no nanostructures are formed in the electrolyte without water addition, and with increasing water content, either nanopores or nanotubes are obtained (depending also on the applied potential and anodization time). The increase in water content in the electrolyte enables the slow transition from nanopores to nanotubes, which occurs by a pore-wall splitting mechanism. From the current results, one can conclude that the water in the electrolyte has a definite effect on the type of nanostructures obtained by electrochemical anodization in organic electrolytes. This current investigation of effect of water in EG based electrolytes is useful for obtaining the desired morphology of the nanostructures (diameter, length, open-top morphology) for specific bioapplications. 

Study The Influence Of Different Mol% BLTMNZ Doping On KNLN Ceramics By Using The XRD And Impedance spectroscopy

Shweta Thakur; Seema Sharma;Ashutosh Tiwari; Radheshyam Rai

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 29-35
DOI: 10.5185/amlett.2016.6001

Polycrystalline samples of (K0.45Na0.45Li0.1NbO3)1-x-(Ba0.96La0.04Ti0.815Mn0.0025 Nb0.0025Zr0.18 O3)x ceramics (where x = 0.1, 0.3, 0.5, 0.7 and 0.9) were prepared by using a high temperature solid state reaction technique. The XRD patterns of the BLTMNZ doped KNLN at room temperature with x = 0.7 have pure pervoskite phase with tetragonal structure at room temperature and have maximum value of dielectric constant at x = 0.9. Detailed studies of dielectric and impedance properties of the materials in a wide range of frequency (100Hz–1MHz) and temperatures (30 – 500 o C) showed that properties are strongly temperature and frequency dependent. The plots of Zʹʹ and Mʹʹ versus frequency at various temperatures show peaks in the higher temperature range (>300 o C). The compounds show dielectric relaxation, which is found to be of non-Debye type and the relaxation frequency shifted to higher side with increase in temperature. The Nyquist plot and conductivity studies showed the NTCR character of samples.

Photocatalytic Characteristics For The Nanocrystalline TiO2 Supported On Sr4Al14O25: Eu2+, Dy3+ Phosphor Beads 

Hyun-Je Sung; Sang-Chul Jung;Jung-Sik Kim; Byung-Min Ki

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 36-41
DOI: 10.5185/amlett.2016.6106

The photocatalytic behaviors of TiO2-supported on the long lasting phosphor beads were examined. Nanocrystalline TiO2 was coated on ellipsoidal-spherical beads of an alkaline earth aluminate phosphor, Sr4Al14O25:Eu 2+ , Dy 3+ , by low pressure chemical vapor deposition (LPCVD). The photocatalytic reaction was examined by measuring the decomposition of benzene and toluene gases by gas chromatography under ultraviolet, visible light (λ> 410 nm) irradiation, as well as in the dark. The LPCVD TiO2-coated Sr4Al14O25:Eu 2+ , Dy 3+ showed an active photocatalytic reaction under visible irradiation. The mechanisms of the photocatalytic reactivity for the TiO2-coated Sr4Al14O25:Eu 2+ , Dy 3+ phosphor beads were discussed in terms of the crystal structure at the interface, energy band structure and phosphorescence. The coupling of TiO2 with the Sr4Al14O25:Eu 2+ , Dy 3+ phosphor resulted in energy band bending in the junction region between TiO2 and Sr4Al14O25:Eu 2+ , Dy 3+ phosphor, which makes the TiO2 crystal at the interface photo-reactive under visible light irradiation. The LPCVD TiO2-coated Sr4Al14O25:Eu 2+ , Dy 3+ phosphor beads were also photo-reactive in the dark through the light photons emitted from the Sr4Al14O25:Eu 2+ , Dy 3+ phosphor. 

Green Synthesis And Antimicrobial Activity Of Silver Nanoparticles Onto Cotton Fabric: An Amenable Option For Textile Industries 

Anal K. Jha;Kamal Prasad

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 42-46
DOI: 10.5185/amlett.2016.6083

Biosynthesis, characterizations and applications of nanoparticles have become an important branch of nanotechnology nowadays. In this paper, green synthesis of silver nanoparticles (AgNPs) using the alcoholic extract of Clerodendron infortunatum as a reducing and stabilizing agent, has been discussed. This biosynthetic method is simple, cost-effective and reproducible. Formation of AgNPs was established by X-ray diffraction, scanning and transmission electron microscopy, UV-visible spectroscopy techniques. The phytochemicals responsible for nano-transformation were principally phenolics, tannins and organic acids present in the leaves. Further, AgNPs were used for antibacterial treatment of cotton fabrics which was tested by antibacterial activity assessment of textile material by agar diffusion method against Staphylococcus aureus. The colloidal AgNPs have been soaked onto cotton fabrics and studied for their effective antibacterial activity toward Staphylococcus aureus which showed remarkable antibacterial activity.

Rapid Synthesis And Photoluminescent Characterization Of MAl2O4: Eu2+, Dy3+  (M = Ca/Ca + Ba/Ca + Mg) blue Nanophosphors For White Lighting Display Applications

Devender Singh; Pratap S. Kadyan;Ishwar Singh; Vijeta Tanwar; Anura P. Simantilke; Bernabe Mari

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 47-53
DOI: 10.5185/amlett.2016.6103

The persistent MAl2O4:Eu 2+ , Dy 3+ (M may be Ca or Ca+Ba or Ca+Mg) blue light emitting nanophosphors were prepared by rapid facile gel combustion technique. For the syntheses of present series of phosphors, urea was used as an organic fuel and boric acid was used as a flux in presence of air. Photoluminescence properties were studied by excitation and emission spectra. The phosphors showed blue luminescence (λmax= 454-458nm) under the excitation of UV source, attributed to 4f 6 5d 1 →4f 7 transitions of the Eu(II) ion. The effect on photoluminescence intensity and decay time was also studied for varying metal ions in different ratio (Ca or Ca+Ba or Ca+Mg). The existence of divalent europium ions in the synthesized lattices was confirmed by the X-ray photoelectron spectroscopy. The crystal phase and size of the prepared materials were analyzed with X-ray diffraction patterns. The surface morphology of phosphors was studied with scanning electron microscopy and transmission electron microscopy techniques revealed the average size of the prepared materials between the 30-50 nm. The prepared nanophosphors had bright optoelectronic properties that could be efficiently applied in various solid state white light emitting display devices. 

Poly (ε-caprolactone) Synthesis By A Novel Enzymatic Catalyst: Candida Antarctica Lipase B (CALB) Immobilized On A Modified Silica-based Material By Physical Adsorption

Cansu Ulker; Nurefsan Gokalp; Yuksel Avcibasi Guvenilir

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 54-59
DOI: 10.5185/amlett.2016.6058

In the present study, ring opening polymerization of ε-caprolactone was performed by a novel enzymatic catalyst, Candida antarctica lipase B (CALB) immobilized on a modified silica-based material by physical adsorption. Molecular weight distributions and chain structures were compared by using gel permeation chromatography (GPC) and hydrogen nuclear magnetic resonance ( 1 H NMR) analysis, respectively. In addition, for the determination of thermal properties, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed. Scanning electron microscopy (SEM) was applied to observe the surface structure of the polymer. Effects of temperature, reaction time, and enzyme concentration on molecular weight of poly (ε-caprolactone) (PCL) were investigated and optimum conditions for the ring opening polymerization of ε-caprolactone via this new immobilized enzyme were obtained. Highest molecular weight was achieved as 14000 g/mol at the end of 48 hours at 60 ÌŠ C. Moreover, considerably high molecular weights were successfully reached at lower temperatures by this novel enzyme, which makes this process low energy consuming besides being environmentally friendly. It is suggested that, CALB immobilized on a modified silica-based material by physical adsorption may be a great alternative for widely used commercial enzyme, Novozyme 435. This work also makes possible a new route for polymer synthesis. 

Antiferroelectric Liquid Crystal/carbon Nano Tube Duo For Achieving Modified Electro-optical properties; Aiming At Display Applications

Sharmistha Ghosh

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 60-64
DOI: 10.5185/amlett.2016.6049

Antiferroelectric liquid crystals are considered as smarter materials for display technologies owing to their faster response time over conventional nematics. However there is large scope for modifications of its physical properties. In the present study multi-walled carbon nanotubes (MWCNT) are dispersed in a high tilted antiferroelectric liquid crystal composed of rod like molecules. The effects of nano-dispersion on electro-optical and dielectric properties of the host are studied in details. The time for switching between dark and bright states and the rotational viscosity are reduced and spontaneous polarization is enhanced considerably by minute addition of MWCNTs. The high tilt angle of the molecules necessary for obtaining good dark state in displays has not changed after dispersion of nanotubes. The strong interaction of the aromatic cores of the rod like liquid crystal molecules with the honey-comb pattern of the CNT walls is considered responsible behind such improvements of physical properties of the host.

Interaction Of Bovine Serum Albumin With Synthetic Spiropyrimidines

Swarup Roy; K.C. Majumdar;Tapan Kumar Das; Sudipta Ponra; Tapas Ghosh

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 65-70
DOI: 10.5185/amlett.2016.6081

Study of interaction between synthetic spiropyrimidines (SP) with bovine serum albumin (BSA) was investigated by spectroscopy. The fluorescence of BSA was quenched by SP by means of static quenching mechanism. Using Stern–Volmer analysis of the fluorescence quenching data number of binding sites (n) and binding constants (K) at different temperatures were computed. The thermodynamic parameters enthalpy change (ΔH) and entropy change (ΔS) were calculated using Van’t Hoff equation (ΔH = -95.16 kJ/mol and ΔS = -251.49 J/mol/ K) and the results clearly indicated binding process is enthalpy-driven but entropically disfavored. The weak force van der Waals interaction and hydrogen bonding is responsible for BSA-SP complexation. Synchronous fluorescence, UV-Vis and circular dichroism (CD) spectra proposed possibility of alteration in conformation of BSA in the presence of SP. Using Forster’s non-radiation energy transfer (FRET) theory distance between the donor and the acceptor were found to be <7 nm.  

Influence Of Anodizing Time On Porosity Of Nanopore Structures Grown On Flexible TLC Aluminium Films and Analysis Of Images Using MATLAB Software

C. C. Vidyasagar; Parashuram Bannigidad; H. B. Muralidhara

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 71-77
DOI: 10.5185/amlett.2016.5967

The effect of time on nanopore structures formed via electrochemical anodization of high purity Al2O3 was investigated. The electrochemical bath consists of 5 % phosphoric acid electrolyte; a platinum electrode was used as the cathode electrode, and TLC (thin layer chromatography) aluminium film as anode electrode. It is found that the regularity of nanopores arrangement can be significantly improved by increasing anodizing time at constant temperature and voltage. It is observed after the anodizing process, that at every interval of time there is a significant decrease in wall thickness from 58-26nm and increase in the nanopore diameter size about 31-86 nm. According to Nielsch, self-ordering of porous alumina requires a porosity of 10 % independently of anodizing conditions. It means that the most optimum anodizing conditions always results in a porosity of 10 %. The result optimized at 30 min is well matched with 10 % porosity. The morphology and phase composition were characterized by field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDX). The nanopores thin film images obtained by FESEM are used for image analysis using MATLAB software and porosity and nanowall thickness results are compared with experimental and automated methods, which demonstrate the efficacy of the proposed method.

Recycled Plastic Material Properties Defined By Nanoindentation

Zdenka Prochazkova; Vlastimil Kralik; Jiri Nemecek; Michal Sejnoha

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 78-82
DOI: 10.5185/amlett.2016.6170

Introduction of recycled plastic materials in structural applications such as bridges, retaining walls or railway sleepers requires a proper identification of necessary material properties. Given similarities in the microstructure of various structural elements we limit our attention to beams having a rectangular cross-section. Owing to the manufacturing process the cross-section is represented by a porous-core (inner section) surrounded by a homogeneous material (outer section). The influence of microstructural details on material parameters is examined here with a reference to the elastic Young’s modulus derived from nanoindentation measurements. To identify a gradual evolution of the stiffness of plastic material from the outer section into the core the grid indentation method based on the statistical evaluation of a large number of indentations was adopted. These tests were accompanied by standard static indentation measurements to address also the effect of temperature in the range of 20–40°C. When dealing with these types of recycled plastics, even a 5°C temperature variation leads to a significant change in the material stiffness. In addition, standard macroscopic material properties were measured by tensile tests of samples with and without the porous core and compared with microscopic parameters. The elastic modulus obtained from nanoindentation was found to be ~20 % higher than that provided by the tensile tests. 

Structural, Growth and Characterizations of NLO Crystal: Triglycinium Calcium Nitrate

M. Esthaku Peter; P. Ramasamy

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 83-88
DOI: 10.5185/amlett.2016.5944

Single crystals of triglycinium calcium nitrate, a semiorganic nonlinear optical (NLO) material, have been grown by slow solvent evaporation technique at room temperature. The size of the grown crystal is up to the dimension of 29×19×5 mm 3 . The structure of the crystal was analyzed by single crystal X-ray diffraction and the functional groups present in the sample were identified by FTIR spectral analysis in the range 4000-450 cm -1 . The UV-vis-NIR studies was undertaken to find the transmittance in the ultraviolet and visible region. The efficiency of second harmonic generation was analyzed by Kurtz-Perry powder technique and compared with standard KDP crystal. Thermogravimetric and differential thermal analysis have been performed to determine the thermal stability of the crystal. Dielectric properties such as dielectric constant and dielectric loss were studied at various temperatures and frequencies. Vickers microhardness testing was carried out on the as-grown crystal surface to reveal the mechanical properties of the crystal. Etching studies were made on the as grown crystal to analyze the structural imperfection of the crystal.