Volume 7, Issue 11, November 2016

Investigation Of Density Of States And Electrical Properties Of Chemically Synthesized Ba0.5Co0.5Bi2NbTaO9 Nanoceramics

Mrinal Kanti Adak; Prasanta Dhak; Atreyee Kundu; Debasis Dhak

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 852-860
DOI: 10.5185/amlett.2016.6203

In this present work, nanocrystalline Co 2+ and Ta 5+ substituted barium bismuth niobate Ba0.5Co0.5Bi2NbTaO9 was synthesized by chemical process. Room temperature single phase, tetragonal structure was confirmed using X-ray diffraction (XRD) study. Average crystallite and particle sizes were found to be 33 nm and 40 nm, when analyzed through XRD and transmission electron microscopy (TEM) respectively. Field emission scanning electron microscopy (FESEM) was used for micro-structural investigation of samples sintered at 950?C for 4h. The investigation revealed that the material was exhibiting high dielectric constant value of 1017 at Curie temperature (Tc), 500?C when measured at 10 kHz. Impedance spectroscopy analysis showed that above 425?C, the material exhibited both bulk and grain boundary conductivities which were evidenced from FESEM studies. Density of states, minimum hoping distance, binding energy etc. were studied along with other electrical properties from impedance analysis. Hysteresis behavior was also investigated using polarization study.

Fabrication Of Cost Effective Pt And FTO-free Counter Electrode For ZnO Based Dye Sensitized Solar Cell Using Thermally Decomposed Cu2ZnSnS4 Nanoparticles

Chaitanya Bathina; Krishnaiah Mokurala; Prasanth Ravindran; Parag Bhargava; Sudhanshu Mallick

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 861-865
DOI: 10.5185/amlett.2016.6234

Use of Pt and fluorine-doped tin oxide (FTO) substrate together as a counter electrode (CE) significantly increases the fabrication cost of dye-sensitized solar cells (DSSCs). In the present study, we report the cost effective Pt and FTO-free (Cu2ZnSnS4 (CZTS) nanoparticle coated on W substrate) CE for ZnO-based DSSCs. Phase purity, the morphology and elemental composition of synthesized ZnO, CZTS nanoparticles and films were confirmed by physical characteristics such as XRD, FEG-TEM, and FEG-SEM respectively. Cyclic voltammetry study confirmed electrochemical catalytic activity of CZTS films. DSSCs fabricated with CZTS film on W and FTO substrate as CE exhibited efficiencies of 2% and 2.8%, respectively. Conventionally used Pt-based CE demonstrated an efficiency of 3.8 %.

Ionic Salt Induced Morphology And Drug Release Control Of Insulin Incorporated Biodegradable PLGA Microspheres

Himansu Sekhar Nanda; Naoki Kawazoe; Guoping Chen

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 866-871
DOI: 10.5185/amlett.2016.6907

Biodegradable polymeric microspheres have been used for microencapsulation of number of drugs for controlled delivery applications. Water-in-oil-in-water (w/o/w) double emulsion has been employed for preparation of drug incorporated poly(lactic-co-glycolic acid) (PLGA) microspheres. In the present study, existing double emulsion method was modified by introducing ionic salt in continuous phase of emulsion process. Insulin incorporated microspheres were prepared from wide range of PLGA concentrations under an identical preparation condition and the influence of varied concentration of salt on microsphere characteristics was studied. The results demonstrated, the degree of solidification of PLGA was controlled using ionic salt and the prepared formulations showed improved morphology, enhanced encapsulation efficiency and a positive modulation over the drug release characteristic compared to control. The modified method should be useful for elimination of highly porous and collapsed microspheres in the formulations prepared from low range PLGA concentration and should pave the way to improve several microsphere formulations for controlled drug delivery applications.

Study Of Water Transport Behaviour In Polylactide Plates Filled With Rice Hulls

Bwire S. Ndazi; Sigbritt Karlsson

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 872-877
DOI: 10.5185/amlett.2016.6087

The influence of sorption temperatures and rice hull content on diffusion, permeability and solubility of water into PLA has been investigated by theoretical models with the support of experimental data. As expected and experimentally demonstrated water transport rates was higher at higher temperatures. This agrees with the increase in diffusion (D = 0.67 to 3.45?10 -11 m2/s) and permeability (P = 0.33 to 0.55?10 -13 m2/s) obtained by Equation (1). In contrast, the decrease in solubility from S = 5.0?10-3 to S = 0.54?10-3 as temperature was increased from 23?C ?70?C confirms the reduction of PLA’s permeable domains during hydrolysis. Change in molecular weight confirms that hydrolysis was reaction controlled. Furthermore, S, D and P decreased with the increase of rice hull in PLA from 0 to 40 %, contrary to experimental results of Figs. 2 and 3. Rice hull was expected to enhance diffusion and permeability of water into PLA on the fact that being hydrophilic, rice hull do not bond perfectly with PLA leading to more permeable products. This leads to the conclusion that the mathematical relations applied need to be modified to account for other factors such as interface properties, type and form of fillers and chemical reaction of the polymer in order to predict reliably water transport behaviour in filled PLA or similar polymers.

Facile And Efficient Strategy For Removal Of Reactive Industrial Dye By Using Tea Waste

Arif Reza; Faheem A Sheikh; Hern kim; Mohammad Afzal Zargar; M. Zainal Abedin

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 878-885
DOI: 10.5185/amlett.2016.6363

The present study deals with the study tea waste as an effective functional adsorbent for the removal of reactive blue 21(RB21) from aqueous solutions. The batch adsorption experiments were influenced by several parameters such as contact time, solution pH and mass of adsorbent and initial dye concentration. The results indicated that the maximum removal of RB21 dye by tea waste was after 90 minutes of contact time and at the nearly neutral pH of 6.0. Moreover, two isotherm models, namely Langmuir and Freundlich adsorption isotherm were used to describe the adsorption equilibrium of RB21 dye onto tea waste. The data obtained was in good agreement with Langmuir model than that of Freundlich model, showing a monolayer adsorption capacity of 28.99 mg/g. Furthermore, it was observed that tea waste did not require any supplementary pre-treatments; such as activation before the application. Collectively, this work highlights the promise of pristine TW, ability to harness it for adsorption of dyes, while also prioritizing areas for future research and development (e.g., collection of TW from local vendors and resulting in environmental friendly disposal of the same). The presented strategy exhibited excellent adsorption capacity of TW for the removal of RB21 from the aqueous solutions. Nonetheless, in most parts of the globe TW from local vendors is available without any cost, regeneration is not required and the saturated adsorbent can be disposed by incineration.

Characterization And Synthesis Of Bi2Se3 Topological Insulator Thin Film Using Thermal Evaporation

Bushra Irfan;Ratnamala Chatterjee

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 886-890
DOI: 10.5185/amlett.2016.6208

Topological insulators are the new phase of matter with bulk insulating and conducting surface states. Among the known three dimensional topological insulators, bismuth selenide (Bi2Se3) is one of the most promising materials for studying topological insulating properties. Bi2Se3 thin films are grown using thermal evaporation technique and atomically smooth films are obtained by post annealing treatment. Pure phase of Bi2Se3 is confirmed using x-ray diffraction; Raman spectroscopy shows a strong intensity of A 1 1g, E 2 g and A 2 1g 2Se3 thin films. The surface studies on these films are carried out using scanning electron microscopy and atomic force microscopy. X-ray photoelectron spectroscopy (XPS) is used for elemental analyses in Bi2Se3 thin film. The surface quality of the film is improved with plasma etching (i.e. argon etching) in XPS. High quality Bi2Se3 thin films can be used further for investigation on transport properties of topological insulators.

Room Temperature Ferromagnetism In ITO And Ni Doped ITO

Seelam Harinath Babu; Shaik Kaleemulla

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 891-896
DOI: 10.5185/amlett.2016.6391

To fabricate spintronics devices with easy of processing we require reliable dilute magnetic semiconductors (DMS) at room temperature. Here we report the development of DMS material based on Indium tin oxide (ITO) with optimal tin concentration ((In0.95Sn0.05)2O3). The ITO and Ni-doped ITO nanoparticles were synthesized in quartz tube under reduced pressure at elevated temperature. The stoichiometric samples were crystallined in cubic bixbyite structure with change in the unit cell volume with Ni doping and shown average particle size of 50 nm in electron micrographs. Estimated energy band gap of Ni-doped ITO is found to be 3.15 eV. The magnetic properties of materials revealed that optimal doping of Sn gives highest magnetization and further increase of doping with Ni 2+ ions in In 3+ sites lead to deterioration of ferromagnetism induced by Sn 4+ . The observed ferromagnetism is attributed to the localized ferromagnetic exchange interactions induced by spin polarized electrons trapped in oxygen vacancies. The deterioration of ferromagnetism is attributed to excess anionic vacancies created by Ni doing and promotion of antiferromagnetic exchange with increase of Ni 2+ ion concentration as evidenced from magnetic hysteresis loop at 100 K.

Urea-phenol-formaldehyde Microcapsules Containing Linseed Oil For Self-healing Anticorrosive Coating Applications

Deepak Patil; Ajay Vasudeo Rane; K Kanny; Abitha V K; Anagha Sabnis

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 897-902
DOI: 10.5185/amlett.2016.6399

Novel self-repairing Urea-Phenol-Formaldehyde (UPF) microcapsules containing linseed oil were prepared via in-situ polymerization in an oil-in-water emulsion. The main purpose of encapsulation is to control the release of linseed oil, when external conditions such as mechanical stress or energy cause microcapsules to break. These controlled release mechanisms of linseed oil make them suitable for application in self-healing coatings. Chemical structure analyses of microcapsules were studied by Fourier transform infrared spectroscopy (FTIR), optical microscopy and scanning electron microscopy for their structural & morphological illustrations. Controllable particle sizes were determined under optical microscope and as well using particle size analyzer. To determine the healing efficiency, the microcapsules, were incorporated in the epoxy coatings in varying proportions. The effects of the same on anti-corrosion performance was carried out in 5% NaCl aqueous solution (ASTM B117) and Decreasing trend of pencil hardness, scratch hardness, Impact resistance with the increase in concentration of microcapsules was observed. Chemical resistance could also be attributed to the presence of aromatic structures in epoxy which impart chemical stability. Secondary hydroxyl moiety in epoxy chain forms hydrogen bonding with the metal substrate that would contribute to good adhesive forces. Epoxy coatings incorporated with microcapsules showed better corrosion resistance than neat epoxy coating, where neat epoxy coating showed rust and spreading of rust observed on tested panel. Mechanical properties decreased on incorporating microcapsules into epoxy matrix, hence development of mechanical properties without effecting the corrosion properties shall be studied further.

Nanocrystalline Diamond Films As A Protective Coating For Implantable Bio- Devices

Rishi Sharma; Neelima Sharma; Rahul Parmar; Vijay Chatterjee; Anoop Kumar; N. Woehrl; V. Buck; P. K. Barhai

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 903-909
DOI: 10.5185/amlett.2016.6050

Nanocrystalline diamond (NCD) films are deposited on silicon substrates using Microwave Plasma Enhanced Chemical Vapor Deposition technique with the variation of microwave power from 800 W to 1800 W at 200 mbar for 5 hrs. Methane is used as a precursor along with argon and hydrogen as carriers for deposition. Deposited films are characterized by using Raman, FTIR, optical contact angle, AFM and SEM. The biocompatibility study has been carried out by cell viability assay, haemolysis test and simulated body fluid (SBF) adsorption assay. The Lymphocytes and Fibroblast cell lines are cultured on the NCD coated samples and cell viability has been determined by MTT assay. The surface morphology of the samples has been studied by using AFM, before and after interaction with SBF. It has been observed that NCD coated substrates are biocompatible, haemocompatible and also promote the growth of the cells, while the uncoated substrates cause cell death.

Tunable Silver Nano-ink For Printable Electronics And Pen-on-paper-writing

Neha Singh; Jyoti Srivastava;Pawan K. Khanna; Priyesh V. More

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 910-917
DOI: 10.5185/amlett.2016.6350

The article describes an efficient method for the preparation of silver nanoparticles ink for its application in printed electronics. The effective formulation using polyvinylpyrrolidone (PVP) and triethylamine leads to highly stable silver nano-ink. The spin-coated silver nanoparticulate films fabricated using the as-prepared nano-ink exhibit bulk-like conductivity at moderate annealing temperature of 60°C -100°C. Additionally; pen-on-paper type of conventional writing is successfully demonstrated with modifying the formulation of such nano-inks. The viscosity of as-prepared Ag nano-ink can be easily altered by varying the concentration of binders and solvents to suit its end applications. Such flexibility coupled with high conductivity and amphiphilic nature makes this silver nano-ink highly useful in various advanced printing techniques.

Effect Of Sr-substitution On Structural, Dielectric And Impedance Characteristics Of MPB-PZT

Patri Tirupathi; Anil Tejomurthula; Nawnit Kumar; Mukul Pastor; R. N. P. Choudhary

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 918-925
DOI: 10.5185/amlett.2016.6233

The polycrystalline sample of Sr-modified Pb(Zr0.5Ti0.5)O3 (i.e. Pb1-xSrx(Zr0.5Ti0.5)O3 (x = 0.05-0.15)) ceramics were synthesized (close to morph-tropic phase boundary) by a cost effective (solid state reaction) method. Detailed investigation of structural phase transition was carried out using room temperature X-ray diffraction data adopting Rietveld refinement technique. The coexistence of two crystal phases (i.e., tetragonal (P4mm) and rhombohedral (R3c) for x = 0.05, and single tetragonal (P4mm) phase for x = 0.1, 0.15) were observed. Elemental analysis, grain shape and size distribution were studied using scanning electron microscope. The decrease in grain size on increasing Sr 2+ concentration was also observed. Detailed analysis of temperature and frequency dependence of dielectric exhibits the increase in dielectric permittivity as function of Sr 2+ concentration at room temperature. Beside this, the greatly reduced Curie (TC) temperature and broadening of dielectric maxima as function of increasing Sr 2+ concentration in PZT was observed. The multiple relaxation processes associated with grain, grain boundaries and interfacial polarization was noted for x=0.05 and x=0.10 to analyze the Nyquist plots. The dominant of grain boundary resistance with increasing in dopent concentration x=0.15 was observed.

Studies On The Role Of Co-oxidant And Surfactant In Interfacial Polymerisation Of Polyaniline Nanofibers And Its Nonlinear Optical Limiting Applications

Divya P. R; P. M. Sabura Begum; Rani Joseph; Indu Sebastian

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 926-932
DOI: 10.5185/amlett.2016.6293

Herein, we have prepared Polyaniline (PANI) nanofibers by interfacial polymerization in the presence of co-oxidant and surfactant. The additives are found to have a profound impact on the polymers morphology and improved room temperature conductivity. It was found that PANI nanofibers prepared in the presence of aqueous sodium hypochlorite solution (NaOCl) and cetyl trimethyl ammonium bromide (CTAB) were of shorter diameter (30 nm) and high conductivity (6.59Scm -1 ) than those formed in the absence of those chemicals. The diameter of the fibers was intricately tuned by changing the ratio of NaOCl to aniline. The effect of co-oxidant and surfactant concentration in the nanofibers has been investigated with the help of SEM, IR, XRD, UV and conductivity studies. A comparative investigation with other surfactant sodium dodecyl sulphate (SDS) has been done and the variations in diameter were noted. We also studied the third-order optical nonlinearity and optical limiting properties of polyaniline nanofibers using a single-beam z-scan technique. The experiments were performed with a Nd-YAG laser at wavelength of 532 nm The mechanism behind nonlinear absorption could be predicted as two photon absorption. The results show that the polyaniline nanofibers have useful applications in futuristic nonlinear optics.

Alumina Nanoparticles: A New And Reusable Catalyst For Synthesis Of Dihydropyrimidinones Derivatives

Jay A Tanna; Ratiram Gomaji Chaudhary; Nilesh V Gandhare; Harjeet D Juneja

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 933-938
DOI: 10.5185/amlett.2016.6245

Present study demonstrates the synthesis of alumina nanoparticles (NPs) by sol-gel method and characterized by various standard microscopic techniques like Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Energy Dispersive Spectroscopy (EDS), FT-IR, UV-visible, and Thermogravimetry-Differential Thermogravimetry (TG-DTA) to evaluate the size, shape and composition of nanoparticles. Furthermore, a solvent free green synthesis of 3, 4-dihydropyrimidinones derivatives were carried by using alumina nanoparticles (γ-Al2O3 NPs) as a catalyst through Biginelli reaction of aromatic aldehydes, β-ketoesters, and urea. The structures of the obtained products were confirmed by Fourier transform infrared (FT-IR), and proton nuclear magnetic resonance ( 1 H NMR) spectra. Effective results were obtained by using nano catalyst. Therefore, present protocol is favored as it offers advantages of higher productivity, short reaction times, simplicity and easy workup. Besides, catalyst is an inexpensive, reusable and recyclable up to four cycles without loss of its activity.

Synthesis And Characterization Of Silver Nanoparticles With Natural Carbohydrate Capping Using Zataria Multiflora

Alireza Ebrahiminezhad; Saeed Taghizadeh; Aydin Berenjian; Amid Rahi; Younes Ghasemi

Advanced Materials Letters, 2016, Volume 7, Issue 11, Pages 939-944
DOI: 10.5185/amlett.2016.6458

For the first time, green synthesis of silver nanoparticles was developed by treating Ag + ions with Zataria multiflora leaf extract. Leaf extract quantity, AgNO3 concentration and reaction temperature were determined as significant factors in the bioreduction reaction. Carbohydrates of the leaf extract were identified as the effective compound for reduction and capping of AgNPs. Also, TEM micrographs illustrated that micro and nano scale carbon-based materials act as structural scaffold for nucleation and growth of particles. Oxygen-bearing functional groups were identified as active groups for reduction of Ag + ions. The prepared particles were spherical from 16.3 nm to 25.4 nm with mean particles size of 20.3 nm.