Issue 10

Asian Graphene Forum (AGF - 2017), Singapore

Ashutosh Tiwari

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 770-770
DOI: 10.5185/amlett.2016.10001

VBRI Press is pleased to announce ‘Asian Graphene Forum (AGF - 2017), Singapore during 11 – 16 March 2017, Singapore. It is a six-day international event organised by the International Association of Advanced Materials (IAAM) with the collaboration of VBRI Press AB Sweden. Forum will be held on the Diamond Princess Cruise Ship cruising from Singapore - Kuala Lumpur (Malaysia) - Penang (Malaysia) - Phuket (Thailand)- Singapore. The aim of the event is to cover the latest technology developments, applications, commercialization progress, end user requirements and challenges of Graphene and related 2D Materials.

Field Emission Image Analysis: Precise Determination Of Emission Site Density And Other Parameters

Rajkumar Patra; Anjali Singh; V. D. Vankar; S. Ghosh

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 771-776
DOI: 10.5185/amlett.2016.6368

We report a simple and detailed simulation based analysis of an experimental field emission (FE) image captured on a phosphor coated indium tin oxide (ITO)/glass plate due to the electron emission from a multiwalled carbon nanotube (MWCNT) film. Emission intensity versus effective emissive area, number of CNTs present in the film contributing emission process and number density of MWCNTs at high field (during FE process) along with other FE parameters viz. turn on field, threshold field are determined, which agrees well with experimental results. Over estimation of calculated value over experimental results is realized with creation of new emission sites at high electric field due to combined effect of divergence of electron within electrode because of electron-air molecule collision, assumption of evenly placement of emitters during calculation, damages and/or tear-off of emitters at high electric field, contribution of adsorbates of MWCNT walls and the energy loss due to absorption of phosphor atom. This analysis renders a unique way to analyze field emission data and supports the theoretical formulation to evaluate the best possible values of FE parameters.

Structural And Optical Properties Of Bulk MoS2 For 2D Layer Growth

Akhilesh Pandey; Shankar Dutta; Anand Kumar; R. Raman; Ashok K. Kapoor; R Muralidhran

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 777-782
DOI: 10.5185/amlett.2016.6364

Molybdenum-di-sulfide (MoS2) is being considered as an alternative 2-D material to graphene. Deposition of ultrathin MoS2 layer from bulk MoS2 sample is an important criterion in determining the viability of its application.  This paper discusses about growth and characterization of bulk MoS2 pellet from MoS2 powder and exfoliation of MoS2 layer from it. The MoS2 pellets were sintered at different temperatures (500 - 850 ° in nitrogen atmosphere. The sintered samples were found to be polycrystalline in nature with hexagonal flakes of 100 nm – 1.0 µm sizes. In addition to MoS2 phase, surface of the bulk samples also has also some MoO3 phase content, which was found to decrease with the increase in sintering temperature, confirmed by XRD. The optical absorption study showed MoS2 absorptions around 1.82 eV, 2.01 eV due to spin orbit and direct band to band absorption from ?k-k valley. The sintered MoS2 samples were found to have characteristic Raman peaks of A1g and E2g with a separation of 26.5 cm -1 . Ultrathin MoS2 layers, exfoliated from the sintered sample, showed the reduced separation between Raman peaks A1g and E2g of 24.5 cm -1 few layer MoS2.

Impact Of Cross Linking Chain Of N,N’-bis(napthalen-|-y|)-N,N’-bis(phenyl)-benzidine On Temperature dependent Transport Properties

M. Ramar; S. S. Rawat; R. Srivastava; S. K. Dhawan; C. K. Suman

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 783-789
DOI: 10.5185/amlett.2016.6305

The impact of cross linking chain of N, N’-bis (napthalen-|-y|)-N, N’-bis(phenyl)-benzidine (NPB) was studied for opto-electrical properties having focus on temperature dependent transport properties. The Spiro structured NPB compound is closed in itself and the thin film surface roughness is less in comparison to NTNPB compounds. Both absorptions and photoluminence shows a shift of 10 nm towards higher wavelength in case of cross linked spiro structured compound. The mobility calculated in SCLC region for NT and Spiro NPB was 1.32×10 -7 and 3.3x10 -7 cm 2 V -1 s -1 , respectively. Both the compounds show single relaxations and can be modeled as an RC equivalent circuits. The dc conductivity for both the compounds was explained by Mott’s VRH models showing 3D transport mechanism. The hopping distance for NT and Spiro NPB compounds is 0.8 and 0.5 nm, respectively. The hopping conduction process can be explained clearly using correlated barrier hopping model. The cross linking of the compounds shows two orders of less density of states.

Eco-friendly Approach: Graphene Like Boron Nitride Modified Calcium Material For The Synthesis Of 2-amino-4H-pyran-3-carbonitrile Derivatives

T. Muthu; K. Anand; M. Sureshkumar; R. M. Gengan

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 790-794
DOI: 10.5185/amlett.2016.6850

An efficient one-pot multi-component synthesis of medicinally important 2-amino-4H-pyran-3-carbonitrile derivatives using a new heterogeneous calcium loaded boron nitride (CaBNT) catalyst is described herein. This transformation transpires by Knoevenagel condensation, Michael addition and intramolecular cyclization. Alkaline earth metal-based green catalyst was successfully prepared and characterized by XRD, SEM with EDX, Raman spectroscopy, BET, DSC-TGA and FT-IR. The reaction works up is facile and CaBNT catalyst can easily be separated from the reaction mixture and re-used more than five times in subsequent reactions. This methodology offers several advantages such as excellent yields, use of inexpensive solvent and relatively shorter reaction time.

Encapsulation And Release Characteristics Of Marigold Oleoresin In Chitosan Grafted Sodium Acrylate-acrylate-co-acrylamide

Shruthi. S. B; Pratik Roy; R. R. N. Sailaja; Chandan Sengupta

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 795-801
DOI: 10.5185/amlett.2016.6342

Marigold oleoresin has been widely used in the pharmaceutical industry because of its medicinal properties. In this study, marigold oleoresin was encapsulated in chitosan grafted sodium acrylate-co-acrylamide. Emulsification process was used to prepare the beads containing marigold oleoresin and the grafted polymer was characterized using FTIR, SEM and TGA. The properties of the beads such as size, swelling characteristics, encapsulation efficiency and release kinetics were studied. The bead size was in the range of 0.46 to 1.05 mm. The antimicrobial activity and cyto-compatibility studies of marigold oleoresin were also conducted. The marigold oleoresin beads showed zero order release kinetics.

Photonic Effects On Nanostructures In The  Ti- TiO2 Interphase

C. P. Barrera-Pati

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 802-805
DOI: 10.5185/amlett.2016.6623

In this work we present a theoretical-experimental study of optics effects in nanostructures formed during the growth of titania nanotubes. Titania nanotubes were fabricated via electrochemical anodization method using Ethylene glycol. Traces or prints left by the nanotubes on the titanium surface are observed thought X-ray diffraction measurements. The pattern shows a polycrystalline structure with the presence of Anatase and titanium phases. The reflectance and absorbance spectra reveal in the traces optical phenomena similar to iridescence. The iridescence behavior is commonly found in nature and is traditionally associated to photonic properties. Using the plane wave method and modelling the nanostructures observed on the interphase like two-dimensional photonic crystals, the photonic dispersion relation was calculated in function of geometrical parameters. Enlargement of the photonic band gap was found as spatial contrast is increased. These results suggest that these types of nanostructures can be promissory candidates to develop photonic devices.

Morphology Control In The Bulk Heterojunction Blend Of Inverted Organic Solar Cell Via Co- Solvent Addition

Sarita S Nair; D Kumar

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 806-812
DOI: 10.5185/amlett.2016.6204

This work is supposed to expand the concept of solvent induced crystallisation of donor poly(3-hexylthiophene) (P3HT) polymer, to the photoactive blend of inverted organic solar cells. With the optimised concentration of cyclohexanone (CHN) co-solvent and ageing period of 2 h for the active layer precursor solution, the power conversion efficiency of a typical device increased to 3.09% compared with 2.77% efficiency achieved in a similar kind of inverted device without CHN modification. This improvement of 10% in the efficiency of inverted device with CHN addition was related to the increased current density and fill factor of the device. Increased P3HT crystallinity for efficient photo-absorption and commensurate vertical concentration gradient observed in the P3HT fractions of the blend for efficient hole transport is possibly responsible for the betterment of the photovoltaic parameters in the modified device.

Unusual Magnetism In TbRu2Ge2 Compound

Rashmi Singh; Puneet Jain; Rachana Kumar; Pramod Kumar

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 813-816
DOI: 10.5185/amlett.2016.6309

Magnetic properties of TbRu2Ge2 were studied. TbRu2Ge2 shows unusual magnetism, i.e. at low field it shows frustration (like spin glass) and at high field, this frustration starts to disappear. It has been found that TbRu2Ge2 has a TN of 37K. To confirm the frustration in TbRu2Ge2, AC susceptibility and normalized magnetization calculations were also performed .

Synthesis And Characterization Of Polymer Membranes Using Advance Analytical Tools And Techniques For Water Purification

Neha P. Ingole; Pravin G. Ingole

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 817-820
DOI: 10.5185/amlett.2016.6444

In this paper we studied the synthesis of polymer membrane materials and their characterization by various techniques such as Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), CHNS/O analysis, scanning electron microscopy (SEM), and performance in the form of volumetric flux and salt rejection. Herewith we have discussed about these techniques simply in details. The techniques are discussed as follows along with examples. Herewith we used polysulfone (PSf) membrane as a support membrane for our studies and we use all aforementioned techniques for polymer membrane characterizations. Thin film composite (TFC) membrane was prepared via interfacial polymerization (IP) on the surface of PSf membrane. The selective layer was prepared by the interfacial polymerization of 1, 3-benzenedithiol (BDT), and trimesoyl chloride (TMC) for water purification and the results have been discussed well in this paper. The result indicated that volumetric flux depends on the hydrophilicity of thin film. BDT 2 wt % and TMC 0.1 wt % solutions were found appropriate for high performance membrane. Such membrane exhibited 98.3 % salt rejection and as high as 79 L m 2 h water flux.

Thickness Effect On Nano-multilayered Sb/As2S3 Chalcogenide Thin Films

Ramakanta Naik

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 821-825
DOI: 10.5185/amlett.2016.6339

The nano multilayered thin films of Sb/As2S3 metal chalcogenide were prepared by thermal evaporation technique under high vacuum. The optical parameters such as optical band gap, tauc parameter, urbach energy were determined from the transmission spectra using Fourier Transform Infrared Spectroscopy. These properties are greatly influenced by the thickness of the nano layered Sb/As2S3 thin film. The Small Angle X-ray diffraction study reveals the amorphous nature of these films. The analysis reveals that the optical band gap decreases with increase in thickness due to Sb metal. The tauc parameter and urbach energy supports the optical property change. Such type of dependence is attributed to quantum size effect in semiconductors.

Influence Of Substrate Temperature On The Adhesion Property Of YSZ Coatings On Inconel 718 Prepared By EBPVD 

T. Dharini; P. Kuppusami; A. M. Kamalan Kirubaharan; R. Ramaseshan; Arul Maximus Rabel; S. Dash

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 826-830
DOI: 10.5185/amlett.2016.6248

The present paper reports on the measurement of coating adhesion with Inconel 718 as a function of substrate temperature in order to qualify the coatings for application in nuclear vitrification furnace.  In the present study, the scratch indentation has been used to determine the critical loads and the friction coefficient offered by the coatings as a function of the substrate temperature. It is noticed that as the substrate temperature increases from 673 to 973 K, the critical load also increases from 2.5 N to 6.1 N, while the friction coefficient remains almost constant.  Initially at lower loads, nested micro cracks which form in the coating open in the direction of the scratch track. As the scratch length increases with increasing load, the tensile cracking of YSZ gets transformed to conformal cracking. For the coatings deposited at higher temperature, chipping formation gets reduced as a consequence of improved adhesion of the coating with the substrate. This coating with an improved adhesion finds its application as diffusion barrier coating in nuclear vitrification furnace. This will reduce the faster degradation or premature failure of the components of vitrification furnace made up of Ni based super alloy. The use of YSZ diffusion barrier coating increases the durability and efficiency of the component.

Effect Of Phases On The Energetics Of Pristine InP Nanowires: An Ab-initio Approach 

Pankaj Srivastava; Avaneesh Kumar; Neeraj K. Jaiswal; Varun Sharma

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 831-835
DOI: 10.5185/amlett.2016.6240

We have investigated the electronic and structural properties of pristine Zinc-blende type InP nanowires (NWs) by using ab-initio approach. We have considered the effect of phases by taking NWs of 7 Å radii in three phases viz. (100), (110), (111). It is revealed that the electronic properties of NWs are highly affected by the wire phases. NW in (100) phase is found to be semiconducting with an indirect band gap of 0.71 eV whereas it becomes semi-metallic and metallic in other two phases. Thus, the nature of nanowires is observed as a function of NW phases. Further, energetic feasibility of InP NWs strongly dependent on their growth phase.

Effect Of TETA Microcapsules On Self-healing Ability Of Dual Component Epoxy System

Ikbal Choudhury; Sudipta Halder; Nazrul Islam Khan; Abhinav Mathur; Writuparna Nath; Aniruddha Phukan

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 836-843
DOI: 10.5185/amlett.2016.6213

To deliver epoxy composites with enhanced self-healing ability, this study investigates healing efficiency of dual component epoxy system consisting of microcapsules containing epoxy (DGEBA) and different variants of hardener (TETA) microcapsules. Morphological investigation under FESEM confirms formation of spherical shaped intact TETA microcapsules at high agitation speed with average size of the ~65.32 µm and reduced wall thickness of ~1.823 µm. Reaction temperature is found to play significant role to tune the roughness of the microcapsule surfaces. The single edge notched bending (SENB) test was performed to evaluate the healing ability. It was found that with incorporation of microcapsules, the fracture toughness decreases but the healing efficiency increases with increase in content of microcapsules. The maximum healing efficiency observed was 65.61%. High concentration of TETA microcapsule (prepared at high agitation speed) in epoxy network gives the essence for their applicability as a potential ingredient to elevate the healing efficiency. To enhance the healing ability further of the composites as well as fibre reinforced composites with unaltered mechanical properties we believe synthesis nanocapsules and their incorporation could have significant impact.

Transport Properties Of Multi-walled Carbon Nanotubes Based Conducting Polythiophene/ Polyaniline Nanocomposites 

Milind D. Deshpande; Subhash B. Kondawar

Advanced Materials Letters, 2016, Volume 7, Issue 10, Pages 844-850
DOI: 10.5185/amlett.2016.6193

In this paper, we report the influence of functionalized multi-walled carbon nanotubes (MWCNTs) on transport properties of conducting polymers polythiophene (PTH) and polyaniline (PANI). Nanocomposites based on multi-walled carbon nanotubes were synthesized by in-situ oxidative polymerization of thiophene/aniline monomer in the presence of functionalized MWCNTs. These nanocomposites have been characterized by SEM, UV-VIS, FTIR, and XRD to study the effect of incorporation of MWCNTs on the morphology, structure and crystalline of the conducting polymers. Nanocomposites have shown high electrical conductivity compared to that of pure PTH/PANI. The enhancement in conductivity of the nanocomposites is due to the charge transfer effect from the quinoid rings of the PTH/PANI to the MWCNT. The effect of MWCNT on the transport properties of PTH and PANI was systematically studied and compared in terms of transport parameters. Charge localization length and most probable hopping distance were found to be decreased with wt % of CNT, whereas the charge hopping energy was found to be increased in nanocomposites. The improved transport properties of both the types of nanocomposites due to incorporation of CNT in conducting polymer matrix can be utilized for solar cells, capacitors, electronic devices as well as chemical sensors.