Volume 5, Issue 11, November 2014


Editorial

Advanced Materials World Congress (AMWC) -2015, Sweden

Ashutosh Tiwari

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 611-611
DOI: 10.5185/amlett.2014.11001

VBRI Press AB is pleased to sponsor ‘Advanced Materials World Congress’ (AMWC) during 23-26 August, 2015, http://vbripress.com/amwc/ in Stockholm, Sweden. It is a four-day international event organised by the International Association of Advanced Materials (www.iaamonline.org), which regularly meet 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) – Tallinn (Estonia) - Stockholm (Sweden) via Mariehamn and Helsinki, Finland 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.

A Review On CdSe Quantum Dots In Sensing

Pragati Malik; Jyoti Singh; Rita Kakkar

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 612-628
DOI: 10.5185/amlett.2014.4562

The primary aim of this review is to survey the literature on the ion sensing ability of quantum dots. Sensing of both cations and anions is important, since both play significant roles in various ecological and biological processes, which makes it important to ensure their concentration at balanced level. Contamination by heavy metal ions and various anions poses a serious threat to humans, aquatic organisms, and to the environment; therefore detection of these ions (in presence of other cations and anions), which are the major cause of environmental pollution is of immense significance at the present time. Owing to their enhanced fluorescence properties and photostability, QDs offer tremendous scope to be used for ion sensing. They offer several advantages over traditional chemical fluorophores. This review throws light on the mechanism adopted by CdSe QDs to act as flourophores. Owing to their enhanced photoluminescence properties, QDs offer selective and sensitive determination of various ions, which is a function of the capping on the surface of the QD nanosensor, i.e. it is possible to tune their sensing ability by changing the capping layer, which influences the QD's interaction with various analytes. Hence, these quantum dots may prove promising candidates in future for sensing approximately all types of analytes.

Martensite Deformation And Phenomenon Of Hysteretic Shape Change In TiNi-based Alloys

Victor E. Gunther; Timofey L. Chekalkin; Ji-Soon Kim; Valentina N. Hodorenko

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 629-633
DOI: 10.5185/amlett.2014.05574

The brief overview of published articles on Nitinol studies reflects, in fact, a little misunderstanding of a thermodynamic importance since there is no whole concept or paradigm considering the martensite transition and related effects in terms of thermodynamic arguments. TiNi-based alloys are basically functional materials. They’re more important for what they do than for what they are. In order to make it easier to understand complicated behavior of TiNi-based alloys under general and special conditions, a new approach is introduced. This work was aimed at studying the hysteretic behavior of TiNi-based alloys. Mechanism of hysteretic phenomenon in TiNi-based alloys showing shape memory effect, superelasticity and ferroelasticity has been considered. Hysteretic behavior in repeatable shape memory effect was thermodynamically analyzed with the aid of Helmholtz potential formalism. Correlation of deformation, temperature and latent heat of phase transition under the constant load was established. Maximum hysteresis width achieves when the product ??? during phase transition tends to ?H, and when the product ??? tends to zero the value of ?T approximates the difference (As – Mf) or (Af – Ms).

Growth Characteristics Of Glancing Angle Deposited (GLAD) Thin Films

Alireza Dolatshahi-Pirouz

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 634-638
DOI: 10.5185/amlett.2014.7591

This paper investigates the effect of surface diffusion and re-emission on the surface morphology of GLAD thin films. This was done through GLAD of platinum and tantalum at two different surface temperatures (293 K and 153 K). The effect of shadowing during the thin film growth was examined by utilizing Atomic force microscopy (AFM) to determine the root-mean square (rms) value, the surface roughness, and thus the growth exponent β. Our results showed that β was not affected by substrate temperature during deposition, however it increased from β = 0.47 ± 0.06 to β = 0.94 ± 0.12 as the thin film material was switched from platinum to tantalum. The change in the growth exponent ??indicates that the kinetics of the film growth at grazing incidence are primarily influenced by re-emission and shadowing effects with surface diffusion playing a minor role.

Optimization Of Thickness Of Sb2Te3 Thin Film As Back Contact For CdTe Thin Film Solar Cells

Shailaja Jeetendra; Naveen C. Shivappa; Raghu Patel; Mahesh H. Matt

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 639-644
DOI: 10.5185/amlett.2014.7589

Sb2Te3 thin films of different thickness ranging from 100 to 500 nm were prepared on glass substrate by thermal evaporation method. The effects of thickness on structural, optical and electrical properties of thin films were studied. XRD revealed that grain size increases from 1.1 to 98.7 nm with increase in film thickness. The internal strain and dislocation density decreased with increase in film thickness. The optical band gap decreases from 1.3 to 0.9 eV with increase in film thickness. AFM images indicated crystalline nature of Sb2Te3. Surface roughness increased up to 400nm after which it decreased. The resistivity decreases with increase in thickness at room temperature ranging from 2.9×10 -3 to 1.35×10 -4 ohm.cm. The work function and barrier height decreases as the film thickness increases from 5.45 to 5.05eV and barrier height from 0.3 to -0.1eV. The results elucidate that Sb2Te3back contact of 400 nm thickness is ideal and efficient to be used in CdTe solar cell.

Surface Modification Of Nanocomposite Polymer Membranes By Ion Plasma Irradiation For Improving Biocompatibility Of Polymer

Narendra Kumar Agrawal; Ravi Agarwal; Kamlendra Awasthi; Y.K. Vijay; K.C. Swami

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 645-651
DOI: 10.5185/amlett.2014.nib502

Polymers are receiving great interest due to their increasing applications in various fields, especially for synthesis of biomaterial. Biomaterials are nonviable materials used in medical devices, intended to interact with biological systems. To use polymer as biomaterial they required properties like antibacterial, antimicrobial, high adhesion and wettability. Low temperature plasma treatment can offer these properties to polymers. Hence a systematic study was carried out for determining the effect of ion plasma treatment on nanocomposite polymer membranes. TiO2 nanoparticles having particle size 10-16 nm were synthesized by chemical method and used for preparation of nanocomposite polymer membranes. Argon ion plasma was used for modified polymer surface. These membranes were characterized by different techniques to identify surface and chemical modification. FTIR results shown significant modification in chemical properties, while SEM images shows increase in surface roughness of nanocomposite polymer membranes after plasma treatment. Bacterial cell adhesion and wettability were also found to be increased after plasma treatment.

Structural, Dielectric And Magnetic Properties Of 0.3CoFe2O4-0.7BaTiO3-PVDF Composite Film

Manjusha and K.L. Yadav; Manjusha;K.L. Yadav

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 652-657
DOI: 10.5185/amlett.2014.4567

Structural, Dielectric and magnetic properties 0.3 CoFe2O4–0.7 BaTiO3–PVDF (polyvinylidene fluride) composite film with different concentration of PVDF: 20, 30 and 40 wt% are reported here for the first time. The structural analysis was carried out using X-Ray diffraction technique, which indicates cubic spinel structure for ferrite phase CoFe2O4 (CFO) and tetragonal structure for ferroelectric phase BaTiO3 (BT). The average grain size was observed to be (~106 nm, 30 nm and 26 nm) for 20%, 30% and 40% addition of PVDF by using AFM analysis. The dielectric constant variation with temperature at three fixed frequencies (1 kHz, 50 kHz and 100 kHz) was studied and it was found that the dielectric constant and dielectric loss decrease with increasing amount of polyvinylidene fluride. The values of ac conductivity for 0.3CoFe2O4 – 0.7BaTiO3 –PVDF composite film were found to decrease with increasing concentration of PVDF. The ferroelectric hysteresis loops also indicate that the value of polarization decreases with the addition of PVDF and the value of remnant polarization for 20% PVDF was found to be 0.5286 µC/cm 2 . The magnetocapacitance of 0.3 CoFe2O4–0.7 BaTiO3–0.3 PVDF was found higher for this composition.

Influence Of BiFeO3 Addition On The Electrical Properties Of (Na, K) (Nb, Ta)O3 Ceramic System Using impedance Spectroscopy

Raju Kumar; Rashmi Rani; Seema Sharma

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 658-665
DOI: 10.5185/amlett.2014.3600

Polycrystalline samples of 1- x(Na0.5 K0.5)(Nb0.95 Ta0.05) ) -x(Bi Fe)O3 with x=0, 0.003, 0.005, 0.007) hereby denoted as NKNT-BF were prepared by the mixed oxide method. Preliminary structural studies carried out by X-ray diffraction technique showed the formation of perovskite structure with orthorhombic symmetry. Addition of BF in the NKNT system lowered the sintering temperature by 500C. The nature of the frequency dependence of ac conductivity of NKNT compounds follows Jonscher power law. Complex impedance and modulus spectra confirm the significant contribution of both grain and grain boundary to the electrical response of the materials. Above the ferroelectric–paraelectric phase transition temperature, the electrical conduction is governed by the thermal excitation of charge carriers from oxygen vacancies exhibiting Negative temperature coefficient (NTCR) behaviour. Detailed study on the multiferroic properties (where magnetism and ferroelectricity are strongly coupled together) of the system is under process which is likely to form key components in the development of future technology, for example, in memories and logic devices.

SHI Irradiation Induced Amorphization Of Nanocrystalline Tin Oxide Thin Film At Low Temperature

R.S. Chauhan; Vijay Kumar; Anshul Jain; Deepti Pratap; D.C. Agarwal; R.J. Chaudhary; Ambuj Tripathi

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 666-670
DOI: 10.5185/amlett.2014.nib501

Nanocrystalline tin oxide (SnO2) thin films were fabricated using pulsed laser deposition (PLD) technique. The as-deposited films were irradiated at liquid nitrogen (LN2) temperature using 100 MeV Ag ions at different fluences ranging from 3×10 13 to 3×1014 ions/cm 2 and at 75o with respect to surface normal. Pristine and irradiated samples were characterized using XRD, AFM, Raman and I-V (current-voltage characteristics) for the study of modifications in structural, surface morphological, bond angle and resistivity respectively. XRD patterns show that the pristine film is highly polycrystalline and irradiation amorphizes the film systematically with increasing the irradiation fluence. The surface of the pristine film contains nanograins of tin oxide with roughness 5.2 nm. Upon irradiation at lower fluences agglomeration is seen and roughness increased to 10.8 nm. Highest fluence irradiation again develops nanograins with roughness 7.5 nm. Raman spectra and I-V characteristics also confirms the irradiation induced amorphization. The observed results are explained in the frame work of thermal spike model.

Structural And Magnetic Properties Of Undoped And Mn Doped CdS Nanoparticles Prepared By Chemical Co-precipitation Method

Nikita H. Patel; M.P. Deshpande; Sandip V. Bhatt; Kamakshi R. Patel; S. H. Chaki

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 671-677
DOI: 10.5185/amlett.2014.1574

Undoped and Mn doped CdS nanoparticles with varying Mn concentration of 10,15 and 20 mol % have been prepared by chemical co-precipitation method with polyvinylpyrrolidone (PVP) as capping agent at room temperature. EDAX has shown that no foreign impurities are present in the synthesized nanoparticles and X-ray diffraction (XRD) revealed that undoped and Mn doped CdS nanoparticles possess cubic phase with crystallite size ranging from 4-6 nm. Transmission electron microscopy (TEM) images indicated that nanoparticle sizes are between 2-6 nm and exhibits polycrystalline nature as seen from selected area electron diffraction (SAED) pattern. Raman spectra of undoped and Mn-doped CdS nanoparticles have shown 1LO and 2LO phonon modes and their intensity ratio decreases as Mn concentration increases. Magnetic susceptibility clearly pointed out that undoped CdS behaves as diamagnetic whereas Mn doped CdS as paramagnetic and varies nonlinearly with Mn concentration in CdS. Rapid increase in magnetization below 50 K temperature is observed in M-T curves which can be assigned to Mn ions isolated in CdS crystal field or extrinsic defects. The M-H curve at 5 K and 300 K for 20% Mn doped CdS nanoparticles at different magnetic fields showed no hystersis. In near future Mn doped CdS nanoparticles can be used for application in dilute magnetic semiconductor and fabrication of solar cells. The result and discussion drawn from this work are elaborated in detail in the paper.

Synthesis Of Tb0.7Eu0.3(acac)3 Phen Organic Polymer Complex For Display Devices

P. W. Yawalkar;S. J. Dhoble

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 678-681
DOI: 10.5185/amlett.2014.amwc1033

Synthesis of volatile Eu(acac)3phen and Tb(acac)3phen complexes by solution technique were reported in this paper. The combination of Eu and Tb complexes, namely TbxEu(1-x)(acac)3phen (x=0.1,0.3,0.5,0.7,0.9) were also synthesized by maintaining stoichiometric ratio. Optical properties of these synthesized complexes were studied using photoluminescence technique. Eu(acac)3phen exhibits red intense emission at 612 nm with a sharp spectral bandwidth 5 nm when excited at a wavelength of 323nm, while Tb(acac)3 phen shows green emission at 547 nm when excited at 347nm. The emission spectra of TbxEu(1-x)(acac)3phen reveals that Tb0.7Eu0.3(acac)3 phen complex exhibits maximum intensity among all the stichiometrically doped complexes. When Tb0.7Eu0.3(acac)3 phen was molecularly doped in poly methyl Metacrylate (PMMA) to check its compatibility in polymers, enhancement in intensity was observed in these blended films, proving that these complexes can be used as emissive materials for fabricating OLEDs and displays by vacuum deposition as well as solution techniques.