Volume 8, Issue 5, May 2017

Invite proposals for symposium in the Advanced Materials Congresses (2017 - 2018)

Ashutosh Tiwari

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 577-577
DOI: 10.5185/amlett.2017.5001

International Association of Advanced Materials (IAAM) invites symposia proposals for our upcoming annual congresses in 2017-2018. We welcome proposals that explore interdisciplinary connections with areas of advanced materials. The symposia can include about 8-10 sessions, each session running for 2 - 3 hours. Symposia should cover the scientific subject area of Congress and proposals are encouraged to address the theme.

Progresses on structure and functionality of vapor-deposited polymers as thin films and in multilayers

Anna Maria Coclite

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 578-586
DOI: 10.5185/amlett.2017.1484

Functional organic thin films (< 100 nm) are typical components of current devices in a variety of fields, including microelectronics, biotechnology and microfluidics. The need for miniaturization and structuration has boosted the development of advanced thin film growth techniques that can be easily implemented in the manufacturing steps of current device production. This review aims at presenting the latest progresses made in the field of chemical vapor deposition (CVD) methods of organic thin films. In CVD processes, the chemicals are delivered through the vapor-phase to the substrate, without the use of solvents, with the advantage of enlarging the applicability of polymer thin films to fields where the presence of solvent is detrimental. Among other methods, the initiated Chemical Vapor Deposition (iCVD) will be reviewed. High control over chemical composition, structure and film functionality has been largely demonstrated by iCVD. This technique allows coating virtually any substrate with conformal polymers at very low energy consumption. The specific chemical composition and the nanoengineered thickness control are desirable parameters for driving application-specific properties into the material. Further development of this field will certainly lead to progresses on the use of polymers in functional devices, as electrolytes, stimuli-responsive materials, encapsulants for drug-delivery and as membranes or barriers for permeation.

Biomimetic electroconductive scaffolds for muscle regenerative engineering

Xiaoyan Tang; Yusuf Khan; Cato T. Laurencin

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 587-591
DOI: 10.5185/amlett.2017.7106

Conducting polymers are emerging as highly attractive materials since they can be used alone or in combination with other biomaterials to provide electrical stimulus for tissue regeneration. Here, we report the fabrication of a novel stimuli-responsive conducting polymer scaffold, which can be used to regulate muscle cell adhesion, proliferation and differentiation. Our goal in this study was to develop electroconductive nanofiber polymer scaffolds that can modulate the cellular physical microenvironment to increase electrical communication between cells and ultimately generate a more robust and functional construct for muscle regeneration. Matrices such as those designed here could have a significant impact in the clinical setting, where muscle atrophy and fatty infiltration prevent healing of common injuries such as rotator cuff tears. The bio-interface consists of a conducting polymer, poly (3,4ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS), with a dopamine-polymerized biodegradable substrate made from poly (ε-carprolactone) (PCL) that is rationally assembled together based on the native structure of muscle fibers. XPS analysis confirmed that poly (dopamine) deposition on the PCL scaffolds was successful. The coating of PEDOT: PSS on the poly(dopamine) modified PCL scaffolds was stable as both representative peaks were shown. C2C12 cells, a myoblast cell line was cultured on conductive substrates with different concentrations. Biocompatibility and cellular proliferation of the conducting polymer scaffolds were assessed. It was found that conducting polymers scaffolds of all groups were biocompatible. PEDOT:PSS coating of a low and medium concentration(1% and 10%) showed stimulatory effect on C2C12 growth compared to the control groups. These results showed that the presence of PEDOT:PSS at optimum concentration might enhance C2C12 cell growth and proliferation. These conducting polymer scaffolds hold great promise as biomimetic platforms for skeletal muscle regeneration.

Surface modified alumina compact: A potential material for decontamination of trivalent and hexavalent chromium and growth inhibitor of microbes from water

Himani Uppal; Nijhuma Kayal; Sneha Chawla; S. Swarupa Tripathy; Sonali Gupta; Rajni Singh; Bharti Sharma; Nahar Singh

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 592-599
DOI: 10.5185/amlett.2017.6475

A new hydrothermal approach has been investigated for synthesis of alumina which has been utilized for decontamination of trivalent and hexavalent chromium (Cr) as well as microbes from water. The heat treatment of aluminum nitrate and sucrose forms single phase g-alumina compact of 318 m 2 /g surface area at 1100 °C. The carbon particles present in aluminum nitrate- sucrose system get oxidized as carbon dioxide. The removal efficiency of synthesized alumina has been compared with commercial alumina and studied as a function of pH, time and adsorbent dose. Interestingly, synthesized alumina have better removal efficiency than commercial one. The adsorption data was best fitted to Langmuir isotherm suggesting monolayer adsorption. The adsorption capacity of the proposed material was found to be 11.76 mg g -1 and 11.9 mg g -1 for Cr (III and VI) respectively, which is better than several inorganic materials reported. The proposed alumina also inhibits growth of several bacteria like Bacillus cereus, Bacillus subtilis, Bacillus licheniformis, Staphylococcus aureus, Streptococcus pyogene, Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Salmonella typhimurium and Proteus hauseri upto 98%. The adsorption experiments were carried out in triplicate to get reproducible results. All experimental data for Cr removal has been reported with 95% confidence level (K=2).

Study of manganese germanides formation and their magnetic response

Omar Abbes; Alain Portavoce; Christophe Girardeaux; Lisa Michez; Vinh Le Thanh

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 600-604
DOI: 10.5185/amlett.2017.6908

The Mn-Ge binary system is a potential candidate to the fabrication of Spintronic devices. However, the understanding of the contribution of each possible Mn-Ge phase is crucial. In this work, the reaction between 50 nm thick Mn film and amorphous Ge substrate was studied via in-situ XRD. These experiments lead to the identification of the Mn-germanides formed during the reaction, with structural and magnetic confirmation. Besides, a sequence of germanides formation is studied and proposed. 

Effect of heating rate on microstructure and electrical properties of microwave sintered CaCu3Ti4O12 ceramics

Sandeep Kumar; Neetu Ahlawat; Navneet Ahlawat

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 605-613
DOI: 10.5185/amlett.2017.6398

In the present work, the results of microstructure, dielectric and ferroelectric investigation of microwave sintered CaCu3Ti4O12 (CCTO) ceramic with different heating rate are presented. Scanning electron micrographs revealed that grain size decreases from 1.167 µm to 0.744 µm with increased heating rate from 10ºC/min. to 50ºC/min which can be explained on the basis of phenomenological kinetic equation for grain growth. Dielectric response also found to influence by heating rate. The CCTO ceramic sintered with 50 ºC/min. exhibited highest dielectric constant (ɛr~3915) with nominal losses (0.10) at room temperature in broad frequency range from 10 2 Hz-10 5 Hz. Cole-Cole plots revealed the change in grain boundary resistivity mainly caused by the oxygen vacancy activities and affected by varying sintering heating rate. An anomaly observed for 50 ºC/min heating rate due to trapping of oxygen at grain boundaries. The remnant polarization and coercive field for CCTO ceramic sintered with 50ºC/min were 0.1 µC /cm 2 and 1.477 kV /cm respectively. Remnant polarization found to decrease while the coercive field increases with increasing heating rate applying these are micro-structural dependent.    

Impact of 1% gold’s and copper’s addition on mechanical and corrosion properties of resorbable Mg-based metallic glasses

Ryszard T. Nowosielski; K. Cesarz-Andraczke

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 614-619
DOI: 10.5185/amlett.2017.7062

In the paper the investigations’ results of the Mg69Zn25Ca5Cu1 and Mg69Zn25Ca5Au1 metallic glasses in the range corrosion mechanical, thermal and structural properties were presented. The results were obtained from compression tests, immersion and potentiodynamic corrosion tests, DTA, XRD. The bulk metallic glasses’ samples for investigations, in the form of rods, were produced by pressure casting. By the way of samples’ manufacturing the GFA (glass forming ability) of the alloys was determined. The gold’s and copper’s additions influence, first of all, for corrosion’s properties, decreasing of corrosion’s rate and increasing compression strength, in comparison with properties of resorbable Mg-Zn-Ca metallic glasses. After two hours of immersion the corrosion’s rate of the Mg69Zn25Ca5Cu1 and Mg69Zn25Ca5Au1 metallic glasses on the level 1,68 mm/year and 0,93 mm/year respectively, were determined. On account of lower corrosion’s rate and neutral impact for human body of the gold, the alloy with gold’s addition may be used as a resorbable material for medical implants.

On the effect of HPT processing conditions on relative density, mechanical properties and microstructural evolution of hot compacted AA6061– mathematical empirical and response surface approach

Waleed H. El-Garaihy; Ayman M. Alaskari; Eisa A. Ameshaiei; Samy E. Oraby

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 620-628
DOI: 10.5185/amlett.2017.1402

A loading combination of hot compaction (HC) together with high-pressure torsion (HTP) was used to consolidate discs of AA6061 considering rotations up to 4 revolutions and loading pressure values of 1 and 3 GPa. Mathematical models were established to grasp the true functional interrelationships and variations in the resulting relative densities, mechanical properties, and micro-structural evolutions as affected by the HPT processing pressure and the imposed strain. Sequential iterative nonlinear regression procedures were employed to get the most suitable mathematical relationships that express the relationship between the variables under study.  The developed models were examined for its adequacy and significance by using ANOVA analysis as well as many other statistical criteria. Response surface and contour graphs were established for a better understanding of the true functional dependence and, for a quantitative assessment of the intended relationships. It was observed that uniformity of hardness distribution increased with increasing each of the equivalent strain (εef) and the imposed pressure. A remarkable increase in the compressive strength of deformed discs has been observed. HPT processing produced a tri-model structure with micron scale grains and subgrains, and nano-scale substructure. 

Temperature dependent photoluminescence studies of Cu2SnS3/AZnO heterostructure

Sandra Dias; S. B. Krupanidhi

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 629-634
DOI: 10.5185/amlett.2017.7091

The Cu2SnS3/AZnO p-n heterojunction was fabricated and the structural and optical properties of the films were studied. The phase formation and the crystallite size of the films was analysed using X-ray diffraction. The morphology was studied using field emission scanning electron microscopy and transmission electron microscopy. The temperature dependent photoluminescence studies were conducted from 123 K to 353 K. The various possible transitions corresponding to the luminescence peaks were indexed. The intensities of the peaks were found to decrease with increase in temperature whereas there was found to be no change in the energy of emission. The chromaticity coordinates for the CTS/AZO heterojunction for different temperatures were found and it corresponded to white light emission at all temperatures.

Measurement and numerical analysis of the artificial muscles made of fishing line

Justin Murin; Vladimir Goga; Juraj Hrabovsky; Dalibor Buc; Pavel Podesva

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 635-640
DOI: 10.5185/amlett.2017.7105

This paper presents results of experimental and computational analysis of the artificial muscle (in form of coiled spring) made of nylon fishing line. By experimental measurement, the elasticity modules of chosen untwisted and twisted fishing line as well the spring constant of the coiled spring are found The prestressing force in the twisted line and the coiled spring is measured as well. The measured parameters are put into the analytical and Finite Element Method (FEM) computational model of the coiled spring to calculate the elongation that results from the applied mechanical load. Linear and non-linear numerical elastostatic analysis is performed. An expression is established for analytical calculation for the thermoelastic stroke of the muscle. A good agreement of the measured and calculated results is obtained. Contrary to analytical methods, FEM enables modeling and simulating complex mechanical structures that occur in biomechanical and mechatronic applications of the artificial muscles in a form of nylon springs.

Effect of quenching & partitioning process on a low carbon steel

Andrea Di Schino; Paolo Emilio Di Nunzio; Josè Maria Cabrera

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 641-644
DOI: 10.5185/amlett.2017.1487

Aim of this paper is to analyze the effect of manganese percentages on steel compositions. Laboratory as cast materials, in particular designed for Quenching and Partitioning process (Q&P), are here considered. The considered steel chemical composition was that of a 0.15C with 1.5Si, two different Mn contents and with no significant Al content. Two-Step Q&P heat treatments were carried out in laboratory by means of dilatometric tests. X-ray diffraction measurements have been carried out aimed to assess the retained austenite volume fraction. The tensile properties of the quenched and partitioned materials were analyzed. Results showed a marked dependence of strength, ductility and strain capacity values on heat treatment conditions.  In the case of higher austenite contents, higher uniform elongation values were found. Higher tensile properties were found in the case of higher Mn steel with respect to the lower Mn one. The main novelty of this paper consists in applying Q&P to low carbon (low hardenability steel) showing the effect of such a process on mechanical properties of steels usually adopted for automotive applications. 

Interfacial layer effect on specific heat of colloidal suspensions

Gaganpreet Chadha; Sunita Srivastava

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 645-649
DOI: 10.5185/amlett.2017.6378

A theoretical model for the specific heat of nanofluids containing oxide-based nanoparticles of different sizes and at different temperatures has been presented. The model proposed by Xuan and Roetzel has been modified by incorporating the effect of semi-solid interfacial layer, which is formed due to adsorption of base fluid molecules on the surface of nanoparticles. The contribution of this layer has been taken into account by assuming that the heat capacity, as well as the density of interfacial layer, lies between the corresponding values for the nanoparticle and the fluid and as such these have been estimated by taking the arithmetic and the geometric means of the relevant quantities. It is observed that the specific heat capacity of the nanofluid decreases with increase in particle volume fraction and that the presence of interfacial layer enhances the value even though its thickness has been taken to be only 1-2 nm as estimated by Xue et al. using molecular dynamics simulation. The effects of interfacial layer thickness, nanoparticle size, volume fraction, and specific heat ratio of particle to fluid have been discussed. The obtained results are in good agreement with some recent available experimental data.

Optical and structural properties of GaSb-doped Mn based diluted magnetic semiconductor thin films grown via DC magnetron sputtering

Jorge A. Calderón; Heiddy P. Quiroz; A. Dussan

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 650-655
DOI: 10.5185/amlett.2017.7110

In this work, diluted magnetic semiconductor GaSb:Mn thin films were grown via DC magnetron Co-sputtering on glass substrates. The effect of synthesis parameters on the optical and structural properties was determined through spectral transmittance measurements and X-ray diffraction (XRD), respectively. Substrate temperature was changed from 373 to 523 K and layer thicknesses were obtained between 200 and 330 nm. All samples were subjected to annealing process to 623 K in situ. It was found that the optical constants (refractive index (n), absorption coefficient (a), extinction coefficient (k), and energy gap (E1)) are significantly affected by the temperature and target power used during the synthesis process. In particular, a variation of the energy gap between 0.58 and 0.98 eV was obtained when the target power of GaSb varied between 80 and 140 W. GaSb, Mn2Sb and SiO2 phases were observed for lowest values of target power, where SiO2 phase is a contribution of the substrate. The dielectric function of the compound with a dependence on synthesis parameters such as, the substrate temperature and deposition time was obtained, both real (e1) and imaginary part (e2). Analysis of the XRD measurements allowed to find that the (GaSb)Mn films grow with a mixture of the GaSb and Mn2Sb phases, and an amorphous halo associated with the glass substrate. A correlation between synthesis parameters and optical properties is presented. Diluted magnetic semiconductors, like GaSb:Mn, are considered among promising materials for the development of new spin-electronic devices, high speed quantum-mechanical in computational information, other more; in this case, studies on magnetic properties in digital alloys of GaSb/Mn can be realized around of the optimization of Curie temperature.

Europium doped silicate phosphors: Synthetic and characterization techniques

Devender Singh; Suman Sheoran; Vijeta Tanwar

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 656-672
DOI: 10.5185/amlett.2017.7011

In this review article, different synthetic procedures and characterization techniques used for the development of materials are discussed briefly. The stability and high luminous intensity of silicate materials makes them practically important in the field of white light emitting diodes (WLEDs). During the experimental designing of our research, we have understood carefully the theoretical and methodological strategy regarding the synthesis of phosphors and then, a large number of silicate-based luminescent materials have been prepared using sol-gel technology. Among them, a series of silicate materials having composition M(2-x)EuxSi2O7 (M = Y, Gd, La and x = 0.03 moles) have been described in this review prepared with sol-gel process. Intense peak in europium (III) doped M2Si2O7 silicates originate from 5 D0→ 7 F2 transition of Eu 3+ ion available in crystal lattices. X-ray diffraction pattern have triclinic structure for Y2Si2O7 and Gd2Si2O7 silicate phosphors. However, hexagonal and monoclinic structures are obtained for La2Si2O7 material at different temperatures employed for further annealing. Transmission electron microscopic analysis is used to study the morphology and particle size of prepared phosphors. Excellent luminescence response of these silicate phosphors make them suitable for photonic applications and also open up new avenues for solid-state lighting, cathode ray tubes, fluorescent lamps and scintillators etc.

Effect of heat treatment on the structure and magnetic properties of Sm-Fe alloys obtained by mechanical alloying

Nikolay G. Razumov; Aleksandr S. Verevkin; Anatoly A. Popovich

Advanced Materials Letters, 2017, Volume 8, Issue 5, Pages 673-677
DOI: 10.5185/amlett.2017.7071

The effect of heat treatment on the structure and magnetic properties of Sm-Fe alloys obtained by mechanical alloying was investigated. The crystallization temperature of Sm2Fe17, an amorphous alloy obtained by mechanical alloying, was determined using differential scanning calorimetry. Based on these results, various samples were annealed at different isothermal holding temperatures, and those with the best magnetic properties were found. Experimental studies show that decreasing the isothermal holding temperature from 750 °C to 630 °C increases magnetic characteristics nearly four times. The saturation magnetization, romance and coercivity of the Sm2Fe17 powder were 121 emu/g, 28.5 emu/g and 800 Oe, respectively.