Kamel Chaari; Jamel Bouaziz; Khaled Bouzouita
Abstract
Biomedical porous fluorapatite scaffolds were fabricated using an improved polymeric sponge replication method. The specific formulations and distinct processing techniques such as the mixture of water and dispersant (Sodium TriPolyPhosphate) as solvent, the multiple coatings with the desired viscosity ...
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Biomedical porous fluorapatite scaffolds were fabricated using an improved polymeric sponge replication method. The specific formulations and distinct processing techniques such as the mixture of water and dispersant (Sodium TriPolyPhosphate) as solvent, the multiple coatings with the desired viscosity of the Fap slurries were duplicated from Chaari et al. [11]. The heat treatment was conducted in two stages: a delicate stage of polymeric structure degradation at 290 0 C and then at 600 0 C followed by a sintering stage at 1000 0 C for three hours. The obtained porous Fap scaffolds had uniform porous structures with completely interconnected macropores of 850 μm. In addition, micropores of 4 μm were formed in the skeleton of the scaffold. Finally, the porous Fap scaffold with a porosity of 65 vol.% and a surface of 400 mm 2 had a compressive strength of 7 MPa.
Zahra Rezvani; Mazaher Gholipourmalekabadi; Saeid Kargozar; Peiman Brouki Milan; Masoud Mozafari
Abstract
In this study, organic montmorillonite (OMMT) is a modified form of montmorillonite (MMT) in which chitosan (CS) intercalated MMT by ion exchange of sodium ions from Na/MMT with –NH3 + of CS. The structural analysis confirmed intercalation of CS into MMT layers, indicating that CS molecular chains ...
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In this study, organic montmorillonite (OMMT) is a modified form of montmorillonite (MMT) in which chitosan (CS) intercalated MMT by ion exchange of sodium ions from Na/MMT with –NH3 + of CS. The structural analysis confirmed intercalation of CS into MMT layers, indicating that CS molecular chains incorporated into the MMT layers. The interlayer distance of the MMT layered was 1.128nm and in the OMMT layers enlarged to 2.365 nm. Antibacterial activity analysis showed that unmodified MMT could not inhibit the growth of bacteria. Nevertheless, after addition of the CS molecules, an increase in the interlayer distance of MMT was observed. No difference was observed between the viability of the human dental pulp stem cells (hDPSCs) contacted to different concentrations (ranging from 0.5 to 2mg/ml) of MMT and OMMT in all time intervals, when compared with the control samples. Furthermore, neither MMT nor OMMT showed apoptosis and cytotoxicity effect on the cells. The strong antibacterial activity of the synthesized OMMT nanocomposite was also confirmed against E. coli, S. aureus, K. pneumonia and P. aeruginosa, suggesting its high potential for the prevention of post-surgical infections.
E. Donnelly; F. M. Weafer; T. Connolley; P.E. McHugh; M. S. Bruzzi
Abstract
For many years, computational modelling and simulation studies have been used by developers to advance device design and have been reported in regulatory medical device submissions. However, cardiovascular stent materials in such computational models are typically assumed to behave as a continuum. This ...
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For many years, computational modelling and simulation studies have been used by developers to advance device design and have been reported in regulatory medical device submissions. However, cardiovascular stent materials in such computational models are typically assumed to behave as a continuum. This approach assumes that bulk material properties apply to the micro-sized structure, i.e. material behavior is scale independent. However, as size is reduced, mechanical size effects arise as the grain size to specimen width ratio drops below a critical value. These size effects cause material behavior to deviate significantly from bulk material behavior. If such a deviation in material behavior is to be captured within computational models, it is necessary to represent the crystalline structure of a metal and to capture the anisotropic behavior of individual grains within these models. This paper describes the development of such a modelling methodology to investigate the phenomenon of strain localization within grains of a 316L stainless steel specimen under fatigue loading conditions.
Toshinori Okura
Abstract
This review article describes a series of studies on the glass-ceramic Na + superionic conductors with Na5YSi4O12 (N5)-type structure synthesized using the composition formula of Na3+3x-yR1-xP < em>ySi3-yO9 for a variety of rare earth elements, R, under the appropriate composition parameters. Recent ...
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This review article describes a series of studies on the glass-ceramic Na + superionic conductors with Na5YSi4O12 (N5)-type structure synthesized using the composition formula of Na3+3x-yR1-xP < em>ySi3-yO9 for a variety of rare earth elements, R, under the appropriate composition parameters. Recent researches on structural control of the Na + superionic conducting glass-ceramics are also introduced. The optimum conditions for crystallization were discussed with reference to the conduction properties and the preparation of crack-free N5-type glass-ceramics. The effects of Si substitution with the various elements with tetrahedral oxygen coordination structure and Y substitution with the various R elements were also discussed on ionic conductivity of N5-type glass-ceramics, respectively.
Jin-Woo Park; Kwang-Ho Kim; Nong-Moon Hwang
Abstract
The effect of the substrate bias on the diamond deposition was studied using a hot filament chemical vapor deposition (HFCVD) reactor. Both growth rate of diamonds and sp < sup > 3 /sp < sup > 2 ratio increased with increasing the substrate bias from – 200 V to + 45 V. At + 60 V where ...
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The effect of the substrate bias on the diamond deposition was studied using a hot filament chemical vapor deposition (HFCVD) reactor. Both growth rate of diamonds and sp < sup > 3 /sp < sup > 2 ratio increased with increasing the substrate bias from – 200 V to + 45 V. At + 60 V where the DC glow discharge occurred, however, the data deviated significantly from the tendency. These results were explained by the new concept of non-classical crystallization, where a building block of diamond growth is a charged nanoparticle rather than an atom. Based on the previously reported experimental confirmation of the gas phase generation of negatively-charged diamond nanoparticles, the bias effect on the diamond deposition behavior could be consistently explained.
Premanshu Jana; Santanu Mandal;Koushik Biswas; Ponnarassery S Jayan
Abstract
The isothermal aging characteristics of rare earth magnesium hexaaluminate (REMHA) based thermal barrier coatings (TBC) such as lanthanum magnesium hexaaluminates (LMHA), Neodymium doped LMHA (LNMHA) and LNMHA-Yttrium aluminium garnet (YAG) composite were evaluated at 1400 °C and compared with standard ...
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The isothermal aging characteristics of rare earth magnesium hexaaluminate (REMHA) based thermal barrier coatings (TBC) such as lanthanum magnesium hexaaluminates (LMHA), Neodymium doped LMHA (LNMHA) and LNMHA-Yttrium aluminium garnet (YAG) composite were evaluated at 1400 °C and compared with standard yttria stabilized zirconia (YSZ) coating. The platelet structure of hexaaluminate forms meso-porous structure and provides superior sintering resistance than YSZ coating. Faster grain growth kinetics is observed in YSZ coating as compared to hexaaluminate-based coatings. As a result, the mechanical properties of YSZ coating deteriorate severely whereas hexaaluminate based coating remains almost unaltered. The LNMHA coating is found to be the best sintering resistance among them. LNMHA and LNMHA-YAG composite have potential to meet the requirement of advanced TBC operating even at 1400 °C.
Miloš Janeček; Peter Minárik; Tomáš Krajňák; Kristína Bartha; Josef Straskuy; Jakub Cizek
Abstract
Mg22Gd alloy was processed by high pressure torsion (HPT) at room temperature and the pressure of 2 GPa. A series of specimens with different number of rotations N (N = 0-15) was prepared from the initial coarse grained as cast material. Mechanical properties were investigated by microhardness mapping. ...
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Mg22Gd alloy was processed by high pressure torsion (HPT) at room temperature and the pressure of 2 GPa. A series of specimens with different number of rotations N (N = 0-15) was prepared from the initial coarse grained as cast material. Mechanical properties were investigated by microhardness mapping. The microhardness was found to increase with increasing strain imposed by HPT and tend to saturate at about HV = 145. The microstructure (phase morphology and composition, etc.) evolution with strain was investigated by scanning electron microscopy and EDS. High Gd content in the alloy resulted in the precipitation of stable Mg5Gd phase. This phase exhibited apparently higher hardness than the magnesium matrix. During straining the phase was continuously fragmented and only tiny particles were found in heavily strained material. Electron back scatter diffraction (EBSD) and automated crystallographic orientation mapping in transmission electron (ACOM-TEM) were employed to characterize the fragmentation of the grain structure. HPT was found to result in strong grain refinement by the factor of approximately 1000. The dislocation density was determined by positron annihilation spectroscopy. Significant twinning was found in the initial stages of HPT straining. At high strains twin formation was suppressed and only dislocation storage in the material occurs.
Balakrishnan G; Elangovan T; Shin-Sung Yoo; Dae-Eun- Kim; Kuppusami P; Venkatesh Babu R; Sastikumar D; Jung il Song
Abstract
Nanostructured single layer aluminium oxide (Al2O3), single layer zirconium oxide (ZrO2) and the (Al2O3/ZrO2) nano multilayer films were deposited on Si (100) substrates at an optimized oxygen pressure of 3×10 -2 mbar at room temperature by pulsed laser deposition. The Al2O3 layer was kept constant ...
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Nanostructured single layer aluminium oxide (Al2O3), single layer zirconium oxide (ZrO2) and the (Al2O3/ZrO2) nano multilayer films were deposited on Si (100) substrates at an optimized oxygen pressure of 3×10 -2 mbar at room temperature by pulsed laser deposition. The Al2O3 layer was kept constant at 5 nm, while ZrO2 layer thickness was varied from 5 nm to 20 nm. The X-ray diffraction (XRD) studies of single layer of Al2O3 film indicated the cubic γ-Al2O3, while the single layer of ZrO2 indicated both the monoclinic and tetragonal phases. The Al2O3/ZrO2 multilayer films of 5/5 nm and 5/10 nm indicated the tetragonal phase of ZrO2 with nanocrystalline nature. The FESEM and AFM studies showed the dense and smooth morphology of the films. The pin-on disc revealed that the 5/10 nm multilayer film has low friction coefficient ~ 0.10. The wear rate of multilayers film is half of the wear rate of the single layer films and 5/10 nm multilayer film showed a reduced wear rate when it is compared to other single and multilayers. The Al2O3-ZrO2 ceramics find wide applications in wear and corrosion resistance components, high temperature applications and bio-implant materials.
Nelson H. A. Camargo; Eliakim E. G. de Borba; Priscila F. Franczak; Enori Gemelli
Abstract
Microporous calcium phosphate biomaterials are known for their physical and biological applications. Among the best known are the stoichiometric hydroxyapatite (HA) and tricalcium phosphate (TCP). This is because these biomaterials exhibit chemical and crystallographic compositions which are similar ...
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Microporous calcium phosphate biomaterials are known for their physical and biological applications. Among the best known are the stoichiometric hydroxyapatite (HA) and tricalcium phosphate (TCP). This is because these biomaterials exhibit chemical and crystallographic compositions which are similar to that found in bones and teeth. The use of nanotechnology enables obtaining calcium phosphate nanostructured powders and calcium phosphate nanocomposite matrix formed by a second nano phase of type SiO2, TiO2, Al2O3-a, ZrO2, Mg. Different methods and techniques for the synthesis and preparation of nanostructured powders and biomaterials are noted in the literature, but it is known that not all lead to the same results. Calcium phosphates nanostructured biomaterials are a new class of biomaterials which provide new physical, morphological, nanostructural and microstructural features with interconnected microporosity which are promising to wettability, capillary action, cell adhesion and proliferation on the surface of grains and micropores. Based on research of these biomaterials, it has been found that they show potential applications in traumatology, orthopedic and dental applications in reconstruction, defects and bone tissue repairing, implants attachment and dental remineralization treatment. This study was aimed at the sintering and characterization of an HA matrix and three nanocomposite biomaterials with 5% by volume of the respective second phases: SiO2, ZrO2 and Al2O3-a in the HA matrix. The HA powder and nanocomposite HA/SiO2 were sintered at 1100 °C/2h. HA/ZrO2 nanocomposite powder followed two sintering conditions: a temperature of 1100 °C/2h and the other, at 1300 ºC/2h. HA/Al2O3-a nanocomposite powder was only sintered at 1300 ºC/2h. The biomaterials were characterized by scanning electron microscopy, X-ray diffraction and open porosity and hydrostatic density were also determined by applying the Arthur method. The results are encouraging and show for HA, HA/SiO2, HA/ZrO2 biomaterials (obtained by sintering at 1100 °C) interconnected microporous microstructures, formed by fine grains which are favorable for the expected wettability and capillarity characteristics.
Sandeep K. Pundir; Sukhvir Singh; B. Sivaiah; Rajesh Kumar; Ajay Dhar
Abstract
Thermoelectric properties of n-type bismuth telluride and its nanocomposite reinforced with different concentration of multi wall carbon nanotubes (MWCNTs) are reported. Nanocomposites of bismuth telluride with MWCNTs were synthesized by using high energy ball milling followed by spark plasma sintering ...
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Thermoelectric properties of n-type bismuth telluride and its nanocomposite reinforced with different concentration of multi wall carbon nanotubes (MWCNTs) are reported. Nanocomposites of bismuth telluride with MWCNTs were synthesized by using high energy ball milling followed by spark plasma sintering (SPS). MWCNTs reinforced nanocomposites of bismuth telluride resulted improvement in its figure of merit ZT from 0.76 (for Bi2Te3) to 0.85 (for Bi2Te3 + 2%MWCNTs) at 473K temperature. Thermoelectric parameters of nanocomposites of Bi2Te3 were characterized by Laser Flash Technique. The improvements found in ZT value may be due to decrease in thermal conductivity of the nanocomposites. Concentration of MWCNTs in bismuth telluride leads to dampening the phonon propagation with addition to the interface scattering of phonons from phase boundaries as well as grain boundaries which leads to decrease in thermal conductivity.
Anal K. Jha;Kamal Prasad
Abstract
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. ...
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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.
Zdenka Prochazkova; Vlastimil Kralik; Jiri Nemecek; Michal Sejnoha
Abstract
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 ...
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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.
Anal K. Jha; K. Prasad
Abstract
Biosynthesis and characterizations of nanoparticles has become an important branch of nanotechnology nowadays. In this paper, green synthesis of silver nanoparticles (AgNPs) using the alcoholic extract of Argemone mexicana Linn. as a reducing and stabilizing agent, has been discussed. This biosynthetic ...
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Biosynthesis and characterizations of nanoparticles has become an important branch of nanotechnology nowadays. In this paper, green synthesis of silver nanoparticles (AgNPs) using the alcoholic extract of Argemone mexicana Linn. 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, transmission electron microscopy and UV-Visible spectroscopic techniques. Nanoparticles almost spherical in shape having a size of 2-6 nm are found. UV-visible study revealed the surface plasmon resonance at 414 nm. A possible involved mechanism for the biosynthesis of silver nanoparticles has also been proposed. Further, it was found that AgNPs sol when applied to the SiHa cancer cell line was found to inhibit the growth by 70-80%. It is cumulative effect of the unutilized plant extract and nanosilver. The work signifies the importance of medicinal plants in synthesis of nanomaterials as it bestows double benefit in terms of drug delivery as well as safety. It may open a fresh avenue in future cancer therapeutics.
M. R. Biswal; J. Nanda; N. C. Mishra; S. Anwar; A. Mishra
Abstract
Multiferroic bismuth ferrites (BFO) and Ni substituted bismuth ferrites (BFNO) were synthesized by standard solid state reaction route. The structural and microstructural studies were carried out. The effect of Ni substitution on dielectric constant and dielectric loss of the samples was studied in a ...
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Multiferroic bismuth ferrites (BFO) and Ni substituted bismuth ferrites (BFNO) were synthesized by standard solid state reaction route. The structural and microstructural studies were carried out. The effect of Ni substitution on dielectric constant and dielectric loss of the samples was studied in a wide range of frequency (100 Hz- 1 MHz) and temperature (27 o C – 420 o C). It has been observed that the dielectric constant increases with increase in Ni doping concentration and attained a maximum value for BFNO(x = 0.075) sample while the dielectric loss has been found to decrease with the doping concentration. This implies a reduction in the conductivity and hence improved the dielectric properties of Ni doped BFO. The anomalous peaks in temperature dependent dielectric studies indicate the increase in antiferromagnetic ordering temperature and possible existence of spin glass states upon Ni substitution in place of Fe. The complex impedance spectroscopic analysis suggests purely the intrinsic nature of the dielectric anomalies. Temperature dependent non-Debye type of dielectric relaxation has also been observed. The Nyquist plots show the negative temperature coefficient of resistance behavior of these compounds. Further it would be interesting to study their magnetic and magnetoelectric properties with the aim of identifying new multifunctional device applications.
Samir Mansour; Naima Boutarek; Sif Eddine Amara
Abstract
The present work is a continuation of research on alloys based on iron, with the aim to understanding the solidification behaviour of Fe-V-Nb alloys. Solidification sequences are proposed in relation to the observed microstructures for Fe-V-Nb synthesis alloys. Fe-V-Nb binary alloys with different concentrations ...
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The present work is a continuation of research on alloys based on iron, with the aim to understanding the solidification behaviour of Fe-V-Nb alloys. Solidification sequences are proposed in relation to the observed microstructures for Fe-V-Nb synthesis alloys. Fe-V-Nb binary alloys with different concentrations are arc melted and characterized systematically by means of differential thermal analysis, optical and scanning electron microscopy coupled to an energy dispersive X-Ray microprobe analysis, quantitative XRF spectrometry and X-Ray diffraction. In the present work, the thermal and microsructural behavior of Fe–V –Nb alloys with different concentrations have been studied with the aim of answering some questions and especially paying attention to the microstructures and temperature transition. Two primary surfaces are identified: a(Fe) and Fe2Nb. Moreover, one invariant line is also identified as a binary eutectic reaction (L « a + Fe2Nb), which is clearly shown according to the observed microstructure. In perspective, other shades of this ternary alloy will be studied for a path projection of liquidus surface.
S. Behera; Piyush R. Das; B. N. Parida; P. Nayak; R. N. P Choudhary
Abstract
The polycrystalline sample of complex tungsten-bronze compound Li2Pb2Sm2W2Ti4Ta4O30 was prepared by a high-temperature solid-state reaction technique. Room temperature X-ray diffraction (XRD) study suggests the formation of a single-phase compound. Microstructure of the pellet sample was studied by scanning ...
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The polycrystalline sample of complex tungsten-bronze compound Li2Pb2Sm2W2Ti4Ta4O30 was prepared by a high-temperature solid-state reaction technique. Room temperature X-ray diffraction (XRD) study suggests the formation of a single-phase compound. Microstructure of the pellet sample was studied by scanning electron microscope. The temperature variation of dielectric constant shows dielectric anomaly in the sample. Study of electrical properties (impedance, conductivity, etc.,) of the material exhibits a strong correlation between its micro-structure (i.e., bulk, grain boundary, etc) and electrical parameters. A typical Arrhenius behavior was observed in the temperature dependence of dc conductivity.
Radheshyam Rai; M. A.Valente;Andrei L. Kholkin; Indrani Coondoo
Abstract
AnchorStructural and Magnetic properties are investigated for the Sr doped YMnO3 samples with different composition synthesized by a solid state reaction method. Sr doped YMnO3 is the most distorted perovskite of the RMnO3 series (R=rare earths); the observed sinusoidal magnetic structure is in contrast ...
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AnchorStructural and Magnetic properties are investigated for the Sr doped YMnO3 samples with different composition synthesized by a solid state reaction method. Sr doped YMnO3 is the most distorted perovskite of the RMnO3 series (R=rare earths); the observed sinusoidal magnetic structure is in contrast with those exhibited by the less-distorted members, which are commensurate-type antiferromagnetic structures. A typical anti ferromagnetic (AFM) to paramagnetic (PM) phase transition is observed for the sample with concentration x = 0.12 and the Néel temperature (TN) is about 160 K. With decreasing temperature, the sample with x = 0.12 exhibit a magnetic transition from a paramagnetic (PM) to a ferromagnetic (FM) state.
B. N. Parida; R. Padhee;R. N. P. Choudhary; Piyush R. Das
Abstract
A new ferroelectric oxide (Li2Pb2Gd2W2Ti4Nb4O30) of the tungsten bronze structural family was synthesized using a high temperature solid-state reaction (i.e., mixed-oxide) method at 1100 o C. Room temperature structural analysis (XRD) shows the formation of a new compound in single phase. The ferroelectric ...
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A new ferroelectric oxide (Li2Pb2Gd2W2Ti4Nb4O30) of the tungsten bronze structural family was synthesized using a high temperature solid-state reaction (i.e., mixed-oxide) method at 1100 o C. Room temperature structural analysis (XRD) shows the formation of a new compound in single phase. The ferroelectric phase transition temperature (much above the room temperature) was determined by the dielectric and polarization measurements. Impedance, modulus and electrical conductivity of the material exhibit a strong correlation between its micro-structure and electrical parameters. The existence of non-exponential-type of conductivity relaxation in the compound was confirmed by detailed studies of its transport properties.
Manauti M. Salunkhe; S. M. Patil; R. M. Mane; S. V. Patil; P. N. Bhosale
Abstract
Molybdenum bismuth telluride thin films have been prepared on clean glass substrate using Arrested Precipitation Technique (APT) which is based on self organized growth process. As deposited MoBi2Te5 thin films were dried in constant temperature oven at 110 o C and further characterized for their optical, ...
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Molybdenum bismuth telluride thin films have been prepared on clean glass substrate using Arrested Precipitation Technique (APT) which is based on self organized growth process. As deposited MoBi2Te5 thin films were dried in constant temperature oven at 110 o C and further characterized for their optical, structural, morphological, compositional and electrical analysis. Optical absorption spectra recorded in the wavelength range 300-800 nm showed band gap (Eg) 1.44 eV. X-ray diffraction pattern and scanning electron microscopic images showed that MoBi2Te5 thin films were nanocrystalline having rhombohedral structure. The energy dispersive spectroscopic analysis of as deposited thin films showed close agreements in theoretical and experimental atomic percentages of Mo 4+ , Bi 3+ and Te 2- and suggest that the chemical formula MoBi2Te5 assigned to molybdenum bismuth telluride thin film material is confirm. The resistivity and thermoelectric power measurement studies showed that the films were semiconducting with n-type conduction. The fill factor and conversion efficiency (η) are determined by fabricating PEC cell using MoBi2Te5 thin film electrode. In this article we report the optostructural, morphological, compositional and thermoelectric characteristics of nanocrystalline MoBi2Te5 thin films to check its suitability as photoelectrode in PEC Cell.
Rashmi Mittal; Aruna Tomar; Devendra Singh
Abstract
Spray forming technique was employed to produce a near net-shape disc of Al-Si-Pb alloys. Different substrate distances and inclination angles were studied to obtain the disc shape preforms. The substrate was also offset by 40 mm from the atomizer axis in case of 15 and 30 degree inclination angles. ...
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Spray forming technique was employed to produce a near net-shape disc of Al-Si-Pb alloys. Different substrate distances and inclination angles were studied to obtain the disc shape preforms. The substrate was also offset by 40 mm from the atomizer axis in case of 15 and 30 degree inclination angles. Microstructures were investigated in different regions of the preforms. Results exhibited equiaxed grains of primary Al and Si was present within these grains and along the grain boundary. The size of the Al grains was 20-30 µm and size of Si particles was sub-micron to 5 µm. The size of Pb particles varied from sub-micron to 20 µm and it was uniformly dispersed throughout the aluminum phase.
Wang Zhongjun; Zhu Jing; Wang Zhaojing; Kang Baohua
Abstract
In this paper, the microstructure and creep properties of a cast Mg-3Er-0.2Mn alloy was investigated. The results showed that the cast alloy under both as-cast and solution treated conditions is mainly composed of α-(Mg) matrix and Mg24Er5 phase particles. The value of activation energy Q (240~244KJ/mol), ...
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In this paper, the microstructure and creep properties of a cast Mg-3Er-0.2Mn alloy was investigated. The results showed that the cast alloy under both as-cast and solution treated conditions is mainly composed of α-(Mg) matrix and Mg24Er5 phase particles. The value of activation energy Q (240~244KJ/mol), for creep deformation of the solution treated alloy, was calculated in the temperature range of 190~210 o C, and in the stress range of 50~60 MPa, respectively, which can explain that the creep mode involved cross slip of dislocations from basal to prismatic planes in the hexagonal structure or climb.
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