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Microstructure versus magnetic properties correlations in melt-spun Hf-Zr-Co-Fe-B alloys: role of thermal treatment
No full textEffect of annealing on magnetic property-structure/microstructure correlation in nanostructured ribbons of a rare-earth-free Hf1.5Zr0.5Co10FeB alloy has been reported in the present study. Melt-spinning of the arc melted alloy was employed to obtain the ribbons. The compositional, structural and magnetic measurements demonstrate that under optimized annealing conditions, the magnetically hard phases Hf2Co11B and ZrCo5.1 appear as the dominant ones, while the magnetically soft phases Zr6Co23 and cubic Co appear as minor phase. The optimally annealed ribbons show promising values for characteristic magnetic parameters such as the saturation magnetization M-s similar to 76.7 emu g(-1), intrinsic coercivity H-i(c) similar to 2.4 kOe and magnetic energy product (BH)(max) similar to 4 MGOe. Processing steps like magnetic alignment and magnetization would further improve the characteristic parameters
Deciphering the Role of Oxygen Vacancies on Structural, Electrical, and Magnetic Properties of Fe-Substituted Strontium Titanate
No full textA comprehensive investigation of incorporation of Fe into SrTiO3 is reported. SrFexTi1-xO3- (x=0.0 - 0.3) powders are prepared via solid state route. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques are used to analyze the phase formation, surface chemistry, and electronic structure while scanning electron microscope (SEM) is employed to investigate the surface morphology and microstructural properties. The electrical and magnetic properties are studied at room temperature (RT) to explore the effect of iron substitution on the current conduction and magnetic phase transformation. XPS results indicate the presence of mixed valence state as Fe content increased resulting in considerable enhancement of oxygen vacancies. Moreover, a continuous decrease in Fermi level (FL) is observed as Fe concentration is increased. The increment in Fe concentration leads to variation of current-voltage (I-V) characteristics from linear to non-linear. Magnetic measurements demonstrate three behaviors; an intrinsic diamagnetic behavior (x=0.0, 0.05) followed by ferromagnetic behavior (x=0.1, 0.2), and finally a paramagnetic behavior (x=0.3) due to transition metal impurities and defects. These studies have been used to establish correlation between the evolution of oxygen vacancies emanating from Fe-substitution on structural, electrical, and magnetic properties
A novel method of diameter measurement of pistons used in pressure standards using scanning principle and fusion technique
No full textThe requirement of improved certainties in the measurement of the diameter and the form of cylindrical artifacts is increasing day-by-day. Such requirements become indispensable in typical applications, like the inspection of the fuel injection systems and calibration of pressure balances. A new experiment is set to measure the diameter of a cylindrical artifact, particularly the piston of a pressure-measuring device. Three displacement sensors are used to scan the cross-section of a cylinder and a reference gauge block. At the same time, the scanning process is simulated for ideal conditions. The coordinate data thus obtained in the scanning is fused on to a circle. The misalignments in the experimental setup are refined by iterative scanning the artifacts under test until the experimentally obtained surface profiles match with the simulated ones. Then, the fused circle represents the diameter of the cylindrical object. According to substitution technique, the deviation of the diameter of the artifact under test is determined from the size of the gauge block. Finally, the expanded measurement uncertainty is estimated
AFe(2)O(4)/(Pb0.80Sr0.20)TiO3 (A = Mn, Ni and Co): a New Room-Temperature Magnetoelectric Multiferroic Bi-layered Composite Films
No full textThe room temperature and magnetic field-dependent dielectric, impedance and magnetoelectric (ME) coupling effect of polycrystalline AFe(2)O(4)/(Pb0.80Sr0.20)TiO3 (A = Mn, Ni and Co) bi-layered composite films have been investigated. The structural and microstructural analyses using the X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) reveal the presence of homogenous growth of both tetragonal and spinel phases without any extra phase and diffusion in the AFO/PST20 bi-layered composite films. Our results show that all composite films exhibit ferroelectric as well as considerable magnetic, indicating magnetoelectric coupling effect. Our results show that the dielectric and impedance properties of AFO/PST20 bi-layered composite films can be manipulated by the magnetic field at room temperature, also indicating the existence of magnetoelectric coupling. The impedance (Z (') and Z (aEuro3)) Nyquist plots show distinct electrical responses with the magnetic field. The maximum magnetoelectric coefficient (alpha) is found to be alpha (ME) 239 and 195 mV/cm/Oe for the MFO/PST20 and CFO/PST20 bi-layered composite films, respectively. The above results show that the AFO/PST20 bi-layered composite films are room-temperature multiferroic material that can be potentially used in magnetoelectric devices
A first principles study of key electronic, optical, second and third order nonlinear optical properties of 3-(4-chlorophenyl)-1-(pyridin-3-yl) prop-2-en-1-one: a novel D-pi-A type chalcone derivative
No full textIn this work we assess the significant electrooptic properties of a novel chalcone derivative 3-(4-chlorophenyl)-1-(pyridin-3-yl) prop-2-en-1-one using a computational approach. The ground-state molecular geometry was optimized, and geometrical parameters and vibrational modes are established and found to be in strong correlation with experimental results. The excitation energy is observed to be 326 nm (3.8 eV), calculated at the TD/B3LYP/6-31G level (stands for time dependent/Becke's three Lee-Yang-Parr/basis set). Additionally, a unique insight was gained on a number of properties of the molecular levels such as the HOMO-LUMO gap (i.e.) and electrostatic potential maps. The potential applications of the 3-(4-chlorophenyl)-1-(pyridin-3-yl)prop-2-en-1-one (CPP) molecule in nonlinear optics are confirmed by second and third harmonic generation studies at five different characteristic wavelengths. The static and dynamic polarizability are found to be many-fold higher than that of urea. The second and third harmonic generation values of the titled molecule are found to be 56 and 158 times higher than standard urea molecule, respectively, computed at same wavelength (i.e. 1064.13 nm). From these studies it is clear that the material possesses superior properties and could be applied in optoelectronic device fabrications
Characterization and source apportionment of organic compounds in PM10 using PCA and PMF at a traffic hotspot of Delhi
No full textAn attempt has been made to develop a cement paint composites containing MWCNT, fly ash & ferrite encapsulated glass fibers for absorbing electromagnetic interference (EMI) pollution. The ferrite particles were encapsulated onto glass fibers by in situ polymerization method. However fly ash has been added in controlled amount to the composite in order to perform a dual function, first as dielectric filler and second to reduce solid waste generated from the thermal power plants. These composites have been used to evaluate shielding effectiveness in X b and (8.2-12.4 GHz). The results have shown that this composite can provide an effective absorption dominated shielding effectiveness of 66 dB in X band (8.2-12.4 GHz) with the incorporation of 12 wt% loading of MWCNT along with fly ash and ferrite encapsulated glass fibers in the cement paint matrix. Moreover, the cement paint composites were also tested for surface morphology, hardness, electrical conductivity and structural analysis using TEM, shore hardness test, electrical conductivity and XRD technique, respectively
Enhancement in thermoelectric performance of bulk CrSi2 dispersed with nanostructured SiGe nanoinclusions
No full textCrSi2 is recognized as potential thermoelectric material for mid-temperature energy generation applications owing to its high temperature chemical stability coupled with its cost-effective and non-toxic constituent elements. However, its thermoelectric performance has been reported to be limited owing to its high thermal conductivity, which is reported to dominate by its lattice counterpart. In the present studies, we realize a state-of-the-art (ZT)(max )similar to 0.32 at 673 K in an optimized nanocomposite composition of CrSi2/7.5 wt%SiGe, synthesized using spark plasma sintering of bulk CrSi2 dispersed with SiGe nanoparticles (crystallite size similar to 12 nm). The incorporation SiGe nanoparticles in bulk CrSi2 resulted in a significant reduction in its thermal conductivity owing to enhanced scattering of heat-carrying phonons by a high density of nanoscale interfaces. Concurrently, the power factor of the nanocomposite was also found to increase due to an increase its carrier concentration and mobility on dispersion of SiGe nanoparticles in the CrSi2 matrix. Thus, the favorable tuning of the electrical and thermal transport properties led to a ZT similar to 0.32 which is similar to 125% higher than its pristine counterpart. The as-synthesized pristine and nanocomposites were characterized employing X-ray diffraction and field emission scanning electron microscopy, based on which the enhancement in their thermoelectric properties has been discussed
Surface studies of a 2400-year old corrosion resistant ancient Indian Iron Artifact
No full textSurface morphology and chemical analysis of 2400 year old sickle-blade excavated in early 1940s from the ancient city Hastinapur, Uttar Pradesh, India has been carried out. The discovery of sickle blade is important archaeological evidence that demonstrates the effective role of iron in agricultural operations. Despite being buried over 2300 years, the blade has survived in good condition. Hence it became essential to determine its fabrication technique and corrosion behavior. The study is carried out in order to investigate the corrosion behavior of this ancient Indian iron. Detailed analysis of the characterization results revealed the valuable information about the production technology of the associated culture. The sickle blade is analyzed by using optical microscopy (OM), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), and x-ray diffractometer (XRD). Characterization results lead to the fact that the sickle blade shows heterogeneous microstructure consisting of ferrite, widmanstatten and pearlite structures which is typical of ancient Indian wrought iron produced by bloomery process. Relatively high amount of Phosphorous has been observed which may be responsible for the corrosion resistance behavior of sickle blade. The study reveal the valuable information about the technology and the materials used in the development of iron-based artifacts in India during the ancient period
Silver (Ag) incorporated Cu2ZnSnS4 thin film for improved optical and morphological properties
No full textReplacing copper (Cu) with silver (Ag) which is always in monovalent state can improve the stability and quality of Cu2ZnSnS4 (CZTS). In this work, few copper (Cu) atoms have been substituted by Ag into the crystal lattice of CZTS by Ag deposition using DC (direct current) magnetron sputtering before stacked layer reactively sputtered individual Sn-Cu-Zn targets at room temperature and post annealed at 550 degrees C for 5 min only. Substitution of Cu with Ag reduces antisite defects, secondary phases and also improves the optical absorbance and grain size of the (Ag,Cu)(2)ZnSnS4 (ACZTS) thin film. Rice-like structured ACZTS film showed optical absorption coefficient one order of magnitude higher than CZTS thin film. The band gap was slightly smaller 1.4 eV for ACZTS as compared to 1.5 eV for CZTS film. To the best of our acquaintance, this is the first study on synthesis of rice-like structured ACZTS film and investigation of optical and morphological properties. Also the method used for sample preparation (sputtering) with short annealing time can be an industrially viable technique
Novel synthesis process of methyl ammonium bromide and effect of particle size on structural, optical and thermodynamic behavior of CH3NH3PbBr3 organometallic perovskite light harvester
No full textA simple, cost effective production approach having high stability is pertinent to any organic-inorganic perovskite solar cells. The main focus of the present work has been to formulate and estimate the stability of CH3NH3PbBr3 micro-cubes and nanoparticles based perovskite solar cells. Firstly, novel synthesis route has been introduced for the preparation of CH3NH3Br (MABr) electrolyte salt which is less time consuming, as well as cost effective than pristine methods. We also reported a facile single solution process to grow large scale CH3NH3PbBr3 (MAPbBr(3)) hybrid perovskite micro-cubes and nano-particles. The effect of different size (micro-cube & nano-particles) of perovskite material on structural, optical, thermal stability and degradation kinetics has been examined. X-ray diffraction spectra of MAPbBr(3) perovskite reflect high crystallinity and cubic structure of the material at the room temperature. The surface morphology of micro-cubes and nano-particle MAPbBr(3) has been obtained from scanning electron microscope (SEM). Broad absorption spectrum has found in the visible region with high absorption coefficient and PL spectra show the green emission which is in good agreement with the optical band gap of MAPbBr(3) from absorption measurements. With decreasing the size of perovskite materials, band gap and emission spectra tuned towards the blue region. The simultaneous thermal analysis (STA) study indicates towards the more thermal stability of micro-cubes structures than nanoparticles material while the change in enthalpy (Delta H) and specific heat capacity (Delta Cp) of nano particle have increased by reducing the particle size of perovskite due to modification of endothermic peaks