Investigation of magnetic and ferroelectric properties along with the magnetoelectric coupling behavior for asserting a room temperature bi-phase composite as multiferroics

Various composites of nominal composition (1-x)Ba_0.95Ca_0.05TiO₃?+?xLi_0.1Cu_0.1Co_0.1Zn_0.6Fe_2.1O₄ have been prepared and studied thoroughly. X-ray diffraction and Rietveld refinement confirmed the presence of Ba_0.95Ca_0.05TiO₃ and Li_0.1Cu_0.1Co_0.1Zn_0.6Fe_2.1O₄ phases in the composites. The microstructures have been investigated by field emission scanning electron microscopy. Temperature dependent dielectric constant shows two peaks, one is at 150 °C and another at 270 °C for x?=?0.10 composite which resembles the characteristic ferroelectric and ferromagnetic transition peaks. A gradual progression of ferro-para electric transition towards room temperature is observed with doping. The non-Debye type dipole relaxations have been found. The linearity in the log(σ_AC) vs. log(ω) plots indicate that conduction is due to small polaron hopping. The real part of initial permeability increases with growing ferrite concentration but the cut-off frequency decreases. The magnetic property is also enhanced with doping content. The typical ferroelectric hysteresis loops have also seen with the addition of Li_0.1Cu_0.1Co_0.1Zn_0.6Fe_2.1O₄ up to x?=?0.40. The impedance values are found to decreases in the Nyquist plots. The magnetoelectric voltage coefficient is obtained 287?×?10³ V/mT for x?=?0.15 at room temprrature. We found both ferromagnetic and ferroelectric hysteresis loops at room temperature. So, it confirms that the composites exhibit room temperature multiferroicity. This type of composites offers variety of opportunity for multifunctional devices application like hetero-structured read / write memory devices, switching devices and magnetic field sensing devices.

     

Bandgap Tuning of Sm and Co Co-doped BFO Nanoparticles for Photovoltaic Application

Multiferroic \(BiFeO_3\) (BFO) with bandgap energy (\(E_g\)) between 2.2 eV to 2.7 eV is a potential candidate for photovoltaic (PV) application. However, the efficiency of BFO based PV solar cells is reportedly still too low (less than 2%) to be used for practical applications. Reducing \(E_g\) of BFO without compromising the ferroelectric properties is a big challenge to the scientific community to obtain power conversion efficiencies beyond the maximum value of 26.6% reported in general for silicon based hetero-structure PV solar cells. In this context, samarium (Sm) and cobalt (Co) co-doped BFO (\(Bi_{0.9}Sm_{0.1}Fe_{0.9}Co_{0.1}O_3\)) nanoparticles were synthesized using the sol-gel method. X-ray diffractometry was employed to determine the structure of synthesized nanoparticles. A well-defined crystalline structure of co-doped BFO nanoparticles was confirmed. Field emission scanning electron microscopy was carried out to study grain morphology of synthesized nanoparticles. Sm and Co dopants have been shown to reduce grain size significantly from 68.3 nm to 18.5 nm. An UV-Vis-NIR spectrophotometer was used to measure diffuse reflectance to calculate \(E_g\). A significant reduction of \(E_g\) down to 1.50 eV of co-doped BFO compared to undoped and or single doped counterpart has been manifested.     

Radiation from a small monopole in a uniaxially anisotropic plasma

The radiation field of a small monopole over a ground plane covered with a uniaxially anisotropic plasma with an arbitrary inclination of the optical axis is studied. A steepest descent evaluation of the field integrals has been performed under the elliptic condition, and some calculated power patterns have been studied in comparison with those for a small dipole in an unbounded uniaxially anisotropic plasma. For an arbitrary inclination of the optic axis, considerable differences between the power patterns of the two configurations have been observed. Lateral waves and concentrated field regions are found to occur from mode coupling at the surface of the ground plane.     

Modeling of threshold voltage of a quadruple gate transistor

In this paper, a three dimensional analytical solution of electrostatic potential is presented for undoped (or lightly doped) quadruple gate MOSFET by solving 3-D Poisson's equation. It is shown that the threshold voltage predicted by the analytical solution is in close agreement with TCAD 3-D numerical simulation results. For numerical simulation, self-consistent Schrodinger-Poisson equations, calibrated by 2D non equilibrium green function simulation, are used. This analytical model not only provides useful physics insight of effects of gate length and body width on the threshold voltage, but also serves as a basis for compact modeling of quadruple gate MOSFETs.     

Performance of CDMA overlay system using filtering and diversity

This correspondence considers an interference suppression scheme for a direct-sequence code-division multiple-access overlay system operating in a multipath Nakagami fading environment. The receiver employs suppression filters and diversity to mitigate the effect of multipath and narrow-band jammer interference. The system performance is presented in terms of the bit error rate with different system parameters such as bit energy, jammer-to-signal power, multipath, diversity, ratio of interference bandwidth to spread-spectrum bandwidth, and number of active users. Numerical results indicate substantial improvement in system performance.     

High-Temperature Thermoelectric Properties of Compoundsin the System Zn x In y O x+1.5y

Based on results obtained utilizing combinatorial chemistry techniques to screen the thermoelectric power factor of materials in the system Zn _x In _y O _x+1.5y , several multiphase candidates were down-selected and investigated in terms of their thermoelectric response from room temperature to 1050°C. While the screening experiments suggested that peaks in the power factor occur at relatively high indium oxide content, only the thermoelectric properties of zinc-oxide-rich homologous layered phases in the system (In₂O₃)(ZnO) _k have been well documented, since the phases where k < 3 cannot be easily formed. In the present study, indium-oxide-rich materials in the system In₂O₃–(In₂O₃)(ZnO)₃ were fabricated and their figures of merit were determined. The results suggest that the indium-oxide-rich phases have improved figures of merit, especially at elevated temperatures, relative to the best performing k phases by combining the high power factor of In₂O₃ and the low thermal conductivity of (In₂O₃)(ZnO) _k .     

Genealogy of the 129 inbred strains: 129/SvJ is a contaminated inbred strain

The 129 mouse is the most widely used strain in gene targeting experiments. However, numerous substrains exist with demonstrable physiological differences. In this study a set of simple sequence length polymorphisms (SSLPs) was used to determine the relatedness of selected 129 substrains. 129/SvJ was significantly different from the other 129 substrains and is more accurately classified as a recombinant congenic strain (129cX/Sv), being derived from 129/Sv and an unknown strain. This mixed genetic background could complicate gene targeting experiments by reducing homologous recombination efficiency when constructs and ES cells are not derived from the same 129 substrain. Additionally, discrepancies due to different genetic backgrounds may arise when comparing phenotypes of genes targeted in different 129-derived ES cell lines.     

Highly efficient maximum power point tracking using DC–DC coupled inductor single-ended primary inductance converter for photovoltaic power systems

Solar photovoltaics (PVs) have nonlinear voltage–current characteristics, with a distinct maximum power point (MPP) depending on factors such as solar irradiance and operating temperature. To extract maximum power from the PV array at any environmental condition, DC–DC converters are usually used as MPP trackers. This paper presents the performance analysis of a coupled inductor single-ended primary inductance converter for maximum power point tracking (MPPT) in a PV system. A detailed model of the system has been designed and developed in MATLAB/Simulink. The performance evaluation has been conducted on the basis of stability, current ripple reduction and efficiency at different operating conditions. Simulation results show considerable ripple reduction in the input and output currents of the converter. Both the MPPT and converter efficiencies are significantly improved. The obtained simulation results validate the effectiveness and suitability of the converter model in MPPT and show reasonable agreement with the theoretical analysis.     

Yield effects of rust-resistant wheat varieties in Ethiopia

Breeding crops for disease resistance is a sustainable approach to reduce yield losses. While significant research on the adoption and impacts of improved crop varieties exists, most studies have analyzed yield effects in general without distinguishing between different varietal traits and characteristics. Here, panel data from wheat farmers in Ethiopia were used to compare improved varieties that are resistant to stripe rust (caused by Puccinia striiformis f. sp. tritici) with improved susceptible and traditional susceptible varieties. Production function estimates suggest that improved resistant varieties raise effective yields by 8% in comparison to local susceptible varieties. The yield difference between improved resistant and improved susceptible varieties is positive but small because rust levels were not very high in the years under study. However, under drought and other abiotic stresses, improved varieties – with and without resistance to stripe rust – performed notably worse than local varieties. The worse performance under abiotic stress may explain why many farmers have recently switched back to growing traditional varieties. Sustainable adoption needs a combination of various traits in the same varieties, including high yield potential, grain quality, disease resistance and tolerance to drought and other production stresses.