Search results for "MAG"
showing 10 items of 30133 documents
Theoretical insights on the importance of anchoring vs molecular geometry in magnetic molecules acting as junctions
2019
The anchoring of the molecule to an electrode is known to be a key factor in single-molecule spintronics experiments. Likewise, a relaxation down to the most stable geometry is a critical step in theoretical simulations of transport through single-molecule junctions. Herein we present a set of calculations designed to analyze and compare the effect of different anchoring points and the effect of perturbations in the molecular geometry and interelectrode distance. As model system we chose the [V($\alpha$-C$_3$S$_5$)$_3$]$^{2-}$ complex connecting two Au(111) electrodes in a slightly compressed geometry. In our calculations, the attachment happens through an S-Au bond, a common anchoring stra…
Synthesis of ZnO–Ag2CO3–Fe3O4@rGO core–shell structure: magnetically separable photocatalyst for degradation of MB using the Box–Behnken design
2020
In this work, a simple microwave method was utilized to prepare ZnO sheet linked with Fe3O4@rGO core–shell and of Ag2CO3 through formation of the quadri-photocatalytic with high activity. The microstructure, morphology, spectroscopic, and magnetic characteristics of the prepared samples were assessed using XRD, SEM, PL, TEM, FT-IR, DLS, and VSM analysis. The photocatalytic activity of the material was evaluated for photodegradation of methylene blue dye under the UV and visible light with home-made photoreactor. The response surface method in a Box–Behnken design was utilized to design the experiments. The parameters affecting the efficiency of the degradation including, pH (5–9), photocata…
Thermal expansion and polarization of (1-x)PNN-xPT solid solutions
2019
The paper presents the results of detailed studies of the thermal expansion of (1-x)PbNi1/3Nb2/3O3-xPbTiO3 solid solutions with x = 0-0.8. The anomalous and lattice contributions to deformation and...
Temperature Coefficients of Crystal Defects in Multicrystalline Silicon Wafers
2020
This article investigates the influence of crystallographic defects on the temperature sensitivity of multicrystalline silicon wafers. The thermal characteristics of the implied open-circuit voltage is assessed since it determines most of the total temperature sensitivity of the material. Spatially resolved temperature-dependent analysis is performed on wafers from various brick positions; intragrain regions, grain boundaries, and dislocation clusters are examined. The crystal regions are studied before and after subjecting the wafers to phosphorus gettering, aiming to alter the metallic impurity concentration in various regions across the wafers. Most intragrain regions and grain boundarie…
Anomalies of dielectric properties and conductivity in single domain LiNbO3:Zn crystals
2016
ABSTRACTA study of the temperature dependence of dielectric constant, conductivity, and piezoelectric modulus in the single-domain state of LiNbO3 crystals modified by Zn admixture at threshold concentration is reported. Unipolarity of the LiNbO3:Zn crystals is observed to increase after treatment of brand-new samples by high-temperature electro-diffusion annealing and by subsequent high-temperature annealing of short-circuited samples. The observed effects are explained as a result of meta-stable residual domains collapsing at high temperature the collapse being assisted by disintegration of charged clusters stabilizing domain walls. The rise of unipolarity is accompanied by anomalies on t…
Revision of the freezing concept in relaxor ferroelectrics: the case of Na0.5Bi0.5TiO3-Sr0.7Bi0.2TiO3 solid solutions
2020
Presence of a frequency-independent maximum and a frequency-dependent shoulder in temperature-frequency dependence of dielectric permittivity are characteristic features of NBT-based solid solution...
Half-Heusler superlattices as model systems for nanostructured thermoelectrics
2015
The efficiency of thermoelectric materials is directly related to the dimensionless figure of merit , therefore, one of the means to improve ZT is to reduce the thermal conductivity. Our research focuses on half-Heusler superlattices (SLs) and the relationship between the SL period and the thermal conductivity. The cross-plane thermal conductivity of DC-sputtered TiNiSn/HfNiSn SLs was measured by the 3 method at room temperature and a clear reduction of was achieved for all SL periods, in particular for periods smaller than 20 nm. Moreover, the thermal conductivities of TiNiSn and HfNiSn single films display reduced values compared to the literature data for bulk materials. Furthermore, we …
Electronic structure and magnetic order in Cu Zn(1−)O: A study GGA and GGA + U
2019
Abstract Based on density functional theory within GGA formalism, first-principles calculations were performed in order to study the structural, electronic, and magnetic properties of Cu-doped ZnO compound with dopant concentrations x = 0.028, 0.042, 0.056, and 0.125. It was found that CuxZn(1−x)O is ferromagnetic for both the closest and farthest impurity distances, but it is more stable energetically for the closest one. For all concentrations we obtained nearly half − metallic behavior. The calculations show that two substitutional Cu atoms introduce a magnetic moment of about 2.0 μB for all dopant concentrations. The results indicate that the magnetic ground state originates from the st…
Hole localization in thermoelectric half-Heusler (Zr0.5Hf0.5)Co(Sb1−xSn ) thin films
2019
Abstract The (Ti, Zr, Hf)Co(Sb 1 − x Snx) material class has recently come into focus as an attractive p-type high-temperature thermoelectric material. This study experimentally demonstrates that homogeneous, highly textured (Zr0.5Hf0.5)Co(Sb 1 − x Snx) thin films can be grown on single crystalline MgO. By varying the sputter power, samples with both positive and negative Seebeck coefficient can be grown. The underlying reason for the sign change is the segregation of Sn nano-inclusions, which lower the effective doping of the half-Heusler matrix. Similarly the Hall constant also switches sign at low temperatures, which is modeled assuming semi-metal behavior and low temperature hole locali…
Half-Heusler materials as model systems for phase-separated thermoelectrics
2015
Semiconducting half-Heusler compounds based on NiSn and CoSb have attracted attention because of their good performance as thermoelectric materials. Nanostructuring of the materials was experimentally established through phase separation in (T1−x′Tx″)T(M1−yMy′) alloys when mixing different transition metals (T, T′, T″) or main group elements (M, M′). The electric transport properties of such alloys depend not only on their micro- or nanostructure but also on the atomic-scale electronic structure. In the present work, the influence of the band structure and density of states on the electronic transport and thermoelectric properties is investigated in detail for the constituents of phase-sepa…