Search results for " magnetic materials"
showing 10 items of 4666 documents
Magnetic tunneling junctions with the Heusler compound
2005
Abstract Certain Heusler phases belong to the materials which are discussed as potential half metals. Here, results of tunneling experiments with the full-Heusler alloy Co 2 Cr 0.6 Fe 0.4 Al are presented. The Heusler alloy is used as an electrode of magnetic tunneling junctions. The junctions are deposited by magnetron DC sputtering using shadow mask techniques with AlO x as a barrier and cobalt as counter electrode. Measurements of the magnetoresistive differential conductivity in a temperature range between 4 and 300 K are shown. An analysis of the barrier properties applying the Simmons model to the bias dependent junction conductivity is performed. VSM measurements were carried out to …
Kinetics of Zn2+ complexation by a ditopic phenanthroline-azamacrocyclic scorpiand-like receptor.
2012
Coordination of Zn(2+) to a ditopic phenanthroline-macrocycle receptor takes place in three steps, the first one being the coordination to the phenanthroline, followed by the slow movement of the metal to the polyamine macrocycle and a final re-arrangement to coordinate the pendent arm.
The azido ligand: a useful tool in designing chain compounds exhibiting alternating ferro- and antiferro-magnetic interactions
1997
A one-pot reaction of NiII 1, CoII 2, FeII 3 and MnII 4 with 2,2A-bipyridine (bipy) and azide in water leads to [M(bipy)(N3)2]n chains where the metal ion is alternatively bridged by double end-on (EO) and end-to-end (EE) azido bridges; theoretical analysis of the variable-temperature magnetic susceptibility data of 1 and 4 reveals the occurrence of intrachain alternating ferro- (through EO) and antiferro-magnetic (through EE) interactions. Julve Olcina, Miguel, Miguel.Julve@uv.es ; Lloret Pastor, Francisco, Francisco.Lloret@uv.es ; Clemente Juan, Juan Modesto, Juan.M.Clemente@uv.es
Novel azobenzene precursors for NLO active polyuretanes: Synthesis, quantum chemical and experimental characterization
2009
Abstract For the development of electro optical active polyurethanes six new derivatives of 2-{(2-hydroxyethyl)-[4-(4-nitrophenylazo)phenyl]amino}ethanol and two of 2-{(2-hydroxyethyl)-[4-(5-nitropyridin-2-ylazo)phenyl]amino}ethanol were synthesized by azocoupling reaction. Molecular geometry, hyperpolarizability βFF and ground state dipole moment μg were acquired by RHF ab initio (6–31G∗∗) calculations using HyperChem software package. To characterize NLO performance of synthesized azo compounds second order non linear coefficients d31 and d33 were measured as function of chromophore load in guest–host films (PMMA). Eight synthesized compounds can be grouped in four similar gross formula p…
Structural and electronic properties of β-NaYF4 and β-NaYF4:Ce3+
2020
AP is indebted for a financial support provided by Scientific Research Project grant for Students and Young Researchers Nr. SJZ/2017/3 sponsored at the Institute of Solid State Physics, University of Latvia , while AIP is thankful for the financial support from Latvian Research Council lzp-2018/1-0214 .
First principles calculations of SrZrO3 bulk and ZrO2-terminated (001) surface F centers
2016
Abstract Using a supercell model and B3PW hybrid exchange-correlation functional in the framework of the density functional theory (DFT), as it is implemented in the CRYSTAL computer code, we performed ab initio calculations for the F -center located in the SrZrO 3 bulk and on the ZrO 2 -terminated (001) surface. According to the results of performed relaxation of atoms around the defect, two nearest Zr and four Sr atoms are repulsed, but all oxygen atoms are attracted towards both, the bulk and (001) surface F -center. The displacement magnitudes of atoms surrounding the bulk F -center are smaller than around the (001) surface F -center. The B3PW calculated SrZrO 3 bulk optical band gap (5…
Electron Transfer from Organic Aminophenyl Acid Sensitizers to Titanium Dioxide Nanoparticle Films
2009
Electron transfer from three conjugated amino-phenyl acid dyes to titanium and aluminum oxide nanocrystalline films was studied by using transient absorption spectroscopy with sub 20 fs time-resolution over the visible spectral region. All the dyes attached to TiO2 showed long-lived ground state bleach signals indicative of formation of new species. Global analysis of the transient kinetics of the dyes on TiO2 revealed stimulated emission decays of about 40 fs and less than 300 fs assigned to electron injection. The same dyes on Al2O3 substrates displayed long stimulated emission decays (ns) suggesting that electron transfer is blocked in this high band gap semiconductor. For two of the dye…
Influence of the filling factor on the spectral properties of plasmonic crystals
2006
Plasmonics crystals (PCs) comprised of finite-size triangular lattices of gold bumps deposited on a gold thin film are studied by means of a near-field optical microscope. The plasmonic crystals fabricated by electron-beam lithography are illuminated by an incident surface plasmon polariton excited in the Kretschmann-Raether configuration at the gold/air thin-film interface for incident free-space wavelengths in the range $740--820\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. Based on the measurement of the surface plasmon polariton (SPP) damping distance in the crystals, the existence of a band gap for an incident SPP traveling along the two symmetry axes $\ensuremath{\Gamma}M$ and $\ensuremath…
Acid–Base Properties and Surface Charge Distribution of the Water-Soluble Au102(pMBA)44 Nanocluster
2016
The pKa of the p-mercaptobenzoic acid (pMBA) ligands in the Au102(pMBA)44 nanocluster was measured by using acid–base and IR titration. The observed macroscopic pKa = 6.18 ± 0.05 is significantly more basic than that of free pMBA (pKa = 4.16), and the protonation behavior is anticooperative according to the Hill coefficient n = 0.64 ± 0.04. The cluster is truly water-soluble when more than 22 and insoluble when fewer than 7 ligands are in the deprotonated state. In order to obtain more insight into the anticooperative character, the cluster was modeled at pH ∼6.2 using constant pH molecular dynamics simulations. The pKa values of the individual pMBAs are in the range of 5.18–7.58, depending…
Carbon-Coated Anatase TiO2Nanotubes for Li- and Na-Ion Anodes
2014
aInstitute of Physical Chemistry and MEET Battery Research Centre, University of Muenster, 48149 Muenster, Germany bHelmholtz-Institute Ulm (HIU), Electrochemistry I, 89081 Ulm, Germany cKarlsruher Institute of Technology (KIT), 76021 Karlsruhe, Germany dInstitute for Organic Chemistry, University of Mainz, 55128 Mainz, Germany eGraduate School Materials Science in Mainz, 55128 Mainz, Germany fInstitute for Inorganic and Analytical Chemistry, University of Mainz, 55128 Mainz, Germany gMax Planck Institute for Polymer Research, 55128 Mainz, Germany