Home About us Contact
|
Home About us Contact | ||
|
|
||
Magnetization Measurements (magnetization + measurement)
Selected AbstractsThe New Ternary Silicides Ln6Co1.67Si3 (Ln: Ce, Nd, Gd, Tb, Dy) Investigated by X-Ray Diffraction and Magnetization Measurements.CHEMINFORM, Issue 39 2007B. Chevalier Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] The influence of Pb-ion irradiation on melt-textured YBa2Cu3Ox crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2009I. M. Obaidat Abstract Melt-textured YBa2Cu3Ox crystals have been irradiated along the c -axis with 208Pb56+ ions corresponding to dose matching fields, B, = 0.5 T and B, = 2.0 T. Magnetization measurements were conducted along the ab plane of the samples. The strength of pinning sites was investigated by measuring magnetization hysterisis and the saturation remanent magnetization MR at several temperatures. We have found that the pinning strength was considerably enhanced after irradiation at both doses. Interestingly, the pinning strength at a Pb-ion irradiation which corresponds to the dose matching field B, = 0.5 T, was found to be significantly larger than that at the dose matching field B, = 2.0 T at all temperatures. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Magnetic characterization of U/Co multilayersPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003M. A. Rosa Abstract With the aim of expanding the studies on 2D systems containing uranium, U/Co multilayers with layer thickness ranging from 50 to 200 Å were recently prepared by dc magnetron sputtering onto glass. The multilayers were characterized by Grazing-Incidence X-Ray Diffraction (GIXRD) and Rutherford Backscattering Spectrometry (RBS). Magnetization measurements performed with a squid magnetometer showed that the multilayers have a ferromagnetic behaviour, with the magnetic signal increasing with the thickness of the layers. The analysis of magnetic anisotropy evidenced an easy magnetic direction in the film plane with large anisotropy fields, which increase with the thickness of the layers and suggests a positive contribution of surface anisotropy to the effective anisotropy Keff. [source] Coagulations in a water based magnetic fluid under magnetic fieldPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2004Y. Matsuno Abstract The paper deals with the coagulations of magnetic solid particles in a water based magnetic fluid under magnetic field. The coagulations can be detected by measuring the magnetization of supernatant fluid of magnetic fluid in test tubes under magnetic field. As the coagulations increase , the magnetization of supernatant fluid decreases due to the sedimentation of coagulations. So the more the coagulations, the lower the magnetization of supernatant fluid. Moreover, when test tubes are centrifuged before magnetization measurement, the sedimentation of coagulations is accelerated and the magnetization becomes lower and the detection of coagulations becomes easier. The test results show that latent coagulations can be detected by means of centrifuging, which can not be found out without it. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and characterization of compounds LixMn1+xFe2,2xO4 with spinel structure in the quasiternary system "LiO0,5 , MnOx , FeOx"CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2006C. Wende Abstract The thermal decomposition of freeze-dried Li-Mn(II)-Fe(III)-formate precursors was investigated by means of DTA, TG and mass spectroscopy. By the thermal treatment of the prefired precursors between 400 and 1000°C, single phase solid solutions LixMn1+xFe2,2xO4 (0 , x , 1) with cubic spinel structure were obtained. To get single phase spinels, special conditions concerning the temperature T and the oxygen partial pressure p(O2) during the synthesis are required. Because of the high reactivity of the freeze-dried precursors, in comparison with the conventional solid state reaction, the reaction temperature can be lowered by 200°C. The cation distribution and the properties of the Li-Mn-ferrites were studied by chemical analysis, X-ray powder diffraction and magnetization measurements. It was found that for high substitution rates, almost all lithium occupies the tetrahedral coordinated A-sites of the spinel lattice AB2O4, while at small x-values, lithium ions are distributed over the tetrahedral and octahedral sites. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ferrocene-Substituted [Mn4] Dicubane Single-Molecule MagnetsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2009Katie J. Heroux Abstract Two new mixed-valent [Mn4] single-molecule magnets (SMMs) have been synthesized by using N -alkylated diethanolamine ligands and ferrocenecarboxylic acid. Both complexes exhibit weak ferromagnetic exchange and appreciable axial zero-field splitting as evidenced by DC magnetic susceptibility and field-dependent magnetization measurements. A significant frequency-dependent out-of-phase signal in the AC susceptibility is also observed for both complexes, a feature that is characteristic of SMMs. The ground-state spin of each complex was determined from the DC data and extrapolation of the low-frequency AC data, giving a value of S = 8. This result is consistent with the previously reported and structurally similar S = 8 and S = 9 [Mn4] dicubane SMMs. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis, Structural, and Magnetic Characterization of YCrMnO5EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2005José A. Alonso Abstract A new oxide of nominal stoichiometry YCrMnO5 has been prepared in polycrystalline form by wet-chemistry procedures followed by thermal treatments under high-oxygen-pressure conditions. This material has been characterized by X-ray and neutron powder diffraction (NPD), magnetotransport and magnetization measurements. YCrMnO5 is isostructural with RMn2O5 oxides (R = rare earths); its crystal structure has been Rietveld refined from NPD data in the space group Pbam, and it contains infinite chains of(Cr,Mn)4+O6 octahedra sharing edges, linked together by (Mn,Cr)3+O5 pyramids and YO8 units. An important level of cationic disorder has been found between both metallic sites; the refined crystallographic formula is Y[Mn0.47(1)Cr0.53(1)]oct[Cr0.37(1)Mn0.63(1)]pyrO5. The magnetic susceptibility indicates the onset of magnetic ordering below Tc , 85 K; the magnetization isotherms are characteristic of a weakly ferrimagnetic material reaching a net magnetization of0.25 ,B/f.u. for H = 50 kOe. Low-temperature NPD patterns do not exhibit any additional magnetic contribution, confirming that a long-range magnetic ordering is not fully established. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Comment on "The Magnetocaloric Effect of LaFe11.6Si1.4, La0.8Nd0.2Fe11.5Si1.5, and Ni43Mn46Sn11 Compounds in the Vicinity of the First-Order Phase Transition"ADVANCED MATERIALS, Issue 37 2009Lluís Mañosa The aim of the present comment is to show that when both calorimetric and magnetization measurements are properly executed, there is no significant discrepancy in the entropy values obtained from the two methods, thus validating the use of the Maxwell relations, which is the most commonly used technique in the study of the magnetocaloric effect. [source] Microwave-assisted graft polymerization of ,-caprolactone onto magnetiteJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2009Alexandrina Nan Abstract The graft polymerization of ,-caprolactone (,-CL) onto magnetite was carried out under microwave irradiation in the presence of tin(II) 2-ethylhexanoate. The molar ratio of ,-CL to tin(II) 2-ethylhexanoate was 300, whereas the molar ratio of ,-CL to magnetite was 5. The chemical structures of the obtained poly(,-caprolactone) coated magnetic nanoparticles were characterized by FTIR and XPS spectroscopy. These magnetic-polymer hybrid nanostructures were further investigated by X-ray diffraction and magnetization measurements. The morphology of the magnetic core-shell nanostructures were determined by TEM. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5397,5404, 2009 [source] Phase diagram of the NdFe1,xRhx AsO superconductorPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 3-4 2010H. Y. Shi Abstract Polycrystalline samples with a nominal composition of NdFe1,xRhx AsO (0 , x , 0.25) were synthesized using a solid state reaction method. Bulk superconductivity with a maximum TC = 13 K is observed in the x = 0.1 sample. A temperature,composition phase diagram is established for the NdFe1,xRhx AsO system based on the electrical resistivity and magnetization measurements. A first-order-like transition from an antiferromagnetic state to the superconducting state at a critical Rh-doping point xC , 0.045 is observed in the present phase diagram. The value for the upper critical field ,0Hc2(0) is estimated to be about 26 T for the x = 0.10 sample by using the Werthamer,Helfand,Hohenberg theory. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Magnetic study of Hitperm alloys (Fe0.5Co0.5)1,x ,y ,zMxByCuz (M = Hf, Zr, Nb)PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006Abstract A family of the Hitperm alloys (Fe0.5Co0.5)1,x ,y ,zMxByCuz (M = Hf, Zr, Nb) produced in an argon atmosphere as amorphous ribbons with 0.025 mm thickness are investigated up to 1200 K. The partial replacement of Fe by Co with optimal Fe0.5Co0.5 ratio increases the Curie temperature of the amorphous phase and the magnetic moment per formula unit. The early stages of crystallization can be observed by magnetization measurements. Alloys subjected to the first controlled crystallization stage are built of bcc-(Fe,Co) nanocrystals that are homegeneously embedded in the amorphous matrix. Mean grain sizes are about 11 nm. These two-phase alloys exhibit good soft magnetic properties with the relatively low coercive fields up to 50 A/m. Hafnium and hafnium/zirconium mixture are found to be the best inhibitors of the nanograin growth resulting in the best soft magnetic parameters. Alloys with niobium exhibit lower thermal stability and higher coercive fields. The correlation between the structure evolution and the magnetic properties is analysed and discussed. Conditions for optimum heat treatment are also determined. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Observation of weak ferromagnetism in the C14 Laves phase of the (Fe1,xNix)2Nb systemPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2009C. Paduani Abstract In this work we report the observation of weak ferromagnetism in the hexagonal C14 Laves phase (s.g. P63/mmc) of the (Fe1,xNix)2Nb system, which has been reported as nonmagnetic in the literature. A larger unit cell volume is observed as compared to Fe2Nb. From low-temperature magnetization measurements it is found that the Ni substitution for Fe indeed leads to the onset of a weak ferromagnetic ordering in the C14 Laves phase of this pseudobinary system. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Study of magnetization processes using higher harmonic ac-susceptibilityPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 8 2008S. Prüfer Abstract The ac-susceptibility of a La0.7Sr0.3MnO3 epitaxial film was measured up to the 11th harmonic as a function of ac-field amplitude, superimposed dc-field and temperature. The experimental data reflect the magnetization hysteresis-loop shape in a very precise and detailed way. This is further elucidated by numerical simulations of the ac-susceptibility within a Preisach model with Gaussian distribution function. Using parameters from magnetization measurements the simulated ac-susceptibility curves were found to be in good agreement with the experimental results. This shows that measurements of higher harmonic susceptibilities are a powerful tool for the precise study of magnetization processes. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of the oxygen nonstoichiometry on the structure and magnetic properties of Nd2CoMnO6+, double perovskitesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2007A. P. Sazonov Abstract The properties of Nd2CoMnO6+, (, up to 0.12) were investigated by means of neutron powder diffraction and magnetization measurements. It is found that the samples exhibit partial ordering of Co and Mn ions which strongly affects the magnetic properties. Ionic disorder increases with the oxygen content. According to neutron diffraction the stoichiometric and nonstoichiometric samples show ferromagnetic components which decreases as the oxygen content increases. The magnetization study of the strongly oxidized sample reveals a metamagnetic behavior. It is assumed that metamagnetism results from clusters with short-range antiferromagnetic order. Enhancement of the oxygen content leads to a conversion of Co2+ into low spin Co3+ and the appearance of a cationic vacancy which destroys the ionic order and stabilizes the overall antiferromagnetic behavior. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] On the strength of the double exchange and superexchange interactions in La0.67Ca0.33Mn1,yFeyO3 , an NMR and Mössbauer studyPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2006J. Przewo Abstract A combined study of La0.67Ca0.33Mn0.9757Fe0.03O3 compound by means of zero field 55Mn and 57Fe NMR as well as 57Fe Mössbauer spectroscopy (MS) is reported. The 55Mn NMR spectra exhibit a single double exchange (DE) line up to the magnetic ordering temperature (TC), 200 K, determined from magnetization measurements. The hyperfine field (HFF) remains finite at the TC, which reveals discontinuous character of the transition and the occurrence of a ferromagnetic-paramagnetic phase segregation. The 57Fe MS HFF decreases much faster with increasing temperature than the 55Mn NMR HFF. Application of a molecular field model to the temperature dependence of the 55Mn and 57Fe HFF allows to estimate values of the Mn,Mn and the Fe,Mn exchange integrals, which amount to 1.24 meV and ,0.6 meV, respectively. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Oxygen-isotope effect on the magnetic properties of Pr0.7Ca0.3MnO3 under strong pulsed magnetic fieldsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003G. E. Fedorov Abstract Magnetization and susceptibility measurements have been performed on oxygen-isotope substituted (16O and 18O) samples of Pr0.7Ca0.3MnO3 under pulsed magnetic fields up to 35 T. Experiments were carried out within the temperature range 78 to 300 K. Magnetic-field-induced phase transition into ferromagnetic state has been obtained in both samples at temperatures up to 200 K. Isotope substitution has been proved to have a significant impact on the temperature and field of this transition. Phase diagrams of the samples obtained from magnetization measurements are presented. [source] Physical properties of quantum-confined europium sulfide nanocrystalsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007M. L. Redígolo Abstract We report the synthesis and the characterization of quantum-confined europium sulphide nanocrystals, which possess intriguing size-dependent optical and magnetic properties. Transmission electron microscopy, X-ray diffraction spectroscopy, and SQUID magnetization measurements provide evidence for the quantum-confinement effects in this monochalcogenide nanomaterial. Photoluminescence measurements indicate a blue-shifted spectrum for the nanocrystals compared with bulk europium sulphide. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Magnetization of Ancient CeramicsARCHAEOMETRY, Issue 1 2001J. Van Klinken The saturation magnetization , of soft baked pottery appears to be determined during the firing process by transitions between the iron oxides magnetite, maghemite, hematite and perhaps goethite. The finding of large variations in , motivated the design and construction of a ,magnetization,gravitation', or ,MG', balance for rapid non-destructive magnetization measurements. The first results with this MG balance are presented: iso-, contours, typical histograms and correlations with colour features. Practical MG applications are summarized. [source] ChemInform Abstract: Topotactic Redox Chemistry of NaFeAs in Water and Air and Superconducting Behavior with Stoichiometry Change.CHEMINFORM, Issue 37 2010Iliya Todorov Abstract The redox chemistry and transformations of NaFeAs in water and air are characterized by single crystal and powder XRD, magnetization measurements, TEM, and Moessbauer spectroscopy. [source] Homoleptic Organoderivatives of High-Valent Nickel(III)CHEMISTRY - A EUROPEAN JOURNAL, Issue 41 2009Pablo Abstract Homoleptic perhalophenyl derivatives of divalent nickel complexes with the general formula [NBu4]2[NiII(C6X5)4] [X=F (1), Cl (2)] have been prepared by low-temperature treatment of the halo-complex precursor [NBu4]2[NiBr4] with the corresponding organolithium reagent LiC6X5. Compounds 1 and 2 are electrochemically related by reversible one-electron exchange processes with the corresponding organometallate(III) compounds [NBu4][NiIII(C6X5)4] [X=F (3), Cl (4)]. The potentials of the [NiIII(C6X5)4],/[NiII(C6X5)4]2, couples are +0.07 and ,0.11,V for X=F or Cl, respectively. Compounds 3 and 4 have also been prepared and isolated in good yield by chemical oxidation of 1 or 2 with bromine or the amminium salt [N(C6H4Br-4)3][SbCl6]. The [NiIII(C6X5)4], species have SP -4 structures in the salts 3 and 4, as established by single-crystal X-ray diffraction methods. The [NiII(C6F5)4]2, ion in the parent compound 1 has also been found to exhibit a rather similar SP -4 structure. According to their SP -4 geometry, the NiIII compounds (d7) behave as S=1/2 systems both at microscopic (EPR) and macroscopic levels (ac and dc magnetization measurements). The spin Hamiltonian parameters obtained from the analysis of the magnetic behavior of 3 and 4 within the framework of ligand field theory show that the unpaired electron is centered mainly on the metal atom, with >97,% estimated d contribution. Thermal decomposition of 3 and 4 proceeds with formation of the corresponding C6X5C6X5 coupling compounds. [source] Synthesis and Characterization of Mixed-Valent Manganese Phosphonate Cage ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 34 2006Maheswaran Shanmugam Abstract The reaction of phenylphosphonic acid (PhPO3H2) with the mixed-valent basic oxo-centered manganese triangle [Mn3O(O2CCMe3)6(py)3] (1; where py=pyridine) in the presence of a suitable base gives four different manganese clusters depending on the identity of the base. The syntheses and structural characterization of [Mn18(,3 -O)8(PhPO3)14(O2CCMe3)12(py)6(H2O)2] (2), [Mn7(,3 -O)3(O3PPh)3(O2CCMe3)8(py)3] (3), [Mn9Na(,3 -O)4(,4 -O)2(O3PPh)2(O2CCMe3)12(H2O)2(H2O)0.67(Py)0.33] (4), and [Mn13(,3 -O)8(OMe)8(O3PPh)4(O2CCMe3)10] (5) are described. Complexes 4 and 5 are homovalent MnIII cages, while 2 and 3 contain divalent, trivalent, and/or tetravalent ions. All the manganese centers are valence-localized, the octahedral MnIII sites being recognizable by marked Jahn,Teller distortions. The magnetic properties of compounds 2,5 have been investigated in the polycrystalline state by magnetic susceptibility and high-field magnetization measurements, which reveal that spin ground states vary from 0,S,8. AC susceptibility measurements performed on 4 and 5, in the 1.6,10.0 K ranges show the presence of out of AC susceptibility signal (,M,,) for 4, and an effective energy barrier (Ueff) for the re-orientation of the magnetization is found to be 17 K, but for 5, the ,M,, maximum is found to be below 1.5 K. [source] | ||||||||||||||||