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Articles 1 - 12 of 12
Full-Text Articles in Physical Sciences and Mathematics
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, Susanta Hazra, Sujit Sasmal, Michel Fleck, Fernande Grandjean, Moulay T. Sougrati, Meenakshi Ghosh, T. David Harris, Pierre Bonville, Gary J. Long, Sasankasekhar Mohanta
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, Susanta Hazra, Sujit Sasmal, Michel Fleck, Fernande Grandjean, Moulay T. Sougrati, Meenakshi Ghosh, T. David Harris, Pierre Bonville, Gary J. Long, Sasankasekhar Mohanta
Chemistry Faculty Research & Creative Works
The magnetic, electronic, and Mössbauer spectral properties of Fe 2L(µ-OAc)2ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed valence iron(II/III) complex with an electron that is fully delocalized between two crystallographically inequivalent iron sites to yield a [Fe2]V cationic configuration with a St 9/2 ground state. Fits of the dc magnetic susceptibility between 2 and 300K and of the isofield variable-temperature magnetization of 1 yield an isotropic magnetic exchange parameter, J, of -32(2) cm-1 for an …
Synthesis And Characterization Of Two Metallic Spin-Glass Phases Of Femo₄Ge₃, Peter J. Baker, Peter D. Battle, Stephen J. Blundell, Fernande Grandjean, Thomas M. Lancaster, Gary J. Long, Sophie E. Oldham, Timothy John Prior
Synthesis And Characterization Of Two Metallic Spin-Glass Phases Of Femo₄Ge₃, Peter J. Baker, Peter D. Battle, Stephen J. Blundell, Fernande Grandjean, Thomas M. Lancaster, Gary J. Long, Sophie E. Oldham, Timothy John Prior
Chemistry Faculty Research & Creative Works
Polycrystalline samples of FeMo4Ge3 have been synthesized by the reduction of an oxide mixture at 1248 K and characterized by a combination of diffraction, muon spin relaxation (µ+SR), Mössbauer spectroscopy, magnetometry, transport, and heat-capacity measurements. The compound adopts a tetragonal W5Si3 structure (space group I4/mcm); the iron and molybdenum atoms are disordered over two crystallographic sites, 16k and either 4a or 4b. The synthesis conditions determine which fourfold site is selected; occupation of either leads to the presence of one-dimensional chains of transition metals in the structure. In both cases, …
A Mössbauer Spectral Study Of The Gdco₄₋ₓfeₓb Compounds, Fernande Grandjean, Raphäel P. Hermann, Eustachy S. Popiel, Gary J. Long
A Mössbauer Spectral Study Of The Gdco₄₋ₓfeₓb Compounds, Fernande Grandjean, Raphäel P. Hermann, Eustachy S. Popiel, Gary J. Long
Chemistry Faculty Research & Creative Works
The iron-57 Mössbauer spectra of the GdCo4-xFexB compounds, where x is 0.10, 0.15, 0.20, 0.25, 1, 2, 2.5, and 2.6, have been measured at room temperature and reveal relatively small iron hyperfine fields of approximately 12-18 T, relatively large quadrupole interactions of approximately +0.9 and -1 mm/s, and three very different types of spectra for x=0.10 and 0.15, x=0.25, 1, and 2, and x=2.5 and 2.6. The differences result from both the different easy magnetization directions in these compounds and the different cobalt and/or iron occupancies of the crystallographic 2c and 6i sites. The spectra have …
Mössbauer Spectral Study Of The Magnetocaloric Femnp₁₋ₓasₓ Compounds, Raphäel P. Hermann, Ojied Tegus, Ekkehard H. Brück, K. H. J. Buschow, Frank R. De Boer, Gary J. Long, Fernande Grandjean
Mössbauer Spectral Study Of The Magnetocaloric Femnp₁₋ₓasₓ Compounds, Raphäel P. Hermann, Ojied Tegus, Ekkehard H. Brück, K. H. J. Buschow, Frank R. De Boer, Gary J. Long, Fernande Grandjean
Chemistry Faculty Research & Creative Works
The magnetic phase transitions in the FeMnP1-xAsx compounds with x= 0.25, 0.35, 0.45, 0.50, and 0.55, have been studied by iron-57 Mössbauer spectroscopy. The ferromagnetic and antiferromagnetic spectra have been analyzed with a model that takes into account the random distribution of the P and As near-neighbor anions of a given iron site. This distribution is a binomial distribution of the contributions to the spectra of each iron with n As near neighbors. A magnetostriction model has been used to characterize the temperature induced paramagnetic to ferromagnetic first-order phase transition and order parameters, ηF=2.6, 2.3, …
Characterization And Magnetic Properties Of Core/Shell Structured Fe/Au Nanoparticles, Sung-Jin Cho, Susan M. Kauzlarich, Justin Olamit, Kai Liu, Fernande Grandjean, Leïla Rebbouh, Gary J. Long
Characterization And Magnetic Properties Of Core/Shell Structured Fe/Au Nanoparticles, Sung-Jin Cho, Susan M. Kauzlarich, Justin Olamit, Kai Liu, Fernande Grandjean, Leïla Rebbouh, Gary J. Long
Chemistry Faculty Research & Creative Works
Au-coated Fe nanoparticles have been prepared by using a reverse micelle method through reduction of an aqueous solution. Characterizations have been carried out over time to probe the oxidation of Fe. Immediately after synthesis, the samples exhibit metallic conduction and a negative magnetoresistance, consistent with the presence of α-Fe. The temperature dependence of magnetization displays a maximum at a blocking temperature of around 150 K. After a period of 1 month, the samples exhibit insulating behavior, indicating the oxidation of the Fe core. Mössbauer spectroscopy indicates the presence of an α-Fe component and a broad distribution of local environments.
Study Of The Electronic Properties Of Some Ytterbium Filled Skutterudites By Magnetic Susceptibility And X-Ray Absorption And Tin-119 Mössbauer Spectroscopy, Fernande Grandjean, Gary J. Long, Bernard M. Mahieu, Ji Hui Yang, Gregory P. Meisner, Donald T. Morelli
Study Of The Electronic Properties Of Some Ytterbium Filled Skutterudites By Magnetic Susceptibility And X-Ray Absorption And Tin-119 Mössbauer Spectroscopy, Fernande Grandjean, Gary J. Long, Bernard M. Mahieu, Ji Hui Yang, Gregory P. Meisner, Donald T. Morelli
Chemistry Faculty Research & Creative Works
Magnetic susceptibility, ytterbium LIII-edge x-ray absorption and tin-119 Mössbauer spectral measurements have been carried out to probe the electronic structure of ytterbium and tin in the filled or partially filled skutterudite compounds, YbyCo4Sb12-xSnx, over a range of x and y values. The ytterbium valence obtained from the magnetic susceptibility and ytterbium LIII-edge x-ray absorption measurements is in excellent agreement and clearly reveals an evolution from intermediate valence ytterbium for x=0 to nearly divalent ytterbium for x=0.8. This evolution parallels an increase in the unit cell volume and hence …
Magnetic And Mössbauer Spectral Study Of Erfe₁₁Ti And Erfe₁₁Tih, Cristina Piquer, Raphäel P. Hermann, Fernande Grandjean, Gary J. Long, Olivier Isnard
Magnetic And Mössbauer Spectral Study Of Erfe₁₁Ti And Erfe₁₁Tih, Cristina Piquer, Raphäel P. Hermann, Fernande Grandjean, Gary J. Long, Olivier Isnard
Chemistry Faculty Research & Creative Works
The influence of the insertion of hydrogen into the crystal lattice of ErFe11Ti upon its spin reorientation was investigated. It was found that the insertion of hydrogen into ErFe11Ti to form ErFe11TiH expanded the lattice by 1% and increased the Curie temperature by 56 K. The presence of one titanium near neighbor in the environment of an iron site decreased the hyperfine field by ~2T and changed the isomer shift by ~0.05 mm/s.
Electronic Structure Of Thallium Filled Skutterudites Studied By X-Ray Absorption And Mössbauer Spectroscopy, Gary J. Long, Bernard M. Mahieu, Brian C. Sales, Raphäel P. Hermann, Fernande Grandjean
Electronic Structure Of Thallium Filled Skutterudites Studied By X-Ray Absorption And Mössbauer Spectroscopy, Gary J. Long, Bernard M. Mahieu, Brian C. Sales, Raphäel P. Hermann, Fernande Grandjean
Chemistry Faculty Research & Creative Works
The electronic structure of the three sites in the thallium filled skutterudites was studied. Two series of thallium filled skutterudites were formed because thallium has a formal valence of +1 and iron or tin must replace some of the cobalt or antimony respectively, to maintain charge neutrality. Large atomic mean-square displacements were observed for the thallium filling atoms and it helps to produce the large thermal resistivity observed for these skutterudites.
Magnetic And Mössbauer Spectral Evidence For The Suppression Of The Magnetic Spin Reorientation In Tm₂Fe₁₇ By Deuterium, Fernande Grandjean, Olivier Isnard, Gary J. Long
Magnetic And Mössbauer Spectral Evidence For The Suppression Of The Magnetic Spin Reorientation In Tm₂Fe₁₇ By Deuterium, Fernande Grandjean, Olivier Isnard, Gary J. Long
Chemistry Faculty Research & Creative Works
The structural and magnetic properties of Tm2Fe17 and Tm2Fe17D3.2 are investigated by means of x-ray-diffraction, thermal, and ac magnetic susceptibility measurements, and iron-57 Mössbauer spectroscopy. Both compounds crystallize in a hexagonal P63/mmc space group with a Th2Ni17-like structure. Deuterium insertion into Tm2Fe17 induces large increases in the unit-cell volume, the saturation magnetization, and the ordering temperature. The unit-cell expansion is anisotropic, with a larger increase in the a lattice parameter than the c lattice parameter. A spin reorientation is observed at 90 K …
Structural, Magnetic, And Mössbauer Spectral Study Of Er₂Fe₁₇ And Its Hydrides, Fernande Grandjean, Olivier Isnard, Dimitri Hautot, Gary J. Long
Structural, Magnetic, And Mössbauer Spectral Study Of Er₂Fe₁₇ And Its Hydrides, Fernande Grandjean, Olivier Isnard, Dimitri Hautot, Gary J. Long
Chemistry Faculty Research & Creative Works
The structural and magnetic properties of the Er2Fe17Hx compounds, where x is 0, 1, 2, 3, and 3.8, have been investigated by means of powder x-ray diffraction, thermal and ac magnetic susceptibility measurements, and iron-57 Mössbauer spectroscopy. The Er2Fe17Hx compounds crystallize in the hexagonal P63/mmc space group with the Th2Ni17-like structure, a structure which has both an iron-rich stoichiometry and disorder of the erbium and iron-iron 4f-4f dumbbell sites. The increase in the lattice parameters, the magnetic ordering temperature, the saturation magnetization, and the …
Mössbauer Spectral Study Of The Magnetic Properties Of Ce₂Fe₁₇Hₓ (X=0, 1, 2, 3, 4, And 5), Dimitri Hautot, Gary J. Long, Fernande Grandjean, Olivier Isnard
Mössbauer Spectral Study Of The Magnetic Properties Of Ce₂Fe₁₇Hₓ (X=0, 1, 2, 3, 4, And 5), Dimitri Hautot, Gary J. Long, Fernande Grandjean, Olivier Isnard
Chemistry Faculty Research & Creative Works
The Mössbauer spectra of Ce2Fe17Hx, where x=0, 1, 2, 3, 4, and 5, have been measured and analyzed between 4.2 and 295 K. Because Ce2Fe17 exhibits a helical magnetic order between 225 and 90 K and a fan magnetic order below 90 K, its Mössbauer spectra were fit with a distribution of hyperfine fields and θ angles for four of the eight magnetically inequivalent sites. Because the hydrides exhibit a magnetization within the basal plane of the hexagonal cell, their Mössbauer spectra were fit with seven sextets. The four isomer shifts …
Reply To "Comment On 'Mössbauer Effect Study Of Filled Antimonide Skutterudites'", Gary J. Long, Gary J. Long, Dimitri Hautot, Fernande Grandjean, Donald T. Morelli, Gregory P. Meisner
Reply To "Comment On 'Mössbauer Effect Study Of Filled Antimonide Skutterudites'", Gary J. Long, Gary J. Long, Dimitri Hautot, Fernande Grandjean, Donald T. Morelli, Gregory P. Meisner
Chemistry Faculty Research & Creative Works
The temperature dependence of the isomer shift of α-iron between 4.2 and 990 K and of Dy3Fe5O12 between 4.2 and 550 K has been analyzed in terms of the Debye model for the second-order Doppler shift, a model in which an additional parameter, the effective vibrating mass, is included. This mass is found equal to 57 g/mol in the ionic compound, Dy3Fe5O12, and equal to 60 g/mol in metallic α-iron. The deviation of this mass from 57 g/mol is a measure of the covalency of the metallic bonding in …