Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
A Structural, Magnetic, And Mössbauer Spectral Study Of The Tbco₄₋ₓfeₓb Compounds With X=0, 1, And 2, Herv´ Mayot, Olivier Isnard, Fernande Grandjean, Gary J. Long
A Structural, Magnetic, And Mössbauer Spectral Study Of The Tbco₄₋ₓfeₓb Compounds With X=0, 1, And 2, Herv´ Mayot, Olivier Isnard, Fernande Grandjean, Gary J. Long
Chemistry Faculty Research & Creative Works
The TbCo4-x Fex B compounds with x=0, 1, and 2 have been investigated by x-ray and neutron diffraction, magnetic measurements, and iron-57 Mössbauer spectroscopy. The substitution of cobalt by iron induces both an anisotropic increase in the unit-cell volume and a large increase of approximately 250 K in the Curie temperature; the 4.2 K magnetization decreases continuously with increasing iron content. The powder neutron diffraction patterns and the Mössbauer spectra of the TbCo4-x Fex B compounds reveal a strong preferential substitution of iron for cobalt on the 2c site, small transition metal magnetic moments of approximately …
Phase Transitions In Lafeaso: Structural, Magnetic, Elastic, And Transport Properties, Heat Capacity And Mössbauer Spectra, Michael A. Mcguire, Andrew D. Christianson, Athena S. Sefat, Brian C. Sales, Mark D. Lumsden, Rongying Jin, Edward Andrew Payzant, David G. Mandrus, Yanbing Luan, Veerle M. Keppens, Vijayalaksmi Varadarajan, Joseph W. Brill, Raphäel P. Hermann, M. T. Sougrati, Fernande Grandjean, Gary J. Long
Phase Transitions In Lafeaso: Structural, Magnetic, Elastic, And Transport Properties, Heat Capacity And Mössbauer Spectra, Michael A. Mcguire, Andrew D. Christianson, Athena S. Sefat, Brian C. Sales, Mark D. Lumsden, Rongying Jin, Edward Andrew Payzant, David G. Mandrus, Yanbing Luan, Veerle M. Keppens, Vijayalaksmi Varadarajan, Joseph W. Brill, Raphäel P. Hermann, M. T. Sougrati, Fernande Grandjean, Gary J. Long
Chemistry Faculty Research & Creative Works
We present results from a detailed experimental investigation of LaFeAsO, the parent material in the series of “FeAs” based oxypnictide superconductors. Upon cooling, this material undergoes a tetragonal-orthorhombic crystallographic phase transition at ~160 K followed closely by an antiferromagnetic ordering near 145 K. Analysis of these phase transitions using temperature dependent powder x-ray and neutron-diffraction measurements is presented. A magnetic moment of ~0.35µB per iron is derived from Mössbauer spectra in the low-temperature phase. Evidence of the structural transition is observed at temperatures well above the transition temperature (up to near 200 K) in the diffraction data as well …
A Structural, Magnetic, And Mössbauer Spectral Study Of The Dyco₄₋ₓfeₓb Compounds, With X=0-3, Hervé Mayot, Olivier Isnard, Fernande Grandjean, Gary J. Long
A Structural, Magnetic, And Mössbauer Spectral Study Of The Dyco₄₋ₓfeₓb Compounds, With X=0-3, Hervé Mayot, Olivier Isnard, Fernande Grandjean, Gary J. Long
Chemistry Faculty Research & Creative Works
The DyCo4-xFexB compounds, with x=0, 1, 1.5, 2, 2.5, and 3, have been investigated by x-ray diffraction, magnetic measurements, and iron-57 Mössbauer spectroscopy. The substitution of cobalt by iron induces both an anisotropic increase in the unit-cell volume and a large increase in the Curie temperature. The 4.2 K magnetization decreases with increasing iron content. The Mössbauer spectra of the DyCo4-xFexB compounds with x=1, 1.5, and 2 reveal rather small iron hyperfine fields of approximately 16 T and large quadrupole interactions of +1.0 and -1.0 mms, for the 6i and 2c sites, …
The Decomposition Of Yba₂Cu₃O₇₋Δ Doped Into Ba₂Yruo₆, H. A. Blackstead, William B. Yelon, M. Kornecki, M. P. Smylie, P. J. Mcginn, Jinbo Yang, Qingsheng Cai, William Joseph James
The Decomposition Of Yba₂Cu₃O₇₋Δ Doped Into Ba₂Yruo₆, H. A. Blackstead, William B. Yelon, M. Kornecki, M. P. Smylie, P. J. Mcginn, Jinbo Yang, Qingsheng Cai, William Joseph James
Physics Faculty Research & Creative Works
One of the persistent criticisms of claims for observation of superconductivity in Ba2YRu1−uCuuO6 (O6) is that the diamagnetism is actually due to the decomposition of the material into YBa2Cu3O7−delta and other phases. We report a series of experiments in which YBa2Cu3O7−delta is doped into Ba2YRuO6 and carried through a series of sintering steps which were followed by magnetization, neutron diffraction, and scanning electron microscopy/microprobe measurements. It was found that the dopant YBa2Cu3O7−delta decomposed and failed to reform with cooling. It is concluded that the O6 phase is the stable high-temperature phase. The Cu released from the Y123 decomposition doped the …
The Effect Of Cu-Doping On The Magnetic And Transport Properties Of La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William B. Yelon, Paul Ernest Parris, William Joseph James
The Effect Of Cu-Doping On The Magnetic And Transport Properties Of La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William B. Yelon, Paul Ernest Parris, William Joseph James
Physics Faculty Research & Creative Works
The effects of Cu-doping on the structural, magnetic, and transport properties of La0.7Sr0.3Mn1xCuxO3 (0<=x<=0.20) have been studied using neutron diffraction, magnetization, and magnetoresistance (MR) measurements. All samples show the rhombohedral structure with the R[overline 3]c space-group from 10 K to room temperature (RT). Neutron diffraction data suggest that some of the Cu ions have a Cu3+ state in these compounds. The substitution of Mn by Cu affects the MnO bond length and Mn-O-Mn bond angle resulting from the minimization of the distortion of the MnO6 octahedron. Resistivity measurements show that a metal to insulator transition occurs for the x>=0.15 samples. The x=0.15 sample shows the highest MR([approximate]80%), which might result from the co-existence of Cu3-Cu2+ and the dilution effect of Cu-doping on the double exchange interaction
Structure, Magnetic, And Transport Properties Of Ti-Substituted La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William Joseph James, William B. Yelon, D. Buddhikot, Satish K. Malik, Paul Ernest Parris
Structure, Magnetic, And Transport Properties Of Ti-Substituted La₀.₇Sr₀.₃Mno₃, M. S. Kim, Jinbo Yang, Qingsheng Cai, X.-D. Zhou, William Joseph James, William B. Yelon, D. Buddhikot, Satish K. Malik, Paul Ernest Parris
Materials Science and Engineering Faculty Research & Creative Works
Ti-substituted perovskites La0.7Sr0.3Mn1-xTixO3 with 0 ≤ x ≤ 0.20, were investigated by neutron diffraction, magnetization, electric resistivity, and magnetoresistance (MR) measurements. All samples show a rhombohedral structure (space group R3c) from 10 K to room temperature. At room temperature, the cell parameters a,c and the unit cell volume increase with increasing Ti content. However, at 10 K, the cell parameter a has a maximum value for x = 0.10, and decreases for x > 0.10, while the unit cell volume remains nearly constant for x > 0.10. The average (Mn,Ti)-O bond length increases …
Growth And Magnetic Properties Of Mno₂-Δ Nanowire Microspheres, Jinbo Yang, X.-D. Zhou, Satish K. Malik, C. S. Wang, William Joseph James
Growth And Magnetic Properties Of Mno₂-Δ Nanowire Microspheres, Jinbo Yang, X.-D. Zhou, Satish K. Malik, C. S. Wang, William Joseph James
Materials Science and Engineering Faculty Research & Creative Works
We report the synthesis of MnO2-delta microspheres using hydrothermal and conventional chemical reaction methods. The microspheres of MnO2-delta consist of nanowires having a diameter of 20-50 nm and a length of 2-8 µm. The value of oxygen vacancy delta estimated from x-ray photoelectron spectrum is 0.3. The magnetization versus temperature curve indicates a magnetic transition at about 13 K. It is found that a parasitic ferromagnetic component is imposed on the antiferromagnetic structure of MnO2-delta, which might result from distortion of the lattice structure due to oxygen vacancies. The magnetic transition temperature TN is about 10 K lower than that …
Neutron Diffraction Studies Of Erni₅₋ₓcoₓ (X=0.68, 1.68, 2.26) Alloys, Z. Zu, William B. Yelon, G. K. Marasinghe, William Joseph James
Neutron Diffraction Studies Of Erni₅₋ₓcoₓ (X=0.68, 1.68, 2.26) Alloys, Z. Zu, William B. Yelon, G. K. Marasinghe, William Joseph James
Physics Faculty Research & Creative Works
ErNi5-xCox alloys were prepared by RF induction melting and analyzed using neutron powder diffraction. Rietveld analysis neutron diffraction data indicates the unit cell volume increases with Co content while the a and c lattice parameters show different dependencies on the composition. the Co atoms show higher affinity for the 3g sites than for the 2c sites. the Co sublattice tends to couple antiferromagnetically to the Er sublattice. the easy magnetization direction is along the c axis.