E. Devlin

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$Research paper thumbnail of Study of Fe-doped La1-xCaxMnO3 (x≃1/3) using Mössbauer spectroscopy and neutron diffraction$

Study of Fe-doped La1-xCaxMnO3 (x≃1/3) using Mössbauer spectroscopy and neutron diffraction

Physical Review B, 1999

La2/3Ca1/3MnO3 doped with Fe were studied by Mössbauer spectroscopy and neutron powder diffractio... more La2/3Ca1/3MnO3 doped with Fe were studied by Mössbauer spectroscopy and neutron powder diffraction. The Mössbauer spectra (MS) reveal that Fe substitutes for Mn as Fe3+ (S=5/2) and is antiferromagnetically coupled to the Mn host lattice. The magnetic behavior, from the neutron diffraction data, is that of a typical 3D Heisenberg ferromagnet. The temperature evolution of the MS differs from that

Spin fluctuations in La2/3Ca1/3MnO3 probed by 57Fe and 119Sn Mössbauer spectroscopy

by E. Devlin and I. Panagiotopoulos

Journal of Magnetism and Magnetic Materials, 1998

ABSTRACT Spin fluctuations in two samples of the La2/3Ca1/3MnO3 system doped with 1% 57Fe and 5% ... more ABSTRACT Spin fluctuations in two samples of the La2/3Ca1/3MnO3 system doped with 1% 57Fe and 5% Sn were studied by Mössbauer spectroscopy. Fe substitutes for Mn3+ and Sn for Mn4+. A charge redistribution occurs between 4.2 K and Tc. The charge carrier concentration defines magnetic regions with different coupling constants which fluctuate with relaxation rates increasing exponentially with temperature. At ~0.9Tc both probes reveal charge localization which spreads fast in the Mn3+/Mn4+ lattice as the temperature approaches Tc.

Ageing effects in Nd(Dy)Fe(Nb)B alloys and magnets

Journal of Magnetism and Magnetic Materials, 1989

The variations of microhardness with ageing time of bulk alloys of Nd15Fe77B8 and Nd14.5Dy1.5Nb1.... more The variations of microhardness with ageing time of bulk alloys of Nd15Fe77B8 and Nd14.5Dy1.5Nb1.0Fe76.0B7.0 have been investigated, the alloys being first quenched from 1373 K. The data on the Nd15Fe77B8 alloy indicate a low temperature ageing phenomenon which results in a sharp spike in the microhardness which is temperature dependent. An approximate activation energy has been obtained. Similar studies on the stoichiometric Nd2Fe14B alloy did not reveal a similar anomaly. Distinctly different microhardness behaviour was observed in the Nb-containing alloy. The microhardness changes in the alloys have been correlated with changes in the magnetic properties.

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Structural and intrinsic magnetic material parameters of Pr3(Fe,Ti)29 and Pr3(Fe,Ti)29Nx

Journal of Magnetism and Magnetic Materials, 1996

We report the study of the structural and the intrinsic magnetic properties of the Pr member of t... more We report the study of the structural and the intrinsic magnetic properties of the Pr member of the newly discovered class of R3 (Fe, Ti) 29 compounds and its nitride. The X-ray powder diffraction pattern of the alloy is indexed in monoclinic symmetry with lattice parameters a= 10.647 (1) A ̊, b= 8.6014 (7) A ̊, c= 9.755 (1) A ̊ and β= 96.92 (1)° and the structure is described in the A2/m space group. Atomic positions and bond lengths are given. Nitrogenation results in a lattice expansion of 6.6% corresponding to∼ 4N atoms per ...

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Mössbauer and magnetization studies of La[sub 0.5]Ca[sub 0.5]Mn[sub 1−x]Fe[sub x]O[sub 3]

Journal of Applied Physics, 1999

ABSTRACT

Structural and magnetic properties of a novel compound with Y3(Fe, V)29 stoichiometry and disordered CaCu5-type structure

Journal of Alloys and Compounds, 1998

A novel phase with nominal composition Y3Fe27. 5V1. 5 has been synthesized by arc melting element... more A novel phase with nominal composition Y3Fe27. 5V1. 5 has been synthesized by arc melting elemental constituents, followed by annealing at 1123 K. The samples were analyzed by electron microprobe analysis and the stoichiometric composition was Y3. 04Fe27. 56V1. 44. X-ray diffraction from powder samples shows that the structure is of a disordered CaCu5-type (Space Group: P6/mmm) with lattice parameters a= 4.8769 (1) Å, c= 4.1729 (3) Å. This disordered structure, revealed using standard difference Fourier ...

Structural and magnetic studies of B82-type alloys represented by Fe3Ga2−xSbx

Journal of Alloys and Compounds, 1992

ABSTRACT

Experimental and Theoretical Mössbauer Study of an Extended Family of [Fe 8 (μ 4 -O) 4 (μ-4-R-px) 12 X 4 ] Clusters

by E. Devlin and Dalice Pinero

Inorganic Chemistry, 2011

Six [Fe 8 (μ 4 -O) 4 (μ-4-R-pyrazolato) 12 X 4 ] complexes containing an identical Fe 8 (μ 4 -O) ... more Six [Fe 8 (μ 4 -O) 4 (μ-4-R-pyrazolato) 12 X 4 ] complexes containing an identical Fe 8 (μ 4 -O) 4 core have been structurally characterized and studied by M€ ossbauer spectroscopy. In each case, an inner μ 4 -O bridged Fe III cubane core is surrounded by four trigonal bipyramidal iron centers, the two distinct sites occurring in a 1:1 ratio. The M€ ossbauer spectrum of each of the clusters consists of two quadrupole doublets, which, with one exception (X = NCS, R = H), overlap to give three absorption lines. The systematic variation of X and R causes significant changes in the M € ossbauer spectra. A comparison with values for the same clusters computed using density functional theory allows us to establish an unequivocal assignment of these peaks in terms of a nested model for the overlapping doublets. The changes in M € ossbauer parameters (both experimental and computed) for the 1-electron reduced species [Fe 8 (μ 4 -O) 4 (μ-4-Cl-pyrazolato) 12 Cl 4 ]are consistent with a redox event that is localized within the cubane core.

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Bifunctional Fe 3 O 4 -Ag Heterodimer Nanoparticles for Two-Photon Fluorescence Imaging and Magnetic Manipulation

Advanced Materials, 2008

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A study of Nd-Fe-B magnets produced using a combination of hydrogen decrepitation and jet milling

by John Ormerod and E. Devlin

A combination of hydrogen decrepitation (HD) and jet milling (JM) has been used to produce powder... more A combination of hydrogen decrepitation (HD) and jet milling (JM) has been used to
produce powder for the processing of permanent magnets. The procedure has proved to be
very successful for both Nd-Fe-B (Neomax) alloys and the Nd-Dy-Fe-Nb-B high coercivity
alloys. The magnets produced by the H D/J M process showed excellent coercivities when
sintered between 980 and 1 040 ° C; at higher temperatures, excessive grain growth reduced
the coercivity values significantly.

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