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Paul, Rick L.; Lindstrom, Richard M.

doi:10.1023/a:1006796003933

Cited by 107 publications

(29 citation statements)

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“…The magnetic excitations in ZnCr 2 Se 4 were studied using the Disk Chopper Spectrometer (DCS) with E i = 3.3 and 1.7 meV. Long-wavelength neutron powder diffraction data were extracted between −0.2 and 0.2 meV from the elastic contribution of the DCS data at λ = 5.0Å at 1.5 K. Chemical analysis was performed using Prompt Gamma Activation Analysis [34] on the NG-7 instrument [35] at NIST Center for Neutron Research. High-resolution powder x-ray diffraction experiments were performed at both the Swiss-Norwegian and ID31 beamlines at the European Synchrotron Radiation Facility, Grenoble, France from 5 to 500 K, with wavelengths of λ = 0.723 23(1) and λ = 0.400 16(7)Å, respectively.…”

Section: Experimental Methodsmentioning

confidence: 99%

Structure and magnetism in the bond-frustrated spinelZnCr2Se4

Zajdel

Beek

et al. 2017

Phys. Rev. B

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The crystal and magnetic structures of stoichiometric ZnCr 2 Se 4 have been investigated using synchrotron x-ray and neutron powder diffraction, muon spin relaxation (µSR), and inelastic neutron scattering. Synchrotron x-ray diffraction shows a spin-lattice distortion from the cubic Fd3m spinel to a tetragonal I 4 1 /amd lattice below T N = 21 K, where powder neutron diffraction confirms the formation of a helical magnetic structure with magnetic moment of 3.04(3) µ B at 1.5 K, close to that expected for high-spin Cr 3+ . µSR measurements show prominent local spin correlations that are established at temperatures considerably higher (<100 K) than the onset of long-range magnetic order. The stretched exponential nature of the relaxation in the local spin-correlation regime suggests a wide distribution of depolarizing fields. Below T N , unusually fast (>100 µs −1 ) muon relaxation rates are suggestive of rapid site hopping of the muons in static field. Inelastic neutron scattering measurements show a gapless mode at an incommensurate propagation vector of k = [000.4648(2)] in the low-temperature magnetic ordered phase that extends to 0.8 meV. The dispersion is modeled by a two-parameter Hamiltonian, containing ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor interactions with a J nnn /J nn =−0.337.

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Section: Experimental Methodsmentioning

confidence: 99%

Structure and magnetism in the bond-frustrated spinelZnCr2Se4

Zajdel

Beek

et al. 2017

Phys. Rev. B

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“…The five analyzed samples were in the form of powders, weighing between 30 mg and 60 mg. All were derivatives of LiMn 2 O 4 , with a fraction of the Mn replaced by Ni. The samples were sealed in Teflon® Bags and analyzed using the NG7 cold neutron PGAA instrument located at the NIST Center for Neutron Research [57][58][59]. Irradiation times for samples ranged from 18 h to 24 h.…”

Section: Methodsmentioning

confidence: 99%

Formation of Fe and Ni substituted LiMn_2–XM_XO₄nanopowders and their crystal and electronic structure and magnetic properties

Talik

Lipińska

Guzik

et al. 2017

Materials Science-Poland

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The Pechini sol-gel method was applied to obtain LiMn 2 − x T x O 4 (T = Ni, Fe; x = 0.1 to 0.5) nanopowders. Crystal and electronic structures, chemical composition and magnetic properties of the materials were characterized by X-ray diffraction, XPS, SEM/EDX microscopy, prompt gamma-ray activation analysis (PGAA), Mössbauer spectroscopy and magnetic susceptibility, respectively. XRD measurements showed that the LiMn 2 − x Ni x O 4 were single phase for x = 0.1 and 0.2. Three samples with higher Ni content contained some addition of a second phase. Analysis of the oxidation state of the dopants by XPS revealed ionic Ni 2+ and Fe 3+ . Mössbauer spectroscopy also confirmed 3+ oxidation state of iron and its location in octahedral sites, which excluded the inverse spinel configuration. XPS examinations showed that Mn 3+ ions dominated in the iron substituted series whereas the Mn 4+ was dominant in the nickel series.

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“…Evidently, it is a prerequisite for making ko-assisted PGNAA operational, that prompt k0-factors are experimentally determined and, as shown in the survey presented in Table 1, this task is being undertaken by several laboratories world-wide [30][31][32][33][34][35][36][37][38]. Although kofactors have been measured versus H (2223 keV), Ti (1382 keV) or CI (1951 keV), the latter tumed out to be the preferred comparator, since it forms compounds with nearly all elements.…”

Section: The K 0 Nuclear Data Librarymentioning

confidence: 99%

k0-NAA past the turn of the century: problems, concepts, insights, prospects

Corte

2003

Czech J Phys

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Based on experiences gained during two scientific meetings (MARC-V, Kona, HI, 2000 and 3 rd 1% Users Workshop, Bruges, 2001) that were marking the transition to the 21 st century, a survey is given of recent and ongoing activities related to both fundamental developments and applications of k0-assisted NAA. Topics highlighted are: the nuclear data library, the calibration of the irradiation facility, the 1%-concept in PGAA and the development of synthetic multi-element standards (SMELS) for QC/QA/validation of 1%-NAA implemented in a laboratory.

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Untitled

Cited by 107 publications

References 50 publications

Structure and magnetism in the bond-frustrated spinelZnCr2Se4

Structure and magnetism in the bond-frustrated spinelZnCr2Se4

Formation of Fe and Ni substituted LiMn_2–XM_XO₄nanopowders and their crystal and electronic structure and magnetic properties

k0-NAA past the turn of the century: problems, concepts, insights, prospects

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Untitled

Cited by 107 publications

References 50 publications

Structure and magnetism in the bond-frustrated spinelZnCr2Se4

Structure and magnetism in the bond-frustrated spinelZnCr2Se4

Formation of Fe and Ni substituted LiMn2–XMXO4nanopowders and their crystal and electronic structure and magnetic properties

k0-NAA past the turn of the century: problems, concepts, insights, prospects

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Formation of Fe and Ni substituted LiMn_2–XM_XO₄nanopowders and their crystal and electronic structure and magnetic properties