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- Amcoff, Örjan, et al.
(författare)
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Bonanzamalm i mikroskala
- 1998
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Ingår i: Geologiskt forum. - 1104-4721. ; :18, s. 9-11
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 2. |
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| 3. |
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| 4. |
- Ericsson, Tore, et al.
(författare)
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Vacancy ordering in FeTSes-FeTS8 solid solutions studied by Mössbauer, X-ray and magnetization techniques
- 1994
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Ingår i: Hyperfine Interactions. - 0304-3843 .- 1572-9540. ; 90:1, s. 515-520
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Tidskriftsartikel (refereegranskat)abstract
- Superstructures, due to cation vacancy ordering, form in the NiAs-related pseudobinary solid solution Fe7Se8-Fe7S8 close to both end compositions (Fe-7(SxSe1-x)(8) with x less than or equal to 0.15 and x greater than or equal to 0.85) during rapid cooling of quartz ampoules from 600 degrees C, according to X-ray diffractometry (XRD) and magnetization (SQUID) measurements. Mossbauer spectroscopy indicates local vacancy ordering in the whole interval, but XRD and SQUID data exclude long-range vacancy ordering when the anion proportion of sulphur is between 15% and 85%.
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| 5. |
- Nordblad, Per, et al.
(författare)
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Magnetisation and Mossbauer studies of (Fe1-xMex)(2)SiS4, x <= 0.25 and Me = Co or Ni
- 1999
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Ingår i: Physica scripta. T. - : ROYAL SWEDISH ACAD SCIENCES. - 0281-1847. ; 60:4, s. 373-380
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Tidskriftsartikel (refereegranskat)abstract
- The olivine related compound(Fe1-xMex)2SiS4, Me = Co or Ni, has been studied by magnetisation (SQUID) measurements and Mössbauer spectroscopy. There are two crystallographic metal positions in the structure, M1 having an inversion center and M2 possessing a mirror plane. Fe2SiS4 becomes antiferromagnetic (AFM) at 126 K and additionally experiences a ferrimagnetic (FiM) transition at 32 K that gives rise to a net spontaneous magnetic moment of about 0.15 µB/iron atom. The Néel temperature increases slightly for Co and substantially for Ni substitution whereas the FiM transition temperature is strongly suppressed in both cases. The hyperfine field on M2 is up to 8 times smaller than on M1 in the AFM phase, while in the FiM state the hyperfine fields of the two sites become of a more comparable magnitude. A similar anomalous behaviour of the AFM hyperfine fields remains in the samples with Co or Ni substitution. We could also definitely make the assignment that Fe-ions in M2 sites give higher centroid shift values and a lower magnitude of the quadrupole splitting than Fe in M1 sites in the Mössbauer spectra. This result also ascertains that it is the M1 sites that are preferentially occupied by Co and Ni.
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| 6. |
- Winell, Sofia, et al.
(författare)
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Cation ordering in NiFe2-xCrxO4-spinels studied by Mössbauer spectroscopy in external fields
- 2008
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Ingår i: Physica status solidi. B, Basic research. - : Wiley. - 0370-1972 .- 1521-3951. ; 245:8, s. 1635-1640
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Tidskriftsartikel (refereegranskat)abstract
- NiFe2-xCrxO4, 0 < ;= x < ;= 1.8, produced from appropriate oxides, has been studied using Mossbauer spectroscopy (MS) at low and ambient temperatures and in external fields up to 7 Tesla. X-ray diffraction (XRD) shows all samples to be single phase cubic spinels, where a(0) change in x, as a concave curve, with a minimum at around x=1. Analyses, based on Mossbauer spectra, show NiFe2-xCrxO4 to be a nearly perfect inverted spinel for x < ;= 0.6. However, for higher x-values the ordering is more complicated. It is shown that iron also populates the octahedral positions for x > ;= 0.8.
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