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Perkins, H K; Hazony, Y.

doi:10.1103/physrevb.5.7

Cited by 51 publications

(7 citation statements)

References 30 publications

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“…This effect would result from a different temperature variation of the radial expansion of the tzg and eg wave functions (Perkins and Hazony 1972). Assuming a linear dependence 6~(T) = 6~(0) + a.…”

Section: Resultsmentioning

confidence: 99%

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Evaluation of ferrous and ferric Mössbauer fractions

1991

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Abstract. The M6ssbauer fractionsffor various ferrousand/or ferric-containing oxides and oxyhydroxides, silicates and carbonates were evaluated from the experimental temperature dependence of their center shifts, using the Debye approximation for the second-order Doppler shift. It is concluded that ferrous ions exhibit a lower fraction as compared to ferric ions. Using standard mixtures of e-F%O3 with selected Fe z + or Fe 3 + compounds, it is found that the calculated Fe 3 + fvalues are somewhat overestimated with respect to those of Fe 2 +. Possible explanations for this shortcoming are discussed and it is suggested that a different temperature dependence of the intrinsic isomer shift is the most likely reason. This suggestion is corroborated by analyses of hematite and hedenbergite data which are available for temperatures up to 900 K and 800 K respectively.

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Section: Resultsmentioning

confidence: 99%

“…A few authors have reported numerical results indicating that f3 >f2, e.g. for garnets (Amthauer et al 1976) and for FeF2 and FeF3 (Perkins and Hazony 1972), but convincing quantitative arguments that f3 >f2 is generally true, have not been published yet.…”

Section: Introductionmentioning

confidence: 94%

Evaluation of ferrous and ferric Mössbauer fractions

1991

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“…In FeF2 one can derive (dS/d In V), = 1.3 mm/s (considering the assumptions made in ref. [22]), which is exactly the same as for metallic iron 12, 4, 161. These findings are on first sight rather astonishing.…”

Section: (5)mentioning

confidence: 57%

Volume Dependence of Hyperfine Interactions

1974

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RBsumB.-L'influence de variations du volume atomique sur les trois types d'interactions hyperfines (le deplacement isomerique, le couplage quadrupolaire et l'interaction magnktique dipolaire) est passee en revue. La variation d'une interaction hyperfine en fonction du volume est habituellement obtenue par application de pressions elevees ; ces experiences sont discutkes de f a~o n assez dktaillke. Caccent est mis sur l'interprktation des coefficients volumiques du dkplacement isomerique dans des mktaux et des composb. Le coefficient volumique d'une interaction hyperfine peut servir a interprkter d'autres phknomknes qui s'accompagnent de changements de volume. Un exemple caracteristique est la variation avec la tempkrature des interactions hyperfines dans les solides. Afin de donner une idke des problemes relib aces ktudes, une sklection &experiences de ce genre est discutke.

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“…The data are interpreted on the basis of the expression: d(T) = d I + d SOD . The intrinsic isomer shift d I is determined by the s-electron density at the nucleus and in a first approximation exhibits a linear temperature variation: d I (T) = d I (0) + a×10 -5 T. This weak variation is a result of the thermal expansion of the t 2g and e g wave functions of the iron probes (Perkins and Hazony 1972). In contrast, the second-order Doppler shift, d SOD , is strongly dependent on temperature, being related to the vibrational properties of the probe nuclei in the crystal structure.…”

Section: Discussionmentioning

confidence: 99%

Mossbauer spectroscopic study of natural eosphorite, [(Mn,Fe)AlPO4(OH)2H2O]

Alboom

Resende

Costa

et al. 2015

American Mineralogist

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A 57 Fe Mössbauer spectroscopic study of natural eosphorite, (Mn,Fe 2+ )AlPO 4 (OH) 2 H 2 O, is reported. The Mössbauer spectra were collected at temperatures between 295 and 4.2 K. At temperatures exceeding 30 K, the Mössbauer spectra consist of a somewhat broadened quadrupole doublet with a splitting of 1.73 mm/s at 295 K. From the spectrum recorded at 250 K in an external magnetic field of 60 kOe, it is derived that the sign of the principal component of the electric field gradient (EFG) is negative and that the EFG's asymmetry parameter is large (~0.5). From these findings, it is concluded that the octahedral coordination of the ferrous cations exhibits in first order a trigonal compression with a further lowering from axial symmetry due to an additional distortion. The spectrum collected at 4.2 K shows the existence of magnetic ordering. It was analyzed in terms of the full hyperfine interaction Hamiltonian, yielding a magnetic hyperfine field value of 146 kOe and EFG characteristics that are fully in line with those obtained from the external-field spectrum. In the temperature range from 10 to 30 K, the spectra indicate the occurrence of relaxation effects. They could be satisfactorily described in terms of the Blume-Tjon (BT) model for electronic relaxation, assuming a superposition of a slow-and a fast-relaxation component. The observed temperature dependence of the isomer shift is adequately described by the Debye model for the lattice vibrations. The characteristic Mössbauer temperature was found as (360 ± 20) K and the zero-Kelvin intrinsic isomer shift as (1.480 ± 0.005) mm/s. The variation of the quadrupole splitting with temperature is explained by the thermal population of the Fe 2+ electronic states within the T 2g orbital triplet, which is split by the trigonal crystal field in a singlet ground state and an upper doublet state, the latter being further split into two orbital singlets by an additional distortion. The energies of these latter excited states with respect to the ground state are calculated to be 280 ± 20 and 970 ± 50 cm -1 , respectively, based on a point-charge calculation of the 5 D level scheme. This calculation confirms the sign of the V zz component of the electric field gradient being negative as it is determined from the external magnetic field measurement and from the magnetic spectrum acquired at 4.2 K. Iron phosphates are widely spread minerals in the Earth's crust and are expected to occur in soils and rocks on Mars as well. Mössbauer spectroscopy as complementary source of information to the results of other analytical techniques, could therefore be useful to identify and characterize the environmental Fe-bearing phosphates.

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Temperature-Dependent Crystal Field and Charge Density: Mössbauer Studies of FeF2, KFeF3

Cited by 51 publications

References 30 publications

Evaluation of ferrous and ferric Mössbauer fractions

Evaluation of ferrous and ferric Mössbauer fractions

Volume Dependence of Hyperfine Interactions

Mossbauer spectroscopic study of natural eosphorite, [(Mn,Fe)AlPO4(OH)2H2O]

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