RELAXATION MEASUREMENTS IN THE SYSTEM CaF<sub>2</sub> : Fe<sup>2+</sup>

Bonville, P.; Chappert, J.; Garcin, C.; Imbert, Patrick; Regnard, J. R.

doi:10.1051/jphyscol:1980177

Cited by 4 publications

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“…No further analysis is made here of these lines due to their large linewidth and complexity. very close to 16º for Gd 3+ : LaGaO 3 [5], and it differs considerably from those for Er 3+ ( = 38 ) and Yb 3+ ( = 30 ) in EuAlO 3 [18,19].…”

Section: Resultsmentioning

confidence: 61%

An X- and Q-band Gd3+ EPR study of a single crystal of EuAlO3: EPR linewidth variation with temperature and low-symmetry effects

Andronenko

Misra

2012

Physica B: Condensed Matter

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Detailed electron paramagnetic resonance (EPR) studies on a single crystal of Gd 3+doped Van Vleck compound EuAlO 3 , potentially a phosphorescent/ luminescent/laser material, with the Gd 3+ ion substituting for the Eu 3+ ion, were carried out at X-band (9.2 GHz) over the 77 -400 K temperature range. They provide new physical results on magnetic properties of the Eu 3+ ion in a low symmetry environment. The asymmetry exhibited by the variation of the Gd 3+ EPR line positions for the orientations of the external magnetic field about the Z and X magnetic axes in the ZX plane was ascribed to the existence of low, monoclinic, site symmetry, as revealed by the significant values of the spin-Hamiltonian (SH) parameters 1 4 b , 3 4 b , estimated by fitting all the observed EPR line positions at room temperature for the orientation of the magnetic field in the magnetic ZX plane using a least-square fitting procedure. The temperature dependence of the Gd 3+ EPR linewidth is interpreted to be due to the "life-time" broadening, caused by dynamical exchange and dipolar interactions between the impurity Gd 3+ ions and the host Eu 3+ ions. P.A.C.S. Classification: 76.30 Kg

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Section: Resultsmentioning

confidence: 61%

An X- and Q-band Gd3+ EPR study of a single crystal of EuAlO3: EPR linewidth variation with temperature and low-symmetry effects

Andronenko

Misra

2012

Physica B: Condensed Matter

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“…and we predicted that the excited triplet F4 should therefore remain populated out of the thermal equilibrium after the 57Co decay in a MES experiment in CaF2 below 15 K. [8].…”

Section: Kev)mentioning

confidence: 74%

“…In order to analyse the relaxation phenomena in a quantitative way, we fitted the spectra using a stochastic relaxation lineshape adapted from the Tjon and Blume calculations [9], as already described in references [3,8]. Within this model, the 57 Fe nucleus undergoes a randomly fluctuating EFG driven by two different relaxation mechanisms.…”

Section: Intermediate Relaxation Spectra (8 K « T 25kmentioning

confidence: 99%

“…(N.B. These rates were respectively named W and W' in reference [8], and W4 and W4 in reference [3] figure 5A and some representative low temperature spectra are given in figure 2b, where they are to be compared to the corresponding absorption spectra of figure 2a. Despite the complexity of these spectra, we obtained coherent fits by carefully following the thermal variation of the various components (Table II).…”

Section: Intermediate Relaxation Spectra (8 K « T 25kmentioning

confidence: 99%

“…These authors also concluded that the dynamical Jahn-Teller coupling within the Fe2+5E state could be neglected to a first approximation. Soon after, we evaluated the electronic transition rates W(r4 ) within the triplet T4 and W ( r4 , r, ) between the levels T4 and Fl in the temperature range 10 K T 27 K, by fitting the absorption spectra of reference [6] with a convenient relaxation lineshape [8]. We observed that below 15 K the electronic transition rate W ( r 4 --.. r 1 ) became smaller than the nuclear decay rate r = 1 / Tn of 5'Fe (14.4…”

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Mössbauer absorption and emission experiments in CaF2(57Fe): relaxation and after-effect study

Garcin¹,

Imbert²,

Jéhanno³

et al. 1986

J. Phys. France

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La totalité du spectre d'absorption Mössbauer d'impuretés de 57Fe dans CaF2 et la plus grande partie du spectre Mössbauer émis par une source de 57Co dans CaF2 (échantillon en poudre) proviennent d'ions Fe2+ substitués en site cubique. Une faible contribution provenant de l'état de charge Fe1+ (3d7) est également détectée dans les spectres d'émission, mais on n'y observe pas de contribution de type Fe3+. Le spectre émis par les ions Fe2 + en site cubique comporte à basse température deux contributions issues de niveaux électroniques excités, à long temps de vie, et peuplés hors équilibre thermique. La première de celles-ci émane du triplet de spin-orbit 5E-03934 de faible énergie (E ~ 16 cm-1), dont les propriétés de relaxation ont été analysées d'autre part en spectrométrie d'absorption. La seconde émane probablement du niveau excité 5T2 -03935g de grande énergie (E ~ 5 000 cm-1).Abstract. -The entire Mössbauer absorption spectrum of 57Fe impurities in CaF2 and the main part of the emission spectrum of a CaF2 (57Co) powder sample originate from substitutional Fe2+ ions in cubic sites. A weak Fe1+ (3d7) charge state contribution is also detected in the emission spectra, but no Fe3+ contribution is observed. Two long-lived excited electronic level contributions are evidenced out of the thermal equilibrium in the low temperature emission spectra of the cubic site Fe2+ ions. The first originates from the low energy spin-orbit triplet 5E -03934 (E ~ 16 cm-1), whose relaxation properties are also analysed by absorption spectroscopy, and the second probably originates from the highly excited level 5T2 -03935g (E ~ 5 000 cm-1).

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Comparative Mössbauer spectroscopic study of iron impurities in ZnSe

Becze-Deák

Bottyán

Bonville

et al. 2001

Journal of Physics and Chemistry of Solids

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RELAXATION MEASUREMENTS IN THE SYSTEM CaF₂ : Fe²⁺

Cited by 4 publications

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An X- and Q-band Gd3+ EPR study of a single crystal of EuAlO3: EPR linewidth variation with temperature and low-symmetry effects

An X- and Q-band Gd3+ EPR study of a single crystal of EuAlO3: EPR linewidth variation with temperature and low-symmetry effects

Mössbauer absorption and emission experiments in CaF2(57Fe): relaxation and after-effect study

Comparative Mössbauer spectroscopic study of iron impurities in ZnSe

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RELAXATION MEASUREMENTS IN THE SYSTEM CaF2 : Fe2+

Cited by 4 publications

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An X- and Q-band Gd3+ EPR study of a single crystal of EuAlO3: EPR linewidth variation with temperature and low-symmetry effects

An X- and Q-band Gd3+ EPR study of a single crystal of EuAlO3: EPR linewidth variation with temperature and low-symmetry effects

Mössbauer absorption and emission experiments in CaF2(57Fe): relaxation and after-effect study

Comparative Mössbauer spectroscopic study of iron impurities in ZnSe

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RELAXATION MEASUREMENTS IN THE SYSTEM CaF₂ : Fe²⁺