ESR studies of Gd3+centres to investigate the Oh1to D4h18structural transition of the perovskite fluorides RbCaF3and RbCdF3

Buzaré, Jean‐Yves; Fayet-Bonnel, M.; Fayet, J. C.

doi:10.1088/0022-3719/13/5/016

Cited by 38 publications

(7 citation statements)

References 13 publications

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“…However, as shown experimentally for the discussed case [19,20], the 4f 7 wave function is in fact admixed to the 2p and 2s orbitals of 19F and in this admixture a great role is played by the outer electronic shells of Gd 3 + We thus postulate that the strong temperature dependence of the b02 spin-hamiltonian parameter reported in this paper is due to the enhancing role of overlap and covalency effects.…”

Section: Resuits and Discussionsupporting

confidence: 71%

Spin-Phonon Contributions to the b⁰₂Parameter for Gd³⁺in RbCdF₃Single Crystals

1992

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Section: Resuits and Discussionsupporting

confidence: 71%

Spin-Phonon Contributions to the b⁰₂Parameter for Gd³⁺in RbCdF₃Single Crystals

1992

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“…In particular, the cubic and stable perovskites KMgF 3 and KZnF 3 have been well investigated by electron paramagnetic resonance ͑EPR͒ for Cr 3ϩ . [2][3][4][5][6][7] The different studies have concluded the existence of four unequivalent sites for trivalent chromium impurities. KMgF 3 has the standard perovskite structure belonging to the (O h 1 Ϫ Pm3m) space group with aϭ3.973 Å.…”

Section: Introductionmentioning

confidence: 99%

Optical studies ofCr3+inKMgF3:
Mortier
¹
,
Wang
²
,
Buzaré
³

et al. 1997
Phys. Rev. B
39
12
45
1
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Three different sites of the Cr 3ϩ ions in the fluoride perovskite KMgF 3 have been identified by absorption, selective optical excitation, and time-resolved emission spectroscopy of the 4 T 2 ↔ 4 A 2 transition. Highpressure measurements showing the crossover from low-crystal field to high-crystal field, allows us to situate the Dq/B values of the different chromium sites clearly below 2.3. The different spin-orbit components associated with the zero-phonon lines of the 4 T 2 ↔ 4 A 2 transition of each type of site are clearly shown on the optical spectra and identified by group-theory analysis. The decay profiles of the 4 T 2 level are exponential and the lifetimes at 15 K are 903, 919, and 473 s for the cubic, quadratic, and trigonal sites, respectively. The trigonal center which presents the lowest energy levels was peculiarly studied. Emission and excitation spectra are compared; their evolution versus temperature is followed and explained by the thermal population of the different spin-orbit sublevels. The phonon sideband of the trigonal site is compared with our previous lattice dynamic studies of the pure compound. The different peaks of the emission broadband are described in terms of phonons of the matrix and normal modes of the ͓CrF 6 ͔ 3Ϫ complex. ͓S0163-1829͑97͒03430-9͔

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“…-Temperature dependence of the tilt angle ø of CaF6 octahedra in the tetragonal phase of RbCaF3 obtained from : present NMR data in the nearest-neighbour approximation (dotted line) and next nearest-neighbour approximation (dot-and-dash line); neutron scattering determination of ion positions (squares) according to ref. [6]; EPR data using Gd3+-02probe [28] (full circles); the classical displacive model applied to X-ray measurements [14] (dashed line) ; the order-disorder model [22] (solid line).…”

Section: 1 Cubic Phase Measurements -In Order Tomentioning

confidence: 99%

“…bouring rubidium ions. As a comparison, the tilt angle amplitude deduced from EPR experiments [28,15], has also been plotted on figure 6. In spite of the first-order character of this transition, due to the weak discontinuity of the order parameter, it is interesting to fit the temperature dependence of ø with a power law 8P (with 8 = (7~ 2013 7)/7c).…”

Section: 1 Cubic Phase Measurements -In Order Tomentioning

confidence: 99%

87Rb NMR study at the cubic to tetragonal phase transition in RbCaF 3

Bulou

Théveneau²,

Trokiner³

et al. 1979

J. Phyique Lett.

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2014 Le spectre de résonance magnétique nucléaire de 87Rb a été étudié dans un monocristal de RbCaF3 de part et d'autre de la transition de phase cubique-quadratique à 198 K. Dans la phase cubique (phase haute température) la dépendance en température de l'amplitude de la raie de résonance s'écarte de la loi de Curie ce qui peut être attribué à l'existence de domaines de symétrie quadratique. Dans la phase quadratique (phase basse température) on observe un déplacement de la raie centrale dû à une interaction quadripolaire au second ordre, duquel on peut déduire l'angle de rotation de CaF6 (paramètre d'ordre). La dépendance en température du paramètre d'ordre est décrite par une loi de puissance d'exposant 0,5 et 0,32 respectivement au-dessous et au-dessus de 150 K. L'amplitude de rotation a été comparée à celles déduites des études radiocristallographiques et de diffraction de neutrons sur poudre. Abstract. 2014 The 87Rb nuclear magnetic resonance spectrum, in perovskite single crystal of RbCaF3, is studied above and below the cubic-to-tetragonal phase transition occurring at 198 K. In the high-temperature cubic phase, the temperature dependence of the resonance line amplitude deviates from the Curie law and this can be attributed to the existence of tetragonal domains. In the low temperature tetragonal phase, a second-order quadrupole shift of the central line is observed, from which the CaF6 tilt angle (order parameter) is derived. The order parameter temperature dependence is described by a power law with a cross over from exponent 0.5 to exponent 0.32 at 150 K. The tilt angle 03A6 is compared to the values obtained from X-ray and neutron powder diffraction data.

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ESR studies of Gd³⁺centres to investigate the O_h¹to D_4h¹⁸structural transition of the perovskite fluorides RbCaF₃and RbCdF₃

Cited by 38 publications

References 13 publications

Spin-Phonon Contributions to the b⁰₂Parameter for Gd³⁺in RbCdF₃Single Crystals

Spin-Phonon Contributions to the b⁰₂Parameter for Gd³⁺in RbCdF₃Single Crystals

Optical studies ofCr3+inKMgF3:
Mortier
¹
,
Wang
²
,
Buzaré
³

et al. 1997
Phys. Rev. B
39
12
45
1
View full text Add to dashboard Cite

87Rb NMR study at the cubic to tetragonal phase transition in RbCaF 3

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ESR studies of Gd3+centres to investigate the Oh1to D4h18structural transition of the perovskite fluorides RbCaF3and RbCdF3

Cited by 38 publications

References 13 publications

Spin-Phonon Contributions to the b02Parameter for Gd3+in RbCdF3Single Crystals

Spin-Phonon Contributions to the b02Parameter for Gd3+in RbCdF3Single Crystals

Optical studies ofCr3+inKMgF3:Mortier1, Wang2, Buzaré3 et al. 1997Phys. Rev. B3912451View full textAdd to dashboardCite

87Rb NMR study at the cubic to tetragonal phase transition in RbCaF 3

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ESR studies of Gd³⁺centres to investigate the O_h¹to D_4h¹⁸structural transition of the perovskite fluorides RbCaF₃and RbCdF₃

Spin-Phonon Contributions to the b⁰₂Parameter for Gd³⁺in RbCdF₃Single Crystals

Spin-Phonon Contributions to the b⁰₂Parameter for Gd³⁺in RbCdF₃Single Crystals

Optical studies ofCr3+inKMgF3:
Mortier
¹
,
Wang
²
,
Buzaré
³

et al. 1997
Phys. Rev. B
39
12
45
1
View full text Add to dashboard Cite