Parametrization of the Vibronic Contributions to the b⁰₄Spin-Hamiltonian Parameters for⁸S_7/2Ground State Ions in Fluoroperovskites

Abstract

Parametrization of phonon induced contributions to the experimentally determined temperature dependence of the b 0 4 spin-Hamiltonian parameter for Gd3+ doped RbCaF3, CsCaF 3 , RbCdF3 and TlCdF3 single crystals is discussed. Three physically different parametrization schemes are considered, i.e. that of Einstein, Debye and Huang. It is found that the model of Huang, which predicts that the phonon induced contributions should be proportional to the Debye-Waller factor, describes best the experimental data. The method allowing determination of the Debye temperature from EPR data is also suggested.

Spin-phonon and lattice contributions to the ground-state splitting of Gd3+ and Eu2+ in scheelite crystals

“…(3) with the parameters b 2 (0) and ω for Gd 3+ listed in Table 2. Squares at this [7] 108.2(50) 4.28(11) Pfister [7,11] 17.6(11) -0.79(5) 0.23(2) Huang [5,11] 16.7(10) -0.72(5) 32(2) Shrivastava [6,11] 16.7(10) -0.78 (5) 23 (2) Errors in the parameters correspond to 3σ. (1) (stars are the data of [12,13]).…”

“…These parame ters that determine the ground state splitting ΔE of such centers depend on both the coordinates (R i , θ i , ϕ i ) of ligands surrounding the impurity and the ther mal vibrations of the lattice sites of the crystal [4][5][6][7][8][9][10][11]. It is impossible to separate the contributions to ΔE from the variations of the coordinates with increasing temperature and from the thermal vibrations of the lattice with the use of only EPR spectra.…”

“…It should be mentioned that the temperature dependence of b n (L) is usually neglected in such stud ies [9][10][11]. In those works, where this contribution is taken into account, the estimates are carried out in the point charge model with the use of the data on ther mal expansion (compression) coefficients known in a limited temperature range (see references in [4][5][6][7][8][9][10][11]).…”

“…In those works, where this contribution is taken into account, the estimates are carried out in the point charge model with the use of the data on ther mal expansion (compression) coefficients known in a limited temperature range (see references in [4][5][6][7][8][9][10][11]). We calculated b n (L) in the superposition model [18], which has made a good showing.…”

Температурные зависимости параметров начального расщепления Gd-=SUP=-3+-=/SUP=- в CaMoO-=SUB=-4-=/SUB=- (решеточный и спин-фононный вклады)

“…Релаксация энергии в решетке кристалла существенным образом зависит от фононного спектра, определяемого колебаниями узлов решетки [5][6][7][8][9][10][11]. Теоретические модели, объясняющие температурные изменения различных физических пара-метров кристаллов (например, упругих свойств, тепло-проводности, сдвигов линий оптических спектров РЗМ и т.…”