Effect of electric fields on the spectra of off-centre substitutional defects in strontium oxide

Abstract

Experiments involving electric-field modulation of the optical absorption and EPR spectra of off-centre Co2+ ions in SrO are reported. The field-induced changes in the optical spectra are assigned to the combined effects of Stark shifts and to the redistribution of off-centre electric dipoles amongst the 8 possible < 111 > orientations. Measurements of the reorientation rate may be fitted by a classical Arrhénius process with activation energy 0.017 eV and pre-exponential factor τ0 = 1.2 × 10-9 s

Theoretical Studies of the EPR g Factors and the Hyperfine Structure Constants of Cr3+ in MgS and SrS

“…As a result, the local symmetry is reduced from the ideal cubic cation site to low symmetry (e. g., trigonal, tetragonal or rhombic) of the impurity center. These off-center displacements were indeed verified by experiments [29]. However, for Cr 3+ in SrS of this work {where the size (≈ 0.63Å [26]) of the impurity ion is also much smaller than that of the host cation}, the impurity Cr 3+ seems to be intensively confined to the regular Sr 2+ site because of considerable covalency, and then the cubic symmetry of the host Sr 2+ site is conserved in the impurity centers.…”

Theoretical Investigations on the Off-Center Displacement of Co2+in SrO by Analyzing Its AnisotropicgFactors

“…[7] In fact, according to the studies on transition-metal in SrO based on the shell-model interionic potential method, the energy for off-center displacement is minimal in the [111] direction and maximal in the [100] direction, [7] which were verified by experiments. [1,2,21] On the other hand, we can also find from Table 1 that when we consider the contribution from ligand and spin-orbit coupling, 𝐷 𝜂 , and 𝐽-admixture, the calculation result have more or less improved compared with the experimental data. It is proved that taking into account these factors is significant, the relevant detailed discussion may reference our previous work.…”