Theoretical studies of the dependence of EPR g-factors on local structure for the trigonal Er3+–VK centres in KMgF3 and KZnF3

•The complete energy matrix is used in the studies of EPR spectra for the Er3+ ion.•The dependence of g-factors on the local structural parameter ΔZ is characterized.•The g-factors of trigonal Er3+–VK centers in KMgF3 and KZnF3 are well explained.•The origin of the trigonal Er3+–VK centers in KMgF3 and KZnF3 was verified.•The contribution of the J–J mixing effects to g-factors was quantitatively evaluated.

The dependence of the EPR g-factors on the local structural parameter for a 4f11 configuration ion Er3+ in a trigonal crystal-field has been studied by diagonalizing the 364×364 complete energy matrices. Our studies indicate that the EPR spectra of the trigonal Er3+–VK centers in KMgF3 and KZnF3 may be attributed to the translation of the cubic Kramers doublet Γ7. Furthermore, the EPR g-factors of the trigonal Er3+–VK centers may be interpreted reasonably by the shifts ΔZ≈0.340 Å and ΔZ≈0.303 Å of the Er3+ ions toward the charge compensator VK along the C3 axis for the KMgF3:Er3+ and the KZnF3:Er3+ systems respectively.

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