EPR study of Ni3+ in RbCaF3 below the cubic-tetragonal phase transition

Investigations of the g ‐factors and local phase‐transition behavior for Ni3+ ion in the tetragonal phase of RbCaF3 crystal

“…Since |D q /B| < 2.2 in RbCaF 3 :Ni 3+ , its ground orbital state should be the highspin 4 1 T (F) state [18,19]. This point is consistent with the result obtained from EPR g factors in RbCaF 3 : Ni 3+ [4]. So, the above parameters ƒ γ and D q can be regarded as reasonable (in passing, for 3d…”

“…The local tilting angle is different from the intrinsic one (≈ 7∞ [1,4]) in the host crystal RbCaF 3 . As has been said before, for (NiF 6 ) 3− clusters in RbCaF 3 crystal, the parameter a/2 (≈ R 0 h ) in Eq.…”

“…showed that the local tilting angle φ ≈ 5.2∞ at T ≈ 30 K [4]. The local tilting angle is different from the intrinsic one (≈ 7∞ [1,4]) in the host crystal RbCaF 3 .…”

“…the anisotropic g-factor and/or zero-field splitting) of a paramagnetic impurity in crystals are sensitive to its immediate environment, the local phasetransition behavior of an impurity center in RbCaF 3 can be studied by calculating its EPR parameters. From EPR measurements [4], the Ni 3+ ions (at Ca 2+ sites) created by room-temperature X-irradiation of nickel-doped RbCaF 3 crystal were found and their EPR g-factors g || (≈3.833) and g ⊥ (≈4.370) in the tetragonal phase (T ≈ 30 K) were given. As is known, for Ni 3+ (3d…”

“…The intrinsic parameter 4 A (R 0 ) = 3/4 D q with the reference distance R 0 for a 3d n ion in octahedral clusters [9,25,26], and many studies [9,[25][26][27][28] …”