EPR and electron-nuclear-double-resonance investigations ofFe3+in KMgF3

Abstract

Single crystals of iron-doped KMgF3 show a strong axial EPR spectrum with partially resolved hyperfine structure. The spectrum arises from Fe'+ in a crystalline field of [100] axial symmetry. An electron-nuclear-double-resonance study of the hyperfine interaction gives positive support to the model previously proposed. The iron ion substitutes for a magnesium ion, and one of the surrounding six-nearest-neighbor Auorine ions is either missing or replaced by a charge-compensating impurity such as 0, thus giving rise to an axial distortion. The measured values for the spin-Hamiltonian parameters are D = 0.352 + 0.005 cm ', g~--2.0042+ 0.0005, and g, = 2.0120+ 0.0005, where g is axially symmetric about the symmetric axis of the crystalline-field parameter D. The nearest-neighbor hyperftne interaction constants are A, gh = 104.6+ 0.1 MHz and Ar/h = 55.7+ 0.1 MHz for the four "F ions in a (100) plane perpendicular to the symmetry axis of D, and A~(h = 43.2+ 0.5 MHz, A"/h = 24.6 + 0.1 MHz for the single ' F ion along the symmetry axis of D. It is assumed that the hyperfine interaction tensors are axially symmetric about their corresponding Fe-F bond directions.

EPR Investigations on the (FeOF5)4− Cluster in KZnF3

“…4a, b, and c this first order treatment leads to satisfactory results and prevents from the ENDOR measurements or from the more sophisticated calculations which were used for (FeOF,)4-in KMgF3 [7]. All the parameters are given in units of lo-* cm-l.…”

“…I n this paper we analyse, at X band, the EPR spectrum of the (FeOF,)4-cluster in KZnF, in a way somewhat different from that followed for the same cluster in KMgF, [7].…”

Theoretical investigation of local lattice structure of the tetragonal FeF5O cluster in KMgF3:Fe3+ crystal

“…For the tetragonal FeF 5 O cluster in KMgF 3 :Fe 3+ crystal, the local symmetry is C 4v [7,8]. The zero-field splitting parameters of Fe 3+ ions in a tetragonal ligand-field may be studied in terms of the ZFS Hamiltonian [18,19].…”

“…In the case of Fe 3+ ions doped into KMgF 3 crystal, a tetragonal defect center has been observed by electron paramagnetic resonance (EPR) experiment [7,8] in addition to a K-vacancy site [3]. This tetragonal site is characteristic of a very large rank-2 axial zero-field splitting (ZFS) parameter (|b 0 2 | = 0.3572 cm −1 ) [7,8], several times greater in magnetic than those (|b 0 2 | = 0.04 − 0.08 cm −1 ) for M-vacancy sites in AMF 3 crystals [4,5]. This result has been assigned to an FeF 5 O configuration (see Fig.…”

“…In the last years much attention has been paid to the investigations of transition-metal (TM) ions doped into fluoroperovskite-type AMF 3 crystals (A represents an alkali metal and M represents an alkaline-earth metal ion) [1][2][3][4][5][6][7][8][9][10]. Magnetic impurity ions doped in the layered perovskite fluorides are expected to substitute for host cations and form the magnetic impurity center.…”