Experimental and Theoretical Investigation of Spin-Hamiltonian Parameters for the Low Symmetry Fe3+ Centre in LiNbO3

X-band EPR spectra of Fe3+ in LiNbO3 single crystals at room temperature are analyzed with a spin-Hamiltonian of C3 symmetry. First the zero-field splitting (ZFS) parameters b, b, b, and b−34 are calculated using the superposition model (SPM). The SPM-ZFS results for Fe3+ at the Nb site agree better with the experimental ones than those for Fe3+ at the Li site. Next the crystal field (CF) parameters are predicted using SPM and two sets of available structural data for LiNbO3. Diagonalization of the full Hamiltonian, including the CF Hamiltonian, within the whole 3d5 configuration yields the ZF splittings for Fe3+ centres. The ZF splittings obtained from the theoretical SPM-CF calculations for Fe3+ at the Nb site agree better with the experimental EPR data than those for Fe3+ at the Li site. The present results indicate that the observed EPR spectra of Fe3+ : LiNbO3 can be attributed to Fe3+ ions at the Nb sites.

[1]  B. Faust,et al.  New axial Fe3+ centres in stoichiometric lithium niobate crystals , 1993 .

[2]  Wanlun Yu,et al.  Zero‐Field Splitting and the Optical Fine Structure in Fe3+ :Al2O3 Crystals , 1993 .

[3]  J. Spaeth,et al.  The site and local environment of Fe3+ in LiNbO3 investigated with ENDOR , 1992 .

[4]  C. Zaldo,et al.  Determination of the lattice site of Fe in photorefractive LiNbO3 , 1992 .

[5]  Czeslaw Rudowicz,et al.  Ligand Field Analysis of the 3dN Ions At Orthorhombic or Higher Symmetry Sites , 1992, Comput. Chem..

[6]  C. Catlow,et al.  An EXAFS study of dopant substitution in LiNbO3 and LiTaO3 , 1991 .

[7]  Ke,et al.  Trigonal splitting of a S6-state ion. , 1991, Physical review. B, Condensed matter.

[8]  D. Newman,et al.  The superposition model of crystal fields , 1989 .

[9]  M. Glinchuk,et al.  Control of the impurity and proper defects in lithium niobate crystals by esr and endor methods , 1989 .

[10]  Inspec,et al.  Properties of lithium niobate , 1989 .

[11]  C. Rudowicz.  On the derivation of the superposition-model formulae using the transformation relations for the Stevens operators , 1987 .

[12]  Xiao-yu.  Analysis of the electron paramagnetic resonance zero-field splitting for Fe3+ in sapphire. , 1987, Physical review. B, Condensed matter.

[13]  S. Abrahams,et al.  Defect structure dependence on composition in lithium niobate , 1986 .

[14]  S. S. Park,et al.  Magnetic Resonance Studies of 7Li, 93Nb, and Fe^(3+) in Fe-Doped LiNbO3 , 1985 .

[15]  K. A. Müller,et al.  Structure of transition-metal—oxygen-vacancy pair centers , 1979 .

[16]  S. Date,et al.  Mössbauer‐effect study of Co57 and Fe57 impurities in ferroelectric LiNbO3 , 1975 .

[17]  B. A. Scott,et al.  Electron paramagnetic resonance of LiNbO3: Fe3+ , 1972 .

[18]  H. H. Towner,et al.  EPR Studies of Crystal Field Parameters in Fe3+: LiNbO3 , 1972 .

[19]  B. Dischler,et al.  An EPR investigation of Fe3+ and Mn2+ in LiNbO3 , 1972 .

[20]  A. Watanabe,et al.  Spacing of the hyperfine sextet in Mn2+ ESR in LiNbO3 , 1968 .

[21]  H. Levinstein,et al.  Ferroelectric lithium niobate. 5. Polycrystal X-ray diffraction study between 24° and 1200°C , 1966 .

[22]  D. McClure,et al.  Optical Spectra of Transition‐Metal Ions in Corundum , 1962 .

[23]  P. Löwdin,et al.  Studies on the Alternant Molecular Orbital Method. II. Application to Cyclic Systems , 1962 .