Sites of Fe³⁺impurities in a congruent LiTaO₃crystal

Abstract

With electron nuclear double resonance (ENDOR) the superhyperfine interactions of Fe3+ impurities with five shells of Li neighbours were measured in a congruent LiTaO3 crystal. From the analysis of the ENDOR spectra it is found that Fe3+ is on a substitutional Li+ site on the threefold symmetry axis of the crystal. From the shape of the ENDOR spectrum it is concluded that most Fe3+ impurities are on very perturbed sites.

Determination of atomic positions of point defects in solids by ENDOR

“…If it was, one would have observed ENDOR line splittings, for instance, from shells 1, 3, 4 above and below the xy plane (Fig.5b). The quoted uncertainty is derived from ENDOR line width [15]. For LiNbO3, very similar results were obtained [16].…”

“…The isotropic shf constant of a ligand Ni with coordinate RN~, is given by 2 (15) with 0 ~ and 0 ~ the spin-up and spin-down electron densities, respectively. The anisotropic shf constant (bN)k,l = cf (-3xkxl-rs r2) (Q'(F+ 9 ) -~'(7+/~Ni))dr 3 , (16) C= ~ g~g~,r~ifl~~n .…”

“…b Schematic representation of the Li sublattice assuming Fe 3 § on a substitutional Ta 5-site. The numbers 1 -5 represent the Li shells with increasing distance from the Fe 3+ (after 115]ENDOR of Fe 3+ centers in LiTaO 3 (after[15]). a Angular dependence of the Li ENDOR spectra for rotation of the magnetic field in a plane perpendicular to the c-axis.…”

EPR spectra and local lattice structure of Fe3+ impurity ions in ferroelectric LiNbO3

“…LiNbO 3 crystal is of sustained scientific and technical interest, mainly due to its desirable ferroelectric, piezoelectric, and photoelectric properties [1][2][3][4][5][6], even for acoustical memory as recently reported [1]. The most extensive application is the ferroelectric property which mainly origins from the structure distortion in LiNbO 3 itself, i.e.…”

EPR investigation of substitution position for Fe3+ in LiNbO3:Fe3+ system

“…Lithium niobate, LiNbO 3 , is of significant interest due to its ferroelectric, piezoelectric, and photoelectric properties [1][2][3][4][5][6][7][8][9][10], which make it a very good candidate for photoelectric devices.…”