Th. Yeom et al., CR3- EXPERIMENTAL AND THEORETICAL INVESTIGATION OF SPIN-HAMILTONIAN PARAMETERS( CENTERS IN LINBO3 ), Solid state communications, 87(3), 1993, pp. 245-249
X-band EPR spectra of Cr3+ ions in ferroelectric LiNbO3 single crystal
at room temperature are analyzed assuming Cr3+ enters either of the t
hree possible sites: Li, Nb and structural vacancy (SV) site. The obse
rved spectra can be resolved into (I) the main (Cr(l)3+ and (II) the w
eak (Cr(II)3+) spectra. The axial zero-field splitting parameter for a
Cr3+ centre at Li site (D(Li)) as well as Nb site (D(Nb)) is calculat
ed using the superposition model. The values D(Li) and D(Nb) agree wel
l with the experimental D value for Cr(I)3+ and Cr(II)3+, respectively
. This confirms that the main spectra can be attributed to Cr(I)3+ at
the Li site and the weak spectra to Cr3+ at the Nb site. For Cr3+ ion
at the structural vacancy site the parameter D(SV) is calculated as a
function of displacement of Cr3+ ion from the centre of the oxygen oct
ahedron along the [111] direction. Other weak and unresolved spectra a
lso observed by us can possibly be due to Cr3+ centres at vacancy site
.