EPR and dielectric relaxation of Fe3+ in KTaO3

EPR and the method of dielectric losses have been used to investigate Fe3+ centers of axial and orthorhombic symmetry in KTaO3 single crystals. The EPR spectrum of orthorhombic-symmetry Fe3+ obtained in the 8-mm wavelength range nt T=77 K is described by the spin-Hamiltonian (H) over cap=beta(g(x)H(x)S(x)+g(y)H(y)S(y)+g(z)H(z)S(z))+DSz2+E(S-x(2)-S-y(2)) with parameters g(x)=1.98, g(y)=2.01, g(z)=2.00, D=0.43 cm(-1), and E=5.87X10(-2) measurement data we have obtained the following parameters of the relaxation of the orthorhombic Fe3+ centers in KTaO3: characteristic relaxation frequency tau(0)-1=2.33X10(12) Hz and activation energy E-a=0.044 eV. A model of the orthorhombic Fe3+ center in KTaO3 is discussed within the framework of the kinetic parameters obtained. (C) 1997 American Institute of Physics.