Valence-sensitive determination of Cr3+ and Ce3+ concentration in doped Sr0.61Ba0.39Nb2O6 from magnetization studies and paramagnetic relaxation of Ce3+

Abstract

Magnetization- and susceptibility measurements are used as a method to determine the number density of the photorefractive centers Ce3+ and Cr3+ in Sr0.61Ba0.39Nb2O6 (SBN61). The number densities (n) over bar (3+)(Ce)=0.73(1).10(20) cm(-3) and (n) over bar (3+)(Cr)=1.58(8).10(20) cm(-3) were determined for crystals doped with 1.6 wt.%Ce and 20000 ppm Cr, respectively. Frequency dependent susceptibility measurements in the temperature range 3-10 K on SBN61: Ce show that the spin-lattice relaxation in this compound is dominated by the Orbach process. The crystal field splitting of the two lowest ground state doublets is determined to 1.77 meV. The susceptibility of SBN61: Cr shows no frequency dependence in the range 10-10(4) Hz.