Linear and nonlinear dielectric response of the first-order ferroelectric phase transition in K^sub 0.92^Li^sub 0.08^TaO^sub 3^ under dc electric field

The results of measurements of low-temperature susceptibility: linear and nonlinear, and polarization under dc electric field of the lithium-doped potassium tantalate K0.92Li0.08TaO3 (KLT-8%Li) solid solution are presented. The recognized coexistence of the relaxor-like and ferroelectric behavior is presented. The observed ferroelectric phase transition is of the first-order type. Using an external dc electric field Edc = 178 kV/m the temperature of the ferroelectric phase transition is shifted by 3 K toward the value of 117 K, relative to the TC = 114 K observed without external dc electric field. Experimental facts reported in the present paper allowed us to argue that ferroelectricity in K1-xLixTaO3, in the case of x > 0.022 is due to a dynamical correlation of the off-center motions of Ta+5 ions in the octahedral environment of oxygen ions and does not arise directly as a result of the ordering of Li+ ion dipole moments within the so-called polar nanoregions.