From relaxor to ferroelectric behavior in K1−xLixTaO3

The results of low-temperature linear and nonlinear susceptibilities, polarization measurements of the dielectric properties of the KTaO
₃
and K
_1-x
Li
_x
TaO
₃
, x=0.02 and 0.08 solid solution are presented. The coexistence of the relaxor-like and ferroelectric behavior and different mechanisms leading to either of them are discussed. The observed ferroelectric phase transition in K
_1-x
Li
_x
TaO
₃
, x=0.08 is of the first-order type with temperature hysteresis. Clusters of Li
⁺
ions produce a relaxor-like behavior and random electric field. The ferroelectric phase transition is due to the off-center motions of Ta ions in the octahedral environment of oxygen ions. This process leads to the formation of a reversible spontaneous polarization.