Cluster Glass and Domain State Properties of KTaO ₃ Li

The phase boundary between low-temperature dipole glass and ferroelectric states of K 1- x Li x TaO 3 is proposed to lie within 0.016 < x < 0.026 according to new optical birefringence, refractive index and dielectric permittivity data. The low- x glass phases are characterized by freezing temperatures T g < 40 K, whereas in the high- x limit random-field-induced domain states are achieved via rounded first-order transition at T c > 40 K. The crossover concentration x c ∼ 0.022 is extrapolated from the condition T g ( x c ) = T c ( x c ) ∼ 41.5 K.