X-ray scattering study of the random electric dipole system KTaO₂:Li

Measurements are reported of the X-ray scattering from KTaO 3 with 1.6% and 5% of Li substituted for K and, for comparison, with 1.7% of Nb substituted for Ta. Both KTaO 2 :5% Li and KTaO 3 :1.7% Nb are found to undergo transitions to states with long-range ferroelectric order on cooling. However, the low-temperature state of KTaO 3 :1.6% Li does not possess long-range ferroelectric order when cooled in zero applied electric field. The measurements are in agreement with an electric dipole glass or spin glass analogue description of the low-temperature phase of KTaO 3 :Li for Li concentrations below about 4%.