Infrared absorption properties of KTN single crystals

We report the results of a Fourier transform infrared absorption study of two samples of KTa 1−x Nb x O 3 as a function of temperature from 350 to 7 K and for x-value of 0.187 and 0.344. A group of absorption peaks in the vicinity of 3500 cm −1 which display an intensity reversal with decreasing temperature for x = 0.344 and no reversal for x = 0.187 are attributed to Nb atom absorption processes which are perturbed as the KTN crystal undergoes the sequence of phase transitions from cubic to the normally final rhombohedral phase.