Mode softening in quantum ferroelectric KTa 1-x Nb X O 3

Abstract
The temperature dependence of the lowest frequency TO and of the corresponding TA phonon branches in the (00ζ) direction has been investigated by means of coherent inelastic neutron scattering in KTa1-xNbxO3 for two different Nb concentrations x1 = 0. 008 and X2 = 0.012.