STUDY OF "PURE" KTaO3 AND KTN SINGLE CRYSTALS BY THERMAL CONDUCTIVITY MEASUREMENTS DOWN TO 50 mK

We have measured the thermal conductivity of pure and doped (Nb, Na, Li , Co, Ag, etc ...) KTaO3 single crystals to investigate the induced ferroelectric phase transition mechanisms. The strong phonon scattering observed in the "purest" KTaO3 is tentatively explained as well as the enhancement of this scattering by substituing Nb in the crystals. Results of preliminary numerical analysis of the curves are given