Thermal diffusivity of Lu- doped TGS in the ferroelectric phase

The temperature dependence of the thermal diffusivity (ThD) of TGS doped with Lu3+ was investigated in two crystallographic directions in the ferroelectric phase. The thermal diffusivity was calculated at different temperatures from the relation k = Λ/cP p. The measurements of the thermal conductivity (Λ) were performed using a steady-state measuring method. The results show that ThD is closely related to the impurities and imperfections. The marked changes in ThD at low temperatures of Lu-doped TGS crystals compared with the ThD of pure ones suggest the perturbation of the crystal lattice by point defects - Lu3+ ions.In the range of low temperatures - below 50K. the ThD is lower in the ferroelectric [010] direction for pure and Lu-doped TGS crystals both. Domain patterns on the [010]-plane and on the [100]-plane of pure and Lu-doped TGS crystals have been studied through scanning electron microscopy. The domains in pure and Lu-admixtured TGS are generally in the shape of rods oriented along the ferroelectric axis.