Is K_{(1 −x)}Li_xTaO₃ a Real Relaxor?

Li-doped KTaO₃, K_(1-x)Li _x TaO₃ (KTL) has been reported to be a relaxor with an isovalent substitution of Li⁺ for K⁺. For confirming the idea, we performed second-harmonic generation microscopic observations, X-ray diffraction experiments and dielectric measurements of KTL with the critical concentration of Li (x = 3%). These reveal that an intermediate phase exists between 2 characteristic temperatures, T_d and T_p. The former corresponds to an elastic change accompanying small deformation and the latter to a dipolar change of the crystal. It is highly probable that the polar-nano regions appear below Td and transformed into ferroelectric domains at T_p. The present experiments support that KTL is a real relaxor.

Keywords:

• Phase transition
• relaxor
• quantum paraelectrics
• K_{(1 −x)}Li _x TaO₃
• SHG microscope
• impurity effect

Acknowledgments

The work is supported by the grants-in-aid of scientific research (A) of MEXT, the special research program of Waseda University and the 21st century COE program “Physics of systems with self-organization composed of multi-elements” of MEXT, Japan.