Direct observation of non-strain-free style domain in BaTiO crystal by synchrotron X-ray topography

Yoneda, Yasuhiro   ; Komura, Yoshiki*; Suzuki, Yoshio*; Morimura, Ryota*; Kojima, Akira*; Mizuki, Junichiro

We performed X-ray diffraction topography on a BaTiO single crystal by high-coherent synchrotron X-rays. Since the domain configuration of the BaTiO crystal was unstable and fluctuated as temperature fluctuated, an excellent temperature control system is needed for the domain observation. We used a milli-Kelvin (mK) cell, which can control a BaTiO crystal within 1mK. By combining the coherent X-ray and the mK-cell, one can detect the lattice strain very sensitively around the domain boundary. The lattice strain reduced as temperature increased, and disappeared at 100C, which is much lower than the phase transition temperature of the BaTiO, and the BaTiO crystal still remained in the ferroelectric tetragonal phase. This behavior can be interpreted by the existence of the so-called "non-strain-free style domain", which is reported firstly by Takashige et al.