Raman Scattering Study of Nano-Particle BaTiO3

Masayoshi Aoyama ； Takumi Hasegawa ； Norio Ogita ； Nobuo Nakajima ； Hiroshi Maruyama ； Haruki Kurokawa ； Masayuki Udagawa

《Chinese Journal of Physics》 49卷1期 (2011/02) Pp. 49-55

並列摘要

BaTiO3 (hereafter BTO) particles with different sizes, diameters in the range 10-200 nm, were prepared by the hydrothermal synthesis method, and their Raman spectra were investigated in the temperature range 570 to -150℃; the spectra were obtained by micro-Raman spectroscopy. On the basis of the changes in the spectra, the phase diagram of particle size versus temperature was obtained. We can divide the region below the particle diameter of 200 nm into three regions. One is a bulk-like region with particle diameters in the range 100-200 nm; the spectra in this region are similar to that of a single crystal. The second region is a transient region with particle diameters in the range 60-90 nm. The third region is a highly distorted region with particle diameters below 50 nm, where the spectra do not change remarkable from -150 to 570℃. In the spectra of 70- and 85-nm particles, a new peak was observed; this peak corresponds to the vibration at the X-point of the Brillouin-zone boundary. Thus, the translational symmetry in the transient region is broken. The new peak is expected to contain information on the effect of particle size on the dielectric constant of BTO. This implies that it can indicate the maximum dielectric constant of BTO with a particle diameter of 70 nm.