Kunio Tochi

Long-wavelength phonons and effective charges in complex perovskite compounds Ba(Mn1/3Ta2/3)O3 and Ba(Ni1/3Ta2/3)O3

The splitting of the polar modes into TO and LO components is due to the Coulombic field. The neutrality of the primitive unit cell and the independence of the external vibration modes from the internal ones lead to the present calculation. The higher frequencies for the internal vibrations related to tantalum ions than those related to manganese and nickel atoms observed in the two-mode behaviour also helped the consideration

Lattice vibration modes of (1 −x)Ba(Zn1/3Ta2/3)O3-xBaZrO3

Discussion de la variation des modes de vibration par addition des ions zirconium (x compris entre 0 et 0,04)