ABSTRACT
The structural data and Raman spectra of distorted R(3+)B(3+)O(3) perovskites (R(3+)-rare earth, B(3+)=Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga) with BO(6) octahedral tilts were critically reviewed in order to obtain the frequency (ω) versus BO(6) tilt angle (α) dependence of the quasi-soft vibrational modes. It was found that the relation ω = Ï°α is satisfied in a good approximation for each RBO(3) family with fixed B atom, despite the different spatial tilt orientations for compounds of the same series with either orthorhombic Pnma or rhombohedral R Ì
3c structure. The dependence of the proportionality coefficient Ï° on the averaged