Structural disorder, polarisation and the normal to relaxor ferroelectric transition in BaTiO₃ based perovskites

This paper uses structured diffuse scattering to compare and contrast the local crystal structure behaviour of the normal ferroelectric BaTiO₃ with a range of relaxor ferroelectric substituted BaTiO3 materials. The results strongly suggest that both normal ferroelectric BaTiO₃ and the relaxor ferroelectric substituted BaTiO₃'s have the same underlying polarisation mechanism i.e. inherent 1-D correlated Ti cation and neighbouring O anion displacements forming 1-D dipole clusters (or polar nano regions). The role of the substituting ions is not to induce the PNR's but rather to suppress homogeneous strain distortion, transverse correlation of the 1-D PNR's and a transition into a long range ordered ferroelctric state.