The polarisation property of dielectric relaxors and ferroelectric relaxors presents a strong dependence on external fields (incl. temperature, electrical field and mechanical force even magnetic field) which can generate amazing functionalities for developing smart devices. However, the relaxors are structurally disordered, leading to extremely complex and assorted polarisation distribution. The relaxation mechanism of such relaxors has not been fully understood which tremendously obstructs the R&D of functional relaxors. Our research aims to explore the fundamental understanding of the correlation between structural disordering and polarisation relaxation for the development of new or optimisation of well-known functional relaxors, such as Bismuth Zinc Niobate and BaTiO3 material systems.