A structural perspective on giant permittivity CaCu3Ti4O12: One way to quantum dielectric physics in solids

As one typical giant permittivity material in the last 20 years, CaCu3Ti4O12 is need of a clarification between structures and the permittivity in the development of industrialization. Besides, it presents other electrical, antiferromagnetic, and photo-related properties. One model for all phenomena, all doubt for one model. We highlight the importance of intrinsic structures, by identifying the insulating anisotropy of grain boundaries, the undesirable loss effect of twinning boundaries and the dielectric insensitivity of A-site atomic Ca/Cu disorders. Based on both B-site specific titanium ions and A-site copper ions' polaron-like 3d electrons, we have established a comprehensive and self-consistent model of binary dielectric polarizing species, mainly with the Hamiltonian in the Ising model analysis of dielectric polarization. The review points to a new way of applying quantum physics to deepen dielectric researches in transitional metal oxides, by exploiting strong ionic and electronic correlations beyond classical dielectric physics.