Atomic-scale control of TiO(6) octahedra through solution chemistry towards giant dielectric response

The structures of many important functional oxides contain networks of metal-oxygen polyhedral units i.e. MO(n). The correlation between the configurations and connectivities of these MO(n) to properties is essentially important to be well established to conduct the design, synthesis and application of new MO(n)-based functional materials. In this paper, we report on an atomic-scale solution-chemistry approach that for the first time enables TiO(6) octahedral network control starting from metastable brookite TiO(2) through simultaneously tuning pH values and interfering ions (Fe(3+), Sc(3+), and Sm(3+)). The relationship between solution chemistry and the resultant configuration/connectivity of TiO(6) octahedra in TiO(2) and lepidocrocite titanate is mapped out. Apart from differing crystalline phases and morphologies, atomic-scale TiO(6) octahedral control also endows numerous defect dipoles for giant dielectric responses. The structural and property evolutions are well interpreted by the associated H(+)/OH(−) species in solution and/or defect states associated with Fe(3+) occupation within TiO(6) octahedra. This work therefore provides fundamental new insights into controlling TiO(6) octahedral arrangement essential for atomic-scale structure-property design.