Effect of Grain Size on Electrical Properties of Anatase TiO2 under High Pressure

The influence of grain sizes, size effects, has long been a key factor influencing the properties and even the phase transformation pathways of nanomaterials and has resulted in a lot of intriguing abnormal phenomena. The mechanism behind these peculiar phenomena of nanomaterials remains unresolved. In this study, we performed high-pressure electrical and spectroscopic measurements on nanoanatase TiO2 with average grain sizes of 11 and 62 nm, respectively, to characterize the relation between size effects and its electrical properties and thus reveal the mechanism behind these phenomena. Our work has demonstrated that the size effects on TiO2 with certain grain sizes exhibit considerable influence on tuning of its electrical properties upon lattice compression by altering its grain boundary morphology, band gap structure, and relaxation frequency. Such effects have substantial significance in tuning the properties and crystalline structures for other nanomaterials as well.