Hardness Enhancement Induced by UV Irradiation in SrTiO3

A significant enchantment in hardness has been found in polycrystalline SrTiO3 after UV irradiation. Herein, we reported that with UV (405nm) irradiation for 30 mins the hardness of the polycrystalline increased from 1000 ± 55 HV to 1088 ± 75 HV. Specifically, the sizes of Vickers indentations revealed by Scanning Electron Microscope (SEM) statistically decreased from 92 ± 10 μm2 to 85 ± 9 μm2, implying that light-excited electrons, holes, or UV-induced oxygen vacancies could play the key role in the hardness enhancements. Our finding suggests a new route for controlling the hardness of polycrystalline metal oxide by tuning the UV irradiation.