Room-temperature green and ultraviolet emission from different grain sized Mn_2O_3 nanocrystals

摘要

In this letter, we report on the results of green and ultraviolet emission spectra and high-resolution electron micrography studies which reveal the grain sizes of chemical liquid homogeneous precipitation (CLHP) prepared Mn_2O_3 nanocrystals' effect on green and ultraviolet emission spectra under the same excitation conditions. It is found that the intensities of the green and ultraviolet emissions depend on the grain sizes of Mn_2O_3 nanocrystals; the smaller the grain size, the weaker the intensity. A possible process for the peak intensity decreasing is discussed. Experimental results and spectral analyses suggest that the mechanism responsible for the green and ultraviolet emission is the existence of the surface oxygen dangling bonds, which leads to the relaxation of some middle energy levels such as surface, crystal boundary and oxygen hole energy levels, etc. after absorbing photons and releasing phonons.