Chundong Li

Evidences of VO, VZn, and Oi defects as the green luminescence origins in ZnO

In this Letter, by employing a combination of typical treatments and sensitive defect characterization, we discriminate between the roles of different kinds of intrinsic defects in ZnO. Thereby, we offer convincing experimental evidence that the green luminescence can originate from VO, VZn, and Oi-related defects, corresponding to the 2.48 eV, 2.35 eV, and 2.26 eV emissions, respectively. The green emission peaks are found to be dependent on the relative concentration of these defect centers.

Characteristics of point defects on the optical properties of ZnO: revealed by Al–H co-doping and post-annealing

Understanding the influences of lattice defect evolution on the optical properties of ZnO is of significance. To clarify this, we adopted typical treatments on ZnO using Al–H co-doping and post-annealing, combined with comprehensive characterization (absorption spectrum, Raman scattering, photoluminescence, electronic paramagnetic resonance and positron annihilation). The results reveal that the visible luminescence can arise from the VO, VZn and AlZn–Oi defects, while the defect centers responsible for the blue band optical absorption are assigned to ionized Zni and V+O. SEM images illustrated that H+ implantation diluted the ZnAl2O4 second phase, which reaccumulated after O2 annealing.

Radiation Stability of Zinc Oxide Pigment Modified by Zirconium Oxide and Aluminum Oxide Nanopowders

The effect on the reflective spectra of heat treatment and modification of ZnO pigments by 1–30 wt.% ZrO2 and Al2O3 nanoparticles has been investigated before and after irradiation by 100 keV protons with a fluence of 5×1015 cm−2. It is established that with the optimum concentration of 5 wt.% nanoparticles and the temperature of 800° C a 20% increase in the radiation stability is observed for the modified ZnO pigment in comparison with the not modified pigment. The decrease of absorption in the modified pigments is determined by the decrease of the intensity of the absorption bands of the zinc vacancies (Vzn−), oxygen vacancies (Vo+) and donor‐acceptor couples (Vzn‐−Zni0).

The Effect of Small Concentrations of Nanopowders on the Radiation Stability of Lacquers

The purpose of this research is to study the optical properties of the binders-lacquers based on organosilicon lacquers and epoxy resins modified by nanopowders ZrO2, Al2O3, CeO2, SiO2, TiO2 with concentration from 0.5 to 5 wt%, before and after proton irradiation Ep = 100 keV, Ф = 5 × 1015 cm−2. Analysis of the diffuse reflection spectra and calculation of the solar absorptance were performed. It was found that radiation stability of organosilicon lacquer is higher than of epoxy resins for both modified by nanopowders and not modified. It was established that the introduction of small concentrations (1–2 wt%) of nanopowders to binders based on organosilicon lacquer promotes decrease of their solar absorptance. Radiation stability of organosilicon lacquer (ΔaS = 0.06) modified by SiO2 nanopowder (ΔaS = 0.012 for 1 wt%) is higher compared with other types of nanopowders ZrO2, Al2O3, CeO2, TiO2 (ΔaS = 0.024, 0.026, 0.034, 0.04 accordingly for 1 wt%).