RESUMO
The SrZnO2 of beardlike and sheetlike nanobundles, rod and treelike nanostructures have been synthesized by a citrate-gel combusting synthesis approach. As-prepared SrZnO2 shows orthorhombic structure with Pnma space group and unit cell with the lattice parameters: a = 5.830 A, b = 3.340 A and c = 11.348 A. By increasing the sintering temperature, the beardlike nanobundle gradually dissolved to form microrods and treelike microstructure. Citrate acid exerts a major influence in directing the formation of these unique SrZnO2 microstructures. These materials were analyzed for their use to luminescence materials. The as-made samples exhibit an efficient absorption and excitation band in the UV spectral region (centered at 380 nm). In the same time, the samples of with different morphologies showed a broad yellow emission peak centered at approximately 545 nm which should been associated with the composition and morphologies of sample or from the oxygen vacancies of semiconductor SrZnO2. The material may be used as novel conversion phosphors or host material of phosphor for white-light LEDs.
RESUMO
ZnO:LiAc nanopaticles were successfully synthesized though a colloidal-sol technique in nonaqueous solution under ultrasonic irradiation. The luminescent characteristics from blue to red can be tunable by varying [Li]/[Zn] ratios. The possible reason of tunable luminescent characteristics can be attributed to the increase of density of oxygen vacancies caused by Li+ adsorbed in the surface of magic-sized ZnO nanocrystals based on XRD, zeta potential and XPS results. What's more, it is found that SiO2 shell coated on ZnO:LiAc nanoparticles can improve the surface property of ZnO nanoparticles and enhance the PL emission intensity and optical stability. Due to its excellent luminescent characteristic and optical stability, as-prepared SiO2 coated ZnO:LiAc nanoparticles may be a promising candidate for some applications in high-efficiency low-voltage phosphor, solar cells and biological luminescent labels.