Synthesis And Photoluminescence Property Of Ternary Oxide Nanomaterials

The ternary oxides have wide applications in ultraviolet photodetectors, gas sensor, and thin film solar cell. One of the advantages of the ternary oxides is that its properties can be tuned by adjusting the ratio of components. In present work, we chose Zn-Sn-O system as the object of our research, focusing on the controllable synthesis, characterization and physical feature analysis of Zn1-xSnO₄ nanomaterials. Meanwhile, explorations in adjusting luminous properties were also carried out. The main contents and results are as follows:(1) Synthesis and photoluminescence properties of Zn₂SnO₄ nanomaterialsBean-like Zn₂SnO₄ nanomaterials were synthesized by carbon-assisted thermal evaporation method. Both X-ray diffraction (XRD) pattern and Raman spectra confirmed the main product was Zn₂SnO₄ with a small amount of ZnO, which was semi-quantitatively determined as At.%≈8.49 by the following X-ray photoelectron spectroscopy (XPS) analysis. XPS results also revealed that zinc and tin were in the +2 and +4 oxidation states, respectively. We detected two different Zn₂p3/2 binding energies and attributed to ZnO and Zn₂SnO₄, respectively. The binding energy for Zn₂SnO₄ has not been reported before. The two binding energies Sn3d demonstrated that Sn⁴⁺ occupies two distinct sites in Zn₂SnO₄. Our measured room temperature photoluminescence spectrum (PL) exhibited strong and asymmetric emission in the ultraviolet (UV) area besides the commonly observed broad emission in visible region. The visible emission was mainly resulted from crystal defects, such as Oxygen vacancy and Zinc interstitial. After multi-peak Gaussian fitting, the UV emission can be divided into two emission bands (358 nm and 385 nm). Compared with the PL spectrum of pure ZnO, the band centered at 358 nm was assigned to near-band-emission of Zn₂SnO₄.(2) Effect of Sn concentration on the structural and photoluminescence (PL) properties of ZnO nanostructuresWe intentionally changed the ratio of tin/zinc in raw material to investigate the effect of Sn concentration on the structure, morphology, and PL properties of ZnO nanostructures. SEM images represented that the morphology varied with the tin/zinc molar ratio. XRD results revealed that the as-prepared products were pure wurtzite structure ZnO without introduction any Sn-related phase. Further analysis revealed that c axis interplanar spacing increased with that of Sn concentration. EDS results confirmed Sn concentration in the as-grown products increased from 0 to 1.378 %. Room-temperature photoluminescence spectra of the doped samples exhibited that near band emission (NBE) peaks shift to higher energy with the increase of Sn content in doped ZnO nanostructures. The corresponding blue-shift mechanism was attributed to Burstein-Moss effect induced by the change of doping concentration.(3) Sn-doped ZnO nanorotors with modulated structureSn-doped ZnO nanorotors with modulated branches structure were synthesized by vapor transport and condensation method at a relatively low temperature without any catalyst. The modulated structures consisted of alternatively dark and bright contrast stripe along the growth of the branches. Each unit had a periodic length of 25 30 nm. HRTEM image revealed that a non-uniform transition layer with a thickness of 2.4 2.5 nm occurred between two units. The non-uniform transition layer was called inversion boundaries (IBs) and only found in In-doped ZnO previously. XRD results indicated the nanostructures had a preferred growth direction which was consistent with HRTEM structure analysis. The modulated structure was different from the previously reported In-doped ZnO nanostructures. The unique structure has not been reported in Sn-doped ZnO nanostructures. Based on the relaxation of lattice strain during the Sn doping process, a possible atomic structure model was proposed to explain such self-assembly process.