Study On Preparation And Luminescent Properties Of Rare Earth/ZnO Composites

In this thesis,the ZnO and Gd₂O₃@ZnO precursors were prepared by the soft template method,and three rare earth doped ZnO composites were prepared by the hydrothermal method.The effects of rare earth ion concentration,hydrothermal temperature and hydrothermal time on the luminescence properties and microstructure were discussed,and the optimal synthesis conditions of the samples were determined.The detailed research contents as follows:Ordered mesoporous zinc oxide precursor was prepared by soft template method,which used cetyltrimethylammonium bromide as a template.The ordered mesoporous Eu³⁺/ZnO luminescent material was prepared with Eu³⁺ as a light-emitting center ion and sulfosalicylic acid as organic ligand,the sample showed a regular chrysanthemum-like morphology.With the increase of Eu³⁺ doped concentration,the fluorescence intensity was also increased,and it reached the strongest when Eu³⁺ doped concentration was 16%.The optimal hydrothermal temperature was 180?,and the optimal hydrothermal time was 16 h.When 394 nm excitation light was used as exciting light to excite the sample,the strongest emission peak of Eu³⁺ was located at 590 nm which was distinct with the conventional at 615 nm.When 359 nm was used as excitation light to excite the sample,the strongest emission peak of ZnO was located at 417 nm,which was much stronger than the conventional emission intensity.Ordered porous zinc oxide precursor was prepared by soft template method using sodium dodecyl sulfate as a template.The Eu³⁺ was used as luminescent center ion,the 1,10-phenanthroline was used as organic ligand,and the uniform bitter melon-like ordered porous Eu³⁺-phenanthroline/ZnO composite was prepared by hydrothermal method.With the increase of Eu³⁺ doped concentration,the fluorescence intensity was also increased,and it reached the strongest when Eu³⁺ doped concentration was 18%.The optimal hydrothermal temperature was 160?,and the optimal hydrothermal time was 5 h.The prepared materials showed the stronger yellow and blue light emission under 394 and 275 nm excitation,respectively.Using cetyltrimethylammonium bromide as a template,an ordered porous Gd₂O₃@ZnO composite precursor was prepared by the soft template method.The Eu³⁺ was used as a luminescent center ion,the sulfosalicylic acid was used as organic ligand,and a kind of much novel tube-wrapped-wire morphology ordered porous Tb³⁺ doped Gd₂O₃@ZnO composite was obtained by the situ rearrangement of the Gd₂O₃@ZnO composite precursor spheroidal particles in hydrothermal condition.In this tube-wrapped-wire structure,a wire-like Gd₂O₃ was wrapped in a ZnO tube whose surfaces were distributed the ordered mesoporous,and the C₁₂H₁₂O₁₂S₃Tb₂ complex was distributed between ZnO layer and the Gd₂O₃ layer.The average length of the tube-wrapped-wire particles was about 12-21 ?m,the external diameter of the ZnO tube was about 720 nm,and the diameter of the Gd₂O₃ wire was about 440 nm.The optimal synthesis conditions were as follow: the Tb³⁺ doped concentration was 16%,hydrothermal temperature was 180?,and hydrothermal time was 16 h.The Tb³⁺/Gd₂O₃@ZnO sample showed a characteristic peak of Tb³⁺ at 543 nm under 325 nm exciting light,which was 5.3 times of the prepared Tb³⁺/ZnO material and 1.5 times of the prepared Tb³⁺/Gd₂O₃ material.