微波辅助水热法反应参数对NaYF_(4):Dy^(3+)晶相、形貌、发光性能的影响

Effect of Microwave-Assisted Hydrothermal Reaction Parameters on Phase,Morphology and Luminescence Properties of NaYF_(4):Dy^(3+) Phosphors

采用微波辅助水热法快速制备了可重复性良好的NaYF4∶Dy^3+样品,研究了一系列反应参数对NaYF4∶Dy^3+晶相、形貌、发光性能的影响。结果表明微波水热反应时间长短并未对产物的晶相、形貌、光谱性能产生明显的影响。Dy^3+掺杂浓度的增加并未改变样品晶相、形貌和尺寸,但发光强度发生改变,发光强度的变化趋势为先增大后减小,当Dy^3+掺杂浓度(物质的量分数)为1%时发光强度最强。根据具体的理论依据获得的电多极相互作用指数为6,表明Dy^3+之间的相互作用为电偶极-电偶极相互作用。研究了表面活性剂的种类与量对NaYF4∶Dy^3+晶相的影响。当使用柠檬酸钠和CTAB作为表面活性剂时,可制备得到六方相NaYF4∶Dy^3+。增加柠檬酸钠和CTAB的量,样品晶相未发生改变。使用EDTA-2Na作为表面活性剂时,随着EDTA-2Na量的不断增加发生从六方相到立方相晶相的转变。3种表面活性剂使用量不断增加后样品均出现尺寸减小现象。合成的一系列NaYF4∶Dy^3+荧光粉均在350nm紫外光激发下,出现Dy^3+特征峰。蓝光发射中心为479 nm,对应于Dy^3+的4F9/2→6H15/2跃迁;绿光发射中心为572 nm,对应于Dy3+的4F9/2→6H13/2跃迁,样品可实现蓝、绿发光。

The disadvantage of the traditional hydrothermal method was the poor repeatability. Therefore, the conclusions of the influence of various parameters on the morphology of rare earth doped NaYF4 prepared by the traditional hydrothermal method reported by different research groups in the literature were different. In order to clarify the effects of hydrothermal parameters on the structure and morphology of rare earth doped NaYF4, Dy^3+ doped NaYF4 phosphors were prepared by microwave hydrothermal method with good reproducibility and controllability. The effects of various parameters on the structure, morphology and luminescence of the products were systematically studied. The reproducible NaYF4∶Dy^3+ samples were rapidly prepared by microwave-assisted hydrothermal method. The effects of reaction parameters on the crystal phase, morphology and luminescence properties of NaYF4∶Dy^3+ phosphors were investigated. The results show that the microwave hydrothermal reaction time don′t affect the crystal phase, morphology and spectral properties of the as-prepared phosphors. The increase of Dy^3+ concentration do not change the crystal phase and morphology of the samples, but the luminescence intensity changes. The trends of luminescence intensity first increased and then decreased. The maximum luminescence intensity was obtained when the Dy3+ concentration was 1%(n/n). The electric multipole interaction index obtained according to the specific theoretical basis was 6. It is shown that the interaction between Dy^3+ is dipole-dipole interaction. The effects of the type and amounts of surfactant on the NaYF4∶Dy^3+ crystal phase were investigated. It was observed when Na3Cit·2H2O and CTAB were used as surfactants, hexagonal phase NaYF4∶Dy^3+ phosphors were prepared. The amounts of Na3Cit·2H2O and CTAB were increased and the crystal phase of the sample was not changed. When EDTA-2Na was used as the surfactant, the transition from the hexagonal phase to the cubic phase crystal phase occurred as the amounts of the EDTA-2Na increased. As the amounts of surfactants continue to increase, the size of the sample decreased. Under the excitation of 350 nm, Dy^3+ emission peaks appeared. The blue light emission peak centered at 479 nm, which corresponds to the 4F9/2→6H15/2 transition of Dy^3+. The green light emission peak centered at 572 nm, which corresponds to the 4F9/2→6H13/2 transition of Dy^3+.