作为白光LED用铕掺杂氟化镧红色荧光粉的制备与光谱性能研究

采用水热法制备具有单一相六方晶系的LaF₃:Eu3+纳米荧光粉.通过X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、光致发光光谱(PL)和荧光衰减曲线对LaF₃:Eu3+纳米荧光粉进行表征.LaF₃:Eu3+荧光粉的激发光谱主要由250 nm处的宽带(O2-→Eu3+的电荷转移跃迁)和一些尖峰(Eu3+ f-f跃迁)构成，其中位于近紫外区396 nm处有一较强的激发峰.通过发射光谱探测Eu3+在LaF₃晶体中的局部晶场环境.在298 K下激发光谱和发射光谱可知，在六方晶系的LaF₃纳米晶体中的Eu3+晶格位置从D_4h降至到C_2v，这是由于晶格变化所造成的.在396 nm激发下，观测到较优掺杂浓度为10%的LaF₃:Eu3+荧光粉在591 nm(5D₀→7F₁跃迁)处有强烈的红色发射峰.其发光性能表明，LaF₃:Eu3+红色荧光粉在近紫外发光二极管领域具有潜在的应用价值. 

Preparation and Characterization of LaF3:Eu3+ red phosphors as white LED

Nanophosphors LaF₃:Eu3+ with hexagonal structure have been prepared by hydrothermal method.The properties of the resulting phosphors are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), photoluminescence (PL) spectra and decay curve.The excitation spectra of LaF₃:Eu3+ phosphors are mainly consists of the band at about 250 nm that corresponding to O2-→Eu3+ charge-transfer (CT) and some sharp lines of Eu3+ f-f transitions in the near ultraviolet region with one intense peak at about 396 nm.The emission spectra were used to probe the local environments of Eu3+ ion in LaF₃ crystal.Based on the emission and excitation spectra at 298K, it is identified that the lattice site of Eu3+ in tetragonal LaF₃ nanocrystals descending from D_4h to approximate C_2v as a result of the lattice distortion.Under the 396 nm excitation, strong red emission peaked at 591 nm attributed to 5D₀→7F₁ transition of Eu3+ are observed for 10 % LaF₃:Eu3+ phosphors as the optimal doping concentration.The luminescence properties show that LaF₃:Eu3+ phosphor may be considered to be a potential red phosphor candidate for near-UV light emitting diodes (LEDs).