La,Ce,Tb含量对(La,Ce,Tb) BO3发光性能的影响

采用高温固相法合成(La,Ce,Tb)BO3荧光粉,并对该荧光粉进行XRD和SEM分析。结果表明:(La,Ce,Tb)BO3的晶体结构和LaBO3相同,Ce3+,Tb3+的掺入没有改变晶体的结构,发光粉颗粒大小均匀,形貌规则,粒度在5μm左右。研究了(La,Ce,Tb)BO3的光谱性质,在(La,Ce,Tb)BO3的发射和激发光谱中除了有Tb3+的特征发射和激发峰外,还有Ce3+的特征发射和激发峰。

Effect of La,Ce,Tb Concentration on Luminescence Properties of (La,Ce,Tb)BO3

The phosphors of(La,Ce,Tb)BO3 were synthesized by high temperature solid state reaction.X-ray diffractometry(XRD) patterns indicate that the crystal structures of(La,Ce,Tb)BO3 and LaBO3 are the same.The crystal structure has not been changed by Ce 3+ and Tb 3+ doping.Emission scanning electron microscopy(SEM) images show that the particle sizes of phosphors are more uniform,the morphology is more regular,and the granularity is about 5 μm.The content of TbBO3 phase in(La,Ce,Tb)BO3 increases with increasing of Tb content in(La,Ce,Tb)BO3.When Tb concentration reaches 15% and above,the content of TbBO3 phase in(La,Ce,Tb)BO3 increases more rapidly.The luminescence properties of(La,Ce,Tb)BO3 and the sensitization of Ce 3+ to Tb 3+ were studied.In the excitation spectrum of Ce 3+ there are three peaks at 244,268 and 330 nm,respectively.And in the emission spectrum of Ce 3+,there are two peaks at 365 and 380 nm,respectively.All of them have the large overlap.The Maximum emission wavelength of Tb 3+ is 541 nm,and its excitation peaks is 230 nm.Both the Tb 3+ characteristic emission and excitation peaks and the Ce 3+ characteristic emission and excitation peaks were observed in the emission and excitation spectrum of(La,Ce,Tb)BO3.Comparing the excitation spectrum of(La,Ce)BO3 with the emission spectrum of(La,Tb)BO3,it is found that they have the large overlap.It is indicated that there is a remarkable energy transfer from Ce 3+ to Tb 3+ in(La,Ce,Tb)BO3.When the concentration of Ce or Tb in(La,Ce,Tb)BO3 is fixed,because of concentration self-quenching effect,the relative intensity of main emission peak(at 541 nm)increases firstly and then decreases with increasing of the concentration of Tb or Ce.At fixed ratio of Ce concentration to Tb concentration,the relative intensity of the main emission peak of(La,Ce,Tb)BO3 is the highest when La concentration in(La,Ce,Tb)BO3 reaches 70 mol%.The sample with better luminescence properties will be obtained in the wide range of the concentration ratio of Ce to Tb at fixed La concentration of 80 mol%.When La concentration is 80 mol% and above,the relative intensity of the main emission peak of(La,Ce,Tb)BO3 will be the highest at 3/1 concentration ratio of Ce to Tb.