Photoluminescence properties of Ca_4La_6(SiO_4)_4(PO_4)_2O_2-based phosphors for wLEDs

The apatite compound Ca_4La_6(SiO_4)_4(PO_4)_2O_2(CLSPO) was explored as the host material for phosphors used in white light-emitting diodes(w LEDs). The crystal structure of the CLSPO host prepared by the solid-state reaction method was investigated with Rietveld refinement. The rare earth ions(Eu~(3+)/Tb~(3+)/Ce~(3+), Tb~(3+)/Tb~(3+), Mn~(2+))activated CLSPO phosphors were synthesized, and their photoluminescence properties, quantum yields, as well as thermal stabilities, were studied. Under near-ultraviolet excitations, the Eu~(3+) and Tb~(3+) -doped CLSPO compounds exhibited red and green emissions with high luminescence efficiencies. Besides, tunable emissions from green to orange were obtained by introducing Mn~(2+) ions into the Tb~(3+) -doped CLSPO samples. The results showed that the phosphors studied may have potential applications for w LEDs.     

Sm3+掺杂Na0.5Bi0.5TiO3无铅压电陶瓷的发光性能及热稳定性研究

采用传统的固相烧结法,制备了一系列的Sm3掺杂Na0.5Bi0.5TiO3无铅压电陶瓷(NBT∶ xSm3,0.005≤x≤0.04).利用X射线衍射仪和荧光分光光度计分别对NBT∶ xSm3+陶瓷样品的物相结构和光致发光性能以及热稳定性进行了分析.结果 表明,所有样品均为纯的三方钙钛矿结构.样品的激发光谱在480 nm有很强的激发峰,与蓝光LED芯片匹配.发射光谱包含位于563 nm、597 nm、645 nm、709 nm处的四个发射峰,分别归属于Sm3+的4G5/2→6HJ/2(J=5、7、9、11)跃迁,其中发射主峰位于597 nm,呈现橙红色发光.当Sm3+含量为0.02 mol时发光性能最佳.当温度范围在30 ～210℃之间时,NBT∶0.02Sm3陶瓷样品的发光性能具有良好的热稳定性     

基于椭圆形光强分布光栅投影的三维面形测量方法

基于椭圆形光强分布光栅投影测量物体三维面形的方法,将椭圆形光强分布光栅投影到被测物体表面,用摄像机获取变形条纹图,通过系统参量和条纹图携带的相位信息求解出物体的三维面形.推导出通过椭圆形光强分布光栅条纹求解相位的计算公式并对提出方法作了计算机仿真.实验结果表明该方法可以比较准确地测量物体的三维面形,在噪音较大的情况下测量结果仍具有较高准确度.     

Combining Cubic Spline Interpolation and Fast Fourier Transform to Extend Measuring Range of Reflectometry

The reflectometry is a common method used to measure the thickness of thin films. Using a conventional method,its measurable range is limited due to the low resolution of the current spectrometer embedded in the reflectometer.We present a simple method, using cubic spline interpolation to resample the spectrum with a high resolution,to extend the measurable transparent film thickness. A large measuring range up to 385 m in optical thickness is achieved with the commonly used system. The numerical calculation and experimental results demonstrate that using the FFT method combined with cubic spline interpolation resampling in reflectrometry, a simple,easy-to-operate, economic measuring system can be achieved with high measuring accuracy and replicability.     

高热稳定性的SrAl2Si2O8:Eu2+荧光粉的制备与发光性能研究

采用高温固相法制备了SrAl2 Si2 O8:Eu2+(SASO:Eu2+)系列荧光粉,详细研究了荧光粉的晶体结构、激发光谱、发射光谱以及热稳定性.结果表明,在337 nm激发下,发射光谱为一个非对称的宽带单峰,峰值波长404 nm,峰的半高宽约为53 nm,Eu2+的最佳掺杂摩尔浓度为5;,根据Dexter理论,讨论了SASO:Eu2+荧光粉浓度猝灭是由于Eu2+电偶极-电偶极之间的相互作用引起的.当加热到225℃时,SASO:0.05Eu2+荧光粉发光强度仍具有在初始室温下发光强度的97.4;,表明其具有优异的热稳定性.     

橙红色荧光粉Ba2La8(SiO4)6O2∶Sm3+的合成及光致发光特性研究

通过高温固相法合成了新型橙红色荧光粉Ba2 La8(1-x)Sm8x(SiO4)6O2,并对其光致发光特性进行了系统地研究.分析了Sm3掺杂浓度对发光强度的影响,结果显示其最佳掺杂摩尔浓度为3;,离子间能量传递机理为偶极-偶极相互作用.在15 ～250℃温度范围测试了荧光粉的发射光谱,结果表明合成的样品具有良好的温度稳定性.计算了荧光粉的色纯度和相关色温,制备样品的最高色纯度可达99.72;,相关色温低于1900 K.实验结果表明,近紫外光或蓝光可以有效激发此荧光粉.因此,该荧光粉在白光LED领域的具有潜在应用价值.     

基于椭圆形光强分布光栅投影的三维面形测量方法

基于椭圆形光强分布光栅投影测量物体三维面形的方法,将椭圆形光强分布光栅投影到被测物体表面,用摄像机获取变形条纹图,通过系统参量和条纹图携带的相位信息求解出物体的三维面形.推导出通过椭圆形光强分布光栅条纹求解相位的计算公式并对提出方法作了计算机仿真.实验结果表明该方法可以比较准确地测量物体的三维面形,在噪音较大的情况下测量结果仍具有较高准确度.