【作者】 杨保柱；

【导师】 杨志平；

【作者基本信息】 河北大学 ， 光学工程， 2014， 硕士

【摘要】 由于白光发光二极管（LED）具有低能耗、无汞污染、高效和使用寿命长等优点，它被认为是下一代最理想的固态照明光源。随着能够发射350⁴00nm波长的高效近紫外芯片的出现，加速了LEDs的发展，同时对近紫外激发的高效的三基色的荧光粉提出了更高的要求。通过高温固相反应合成了Sr₃SiO₅;Eu²⁺荧光粉。当Eu2+浓度较低时，该荧光粉的发射光谱包括两个发射带，峰值分别位于476nm和578nm。随着Eu2+离子浓度的增加，蓝色发射峰逐渐减弱，当Eu2+离子浓度达到1mol%时消失；黄色发射峰强度随Eu2+离子浓度的增加而增加，当Eu2+离子浓度达到1mol%时发生浓度猝灭。根据Dexter理论和Blasse方程计算得到的临界距离Rc分别为3.06nm和2.62nm。而且，Eu2+在Sr3SiO5中的两个发射中心存在能量传递，浓度猝灭是电偶极－电偶极（d-d）相互作用引起的。采用高温固相法制备了红色SrBPO5:Eu3+荧光粉，并且研究了激活剂Eu3+浓度、助熔剂的种类及含量、电荷补偿剂的种类对荧光粉发光性能的影响。样品的XRD表明，合成的样品为纯相的SrBPO5，且二次烧结有助于晶格结构生长。荧光粉在589nm、596nm、614nm、653nm和687nm处存在发射峰，且596nm处发射峰值最大，对应着由Eu3+的5D0→7F1的跃迁。激发光谱是由一个225nm²80nm的宽带和280⁴50nm的一系列尖峰组成的，其中395nm处的激发峰最强。说明该荧光粉可被紫外光有效激发，并且发出较好的红光。随着激活剂浓度增大，没有明显的浓度猝灭发生。加入助熔剂可有效提高发光强度，对于本体系，采用NH4Cl做助熔剂效果最好。电荷补偿剂采用了Li2CO3、Na2CO3、 K2CO3三种，但是，Li2CO3的效果最好。采用高温固相法合成了Dy3+激活Ca3SiO4Cl2的黄色荧光粉，并对其发光性质进行了研究。在345nm紫外光激发下，测得Ca3SiO4Cl2:Dy3+材料的发射光谱为宽谱带且峰值较多，主要峰值分别位于479nm和569nm，监测479nm和569nm发射峰，测得材料的激发光谱均为300⁴50nm之间的多峰宽谱，分别位于320nm,345nm,363nm,384nm,420nm和449nm。本文研究了合成温度对样品的发光强度的影响，找到了最佳反应温度为1000℃。研究了最佳掺杂浓度及产生浓度猝灭的机理。找到了不同助熔剂的添加对发光性质的影响。Ca3SiO4Cl2:Dy3+可被近紫外光有效激发，也可被蓝光激发，该荧光粉是一种发光性能比较好的蓝白色荧光粉。利用Sm3+离子作为激活剂采用高温固相法制备了Ca3SiO4Cl2:xSm3+红色荧光材料。测量了荧光粉的XRD衍射谱，激发光谱和发射光谱。在紫外光的激发下，该荧光粉的发射光谱为峰值位于564nm、608nm和648nm的三峰谱线，其中位于648nm处的红光发射最强。监测648nm发射峰得到的材料的激发光谱主峰位于363nm、376nm和404nm的线状谱线，说明该荧光粉可被紫外光和近紫外光有效的激发。研究了Sm3+的掺杂浓度对样品发光性能的影响及猝灭机理。结果表明该荧光粉是一种较好的用于白光LED的红色发光材料。更多还原

【Abstract】 White light-emitting diodes (LEDs) are considered to be the next generation solid statelighting devices due to their attractive attributes such as durability, small volume, longlifetime and environment friendly. The development of LEDs is accelerated with the arisingof effectively near UV chip that can emit350~400nm light, which put forward higherrequirements for effectively tri-color phosphor that can be excited by near UV light.A novel Sr3SiO5:Eu2+phosphor was synthesized by high temperature solid state method.The emission spectra are composed of two emission bands centered at476and578nm,respectively when the concentration of Eu2+ions is lower. The blue emission peak weakensgradually with increasing of Eu2+concentration and disappears when Eu2+concentrationreaches1mol%. The yellow emission peak enhances with Eu2+concentration and theconcentration quenching occurs when Eu2+concentration reaches1mol%. The criticaldistance Rc are3.06and2.62nm, respectively according to Dexter theory and Blasseequation. Furthermore, Eu2+ions have energy transfer in the two emission center of Sr3SiO5and the concentration quenching is attributed to electric dipole-dipole transition (d-d).Red SrBPO4:Eu3+phosphor was prepared by high temperature solid state method and theinfluence of Eu3+concentration, types and content of flux and charge compensator on theluminescent properties is investigated. The XRD patterns indicate that the SrBPO5samplesare simple phase and the sintering again help the growth of crystal lattice. There are emissionpeaks at589,596,614,653and687nm, which the peak at596nm attributed to the5D0→7F1transition, is the biggest. The excitation spectrum constitute of a wide band at the region of225to228nm and a series of narrow peaks from280to450nm. The excitation peak at395nm is the strongest. The result indicate that the phosphor can be excited by UV light and emitbetter red light. The concentration quenching does not appear with increasing of the activatorconcentration. The flux can enhance the luminescence intensity and NH4Cl is the optimal fluxin this phosphor. Li2CO3, Na2CO3and K2CO3can be used as charge compensator, in whichthe Li2CO3is the topgallant. The yellow emitting phosphors Ca3SiO4Cl2:Dy3+were synthesized by traditionalhigh-temperature solid state reaction method and the luminescence properties were studied indetail. The results indicate that the emission band is a broad band with multi-peaks，whichconsists of two main peaks located at479nm and569nm, respectively. The excitation peakspositioned around320nm,345nm,363nm,384nm,420nm,449nm. The results illustratethat the emitting of Ca3SiO4Cl2: Dy3+can be changed by adjusting the synthesis temperatureand the Dy3+concentration. The most effective sintering temperature is1000℃. The effectsof different flux on the luminescent intensity were studied in detail. Ca3SiO4Cl2:Dy3+is agood blue-white phosphor candidate for white light emitting diode.The series Sm3+-activated phosphors of Ca3SiO4Cl2:Sm3+were prepared by solid-statemethod. The structure and luminescent properties of these powder samples have beeninvestigated by means of X-ray diffraction (XRD), and fluorescent spectrophotometry,respectively. Under ultraviolet excitation, the emission spectrum of Ca3SiO4Cl2:Sm3+showsseries narrow bands centered at564nm,608nm and648nm, in which the relative intensity ofthe648nm is the strongest. Monitoring for648nm, a series of narrow line spectra peaked at363nm,376nm and404nm, respectively. The phosphor can be efficiently excited when thedoping concentration is6mol%. The mechanism of concentration quench was studiedaccording to the relation between doping concentration of Sm3+ions and the luminescentintensities of samples. This phosphor is a better red phosphor for white LED.更多还原