Eu2+在KNaCa2（PO4）2中的发光及晶体学格位

采用高温固相法制备了KNaCa2(PO4)2:Eu2+蓝色荧光粉,并研究了材料的发光特性.在400 nm近紫外光激发下,材料呈非对称的单峰发射,主峰位于470 nm.监测470 nm发射峰,对应的激发光谱覆盖200~450 nm,主峰位于400 nm,说明材料能够很好的吸收紫外?近紫外光,发射蓝色光.利用van Uitert公式计算了Eu2+取代KNaCa2(PO4)2中Ca2+时所占晶体学格位,得出461和502 nm发射分别归属于八配位和六配位的Eu2+发射.研究了Eu2+掺杂浓度对KNaCa2(PO4)2:Eu2+材料发射强度的影响,结果显示Eu2+的最佳掺杂浓度为1mol%,利用Dexter理论得出其浓度猝灭机理为电偶极?电偶极相互作用.     

Eu~(2+),Mn~(2+)在CaZn_2(PO_4)_2中的发光及Eu~(2+)→Mn~(2+)能量传递

Mn2+作为激活剂加入一些基质中,发光比较弱。因此常常选择使用合适的敏化剂来提高Mn2+的发光效率,本文的研究目就是验证Eu2+是Mn2+的良好的敏化剂。采用高温固相法合成了Eu2+,Mn2+掺杂激活的CaZn2(PO4)2荧光粉,并对其发光性质进行了研究。单掺杂Eu2+时呈现发射峰位于504nm的带谱,属于Eu2+离子的5d-4f能级跃迁辐射,激发峰位于380nm,属于Eu2+的f-d跃迁特征激发谱带。单掺Mn2+时CaZn2(PO4)2不发光。当Eu2+和Mn2+共掺时,出现Mn2+的673nm发射峰,样品发红光,表明Eu2+对Mn2+的发光有很强的敏化作用。研究了Eu2+和Mn2+掺杂浓度对激发光谱和发射光谱的影响,证明在CaZn2(PO4)2:Eu2+,Mn2+中Eu2+对Mn2+的能量传递属于共振能量传递。     

利用碱金属碳酸盐提高空气中制备BaMgSiO_4∶Eu~(2+)的发光性能研究

通过高温固相反应在空气中制备了一系列Eu2+掺杂的BaMgSiO4∶Eu2+发光材料,研究了其发光性能及M2CO3(M=Li、Na、K)助溶剂对其性能的影响。利用X射线粉末衍射(XRD)、荧光光谱(PL)和扫描电镜(SEM)对合成的样品进行表征。研究表明,Eu2+进入Ba(1)和Ba(2)位置有利于Eu2+在空气中稳定存在。M2CO3(M=Li、Na、K)助溶剂促进Eu3+离子在空气中还原成Eu2+离子,提高了BaMgSiO4∶Eu2+的发光强度。当Na2CO3用量为6%时,BaMg-SiO4∶Eu2+的发光强度达到还原气氛中制备的91%。     

白光LED用BaMgAl_(10)O_(17):Eu~(2+)Mn~(2+)蓝绿荧光粉

采用高温固相法制备出一种Eu2+,Mn2+共掺的蓝绿色荧光粉BaMgAl10O17:Eu2+,Mn2+(BAM:Eu2+,Mn2+),对其进行了X射线衍射分析和光谱特性的测试.研究表明,它的发射光谱为双峰结构,峰值分别位于455 nm和525 nm处.455 nm发射峰归结为BAM中部分取代Ba2+离子的Eu2+离子的5d→4f的跃迁辐射;525 nm的发射峰源于部分Eu2+能量传递给Mn2+离子,Mn2+的4T1→6A1的跃迁辐射.采用近紫外LED芯片与该荧光粉以及一种红色荧光粉Ca(La0.5Eu0.5)4Si3O13封装,在20 mA前向电流驱动下,获得了显色指数为88的白光LED.     

调控Al2O3晶型控制MgAl2O4:Mn4+荧光粉中Mn价态研究

Mn4+激活红光荧光粉是白光半导体发光二极管(wLEDs)领域当前研究热点之一.Mn4+离子2E→4A2跃迁在铝酸盐中的最短发光波长是在MgAl2O4中实现的651nm发光,由于其结构中含有形成四面体或八面体配位的两种阳离子格位(Mg2+/Al3+),易造成所掺杂锰元素存在多种价态(+2/+4/+3等).本研究通过改变...     

近紫外白光LED用红色荧光粉In2（MoO4）3:Eu3+,Bi3+的合成及发光性能

通过固相反应法在1000℃空气气氛中合成了In2(MoO4)3:Eu3+、Bi 3+红色荧光粉。粉体分别用X射线衍射(XRD)、荧光分度计测试。结果表明制备的荧光粉具有单相立方晶体结构,该荧光粉能够被近紫外光(395nm)有效激发,发射高强度的612nm红光。Eu3+浓度为40%(摩尔分数)时,In2(MoO4)3:Eu3+发光强度较高。In2(MoO4)3:0.4Eu3+、Bi 3+荧光粉,Bi 3+浓度为3%(摩尔分数)时,发光强度最大,高于没有掺Bi 3+的In2(MoO4)3:0.4Eu3+荧光粉。和CaMoO4:Eu3+相比,In2(MoO4)3:0.4Eu3+、0.03Bi 3+有较高的发光强度。因此,In2(MoO4)3:0.4Eu3+、0.03Bi 3+是一种可能应用于近紫外白光LED的新型红色荧光粉。     

新型白光LED用SrMg_2(PO_4)_2单-基质荧光粉

本文通过高温固相法合成了紫外光LED用SrMg2(PO4)2为基质Eu2+,Tb3+和Mn2+为激活剂的白色荧光粉。采用XRD对荧光粉的结构和相纯度进行分析,Eu2+、Tb3+及Mn2+的加入对其结构没有明显的影响,且无杂相生成;当用Ca部分取代Sr时Eu2+和Mn2+的发射带分别发生红移和蓝移且二者之间存在着明显的能量传递;当引入共激活剂Tb3+时对其荧光光谱进行了详细研究,发现Eu2+和Tb3+,Eu2+和Mn2+之间存在部分的能量传递,通过调整它们的相对掺杂浓度可以得到发白光的荧光粉。     

白光LED用白光荧光粉Gd_2MoB_2O_9:Eu~(3+),Tb~(3+)的制备及其发光性能研究

采用高温固相法首次合成了由Eu3+和Tb3+共激活的Gd2MoB2O9白色荧光粉,并对其发光性质进行研究。该荧光粉在近紫外光(375nm)激发下发出较强的白色荧光(常温),光谱测试显示Gd2MoB2O9∶Eu3+,Tb3+的发射光谱中存在3个发射峰,分别位于486,543和613nm处,能够合成较理想的白光;激发光谱在250~400nm处均有较强的吸收,能与紫外LED很好地匹配,适用于白光LED。     

红色荧光粉BaZn2(PO4)2:Eu3+的制备及其光谱特性

采用高温固相法制备了BaZn2(PO4)2:Eu3+红色荧光材料.测量了BaZn2(PO4)2:Eu3+材料的激发与发射光谱,激发峰位于360-400nm之间,发射光谱主峰位于595nm处.研究了BaZn2(PO4)2:Eu3+材料在595nm的主发射峰强度随Eu3+浓度的变化,发射峰强度先随Eu3+浓度的增加而增大;...     

可用于白光照明的单一基质荧光粉(Sr_(0.95)Mg_(0.05))_3(PO_4)_2:Eu~(2+)的发光特性

采用高温固相法合成系列Eu~(2+)掺杂的单一基质的白光荧光粉(Sr_(0.95)Mg_(0.05))_3(PO_4)_2.该荧光粉可有效被270~390nm的紫外光激发,激发波长范围与紫外LED芯片相匹配.在激发波长为350nm时,发射光谱中有两个发射峰,峰值分别位于410nm和570nm,对应于Eu~(2+)的4f65d1→4f7跃迁,是Eu~(2+)占据了基质中Sr~(2+)的十配位和六配位的两种不同的格位后,形成的两个发光中心.当Eu~(2+)的掺杂浓度为1mol%时,具有最大的发光强度,继续增加Eu~(2+)的浓度后,会出现浓度猝灭现象.通过将Eu~(2+)的掺杂浓度从0到0.01,可以使该荧光粉的CIE色坐标从(0.259 5,0.198 7)的蓝光区域逐渐移动到(0.324 5,0313 3)的白光区域.基于实验结果和理论分析计算表明,这种荧光粉是一种潜在的用近紫外光激发产生白光LED的荧光粉.     

改性沸石对电镀废水中Pb2+、Zn2+、Ni2+的吸附

将天然沸石进行处理制备出多孔质改性沸石颗粒。在静态条件下，研究了改性沸石颗粒对重金属离子Pb^2 ,Zn^2 ,Ni^2 的吸附效果及条件，含Pb^2 ,Zn^2 ,Ni^2 的电镀废水经改性沸石颗粒吸附后，废水中Pb^2 ,Zn^2 ,Ni^2 的含量低于国家排放标准。     

NpO 2 + -UO 2 2+ cation-cation interaction in NaCl-KCl-CsCl and LiCl-KCl-CsCl eutectic melts

Absorption spectra of the NpO ₂ ⁺ ion in UO ₂ ²⁺ -containing NaCl-KCl-CsCl (0.300:0.245:0.455) and LiCl-KCl-CsCl (0.575:0.165:0.260) eutectic melts in the region of the 5f-5f transitions, 700–2000 nm, were studied at 650 and 500°C, respectively. Processing of the spectra allowed the previously discovered phenomenon, cation-cation interaction of actinides in melts, to be interpreted for the first time in terms of the mass action law. It was shown that, at the concentrations of the interacting components studied (C _Np = 0.2 M and C _U = 0.1–2 M), a 1: 1 NpO ₂ ⁺ ·UO ₂ ²⁺ cation-cation complex is formed. Its concentration stability constant was estimated at 0.06(6) and 0.11 1 mol^?1 for the NaCl-KCl-CsCl and LiCl-KCl-CsCl systems, respectively.     

胶团强化超滤中SDS胶团对Cd^2＋，Zn^2＋和Pb^2＋的竞争吸附

胶团强化超滤法是一种将表面活性剂技术和超滤技术结合的新型、高效的重金属废水治理方法.以十二烷基硫酸钠(SDS)为表面活性剂,对含单一镉、锌、铅溶质以及混合溶质体系进行了胶团强化超滤研究,考察了胶团对Cd2 ,Zn2 ,Pb2 的竞争吸附性能.研究发现,当溶液中多种二价重金属离子存在时,各离子之间存在与SDS胶团的竞争吸附,竞争能力为Pb2 ＞Zn2 ＞Cd2 ;Cd-Zn有明显的协同吸附效应,而Cd-Pb,Zn-Pb则表现为拮抗吸附.     

On the Eu2+-Mn2+ energy transfer in BaMgF4

Energy transfer from Eu²⁺ to Mn²⁺ ions is shown to occur in BaMgF₄ : Eu, Mn crystals. The efficiency of this transfer is moderate. This is attributed to the fact that Eu²⁺ and Mn²⁺ ions are distributed randomly in the host lattice. Quantitative evaluation leads to the suggestion that the transfer is restricted to only seven neighbors at 4.0 Å and is thus exchange mediated.     

Observable effects of Ca2+ buffers on local Ca2+ signals

Calcium signals participate in a large variety of physiological processes. In many instances, they involve calcium entry through inositol 1,4,5-trisphosphate (IP(3)) receptors (IP(3)Rs), which are usually organized in clusters. Recent high-resolution optical experiments by Smith & Parker have provided new information on Ca(2+) release from clustered IP(3)Rs. In the present paper, we use the model recently introduced by Solovey & Ponce Dawson to determine how the distribution of the number of IP(3)Rs that become open during a localized release event may change by the presence of Ca(2+) buffers, substances that react with Ca(2+), altering its concentration and transport properties. We then discuss how buffer properties could be extracted from the observation of local signals.     

ESR of Cu2+and Tl2+ in thallium borate glasses

The electron spin resonance (ESR) and optical absorption spectra of Cu²⁺ were measured in thallium borate glasses in order to investigate the effects of glass transition temperature,T _g, upon the responses of cupric ion in alkali borate glasses. The ESR of Tl²⁺ induced by-ray irradiation was also obtained. An abrupt increase in the covalency of in-plane Cu²⁺-O-bonding was observed in the Tl₂O system as well as in the Na₂O system in a similar B₂O₃ composition range althoughT _g for the Tl₂O glasses has little dependency on the composition compared with the Na₂O glasses. The trend in the variation of the S-character of the Tl²⁺ unpaired electron with composition agreed with that of the covalency of in-plane Cu²⁺-O-bonding. The structure of the anion group present in Tl₂O glasses was also examined by laser reman spectroscopy.     

酸改性膨润土吸附去除镍镉离子的研究

在静态条件下,研究了改性膨润土对重金属离子的吸附性能和吸附机理,着重探讨了改性膨润土去除模拟水样中重金属离子Ni2 ,Cd2 的适宜条件及改性膨润土的再生方法.结果表明,改性膨润土对Ni2 ,Cd2 具有较好的吸附性能;pH值是影响改性膨润土对重金属离子吸附的重要因素,不同的金属离子都有其适宜的pH值范围.吸附的最佳条件是pH值5.0～7.0,废水中Ni2 ,Cd2 含量不大于45 mg/L,搅拌时间约60 min.利用改性膨润土吸附处理Ni2 ,Cd2 含量小于45 mg/L的模拟水样,效果很好,Ni2 ,Cd2 的去除率均可分别达到98.5%以上,出水可达到国家排放标准.     

锰矿尾渣对Cu2+和Ni2+的吸附性能研究

研究了锰矿尾渣对重金属离子Cu2 和Ni2 的吸附性能,分析了锰矿尾渣的吸附动力学,就吸附时间、Cu2 和Ni2 浓度及pH值等因素对锰矿尾渣吸附性能的影响作了系统考察,并对锰矿尾渣的吸附机理进行了初步探讨.结果表明,在温度为25°℃、pH值为7.5的条件下,锰矿尾渣对Cu2 和Ni2 的吸附容量可达到1.6 mg/g以上,去除率均可达到97.5%以上,适宜于处理含低浓度Cu2 或Ni2 的废水.锰矿尾渣的吸附机理为离子交换吸附和表面配位吸附.     

Characterization of various Eu2+ sites in Ca2SiO4:Eu2+ and Ba2SiO4:Eu2+ by high-pressure spectroscopy

Photoluminescence of Ba₂SiO₄ and Ca₂SiO₄ activated with Eu²⁺ was investigated at various temperatures (from 10 K to 300 K) and pressures (from ambient to 200 kbar). At ambient pressure and room temperature, under UV excitation both phosphors yielded a green emission band with maxima at 505 nm and 510 nm for Ba₂SiO₄ and Ca₂SiO₄, respectively. The energies of these bands depended on pressure; the pressure shifts were ?12:55 cm^?1/kbar for Ba₂SiO₄:Eu²⁺; and ?5:59 cm^?1/kbar for Ca₂SiO₄:Eu²⁺. In the case of Ca₂SiO₄:Eu²⁺, we observed additional broadband emission at lower energies with a maximum at 610 nm (orange band). The orange and green emission in Ca₂SiO₄:Eu²⁺ had different excitation spectra: the green band could be excited at wavelengths shorter than 470 nm, whereas the orange band — at wavelengths shorter than 520 nm. The pressure caused a red shift of orange emission of 7.83 cm^?1/kbar. The emission peaked at 510 nm was attributed to the 4f⁶5d→4f⁷(⁸S₇₌₂) transition of Eu²⁺ in the β — Ca₂SiO₄:Eu²⁺ phase, whereas the emission peaked at 610 nm — to the γ — Ca₂SiO₄:Eu²⁺ phase. The emission of Ba₂SiO₄:Eu²⁺ peaked at 505 nm was attributed to the 4f⁶5d→ 4f⁷(⁸S_7/2) transition of Eu²⁺ in the β — Ba₂SiO₄ phase.