Y_2O_3:Eu~(3+)红色荧光粉的水热合成及性能研究

利用水热法合成了Y2O3:Eu3+荧光粉,并对所制得的样品进行了XRD、SEM以及荧光光谱等表征。荧光测试结果表明,Eu3+掺杂浓度为5%时制备的Y2O3:Eu3+荧光粉荧光强度最好。其最大发射峰位于612 nm,对应于Eu3+的5D0→7F2电偶极跃迁,最大激发波长为240 nm对应于从O2-的2p轨道到Eu3+的4f轨道的电荷转移跃迁。通过对比,发现采用水热法制备的荧光粉要比固相法发光性能更强。     

蓝光激发的Na_2ZnSiO_4:Eu~(3+)红色荧光粉的合成及发光特性

以H3BO3作助熔剂,采用溶胶–凝胶法合成了Na2Zn Si O4:Eu3+红色荧光粉。用X射线衍射、荧光光谱分析对样品的结构及发光特性进行了表征,探讨了H3BO3助熔剂添加量和掺Eu3+量对Na2Zn Si O4:Eu3+发光性能的影响。结果表明:所得样品属于单斜晶系,样品的激发光谱主要由一系列线状谱峰组成,激发主峰为465 nm,归属于Eu3+的7F0→5D2特征跃迁。在波长为465 nm蓝光激发下发射红光,发射峰分别为578、591、613、653和701 nm,对应于Eu3+的5D0→7FJ(J=0,1,2,3,4)跃迁,发射主峰位于613 nm(5D0→7F2)处。当Eu3+和H3BO3的摩尔掺杂量分别为5%和0.8%时,样品的荧光发光强度最大。Na2Zn Si O4:Eu3+有望成为蓝光激发的白光发光二极管(w-LED)用红色荧光粉。     

红色荧光粉Ca2La8Si6O26:Eu的制备和性能

采用高温固相法合成新型CaeLasSi6O26:Eu红色荧光粉,利用X射线衍射、扫描电镜及荧光光谱对其进行了表征.结果表明:合成的Ca2LasSi6O26:Eu属于六角晶系,可被近紫外光(394 nm)和蓝光(464 nm)有效激发,发射峰值位于614 nm(对应于Eu3+的5D0→7F2跃迁),激发波长与目前广泛使用...     

Eu~(3+)掺杂Gd_2TiO_5荧光粉的制备及其发光性质研究

采用溶胶-凝胶法制备了Eu~(3+)掺杂Gd_2TiO_5红色荧光粉,并且用XRD、激发光谱和发射光谱对其结构组成及发光性能进行了表征分析。结果表明,在612nm波长光监测下,荧光粉的激发光谱为一宽带和一系列锐峰,其最佳激发峰出现在467nm处,因此在467nm蓝光激发下,基于Eu3+的5 D0→7F2电偶极跃迁,Gd2TiO5:Eu3+荧光粉发射出强烈的红光。     

适合近紫外和蓝光激发的Sr2-xZnMoO6:xEu3+红色荧光粉的制备与发光性能

采用高温固相法制备了适合于近紫外、蓝光激发的Sr2–xZnMoO6:xEu3+红色荧光粉。研究了Eu3+掺杂量对样品发光性能的影响。XRD谱显示合成样品为纯相Sr2ZnMoO6晶体。激发光谱由一系列尖峰和电荷迁移带组成,主激发峰位于395nm和465nm处,对应于Eu3+的7F0→5L6和7F0→5D2跃迁。在395nm和466nm激发下,主发射峰分别位于597nm和624nm,对应Eu3+的5D0→7F1和5D0→7F2跃迁。随着Eu3+掺杂量的增加,发射光谱强度先增大后减小,Eu3+最佳掺杂量为0.2。研究了分别以Cl–、Li+、Na+和K+作为电荷补偿剂对发光性能的影响,结果显示Li+补偿效果最为显著。     

α-Zn_3(PO_4)_2:Eu~(3+)的合成及发光性质

采用共沉淀法制备了Eu~(3+)掺杂α-Zn_3(PO_4)_2基红色荧光粉,利用XRD和荧光光谱对其晶体结构、发光性能进行了研究。结果表明,样品为纯α-Zn3(PO4)2,晶相为单斜相。样品在612nm波长光监测下得到的激发光谱图主要由一宽峰和一系列尖峰组成,其中396nm处的激发峰强度最大,这说明此荧光粉可被商业化生产的蓝光InGaN LED芯片有效激发。样品在396nm近紫外光激发下,在593nm和612nm处表现出较强的发射峰,分别对应于Eu3+的5D0→7F1磁偶极跃迁和5D0→7F2电偶极跃迁。     

磷钒酸盐红色发光粉的制备及性能研究

采用燃烧法合成了一种近紫外激发的Ca3((P,V)O4)2:Eu3+发光材料,用X射线衍射谱、荧光光谱对样品进行了表征。结果表明,荧光粉基质Ca3((P,V)O4)2具有畸变的Ca3(VO4)2的结构,VO34-取代了部分的PO34-,但Ca2+的半径与Eu3+接近,因此Eu3+容易进入晶格,表现出良好的发光性能。荧光光谱分析发现荧光粉可被376 nm紫外光激发,主发射峰值位于620 nm(Eu3+离子的5D0→7F2跃迁)的红光,同时详细研究了Eu3+离子掺杂浓度、引发温度及尿素用量对荧光粉发光性能的影响。     

助熔剂对固相微波法合成MgAl2O4∶Eu发光性能的影响

采用固相微波法研究了助熔剂对MgAl2O4∶ Eu3+荧光粉发光性能的影响.利用XRD和荧光光谱仪对合成产物的物相和发光光谱进行研究,分别探讨了助熔剂的类型及含量对发光性能影响.结果表明,加入NaF,CaF2,B2O3和GeO2为助熔剂时可得到红色发光材料;MgAl2O4∶Eu3+荧光粉主发射峰位于612 nm处,对应Eu3+的5D0→7 F2电偶极跃迁,次强发射峰位于589 nm处,为Eu3+的5D0→7F0的跃迁,Eu3+离子处于非对称中心格位.相对于氟化物,氧化物助熔剂有助于提高样品的发光强度,其中,以B2O3为助熔剂时荧光粉的发光强度最高,其最佳掺杂量为4.5wt％.     

镧、钇掺杂铕-樟脑酸-1,10-菲咯啉三元配合物的合成及荧光性能

实验合成了单核铕-樟脑酸-1,10-菲咯啉三元配合物和La、Y掺杂异核铕-樟脑酸-1,10-菲咯啉三元配合物。通过配位滴定、元素分析和红外光谱等测试,确定其组成为RE2(CA)3(phen)2(RE为Eu、La和Y;CA为樟脑酸;phen为1,10-菲咯啉);通过三维荧光光谱图确定其最佳激发波长为330.0 nm,即在330.0 nm激发光下的发射光谱图中均显示出Eu3+离子5D0→7F0(579nm),5D0→7F1(594 nm)和5D0→7F2(612 nm)等三条特征谱线,其中5D0→7F2(612 nm)为最强跃迁峰。荧光强度变化研究表明,适量镧和钇离子的掺杂并没有降低铕离子的荧光强度,说明镧和钇对铕离子荧光发射有敏化作用。     

Li_2ZnSiO_4∶Eu~(3+)红色荧光粉的制备及其发光性能

采用溶胶-凝胶法合成了适合于近紫外激发的Li2ZnSiO4∶Eu3+红色荧光粉,用X射线衍射、红外光谱和荧光光谱对样品进行了结构及发光性能表征。结果表明:合成样品为四方晶相Li2ZnSiO4晶体。样品的激发光谱由O2--→Eu3+电荷迁移带和Eu3+的离子特征激发峰组成。在波长为395nm的紫外激发下样品发射红光,发射主峰位于613nm,对应于Eu3+离子的5 D0→7 F2跃迁。随着Eu3+掺杂量的增加,其发光强度先增加后减小,Eu3+的最佳摩尔掺量为3.5%。     

Ferroelectric Ceramics in the PbMg1/3Nb2/3O3-PbCd1/3Nb2/3O3 System

Solid solutions (1-x)PbMg_1/3Nb_2/3O₃ + xPbCd_1/3Nb_2/3O₃ with x = 0-0.30 are investigated with purpose to work out a capacitor ceramics with good dielectric properties and low sintering temperature. It is found that the perovskite phase forms at sintering near to 980°C and begins to decompose at higher temperatures. When x grows from 0 to 0.30, the Curie temperature linearly grows from -10°C to +25°C, the dielectric permittivity ε_m in the Curie point T_C decreases from 18000 to 6800 and the phase transition becomes more diffused. The dielectric permittivity at room temperature is rather high and the temperature stability is improved. The system is of interest, because it can serve as a base for working out some ceramic materials for capacitors with low sintering temperature, which needs of no special atmosphere at burning.     

3-叠氮甲基-3-甲基氧丁环的合成

以三羟甲基乙烷与碳酸二乙酯为原料,经环化反应合成了3-羟甲基-3-甲基氧丁环(HMM O)。在低温下,HMM O与对甲苯磺酰氯反应生成3-磺酸酯甲基-3-甲基氧丁环(M TM O)。M TM O和叠氮化钠发生叠氮化反应形成叠氮单体3-叠氮甲基-3-甲基氧丁环(AMM O)。三步反应收率分别为76%,96%,85%。用核磁、红外、元素分析和DSC表征了化合物的结构与性能。结构鉴定表明为目标化合物AMM O。     

3-溴甲基-3-甲基氧杂环丁烷的合成

以2,2-二溴甲基丙醇（BBMP）为初始原料,通过与碱发生关环反应生成3-溴甲基-3-甲基氧杂环丁烷（BrMMO）。讨论了碱的种类和用量对BBMP关环产率的影响以及反应体系中碱的浓度、反应温度和反应时间对合成BrMMO产率的影响。通过实验确定的最佳工艺条件为：BBMP与NaOH摩尔比为1.0∶1.1,NaOH醇溶液的质量分数为12%,反应温度为78℃,反应时间为4h时,BrMMO产率为65%。最终产品经元素分析、IR和1HNMR检测确定为BrMMO。该试验工艺简单,原料易得,且溶剂便于回收、污染小。     

3-溴甲基-3-甲基氧杂环丁烷的合成

以2,2-二溴甲基丙醇(BBMP)为初始原料,通过与碱发生关环反应生成3-溴甲基-3-甲基氧杂环丁烷(BrMMO).讨论了碱的种类和用量对BBMP关环产率的影响以及反应体系中碱的浓度、反应温度和反应时间对合成BrMMO产率的影响.通过实验确定的最佳工艺条件为:BBMP与NaOH摩尔比为1.0∶1.1,NaOH醇溶液的质量分数为12%,反应温度为78℃,反应时间为4 h时,BrMMO产率为65%.最终产品经元素分析、IR和1HNMR检测确定为BrMMO.该试验工艺简单,原料易得,且溶剂便于回收、污染小.     

The Preparation and Crystal Structure of TlMnCl3, TlFeCl3, TlCoCl3 and TlNiCl3

The compounds TlMnCl₃, TlFeCl₃, TlCoCl₃ and TlNiCl₃ were prepared by heating T1C1 with the corresponding transition metal dichloride in an evacuated ampoule. Atomic positions were determined from powder photographs. All four compounds were found to be related to the perovskite type structure. TlMnCl₃ has a cubic structure, space group Pm3m, with a_o = 5.025 Å. The other three compounds are hexagonal, probable space group P6₃mc, with cell dimensions (in Å) a₀ = 6.976 and c₀ = 6.008 for the Fe compound, a₀ = 6.907 and c₀ = 5.981 for the Co compound and a₀ = 6.863 and c₀ = 5.881 for the Ni compound. The three hexagonal compounds are isomorphous. A measureable concentration of basal plane stacking faults was found to occur in TlFeCl₃ and also, to a lesser degree, in TlCoCl_3.     

Tunable color emission in LaScO3:Bi3+,Tb3+,Eu3+ phosphor

LaScO₃:xBi³⁺,yTb³⁺,zEu³⁺ (x = 0 − 0.04, y = 0 − 0.05, z = 0 − 0.05) phosphors were prepared via high-temperature solid-state reaction. Phase identification and crystal structures of the LaScO₃:xBi³⁺,yTb³⁺,zEu³⁺ phosphors were investigated by X-ray diffraction (XRD). Crystal structure of phosphors was analyzed by Rietveld refinement and transmission electron microscopy (TEM). The luminescent performance of these trichromatic phosphors is investigated by diffuse reflection spectra and photoluminescence. The phenomenon of energy transfer from Bi³⁺ and Tb³⁺ to Eu³⁺ in LaScO₃:xBi³⁺,yTb³⁺,zEu³⁺ phosphors was investigated. By changing the ratio of x, y, and z, trichromatic can be obtained in the LaScO₃ host, including red, green, and blue emission with peak centered at 613, 544, and 428 nm, respectively. Therefore, two kinds of white light-emitting phosphors were obtained, LaScO₃:0.02Bi³⁺,0.05Tb³⁺,zEu³⁺ and LaScO₃:0.02Bi³⁺,0.03Eu³⁺,yTb³⁺. The energy transfer was characterized by decay times of the LaScO₃:xBi³⁺, yTb³⁺, zEu³⁺ phosphors. Moreover absolute internal QY and CIE chromatic coordinates are shown. The potential optical thermometry application of LaScO₃:Bi³⁺,Eu³⁺ was based on the temperature sensitivity of the fluorescence intensity ratio (FIR). The maximum S_a and S_r are 0.118 K⁻¹ (at 473.15 K) and 0.795% K⁻¹ (at 448.15 K), respectively. Hence, the LaScO₃:Bi³⁺,Eu³⁺ phosphor is a good material for optical temperature sensing.     

2,2,3-三氯-3-苯基-3-(3-甲基苯甲酰基)丙腈的合成研究

以苯甲酰氯、四氯化碳、间甲基苯甲酰氰为原料,合成了标题化合物。重点考察了氰化过程中不同原料配比、反应温度、时间、溶剂和催化剂用量对收率的影响。实验结果表明,其最佳反应条件为:n(1,1,2-三氯-2-苯基乙烯)∶n(3-甲基苯甲酰氰)=1∶1.2,二氯甲烷为反应溶剂,3 mmol催化剂三乙胺,室温反应5 h,总收率达80.6%。     

Thermal analyses of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)

Thermal analyses of poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB–HV)], and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB–HHx)] were made with thermogravimetry and differential scanning calorimetry (DSC). In the thermal degradation of PHB, the onset of weight loss occurred at the temperature (°C) given by T_o = 0.75B + 311, where B represents the heating rate (°C/min). The temperature at which the weight-loss rate was at a maximum was T_p = 0.91B + 320, and the temperature at which degradation was completed was T_f = 1.00B + 325. In the thermal degradation of P(HB–HV) (70:30), T_o = 0.96B + 308, T_p = 0.99B + 320, and T_f = 1.09B + 325. In the thermal degradation of P(HB–HHx) (85:15), T_o = 1.11B + 305, T_p = 1.10B + 319, and T_f = 1.16B + 325. The derivative thermogravimetry curves of PHB, P(HB–HV), and P(HB–HHx) confirmed only one weight-loss step change. The incorporation of 30 mol % 3-hydroxyvalerate (HV) and 15 mol % 3-hydroxyhexanoate (HHx) components into the polyester increased the various thermal temperatures T_o, T_p, and T_f relative to those of PHB by 3–12°C (measured at B = 40°C/min). DSC measurements showed that the incorporation of HV and HHx decreased the melting temperature relative to that of PHB by 70°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 90–98, 2001