白光二极管用荧光粉LiBaPO_4:Tb~(3+)的制备及发光性质

采用高温固相法合成白光发光二极管用绿色荧光粉LiBaPO4:Tb3+,并研究荧光粉的发光性质。测定荧光粉的激发光谱和发射光谱,发射峰由位于436nm(5D3→7F4)、490nm(5D4→7F6)、544nm(5D4→7F5)、587nm(5D4→7F4)及621nm(5D4→7F3)的五组线状峰构成,对应Tb3+的特征跃迁,其中544nm处的最强,样品呈现绿色发光。激发光谱由4f75d1宽带吸收(200～280nm)和4f–4f电子跃迁吸收(330～390nm)组成,其中以380nm处的激发峰最强,可被紫外发光二极管(ultraviolet-light-emittingdiode,UV-LED)有效激发。研究Tb3+掺量(摩尔分数,下同)对发光亮度的影响,结果显示:当Tb3+掺量为9%时,荧光粉的亮度最高,之后出现浓度淬灭现象。Na+、K+和Cl–作为电荷补偿剂均能提高发光亮度,以Cl–作为电荷补偿剂的效果最好。Ce3+对Tb3+具有明显的敏化作用。结果表明:LiBaPO4:Tb3+是一种适用于白光发光二极管用的绿色荧光材料。     

Eu3+,Ce3+共掺硼硅酸锌玻璃的发光性能及能量传递

采用高温液相法制备了50ZnO-30SiO2-20B2O3∶Eu3+,Ce3+玻璃。测试了样品的激发光谱和发射光谱。结果表明:在紫外光激发下,该玻璃可以发出明亮的红色光。其中580 nm,593 nm,617 nm,655 nm和706 nm波长处的发射峰分别对应于Eu3+的5D0→7F0,5D0→7F1,5D0→7F2,5D0→7F3和5D0→7F4跃迁发射,其中5D0→7F2跃迁发射强度最大,同时发现在450 nm处存在Ce3+的5D→2FJ(J=7/2,5/2)特征发射峰。首次发现在该发光玻璃50ZnO-30SiO2-20B2O3∶Eu3+,Ce3+中存在着Ce3+→Eu3+能量传递现象,其中Ce3+起敏化作用。     

GdAlO3:Tb,RE中Tb,RE的能量传递研究

采用柠檬酸盐硝酸盐燃烧法制备了GdAlO3 Tb, RE荧光粉体.在紫外激发下(254nm),GdAlO3Tb发射绿色荧光(5D4→7F5,544nm),Dy共掺杂对绿色发光有增强作用,Ce共掺杂对GdalO3 Tb绿色发光有降低作用.激发谱和能谱研究表明Dy能级嵌入Tb主发射能级5D4(绿色发光能级)、5D3(蓝色发光能级)能级之间,Ce能级嵌入Tb主发射能级5D4、5D3能级上方.这种能级嵌入方式,使得稀土离子之间存在声子支持的共振能量传递,但T→Dy→Tb能量传递使Tb绿色发射(5D4→7FJ (J=3,4,5,6))增强,蓝色发射(5D3→7FJ (J=3,4,5,6))减弱;而Ce→Tb能量传递使Tb蓝色发射增强,绿色发射减弱.     

SrMoO_4∶Tb~(3+)绿色发光材料的微波辐射法合成及发光性能

以活性炭粒为吸收剂采用微波辐射法合成了SrMoO4∶Tb3+绿色发光材料。用X射线粉末衍射仪、荧光分光光度计对样品进行了分析和表征,探讨了微波反应时间、Tb3+的摩尔掺杂量、助熔剂等对样品结构和发光性质的影响。结果表明:所合成的SrMoO4∶Tb3+晶体结构与SrMoO4相似,属四方晶系结构,I41/a空间群。样品的激发光谱是由位于200~350nm的1个宽带和350~500nm的一系列尖峰构成。宽带吸收与Mo--O的电荷转移和Tb3+的4f8--4f7 5d1跃迁过程有关,最强峰位于287nm左右。350nm以后的吸收峰是由于Tb3+的4f--4f跃迁引起的。发射光谱主要由4个发射峰组成:主峰位于544nm处,属于Tb3+的5 D4→7 F5跃迁发射;另外3个弱发射峰位于490、587、622nm处,分别属于Tb3+的5 D4→7 F6、5 D4→7 F4、5 D4→7 F3跃迁。当反应时间为30min,微波功率为中高火(560W),Tb3+摩尔量为0.06,助熔剂H3BO3的用量为4%(质量分数)时,样品的发光强度最大。     

Ba3Tb(BO3)3:Eu3+的制备与发光性质

采用高温固相法合成了Ba3Tb(BO3)3:Eu3+红色荧光粉,并研究了Ba3Tb(BO3)3:Eu3+的发光特性。Ba3Tb(BO3)3:Eu3+的激发光谱包含250nm～330nm和350nm～400nm的2个宽带,最大峰值位于383nm,可以被紫外-近紫外发光二极管(light-emitting diodes,LED)有效激发。Ba3Tb(BO3)3:Eu3+的发射谱显示出4组发射峰,其主发射峰位于620nm,对应Eu3+的5D0→7F2跃迁;Eu3+掺杂摩尔分数为2%时,Ba3Tb(BO3)3:Eu3+发光亮度最高。经分析发现Ba3Tb(BO3)3:Eu3+存在Tb3+→Eu3+的能量传递。     

预压成型对荧光体CaAl2Si2O8∶Eu3+,Li+发光性能的影响

采用高温固相法制备了红色荧光粉Ca0.97Al2Si2O8∶ Eu0.033+,Li0.03+,研究了预压压力对其的晶体结构和发光性质的影响.XRD图谱显示,合成的试样均为纯相的CaAl2Si2O8晶体,三斜晶系,空间群为P-1.随着预压压力的增大时,各试样衍射图谱的各衍射峰的强度均有一定程度的增强,其中衍射最强峰(004)强度呈线性递增,斜率为15.9286,试样的晶胞参数a,b,c逐渐减小.在614 nm波长的监控下,收集到位于220～ 580 nm范围的激发光谱,该激发光谱由220～340 nm宽激发带和一组锐线峰构成,激发光谱中的最强峰为394 nm(7 F0→5 L6),其次为462 nm(7F0→5 D2);预压压力改变对7 F0→5L6影响较大.用394 nm激发Eu3+ (5L6)得到发射光谱,光谱中的锐线峰580am,594 nm,614 nm,655 nm,和705 nm归属于Eu3+的5D0→7FJ(J =0,1,2,3,4)的跃迁;预压压力在0～4 MPa范围内,预压压力对CaAl2Si2O8基质中的Eu3+的电偶极跃迁5D0→7F2影响较大.预压压力4 MPa试样激发和发射光谱强度相比于预压压力0 MPa试样分别增强52.52％,65.80％.荧光粉Ca0.97Al2Si2O8∶Eu0.033+,Li0.03+的色坐标a和色温均随着预压压力的增加而逐渐增加,分别增加0.0089,778 K,各试样的色坐标在(0.624,0.374)左右,色温约为4000K.     

白光LED用Ca_6Sr_4(Si_2O_7)_3Cl_2:Ce~(3+),Eu~(2+),Sm~(3+)荧光粉的合成及其发光性质

采用传统的高温固相法合成了Ce3+,Eu2+,Sm3+离子分别单激活和三种稀土离子共激活的Ca6Sr4(Si2O7)3Cl2荧光粉,并通过X射线粉末衍射、荧光光谱和CIE色坐标对其结构和发光性质进行了研究。荧光粉Ca5.91Sr3.96(Si2O7)3Cl2:0.02Ce3+,0.04Eu2+,0.04Sm3+在365 nm激发下能发射高强度白光,其色坐标为x=0.2183,y=0.2187,有望成为一种新型白光LED灯用荧光粉。     

微乳液法合成Y_2SiO_5∶Eu~(3+)及其发光性质研究

采用微乳液法合成了Y_2SiO_5∶Eu~(3+)系列荧光粉。利用XRD、扫描电镜(SEM)、光电子能谱(EDS)、荧光光谱、色坐标等研究了所制备荧光粉的结构、形貌和发光性能。光电子能谱数据验证了合成样品的离子掺杂量。荧光光谱测试表明,Y_2SiO_5∶Eu~(3+)监测光谱呈现200nm~300nm的宽带吸收峰和Eu3+的系列吸收峰。在253nm紫外光激发下,Y_2SiO_5∶Eu~(3+)材料的发射光谱为一个多峰谱,主峰分别为5D0→7F1(591nm)、5D0→7F2(616nm)的发光峰。当Eu3+掺杂物质的量大于24%时,出现了浓度猝灭现象。通过色坐标图可知,当Eu3+掺杂量为24%时,荧光粉的色坐标(0.503,0.366)与标准的红光色坐标接近,表明Y_2SiO_5∶Eu~(3+)是很好的近紫外光激发下的红色荧光粉。     

稀土离子(Gd~(3+),Ce~(3+)/Ce~(4+),Eu~(3+))对Tb~(3+)掺杂硅酸盐玻璃发光性能的影响

研究了(Gd3+,Ce3+/Ce4+,Eu3+)对Tb3+掺杂硅酸盐玻璃发光性能的影响.结果表明:Tb3+掺杂硅酸盐玻璃可以发出弱蓝光(400～460 mm)和较强的绿光(480～600mm).Gd3+对Tb3+的发光起敏化作用,可提高TB3+掺杂硅酸盐玻璃的发光强度.在空气中熔制的玻璃中Ce3+和Ce4+同时存在,Ce3+对Tb3+发光起敏化作用;而Ce4+对Tb3+发光起淬灭作用.由于Ce4+比例比较高,CeO2加入导致TB3+发光强度降低,同时也缩短了Tb3+发光余辉.加入Eu2O3时,Eu3+自身发光分散了激发Tb3+发光的能量,使Tb3+的特征发射强度降低.     

Eu~(3+)、Gd~(3+)共掺杂Sr_2SiO_4荧光粉的液相沉淀合成及能量转移发光性能

采用液相沉淀法合成了钆单掺杂、铕单掺杂、钆-铕共掺杂的硅酸锶发光材料。用X-射线衍射(XRD)对其结构表征。利用荧光光谱(PL)方法对合成的样品进行发光性能表征。研究结果表明:在250nm紫外光为激发波长时,Eu~(3+)单掺杂Sr_2SiO_4∶0.04Eu~(3+)的发光光谱出现Eu~(3+)的5D0→7F1(584nm)、5D0→7F2(614nm)、5D0→7F3(626nm)跃迁发光峰,钆-铕共掺杂Sr_2SiO_4∶x Gd3+,0.04Eu~(3+)发光体系中,主要表现为Eu~(3+)离子的特征发射。探讨了在硅酸锶发光体中Gd~(3+)→Eu~(3+)能量传递的机理,主要为电偶极-电偶极相互作用。当改变Eu~(3+)离子的掺杂浓度时,样品表现为Eu~(3+)离子的特征发射,此时材料发橙色光。保持Gd~(3+)、Eu~(3+)离子掺杂浓度不变,K+作为电荷补偿剂,对材料发光强度影响很小。     

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-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-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