白光LED用正交相Gd_2(MoO_4)_3:Dy^(3+)荧光粉的制备与发光性能

利用水热法并经过退火煅烧制备了白光LED用正交相Gd2(MoO4)3∶Dy3+荧光粉,用X射线衍射仪和扫描电子显微镜对样品的结构和微观形貌进行表征,利用荧光光谱对其发光性质进行了研究。在389 nm的紫外光激发下,4F9/2→6H15/2跃迁产生的蓝光发射和4F9/2→6H13/2跃迁产生的黄光发射最强。发光光谱分析结果表明,Dy3+的最佳掺杂量为x=16%。此时荧光粉最为接近白光,其色坐标和色温分别为(0.326,0.336)和6 389,是一种很有潜力的白光LED用荧光粉。

白光LED用荧光粉Gd_2(MoO_4)_3∶Eu^(3+)、Dy^(3+)的制备与发光性能

采用高温固相法制备LED用荧光粉Gd2(MoO4)3∶Eu3+、Dy3+,通过样品的X射线衍射图谱以及光致发光光谱的测试和表征,研究Gd2(MoO4)3∶Eu3+、Dy3+的晶体结构和发光性能.结果表明:样品属于正交晶系,常温下在389nm的近紫外光的激发下,样品发射出很强的白光,在Eu3+和Dy3+共同掺杂的体系中,可以观察到由于Dy3+向Eu3+的能量传递使Dy3+敏化Eu3+的发光现象.

水热法合成Gd_2O_3∶Dy^(3+)纳米棒及发光性能

以氢氧化钠为沉淀剂,采用水热方法制备了Gd2O3∶Dy3+纳米棒。通过红外光谱、扫描电镜及X射线衍射对前驱体及目标产物的物相结构、微观形貌进行了分析表征,通过荧光分光光度计测试了所得Gd2O3∶Dy3+的发光性能。结果表明:水热前驱体为六方相氢氧化钆(镝),经900℃焙烧得立方相的Gd2O3∶Dy3+。所得Gd2O3∶Dy3+为直径约100 nm,长度约500 nm～1μm的纳米棒。其激发光谱由一系列激发峰组成,峰值分别位于239 nm、279 nm、314 nm、353 nm,最强峰位于279 nm处;发射光谱主要由两部分组成,分别为460～500 nm的蓝光和560～590 nm的黄绿光发射峰(带),均属于Dy3+的特征发射,且后者的强度远高于前者,因此,在紫外光激发下呈黄光发射。

硼酸镁中Ce^(3+)、Gd^(3+)对Dy^(3+)发光的敏化作用

本文研究了铈、钆、镝激活硼酸镁的激发光谱、发射光谱、发光寿命和能量传递过程。

Gd_2O_3:Dy^(3+)纳米晶的制备和发光性质研究

以Gd2O3和Dy2O3为反应物,共沉淀合成了镝掺杂氧化钆纳米粉体.研究了Gd2O3:Dy3+的光致发光性质随着Dy3+掺杂浓度和煅烧温度的变化关系.通过对荧光强度与激活离子Dy3+离子浓度的关系研究发现,Dy3+在纳米Gd2O3基质中存在浓度猝灭现象,最佳掺杂浓度为0.7%.

稀土（Dy，Gd）苯甲酸盐的红外和荧光光谱研究

合成了系列苯甲酸－镝－钆混合稀土配合物．由元素分析确定其组成为（Ｄｙ＿（１－ｘ）Ｇｄ＿ｘ）Ｌ＿３（Ｌ＝Ｃ＿６Ｈ＿５ＣＯＯ￣－），通过ＦＴ－ＩＲ光谱和荧光光谱研究了配合物中羧酸根离子红外吸收峰的特征和荧光发射光谱的特征．配合物的红外光谱表明，在三个羧酸根中，至少有一个羧酸根是通过螯合－桥式混合配位形式与稀土中心离子键合的．因此，Ｄｙ￣（３＋）离子在配合物中不是位于正八面体的中心，而是处于一个非对称中心的位置．配合物的荧光光谱表明，当ＤｙＬ＿３中部分Ｄｙ￣（３＋）离子被Ｇｄ￣（３＋）离子取代时，Ｄｙ￣（３＋）离子的特征荧光发射强度得到较大提高．

Gd对Mg-3Dy-2Zn-0.5Zr镁合金铸态显微组织和力学性能的影响

研究了Gd添加对铸态Mg-3Dy-2Zn-0. 5Zr(%,质量分数)镁合金显微组织和室温拉伸性能的影响,结果表明:Mg-3Dy-2Zn-0. 5Zr合金的铸态组织主要由α-Mg、少量的Mg3Zn3Dy2和Mg24Dy5相组成,而添加0. 5%Gd和1. 0%Gd合金则主要由α-Mg、Mg3Zn3Dy2、Mg(Dy,Gd,Zn)x相以及少量Mg24Dy5相组成。同时,Gd添加还可细化Mg-3Dy-2Zn-0. 5Zr合金的晶粒,并导致大量呈半连续分布的第二相在晶界析出。此外,在Mg-3Dy-2Zn-0. 5Zr合金中添加0. 5%Gd后,合金的抗拉强度、屈服强度和延伸率大幅度增加,分别达到了248、102 MPa及12. 0%,而添加1. 0%Gd后,合金的拉伸性能不但没有进一步增加,抗拉强度和延伸率反而低于未添加Gd的合金。研究结果表明:Gd合金化和/或微合金化有益于Mg-3Dy-2Zn-0. 5Zr镁合金拉伸性能的改善,但需要控制Gd的加入量。

SiO_2@Gd_2O_3:Dy^(3+)核-壳结构材料的制备与光致发光性质

目的:制备核-壳结构发光材料用。方法:采用溶胶-凝胶法将掺杂Dy3+的均匀的Gd2O3纳米层包覆在球形SiO2表面。结果:显示Gd2O3:Dy3+层400℃开始结晶,并且随着煅烧温度的提高结晶越来越好。核-壳发光粉拥有着完美的球形、狭窄的大小分布及非团聚的。结论:在紫外光激发下,SiO2@Gd2O3:Dy3+粒子显示了Dy3+最为重要的黄光发射4F9/2-6H13/2(575nm)。

Dependence of Amorphous Formation Ability on Intrinsic Parameters in Dy-Gd-Co-Al Alloys

A series of Dy（Gd）-based bulk amorphous alloy rods were prepared by water-cooled copper mold method. Thermal stability and structure of Dy-Gd-Co-Al alloys were investigated by differential scanning calorimetry and X-ray diffraction, respectively. The results show that the Dy-Gd-Co-Al alloys have good glass-formation ability, and the Dy31Gd25Co20Al24 alloy can be readily cast into full glassy rods up to 5 mm in diameter. The glass-forming ability of multicomponent alloys was greatly dependent on their chemical interaction and the equivalent bond parameters among atoms such as equivalent electronegativity difference, equivalent atomic size parameter. The Dy （Gd）-based bulk amorphous alloys could be expected as potential functional materials.

Ba_2Gd_2Si_4O_(13)∶Dy^(3+)发光性能研究

通过高温固相反应制备Ba2Gd2Si4O13∶Dy3+发光材料,利用XRD、FTIR、SEM、XPS和激发-发射光谱表征合成样品的性能。研究表明,使用Li2CO3-NH4F复合助熔剂,形成了长柱状形貌。在349nm或274nm激发下,Ba2Gd2Si4O13∶Dy3+发出Dy3+特征峰,色坐标接近白光区域。Gd3+→Dy3+的能量传递增强了Dy3+发光强度。Dy3+最优的掺杂浓度为2%,临界传输距离为30。Ba2Gd2Si4O13∶Dy3+发光材料可作为潜在的单一掺杂单一组成的白光LED发光材料。

Sr_(3)Gd(BO_(3))_(3)∶Dy^(3+)/RE^(3+)(RE=Tb,Eu)晶体的生长、发光性质及能量传递

黄光激光在医疗美容、原子冷却与捕获、激光雷达等领域具有潜在的应用前景,因此,黄光激光器的研究具有重要意义。Dy^(3+)因其^(4)F_(9/2)→^(6)H_(13/2)辐射跃迁而成为黄光激光的最佳激活离子,但是其在可见光波段为自旋禁戒跃迁,导致其吸收截面和发射截面都很小,从而引起黄光激光输出困难。本文通过提拉法成功生长了Dy^(3+)∶Sr_(3)Gd(BO_(3))_(3)(缩写Dy^(3+)∶SGB)、Dy^(3+)/Tb^(3+)∶SGB和Dy^(3+)/Eu^(3+)∶SGB晶体,通过室温偏振吸收谱、发射谱、荧光衰减曲线以及Judd-Ofelt理论计算分析了其光谱性能和能量传递机制。研究表明,共掺Tb^(3+)和Eu^(3+)增大了Dy^(3+)在黄光波段的发射截面和荧光量子效率,有利于Dy^(3+)的黄光输出。此外,证明了Dy^(3+)/Tb^(3+)∶SGB晶体中发生了Dy^(3+)和Tb^(3+)之间相互能量传递过程,Dy^(3+)/Eu^(3+)∶SGB晶体中仅有Dy^(3+)→Eu^(3+)的能量传递过程。

单基质白光荧光粉Gd3PO7∶Dy3+的制备及其性能研究

采用湿化学法合成单基质的白光发射的Gd3PO7∶Dy^3+荧光粉,使用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)、荧光光谱等对样品的物相结构、形貌与光学性能等进行表征。XRD检测结果表明所制备的样品为含有微量杂质相的Dy^3+掺杂单斜结构的Gd3PO7晶体。荧光光谱检测结果表明在276 nm属于Gd^3+的特征激发带激发下,发射出Dy^3+的特征黄色光发射带(4F9/2→6H13/2)与蓝色光发射带(4F9/2→6H15/2),证实在Gd3PO7∶Dy^3+样品中出现了由Gd^3+到Dy^3+的能量传递现象。样品的发光强度随pH值和Dy^3+掺杂量的变化而变化,在pH值为6.00、Dy^3+掺杂量为0.5%的条件下制备的样品呈现相对更强的发光强度。Dy^3+掺杂量直接影响着Gd3PO7∶Dy^3+样品的发光颜色,当Dy^3+掺杂量为3%时所制备的Gd3PO7∶Dy^3+样品可发射出色坐标为(0.335,0.345)的白色光,这表明Gd3PO7∶Dy^3+是一种潜在的单基质白光发射荧光材料。

同位素稀释质谱法测定U_3O_8中痕量Sm、Eu、Gd和Dy

建立了分析U_3O_8中痕量Sm、Eu、Gd和Dy的IDMS法。在一条灯丝上一次涂样完成4个相对含量10^(-8)的元素测定。方法较简便,测定含Sm、Eu、Gd和Dy分别为8.90×10^(-8)、9.07×10^(-8)、8.65×10^(-8)和8.47×10^(-8)的U_3O_8试样,方法精密度分别为±4.2%、±3.5%、±4.8%和±4.1%。本法与其他方法相比结果相符。测Gd,^(176)〔^(160)Dy^(16)O〕^+与^(176)〔^(160)Gd^(16)O〕^+有叠加。通过测定^(160)Dy^+峰高计算出^(176)〔^(160)Dy^(16)O〕^+峰高,从而校正^(176)〔^(160)Gd^(16)O〕^+峰高。

Synthesis and luminescent properties of polycrystalline Gd_2(MoO_4)_3:Dy^(3+) for white light-emitting diodes

Polycrystalline Gd2(MoO4)3:Dy3+ phosphors have been synthesized by high temperature solid-state reaction method. The phosphors were characterized with X-ray diffractometer, thermogravimetric analysis and different scanning calorimeter, scanning electron microscopy, and photoluminescence spectrofluorimeter. Several peaks at 351, 389, 425, 452, and 472 nm appeared in photoluminescence excitation spectrum, which matched well with the emission of the ultraviolet (UV) and blue-light emitting diode (LED) chips. Upon excitation at 389 nm UV light, intense emissions centered at 484, 575 and 668 nm were attributed to the transitions of 4F9/2→6H15/2, 4F9/2→6H13/2 and 4F9/2→6H11/2 of Dy3+, respectively. The chromaticity coordinates and correlative color temperatures have been calculated and presented in the Commission International de I’Eclairage (CIE) diagrams. The results indicated that Gd1.9(MoO4)3:Dy0.13+ with CIE coordinates of (x=0.38, y=0.41) and the correlative color temperature of 4134 K is a potential candidate for white LEDs.

Age hardening characteristics and mechanical properties of Mg-3.5Dy-4.0Gd-3.1Nd-0.4Zr alloy

Age hardening characteristic and tensile property of Mg-3.5Dy-4.0Gd-3.1Nd-0.4Zr alloy were investigated. The alloy exhibits a considerable age hardening effect up to 250℃. Increasing the aging temperature leads to a shorter aging time to reach the peak hardness and a lower peak hardness. The tensile results show that the peak-aged specimens have higher tensile strength at the temperature below 200℃. However, with the increase of temperature further, the tensile strength decreases dramatically and elongation increases drastically. The loss in tensile strength and increase in elongation at high temperature are possibly associated with the instability of secondary precipitates. The fracture mechanism of alloy transfers from intergranular to transgranular with the increase of experimental temperature.

Study on stability of RECo_5 phases(RE=Dy,Gd)

The eutectoid decomposition reaction that occurred in RECo5 phases（RE=Dy and Gd ） at low temperature was discussed and confirmed by X-ray powder diffraction（XRD）, differential thermal analysis, and scanning electron microscopy.The decomposition temperature of the GdCo5 and DyCo5 were identified as 805.8 and 900 °C, respectively.The GdCo5 and DyCo5 phases could not be found in the isothermal section of Gd-Dy-Co ternary system at 800 K.Reasons for the absence of the RE2Co7 phase in the XRD patterns were discussed in detail.

STRUCTURAL AND MAGNETIC PROPERTIES OF RTiFe_(11),RTiCo_(11) AND RTi(Fe_(1-x)Ni_x)_(11) COMPOUNDS(R=Nd,Sm,Gd,Tb,Dy,Ho,Er AND Y)

The crystallographic structure and intrinsic magnetic properties have been investigated in the RTiFe_(11), RTiCo_(11) and RTi(Fe_(1-X)Ni_X)_(11) compounds,where R represents Nd,Sm,Gd,Tb,Dy,Ho,Er and Y.Neutron diffraction and Mossbauer spectra analyses have been used to study the nuclear and magnetic structure of these compounds.the Fe,Co,Ni and Ti atoms are found to exhibit strong site preference with f and j sites fa- voring Fe,Co and Ni atoms and the i site Ti atoms.Two different types of magnetic behavior were observed in the RTiFe_(11) and RTiCo_(11) compounds.In the former,the interatomic distance and the number of nearest neighbor atoms play essential roles.In particular,anomalous thermal expansion behavior is presented in RTiFe_(11).In the latter,the magnetic properties are essentially determined by the modification of the cobalt electronic configuration brought about by the transfer of rare earth conduction electrons to the transition 3d band.The saturation magnetization,Curie temperature and magnetocrystalline anisotropy data of RTiFe_(11), RTiCo_(11)and YTi(Fe_(1-X)Ni_X)_(11)are presented.A tempt to improve the intrinsic magnetic properties in RTiFe_(11)has been made,and the results are reported.On the basis of the crystalline field theory by using a single-ion model,the anisotropy constants and their temperature dependence of the R ions have been calcu- lated,which helps explain the spin reorientation observed in RTiFe_(11).

THE EXTRACTION EQUILIBRIUM MODEL AND SIMULATION OF COUNTERCURRENT SOLVENT EXTRACTION OF Gd-Tb-Dy-HCl-HEH(EHP)-KEROSENE SYSTEM

The extraction equilibrium mathematic models for gadolinium,terbium and dysprosium in HCl-1.5 mol/L HEH(EHP)system covering a relatively wide range of lanthanide concentration and acidity,have been developed.There are four independent variables and nine parameters.The average relative error is 4.56%.A computer program for the simulation of the counter current solvent extraetion process has also been written.Thus,the Gd,Tb and Dy concentrations in both aqueous and organic phase in eaeh stage as well as the aqueous acidity may be calculated.Product purities,distribution ratio and extraction factors may also be obtained thereby.The simulation results so obtained may serve as the referenee data for designing solvent ex- traction processes including those processes providing apart from the conventional outgoing organic stream, outgoing raffinate and an extra outgoing third exit stream either organic or aqueous.

Dy_3Al_5O_(12)磁热性质研究

用量子理论计算了Dy_3Al_5O_(12)的晶场能谱、Zeeman劈裂能级和波函数.在外磁场H_e为0<H_e<9T,温度为3<T<42K范围内,计算了该晶体的磁矩、磁熵变,计算结果与相关实验数据吻合较好.该计算结果表明,Dy_3Al_5O_(12)内磁性离子间的交换作用非常微弱,可以忽略.从理论上给出了绝热退磁过程中温度变化△T与T的关系,并与Gd_3Ga_5O_(12)晶体进行了比较,发现不同外磁场下,Dy_3Al_5O_(12)和Gd_3Ga_5O_(12)的低温制冷性能在不同温区有差别.在进行低温(T<10K)制冷时,若外磁场较低,选择Dy_3Al_5O_(12)作为磁制冷材料较好;若外磁场较高,选择Gd_3Ga_5O_(12)作为磁制冷材料较好.

Ba3Ga(PO4)3：Dy^3＋荧光粉阴极射线发光研究

本文研究了采用高温固相法合成的Ba3Gd(PO4)3:Dy3+荧光粉的阴极射线发光特性。测试并比较了电子轰击前后荧光粉的CL谱、色坐标以及PL谱变化。Ba3Gd(PO4)3:0.06Dy3 +荧光粉的色坐标为x =0.454 ,y =0.424 ,Tc=2889.3K。测试结果显示该荧光粉是一种低色温、暖白光荧光粉,并且具有高的饱和电流,有耐大电流密度电子束轰击的能力。