真空紫外光激发下Tb~(3+)激活的稀土正硼酸盐的发光

报导了Tb3+、Ce3+激活的稀土正硼酸盐的真空紫外光谱。分析了Ce3+的4f75d能级随基质结构、基质阳离子的变化,讨论了温度、Tb3＋离子的浓度对发光的影响以及Ce3＋－Tb3＋间的能量传递.     

Er~(3+)/Yb~(3+)/Tb~(3+)共掺氟氧锗酸盐玻璃上转化发光性质及机理研究(英文)

在980nm激发下,研究了Er3+、Yb3+和Tb3+单掺或共掺氟氧锗酸盐玻璃的上转换发光性质和机理.室温下,观察到了强的绿色和红色上转换发光,其发光中心位于524、546和658nm处,分别对应于Tb3+离子的5D4→7FJ(J=5和0)和Er3+离子的(2H11/2、4S3/2和4F9/2)→4I15/2跃迁.研究了TbF3、YbF3掺杂浓度以及激光功率对上转换发光强度的影响,讨论了Er3+、Yb3+和Tb3+之间的能量传递和上转换机理.     

稀土离子掺杂硼酸钙发光材料的合成与光谱性质

以硼砂和氯化钙为原料,主要采用化学共沉淀法成功合成了稀土离子Eu3+、Tb3+掺杂的硼酸钙发光材料。通过X射线衍射、荧光光谱对样品物相和发光性能进行了表征。探究了不同的实验条件(即不同煅烧温度、稀土离子浓度)对其发光性能的影响,样品的激发光谱表明,在800℃时,CaB2O4∶Tb3+的发光能力最强;掺杂稀土Tb3+离子的发光材料在5%时发光性能最强。在221nm紫外光激发下,样品在612nm和543nm处有Eu3+和Tb3+离子明显的特征发射峰,而且掺杂Eu3+离子的发光材料的发光性能随着Eu3+浓度的增加而增强。     

CeO_2对Tb~(3+)掺杂硅酸盐玻璃发光和耐辐照性能的影响

采用高温熔制工艺制备出Tb3+掺杂硅酸盐玻璃,研究了CeO2对Tb3+掺杂硅酸盐玻璃发光和耐辐照性能的影响。结果表明,Ce3+的激发带与Tb3+的激发带部分重叠,使激发Tb3+离子发光的能量减少,Tb3+离子在550nm的发光被淬灭;激发停止后,Ce3+/Ce4+减少了由陷阱中逃逸出的空穴和电子的直接复合而传递给Tb3+的激发能量,Tb3+发光余辉缩短。通过铈离子价态变化:Ce4++eCe3+,CeO2引入可以减少辐照对基础玻璃和Tb3+的损伤。综合考虑发光和辐照稳定性,Tb3+掺杂硅酸盐玻璃中CeO2的引入量应控制在0.4%～0.8%(质量分数)。     

SiN_x:Tb~(3+)薄膜中Tb~(3+)与银表面等离激元耦合

本文采用PECVD方法在石英衬底上生长不同剂量比的氮化硅薄膜SiNx,并利用离子注入方法在SiNx中注入Tb3+离子。然后通过在SiNx薄膜表面沉积银岛膜,研究了银表面等离激元和SiNx:Tb3+发光的相互作用。研究发现,银岛膜的存在降低了SiNx:Tb3+发光荧光寿命,而且SiNx:Tb3+发光荧光寿命随着银岛膜厚度的增加而减小。而氮化硅薄膜中的硅纳米晶也会影响Tb3+的光模密度,并对SiNx:Tb3+发光荧光寿命产生影响。     

Ce~(3+),Eu~(3+)共掺Lu_3Al_5O_(12)多晶的发光特性及能量传递研究

利用高温固相反应制备了Ce3+、Eu3+共掺杂的(Ce0.01EuxLu0.99-x)3Al5O12(x=0.02%、0.5%、1%、2%)多晶粉末,并对其结构和光谱学特性,特别是Ce3+向Eu3+的能量传递问题进行了研究。X射线衍射结果显示,所制备样品具有单一的石榴石结构。利用X射线激发发射谱和光致激发发射谱研究了Eu3+掺入浓度对发光中心Ce3+和Eu3+离子发光特性的影响以及Ce3+向Eu3+的能量传递。样品的热释光谱进一步证明Ce3+向Eu3+的能量传递及其与Eu3+浓度之间的变化关系。     

辐照对Tb~(3+)掺杂硅酸盐玻璃结构和发光性能的影响

采用高温熔化工艺制备出Tb3+掺杂硅酸盐玻璃,研究了高能辐照对该玻璃结构和发光性能的影响。结果表明,高能辐照后,Tb3+掺杂硅酸盐玻璃的结构发生变化,表现为两个方面:(1)是部分Tb3+离子被氧化为(Tb3+)+离子;(2)是玻璃体内产生大量色心。辐照对Tb3+掺杂硅酸盐玻璃的发光强度影响较大,发光强度随辐照剂量的增大而降低;然而,辐照对Tb3+掺杂硅酸盐玻璃的发光余辉影响较小,发光余辉基本不随辐照剂量的增加而变化。     

Ba2Gd2Si4O13∶Dy3+的能量传递和热稳定性研究

利用高温固相反应合成了Ba2Gd2Si4O13∶Dy3+荧光粉,从激发光谱、发射光谱、衰减寿命3个方面详细研究了不同激发波长下Gd3+→Dy3+的能量传递和热稳定性能。研究表明,由于Ba2Gd2Si4O13基质中Gd3+→Dy3+的能量传递,Dy3+在274nm激发的发光强度是在349nm激发的5倍;Ba2Gd2Si4O13∶Dy3+荧光粉表现出较好的热稳定性,在250℃的发光强度为常温的85%;随着加热温度的升高,兰光比黄光强度下降更多,而Gd3+发光有所增加。Ba2Gd2Si4O13∶Dy3+荧光粉可作为潜在的单一基质单一掺杂发光材料。     

Ba2Gd2Si4O13∶Dy3+的能量传递和热稳定性研究

利用高温固相反应合成了Ba2Gd2Si4O13∶Dy3+荧光粉,从激发光谱、发射光谱、衰减寿命3个方面详细研究了不同激发波长下Gd3+→Dy3+的能量传递和热稳定性能。研究表明,由于Ba2Gd2Si4O13基质中Gd3+→Dy3+的能量传递,Dy3+在274nm激发的发光强度是在349nm激发的5倍;Ba2Gd2Si4O13∶Dy3+荧光粉表现出较好的热稳定性,在250℃的发光强度为常温的85%;随着加热温度的升高,兰光比黄光强度下降更多,而Gd3+发光有所增加。Ba2Gd2Si4O13∶Dy3+荧光粉可作为潜在的单一基质单一掺杂发光材料。     

Tb3+-Yb3+共掺氟氧化物微晶玻璃的发光特性及其外量子效率的评价

本研究制备了Tb3+-Yb3+共掺杂含CaF2纳米晶相的氟氧化物透明微晶玻璃,并通过XRD验证了CaF2纳米晶的形成。基于Tb3+对Yb3+的协同能量传递,通过激发Tb3+∶5D4能级可观察到由Yb3+∶2F5/2→2F7/2跃迁引起的950~1100nm近红外发射。利用积分球测试系统评价了Yb3+在玻璃及微晶玻璃体系中的外量子效率,数据表明经过热处理后Yb3+的外量子效率有明显的增加,这是由于在微晶玻璃体系中掺杂的Tb3+离子和Yb3+离子富集在具有低声子能量的CaF2晶相从而获得了更有效的能量传递而引起的。同时利用Tb3+荧光寿命计算获得了材料的内量子效率,其值远大于外量子效率,这是由计算过程中的诸多近似所导致。     

Phase diagrams of the ternary liquid systems [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2] and [Ce(NO3)3(TBP)3]-C10H22-[Th(NO3)4(TBP)2] and of the quaternary liquid system [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2]-[Th(NO3)4(TBP)2]

The phase diagrams of the ternary liquid systems [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂] and [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] and of the quaternary liquid system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂(TBP)₂]-[Th(NO₃)₄(TBP)₂] at T = 298.15 K are constructed. The phase diagrams are characterized by areas of homogeneous solutions and of two-phase liquid systems (systems with phase separation), with one phase (I) enriched in [Ce(NO₃)₃(TBP)₃], [Th(NO₃)₄(TBP)₂], and [UO₂(NO₃)₂(TBP)₂], and the other phase (II), in C₁₀H₂₂. Using the data on the mutual solubility of the components in the systems under consideration and equations of the NRTL model, the parameters of intermolecular interactions and the excess Gibbs energies (G ^ex) were calculated for the binary, ternary, and quaternary systems. Passing from the ternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[Th(NO₃)₄(TBP)₂] to the quaternary system [Ce(NO₃)₃(TBP)₃]-C₁₀H₂₂-[UO₂(NO₃)₂ (TBP)₂]-[Th(NO₃)₄(TBP)₂] does not appreciably affect the distribution of C₁₀H₂₂ between phases I and II, but leads to the redistribution of [Ce(NO₃)₃(TBP)₃] into phase II and of [Th(NO₃)₄(TBP)₂] into phase I.     

Stabilization of Ferromagnetic Order in La(0.7)Sr(0.3)MnO(3)-SrRuO(3) Superlattices

The study of spatially confined complex oxides is of wide interest, since correlated electrons at interfaces might form exotic phases. Here La(0.7)Sr(0.3)MnO(3)/SrRuO(3) superlattices with coherently grown interfaces were studied by structural techniques, magnetization, and magnetotransport measurements. Magnetization measurements showed that ferromagnetic order in ultrathin La(0.7)Sr(0.3)MnO(3) layers is stabilized in the superlattices down to layer thicknesses of at least two unit cells. This stabilization is destroyed, if the ferromagnetic layers are separated by two unit cell thick SrTiO(3) layers. The resistivity of the superlattices showed metallic behavior and was dominated by the conducting SrRuO(3) layers, the off-diagonal resistivity showed an anomalous Hall effect from both SrRuO(3) and La(0.7)Sr(0.3)MnO(3) layers. This shows that the La(0.7)Sr(0.3)MnO(3) layers are not only ferromagnetic but also highly conducting; probably a conducting hole gas is induced at the interfaces that stabilizes the ferromagnetic order. This result opens up an alternative route for the fabrication of two-dimensional systems with long-range ferromagnetic order.     

La2/3Sr1/3Mn1-xCuxO3的磁电阻研究

采用溶胶一凝胶(sol-gel)法制备了La2/3 Sr1/3Mn1-x CuxO3(x=0.00、0.05、0.10、0.20)的多晶样品.利用振动样品磁强计测量了样品在室温下的磁性能;利用X射线衍射确定了粉体的组成;利用扫描电子显微镜观察了颗粒的形貌.在1.8T磁场作用下,当x=0时,在370K,样品的磁电阻几乎成...     

Fluorescence properties of Dy(3+) doped La(3)Ga(5.5)Nb(0.5)O(14) nanocrystals

The effects of Dy(3+) doping concentration and calcinations on the fluorescence properties of La(3)Ga(5.5)Nb(0.5)O(14) (Dy:LGN) nanocrystals were examined for the first time. High quality Dy:LGN nanocrystals were synthesized by the sol-gel method. The room temperature fluorescence spectra were measured; they showed a yellow emission, which can be attributed to the (4)F(9/2)-(6)H(13/2) transition. The relationship between the relative emission intensity and the doping concentration of the specimens, sintered at different temperatures, is consistent with a Gaussian distribution according a fitted and modified formula. The optimum value of the Dy(3+) doping concentration in LGN nanocrystals is in the range 2.0-2.5%. Moreover, in LGN bulk crystal for laser use, the optimum value, calculated through the obtained formula, is presumed in the range 1.5-2.0%. The fluorescent lifetime of a 2.0% Dy:LGN nanocrystal is quite short, only about 8.5?ns.     

访港随笔(三)

ＡＭＣ又一城 1 1厅影院隶属于美国ＡＭＣ国际娱乐公司的香港ＡＭＣ又一城 1 1厅影院 ,是位于九龙半岛九龙塘达之路的超大型现代综合性商场《又一城》的重要构成之一。这个有着 1 1个影厅、1 853个座席、约 2 2个轮椅位的新建影城 ,以其位居香港第一且具有国际水准的厅数 ,成为一个典型的美国多厅影院香港版 ,值得我们认真研究。ＡＭＣ ,是美国多厅影院公司 (ＡｍｅｒｉｃａｎＭｕｌｔｉ -Ｃｉｎｅｍａ)的缩写。该公司正式成立于1 968年 ,当时拥有 1 2家影院 ,2 2个影厅。其前身是始建于1 92 0年的杜尔伍德影院 ,院线总部一直设在密苏里州的…     

A 3.7 MHz phased array probe using 0.91Pb(Zn(1/3)Nb(2/3))O(3)-0.09PbTiO(3 )

A novel 128-channel phased array probe for echocardiography with a center frequency of 3.7 MHz using 0.91Pb(Zn(1/3)Nb(2/3))O(3)-0.09PbTiO(3 ) (PZN-9%PT) single crystal has been fabricated to realize greater sensitivity and broader bandwidth properties. The echo amplitude of the PZN-9%PT single-crystal probe is about 5 dB higher than that of the conventional lead airconate titanate (PZT) ceramic probe, and the fractional bandwidth is about 25 percentage points broader. The quality of B mode images obtained by the PZN-9%PT probe satisfies the performance of the two types of conventional PZT ceramic probes that have center frequencies of 2.5 and 3.75 MHz. At the reference frequency of 3 MHz, the Doppler sensitivity of the PZN-9%PT probe is about 5 dB higher than that of the 3.75 MHz PZT probe; the blood flow of a pulmonary vein in a hard-to-image patient is much more clearly imaged than in the case of using the PZT probe. These superior images are attributable to the use of sufficiently large PZN-9%PT single crystals obtained by the self-flux method.     

烧成温度对Pb（Mg_（1／3）Nb_（2／3））O_3－pb（Zn_（1／3

研究了一种满足Ｙ５Ｕ指标要求的ＰＭ计ＰＺＮ－ＰＴ介电陶瓷的恒温老化行为与烧成温度的关系，发现在低温烧结要求的温度范围内（９００∽９５０℃），该材料的老化性能满足有关标准，而过高或过低的烧结温度均导致１０倍时间老化率的增大；利用显微结构结构观察分析了上述结果。