稀土离子Eu3+掺杂Y2SiO5晶体的光谱和结构研究

用５１４．５ｎｍ、４８８．０ｎｍ的Ａｒ＾＋激光和４４１．６ｎｍ的Ｈｅ－Ｃｄ激光激发Ｅｕ＾２＋：Ｙ２ＳｉＯ５晶体的获得了一系列窄带荧光谱线,其中双重谱线结构源于Ｅｕ３＾＋离子发光中在该材料中占据两种不等价的非对称光学格位,测得了Ｅｕ＾３＋：Ｙ２ＳｉＯ５的Ｘ射线多晶衍射谱的面间距数据;计算了晶格常数和晶在角度,通过和非掺杂Ｙ２ＳｉＯ５晶体数据的比较,探讨了Ｅｕ＾２＋和Ｙ２ＳｉＯ５格位的相互影响。     

Y1.95-xGdxSiO5:Eu0.05的真空紫外光谱

利用高温固相法合成了Ｙ１．９５－ｘＧｄｘＳｉＯ５：Ｅｕ０．０５（ｘ＝０．６ｍｏｌ％）荧光体。结构测定表明所合成的荧光体为单斜晶系的Ｘ２型Ｙ２ＳｉＯ５相,空间群为Ｂ２／ｂ。真空紫外光谱表明：随着Ｇｄ＾３＋含的增加,在１９２ｎｍ附近,出现了Ｇｄ＾３＋的激发峰,且此峰的强度随着Ｇｄ＾３＋含量的增加而增在;同时位于１５０￣１８５ｎｍ之间的基质吸收带的强度也增大;而位于２００￣３００ｎｍ之间的Ｅｕ的电荷迁移     

Eu3+:Y2SiO5晶体透射光谱和荧光谱研究

在室温条件下,对Ｅｕ＾３＋：Ｙ２ＳｉＯ５晶体的透射光谱和４５７．９ｎｍＡｒ＾＋激光激发荧光谱进行测量和研究。这些光谱表明,Ｅｕ＾３＋离子在Ｙ２ＳｉＯ５晶体中占据两种最低对称性Ｃ１格位。利用透射光谱和荧光谱对Ｅｕ＾３＋离子的最低激发态＾５Ｄ０的两种格位光谱进行了成功分离。实验发现,在＾５Ｄ０态两种格位谱的谱宽只有０．１ｎｍ左右,其峰间隔约为０．１８ｎｍ。另外,文中还测量了Ｅｕ＾３＋离子的基态＾７ＦＪ     

发光体Mg_2Y_（8－x－y）（SiO_4）_6O_2：Eu_x~（3＋），B

采用Ｓｏｌ－Ｇｅｌ方法首次在比较低的温度下制备了具有氧磷灰石结构的发光体Ｍｇ２Ｙ８－ｘ－ｙ（ＳｉＯ４）６Ｏ２：Ｅｕ，Ｂｉ（ｘ，ｙ≥０），利用ＸＲＤ、ＩＲ、ＴＧ－ＤＴＡ三种手段研究了发光体的形成过程。室温（２９３Ｋ）和液氮温度（７７Ｋ）的荧光光谱表明Ｅｕ３＋和Ｂｉ３＋在这种基质中分别发射红光和蓝光，每ｍｏｌ基质中其最佳掺杂浓度分别为０．１４ｍｏｌ和０．０３ｍｏｌ，并且其发光都存在温度猝灭。Ｅｕ３＋的激光感生荧光光谱中存在两条５Ｄ０－７Ｆ０跃迁线，表明Ｅｕ３＋同时进入４ｆ格位和６ｈ格位。在Ｅｕ３＋、Ｂｉ３＋共掺杂的发光体中，观察到了Ｂｉ３＋→Ｅ３＋的部分能量传递。     

发光体Mg2Y8—x—y（SiO4）6O2：Eux^3^＋,Biy^3^＋的形成过程及发光…

采用Ｓｏｌ－Ｇｅｌ方法首次在比较低的温度下制氧磷灰石结构的发光体Ｍｇ２Ｙ８－ｘ－ｙ（ＳｉＯ４）６Ｏ２：Ｅｕｘ＾３＾＋，Ｂｉｙ＾３＾＋（ｘ，ｙ≥０），利用ＸＲＤ，ＩＲ，ＴＧ－ＤＴＡ三种手段研究了发光体的形成过程。室温（２９３Ｋ）和液氮温度（７７Ｋ）的荧光光谱表明Ｅｕ＾３＾＋和Ｂｉ＾３＾＋在这种基质中分别发射红光和蓝光，每ｍｏｌ基质中其最佳掺杂浓度分别为０．１４ｍｏｌ和０．０３ｍｏｌ，并且其发光都存在     

Sol—Gel法和微波辐射法合成亚纳米级Zn2SiO4：Mn^2＋,Er^3＋高效绿色 …

用Ｓｏｌ－Ｇｅｌ法和微小法合成了亚纳米级Ｚｎ２ＳｉＯ４：Ｍｎ＾２＋,Ｅｒ＾３＋高效绿色荧光体,考究了Ｍｎ＾２＋单掺和Ｅｒ＾３＋敏化的荧光体的发光,探讨了掺杂浓度对发光性质的影响,发交Ｅｒ＾３＋可有效敏化Ｍｎ＾２＋的发光。ＳＥＭ表明Ｚｎ２ＳｉＯ４：Ｍｎ＾２＋,Ｅｒ＾３＋的粒度约为１５０～３５０ｎｍ。     

Y_(1.95-x)Gd_xSiO_5:Eu_(0.05)的真空紫外光谱

利用高温固相法合成了 Ｙ１．９５－ｘＧｄｘＳｉＯ５：Ｅｕ０．０５（ｘ＝０．６ｍｏｌ％）荧光体。结构测定表明所合成的荧光体为单斜晶系的Ｘ２型Ｙ２ＳｉＯ５相,空间群为Ｂ２／ｂ。真空紫外光谱表明：随着Ｇｄ３＋含量的增加,在１９２ｕｍ附近,出现了Ｇｄ＋的激发峰,且此峰的强度随着Ｇｄ３＋含量的增加而增大;同时位于１５０～１８５ｎｍ之间的基质吸收带的强度也增大;而位于２００～３００ｎｍ之间的Ｅｕ的电行迁移带的强度却随着Ｇｄ３＋含量的增加而降低。     

光谱纯Y2O3,La2O3,Lu2O3中微量杂质的光致发光谱研究

测定了光谱纯稀土化合物Ｙ２Ｏ３，Ｌａ２Ｏ３，Ｌｕ２Ｏ３中微量杂质在４８８．０ｎｍ和５１４．５ｎｍ激光线激发下的光致发光谱以及在可见光４４５～７４１ｎｍ范围内吸收谱，Ｙ２Ｏ３，Ｌｕ２Ｏ３样品在４４８．０ｎｍ和５１４．５ｎｍ激光激发下都有发光效应，而Ｌａ２Ｏ３样品只在４８８．０ｎｍ激光激发下才发光，分析了结果表明，Ｙ２Ｏ３，Ｌａ２Ｏ３，Ｌｕ２Ｏ３的发光谱分别是由其存在的微量Ｅｒ＾３＋，Ｓｍ＾３＋和Ｅｕ     

Sol-Gel法和微波辐射法合成亚纳米级Zn_2SiO_4∶Mn~(2+),Er~(3+)高效绿色荧光体

用Ｓｏｌ－Ｇｅｌ法和微波法合成了亚纳米级Ｚｎ２ＳｉＯ４∶Ｍｎ２＋ ， Ｅｒ３＋ 高效绿色荧光体， 考察了Ｍｎ２＋ 单掺和Ｅｒ３＋ 敏化的荧光体的发光， 探讨了掺杂浓度对发光性质的影响， 发现Ｅｒ３＋ 可有效敏化Ｍｎ２＋ 的发光． ＳＥＭ 表明Ｚｎ２ＳｉＯ４∶Ｍｎ２＋ ， Ｅｒ３＋ 的粒度约为１５０～３５０ｎｍ ．     

非晶纳米发光材料(Y,Eu)_2O_3-SiO_2发射光谱的分析研究

ＥＸＡＦＳ测定表明ｓｏｌ－ｇｅｌ方法制备的纳米非晶（Ｙ，Ｅｕ）２Ｏ３－ＳｉＯ２发光材料中，发光中心Ｅｕ３＋的局域环境和晶态Ｘ２型Ｙ２ＳｉＯ５Ｅｕ中Ｅｕ３＋离子的局域环境相似．以此结构为依据，用Ｍ．Ｆ．Ｒｅｉｄ的方案计算了晶场迭加模型中的能级参数及光谱强度参数，并得到了与实验结果基本一致的理论光谱图     

Magnetic properties of Y(Fe0.95Mn0.05)2 compound

Mössbauer spectroscopy, magnetization and X-ray diffrraction measurements of the ternary compound Y(Fe_0.95Mn_0.05)₂ prepared by melting were performed in order to investigate the effect of the substitution of Mn on the magnetic properties of YFe₂. The experimental results show change of the lattice parameter. The magnetization and the Curie temperature decrease with substitution of Fe by Mn.     

Structural,magnetic and XPS studies of Sn0.95Co0.05O2-0.05 and Sn0.95Fe0.05O2-0.05 nanoparticles

Structural, microstructural, X-ray photoemission spectra (XPS) and magnetic properties of transition metal ion [5 mol% of Co (SC5) and Fe (SF5)]-doped SnO₂ nanoparticles have been studied. The SC5 and SF5 nanoparticles were synthesized by a chemical route using polyvinyl alcohol as surfactant. The doped SnO₂ crystallites were found to exhibit a tetragonal rutile structure and the average grains size was measured by the Scherer relation of X-ray diffraction. Transmission electron micrographs showed that the average grain size of SC5 is smaller than SF5. SC5 nanoparticles showed strong ferromagnetic behaviour but SF5 exhibited an F-centre exchange (FCE) mechanism. Temperature-dependent magnetization showed the values of phase transition temperature. XPS confirmed the presence of Sn–O–Co and Sn–O–Fe bonds in these SC5 and SF5 nanoparticles. The oxidation states of Sn, Co and Fe were found to be +4, +2 and +2, respectively, while the core level XPS peaks of Sn 3d, O 1s, Co 2p and Fe 2p were analyzed.     

Structural and electrical properties of SrZr0.95Y0.05O3/SrTiO3 superlattices

Superlattice thin films of a perovskite-type oxide proton conductor SrZr_0.95Y_0.05O₃/SrTiO₃ were fabricated and their structural and electrical properties were investigated. X-ray and electron diffraction analysis reveals that the thin films were epitaxially grown on MgO (001) substrate. High-resolution transmission electron microscopy observation shows that the multilayered structure is uniform and that the interfaces between the different layers are of low roughness. Misfit dislocations are found at the interface, having Burgers vectors in direction a[100]. From the local elemental analysis, the interdiffusion of Zr and Ti between layers was not observed, while Mg impurities diffused from the substrate are observed. The in-plane electrical conductivity of the thin films was measured by impedance spectroscopy. The conductivity of the superlattices shows a higher value than a single SrZr_0.95Y_0.05O₃ film. The activation energies of the epitaxial layers show relatively higher value than the corresponding single crystal.     

Y(PV)O_4:Eu~(3+)荧光粉表面包覆Y(OH)_3的性能

采用化学共沉淀法对Y(PV)O4∶Eu3+荧光粉进行表面包膜处理,获得了表面均匀包覆Y(OH)3膜层的Y(PV)O4∶Eu3+荧光粉。用SEM、XRD等手段对其表面形貌、晶格结构性能进行了表征。结果表明:在Y(PV)O4∶Eu3+粉体表面均匀包覆Y(OH)3膜层后,Y(PV)O4∶Eu3+的晶格结构、发光性能没有改变,亮度较未包覆的荧光粉有较大提高,且没有发生色坐标偏移现象。     

μSR and Mössbauer studies on semiconducting YBa2(Cu0.95Fe0.05)3O6+δ

μSR and⁵⁷Fe Mössbauer spectroscopy were used to study the magnetic properties of powders ofsemiconducting YBa, (Cu_0.95Fe_0.05)₃O_6+δ using the same sample in the temperature range from 4–300 K. TF and ZF μSR were performed at the BOOM facility at KEK using the pulsed surface beam.     

Electrical Properties of the Polycrystalline BiFe0.95Co0.05O3 Films

Physics of the Solid State - Semiconductor BiFe0.95Co0.05O3 thin-film compounds have been synthesized by a burst technique. The film surface morphology and the effect of electronic doping via...     

Structural refinement,optical and ferroelectric properties of microcrystalline Ba(Zr0.05Ti0.95)O3 perovskite

For this study, a microcrystalline Ba(Zr_0.05Ti_0.95)O₃ (BZT) powder was prepared by a high energy ball milling method followed by calcination at 1100 °C for 4 h. The calcined powder was structurally characterized by X-ray diffraction and Rietveld refinement data, which showed that this material has a perovskite-type tetragonal structure with a space group of (P4mmm). The micro-Raman spectrum revealed local lattice distortions due to distorted octahedral [TiO₆] clusters. The temperature and frequency-dependent dielectric study of the BZT ceramic showed normal phase transition behavior. The ferroelectric property was studied by a P–E hysteresis loop. Optical band gap was investigated by ultraviolet–visible (UV–vis) absorption spectroscopy at room temperature. The UV–vis spectrum indicated that the BZT powder has an optical band gap of 3.15 eV.     

The influence of grain structures on the electrical conductivity of a BaZr0.95Y0.05O3 proton conductor

The grain structure and the electrical conductivity of a Y-doped BaZrO₃ perovskite type proton conductor were investigated in terms of preparation method. Powders of Y-doped BaZrO₃ were prepared using two methods and were sintered at various temperatures and durations. In this study, grain structures showed no effect in regard to the two preparation methods. The samples which were sintered for a relatively long period showed broad grain diameter distributions (GDD). It was also revealed that most of grain boundaries were assigned as random and this trend was not affected by sintering condition. The bulk and grain boundary conductivities of the sample sintered for long period were significantly lower than those of other samples by more than three orders of magnitude. However, this was not related to differences of grain structure and grain boundary characteristics.     

Bipolar resistive switching in BiFe_(0.95)Zn_(0.05)O_3 films

Bipolar resistive switching is studied in BiFe0.95Zn0.05O3 films prepared by pulsed laser deposition on （001） SrTiO3 substrate, with LaNiO3 as the bottom electrode, and Pt as the top electrode. Multiple steps of resistance change are ob- served in the resistive switching process with a slow voltage sweep, indicating the formation/rupture of multiple conductive filaments. A resistive ratio of the high resistance state （HRS） to the low resistance state （LRS） of over three orders of mag- nitude is observed. Furthermore, the conduction mechanism is confirmed to be space-charge-limited conduction with the Schottky emission at the interface with the top Pt electrodes in the HRS, and Ohmic in the LRS. Impedance spectroscopy demonstrates a conductive ferroelectric/interfacial dielectric 2-layer structure, and the formation/rupture of the conductive filaments mainly occurs at the interfacial dielectric layer close to the top Pt electrodes.     

三价铕激活的(Y,La)2O2S二元体系的发光

为了寻找新的荧光粉基质料材,本文研究了在阴极射线、紫外线和X射线激发下,三价铕激活的(Y,La)2O2S二元体系的发光亮度、发射光谱和发光颜色等发光特性随组成变化的规律,并研究了三价铕离子浓度对(Y0.9La0.1)2O2S体系发光性能的影响。