Eu~(3+)在YAG中的发光性能及Eu~(3+)、Bi~(3+)间的能量传递

ＹＡＧ作为一种新型的功能材料已引起了人们极大的兴趣，我们采用溶胶、凝胶法合成了ＹＡＧ：Ｅｕ和ＹＡＧ：Ｅｕ，Ｂｉ，研究了Ｅｕ３＋在ＹＡＧ中的发光及Ｅｕ３＋，Ｂｉ３＋间的能量传递。１实验部分将纯度９９．９９％Ｙ２Ｏ３，Ｅｕ２Ｏ３和Ｂｉ２Ｏ３分别溶于ＧＲ级ＨＮＯ３中，配制成一定浓度的溶液，然后以Ｙ（ＮＯ３）３，Ｅｕ（ＮＯ３），Ｂｉ（ＮＯ３）３和Ａｌ（ＮＯ３）３为初始原料，按（Ｙ１－ｘＥｕｘ）３ＡＬ５Ｏ１２和（Ｙ１－ｘ－ｙＥｕｘＢｉｙ）３Ａｌ５Ｏ１２化学式量配比，充分混匀后加入柠檬酸，缓慢蒸干，在４００℃灼烧２ｈ

Application of coupling model for stress relaxation of phenolphthalein polyether ketone

According to stress relaxation curves of phenolphthalein polyether ketone (PEK-C) at different temperatures and the principle of the time-temperature equivalence, the master curve of PEK-C at arbitrary reference temperature is obtained. A coupling model is applied to explain quantitatively stress relaxation behaviour of PEK-C at different temperatures. The parameters obtained from the coupling model have important physical meaning. Copyright (C) 1996 Elsevier Science Ltd.

Comparative study on the doping effect of 3d elements in Bi(1.5)Pb(0.2)Sr(2)Ca(2)Cu(2.8)M(0.2)O(y) (M=Sc,Ti,V,Cr,Mn,Fe,Co,Ni, or Zn)

With XRD, R-T, and ac chi measurements a comparative study on the doping effects of 3d elements in Bi(1.5)Pb(0.2)Sr(2)Ca(2)Cu(2.8)M(0.2)O(y) (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, or Zn) has been carried out. The effects of the former five members are significantly different, both on phase formed and on T-c, from the latter four. It seems that the effect on phase stabilization correlates with the valency of the doped cation. In connection with the instability of the 2223 phase, the correlation has been discussed.

Magnetic and electric properties of Bi(La)Sr(Ca)Mn2O6

Bi1-xLaxSrMn2O6 and BiSr1-xCaxMn2O6 are prepared by solid state reaction. They are n-type semiconductors with ferromagnetism at room temperture. When Bi is substituted partly by rare earth, a negative magnetoresistance effect is observed in the pellet of Bi1-xLaxSrMn2O6. There are semiconductor-metal transitions at 820 K in BiSrMn2O6. The transitions are attributed to the magnetic transition at high temperature. The substitution of Ca for Sr makes the transition temperature increase. However, when Bi is partly substituted by La, the solid solution does not change into metal. (C) 1996 Academic Press, Inc.

多组分氧化物Ag－Bi－V－Mo－O催化作用的光电子能谱研究

多组分氧化物Ａｇ－Ｂｉ－Ｖ－Ｍｏ－Ｏ催化作用的光电子能谱研究宋伟，李静，窦伯生（中国科学院长春应用化学研究所长春１３００２２）关键词　钼钒酸铋，助剂Ａｇ，ＸＰＳ，Ａｒ~＋刻蚀，氧化还原对于烃类选择氧化反应中复合氧化物的催化作用，普遍认为是Ｒｅｄｏｘ机...

丙烷氧化反应中多组分氧化物Bi－V－Mo－O催化作用的红外光谱研究

丙烷氧化反应中多组分氧化物Ｂｉ－Ｖ－Ｍｏ－Ｏ催化作用的红外光谱研究李静，宋伟，窦伯生（中国科学院长春应用化学研究所长春１３００２２）关键词钼钒酸铋，丙烷，选择氧化，催化作用机理，红外光谱迄今对于含有钼、铋复合氧化物催化剂的活性中心和作用机理存在不同看...

STUDIES ON THE PEROVSKITE-TYPE MIXED CATALYSTS OF TITANIUM SYSTEM FOR OXIDATIVE COUPLING OF METHANE - THE INFLUENCE OF CALCINATION TEMPERATURE

The correlations of the calcination temperature, structure and catalytic activity for the oxidative coupling of methane on the LiLa0.5Ti0.5O2+lambda catalysts whose main phase and major active phase is Perovskite-type ternary complex oxide LaTi1-yLiyO3-lambda have been studied. The surface and bulk structures of the catalysts were characterized by means of XRD, XPS, IR, BET and so on, The results cleary indicated that the effect of calcination temperature on the activity for the oxidative coupling of methane is twofold. On one hand, it is favorable for Li+ substitution for Ti3+ to enter into the lattice of LaTiO3 and produce more oxygen vacancies in which active oxygens are formed; however, excessively high calcination temperature make the amount of Li+ substitution for Ti3+ lower, due to a little change of structure or phases for the catalyst. On the other hand, the conversion of CH4 drops because of the decrease of surface area, when the calcination temperature is raised.

A STUDY OF SURFACE OXYGEN SPECIES FROM LA-ME-O (ME=MG, CA, SR, BA) CATALYSTS FOR METHANE OXIDATIVE COUPLING

CO2-TPD was used to study the surface basicity of La-Me-O mixed oxides and O-2-TPD, CH4-TPD were employed to study the surface active oxygen species. Comparing the CO2-TPD with O-2-TPD, we can see that the basicity of catalyst is in parallel with the catalystic activity. The stronger basicity is more profitable for the catalyst to adsorb oxygen to form active oxygen species and to activate CH4 by breaking a C-H bond, By comparing the catalytic activity, the results showed that La-Ba-O(La/Ba=7/3) catalyst had the strongest basicity, and it gave the highest CH4 conversion and C-2 selectivity, The results from the pulse reaction showed that the lattice oxygen participated in the OCM reaction without gas oxygen, and it was the selective oxygen species.

STRUCTURE AND CATALYTIC ACTIVITY FOR PROPYLENE OXIDATION OF BI-MO-NB COMPLEX OXIDE CATALYSTS

The structure and catalytic,activity for propylene oxidation of series oxides B2Mo3-3X-Nb2XO12-4X (X=0.00, 0.02, 0.05, 0.10, 0.15, 0.20, 0.25) have been studied by means of XRD, IR, Raman, SEM, ESR and so on. The results showed that in the range of X < 0.

Study of Methane Oxidative Coupling over Ti-La-Li Mixed Oxides

The composition and structures of Li-Ti-La mixed oxides as well as their catalytic activity for methane oxidative coupling have been studied by means of XRD XPS, IR, SEM and so on. The results indicate that by changing x value in Li-La1-xTixO2 oxides phas

Role of Lithium in Multicomponent Oxide Catalysts for Oxidative Coupling of Methane

The effect of Li content in a series of multicomponent oxides LixLa0.5Ti0.5 For methane oxidative coupling has been studied. The catalytic activities of LiLa0.5Ti0.5 catalyst before and after washing with boiling water have been compared. The surface and

Bi－Mo－Nb复合氧化物催化作用机理的ESR和XPS研究

用ＥＳＲ对比研究了掺杂Ｎｂ对α－Ｂｉ２Ｍｏ３Ｏ（１２）催化剂丙烯还原和氧再氧化的影响，并用ＸＰＳ原位Ａｒ＋溅射研究了催化剂的还原与再氧化过程，观察了上述过程中催化剂内金属离子的价态变化和晶格氧的扩散现象。提出了Ｂｉ－Ｍｏ间通过晶格氧扩散所发生的氧化还原作用及模型，探讨了Ｎｂ（５＋）取代Ｍｏ（６＋）产生的氧空位对加速晶格氧扩散所起的作用。

Y_2O_3－Nb_2O_5－B_2O_3：Eu~（3＋）·Bi~（3＋）的燐光体的晶体结构与光谱性质

采用常规固相反应于１２００℃下制备了具有褐钇铌矿结构的Ｙ２Ｏ３·Ｎｂ２Ｏ５·Ｂ２Ｏ３（Ｙ（０．９３）Ｅｕ（０．０７））２Ｏ３·Ｎｂ２Ｏ５·Ｂ２Ｏ３和（Ｙ（０．９１）Ｅｕ（０．０７）Ｂｉ０．０２））２Ｏ３·Ｎｂ２Ｏ５·Ｂ２Ｏ３等光体，研究了它们的发光性质：结果表明，在２６８ｎｍ紫外光激发下，由于ＮｂＯ４基团于４１０ｎｍ处发生１Ｔ→１Ａ１跃迁，致使Ｙ２Ｏ５·Ｎｂ２Ｏ５·Ｂ２Ｏ３呈现更亮的紫外发射。体系中的Ｂ２Ｏ３可降低反应温度，增强ＮｂＯ４和Ｅｕ（３＋）的发光强度。（Ｙ（０．０９１）Ｅｕ（０．０７）Ｂｉ（０．０２））２Ｏ３·Ｎｂ２Ｏ５·Ｂ２Ｏ３燐光体系中所观察到的ＮｂＯ４→Ｅｕ（３＋）和Ｂｉ（３＋）→Ｅｕ（３＋）的能量传递使红光发射明显增强。

Bi-Mo-Nb复台氧化物的结构与对丙烯氧化的催化活性

本文用XRD,IR,Raman,SEM和ESR等方法研究了系列氧化物Bi_2Mo_(3-3x)Nb_(2x)O_(12-4x)(X=0.00,0.02,0.05,0.10,0.15,0.20,0.25)的结构和对丙烯氧化的催化活性,结果表明,在X≤0.25范围内,催化剂基本保持典型的α-Bi_2Mo_3O_(12)结构,少量Nb~(5+)的掺杂,可取代晶格中的Mo~(6+),产生氧空位,无序分布的氧空位的浓度先随X值的增加而增加,当X=0.15时达最大值,催化剂对丙烯氧化的催化活性与这种氧空位的浓度成正比,反应遵循Redox机理.

溶胶－凝胶法合成（Mg，Ca）O－SiO_2∶Eu~（3＋），Bi~（3＋）发

以Ｍｇ（ＮＯ３）２、Ｃａ（ＮＯ３）２、Ｅｕ（ＮＯ３）３、Ｂｉ（ＮＯ３）３、ＬｉＮＯ３和Ｓｉ（ＯＣ２Ｈ５）４为反应物，采用溶胶－凝胶法，在比较低的温度下，首次合成０．７０１ｍｏＩＭｇＯ－０．１７５ｍｏｌＣａＯ－１．２５ｍｏＩＳｉＯ２∶０．０６ｍｏｌＥｕ（３＋），０．００２ｍｏＩＢｉ（３＋）（加入Ｌｉ＋作为电荷补偿剂）发光体。得到了最佳合成条件。研究了由溶胶向凝胶转变和凝胶向发光晶体的转变过程。探讨了发光体在不同激发波长激发下的发光特性以及在激活剂、敏化剂不同掺杂量下的发光行为。讨论了在（Ｍｇ（ａ）Ｏ－ＳｉＯ２基质中Ｂｉ（３＋）对Ｅｕ（３＋）的能量传递和敏化作用。