P2O3—B2O3—Al2O3—SrO—BaO玻璃中的Yb^3＋非辐射能量转移下E …

本文研究了共掺Ｅｒ＾３＋／Ｙｂ＾３Ｐ２Ｏ３－Ｂ２Ｏ３－Ａｌ２Ｏ３－ＳｒＯ－ＢａＯ玻璃的能量转移过程。实验中制备了高掺杂Ｂｂ＾３＋离子的双掺Ｅｒ＾＃＋／Ｙｂ＆＾３＋的磷酸盐玻璃样品。在Ｅｒ＾３＋／Ｙｂ＾３＋掺杂比率〉１：１８（ｍｏｌ％）时,观测到了基于Ｙｂ＾３＋离子至Ｅｒ＾３＋离子能量转移下Ｅｒ＾３＋（＾３Ｉ１３／２→＾４Ｉ１５／２）的增强发射和ｂ＾３＋（＾２Ｆ７１／→＾２Ｆ５／２）发射的减弱,当Ｂ     

Ti／RuO2＋SnO2＋Sb2O3｜Pb3O4阳极的性能研究

本文对Ｔｉ│ＲｕＯ２＋ＳｎＯ２＋Ｓｂ２Ｏ３│Ｐｂ３Ｏ４阳极进行了ＳＥＭ、ＥＤＳ、ＸＲＤ研究，考察了在ＩＭＨ２ＳＯ４中电极寿命，测定了该电极的电化学动力学参数ａ、ｂ、ｉ０，并用双位垒模型讨论了其电化学性能，结果表明该电极具有优良的电化学性能和较长的使用寿命。     

La2O3—Li2O—B2O3三元系玻璃网络结构的研究

本文用闰曼及红外光谱和差热曲线研究了Ｌａ２Ｏ３－Ｌｉ２Ｏ－Ｂ２Ｏ３三元系玻璃的微观结构，着重研究了锂和镧的氧化物的引入对硼的配位数及玻璃网络结构的影响，发现Ｌｉ２Ｏ和Ｌａ２Ｏ３伯作用相似，它们的增加都会使玻璃网络的基本基团四硼酸盐基团－二硼酸盐基团－偏硼酸盐基团演变。     

三元系ZrO2—Y2O3—Yb2O3材料的低温电性能

采用复阻抗技术对三元系ＺｒＯ２－Ｙ２Ｏ３－Ｙｂ２Ｏ３材料在５７３－８７３Ｋ内的离子电导率随组成的变化关系进行了研究,发现该材料的低温电导率随Ｙｂ２Ｏ２含量的增加而降低。用Ａｒｒｈｅｎｉｕｓ公式对实验数据进行的分析表明,电导率降低的原因在于Ｙｂ＾２＋与结构中氧空位之间的缔合比Ｙ＾３＋与氧空位之间的缔合更甚,阻碍了氧空位在低温下的定向迁移。     

Ce^3＋,Tb^3＋在Al4B2O9和Al18B4O33基质中的发光

采用固相反应法在Ａｌ２Ｏ３－Ｂ２Ｏ３体系中合成了Ａｌ４Ｂ２Ｏ９和Ａｌ１８Ｂ４Ｏ３３两个相关化合物，测定了在两种基质中Ｃｅ３＋，Ｔｂ３＋和Ｃｅ３＋－Ｔｂ３＋的光谱，观察到在两种基质中Ｃｅ３＋的光谱相似，Ｃｅ３＋的发射峰位置在Ａｌ１８Ｂ４Ｏ３３中比Ａｌ４Ｂ２Ｏ９稍有红移。实验表明，Ａｌ１８Ｂ４Ｏ３３将是一种好的发光基质     

CaO—MgO—Fe2O3—Al2O3—SiO2渣系玻璃晶化动力学

根据玻璃形成动力学理论,计算了ＣａＯ－ＭｇＯ－Ｆｅ２Ｏ３－Ａｌ２Ｏ３－ＳｉＯ２渣系中成核速率（Ｉ）和晶体长大速度（Ｕ）,获得晶体形成的最佳温度,研究了热处理温度对ＣａＯ－ＭｇＯ－Ｆｅ２Ｏ３－Ａｌ２Ｏ３－ＳｉＯ２渣系晶体的影响,计算的晶体形成的最佳温度结果表明与该体系的最佳热处理温度一致。     

MgO—B2O3—SiO2—Al2O3—CaO中含硼组分析晶动力学

根据玻璃形成动力学理论，计算了ＭｇＯ－Ｂ２Ｏ３－ＳｉＯ２－Ａｌ２Ｏ３－ＣａＯ渣系中含硼组分２ＭｇＯ·Ｂ２Ｏ３的成核速度（Ｉ）和晶体长大速度（Ｕ），获得了２ＭｇＯ·Ｂ２Ｏ３晶体形成的最佳温度．采用化学分析、Ｘ射线衍射分析（ＸＲＤ）和差热分析（ＤＴＡ）等方法研究了热处理温度对ＭｇＯ—Ｂ２Ｏ３—ＳｉＯ２—Ａｌ２Ｏ３—ＣａＯ渣系硼提取率的影响．结果表明：硼渣最佳热处理温度与２ＭｇＯ·Ｂ２Ｏ３晶体形成最佳温度一致。     

Subsolidus Phase Relations in the Systems M2 +O–M2+O–V2O5(M+ = Li, Na, K, Rb, Cs; M2+ = Mg, Ca)

Subsolidus phase relations in the M₂O(M₂CO₃)–MgO–V₂O₅ and M₂O(M₂CO₃)–CaO–V₂O₅ (M = Li, Na, K, Rb, Cs) systems are studied. Twenty mixed vanadates are obtained, of which Rb₂CaV₂O₇, Cs₂CaV₂O₇, LiMg₄(VO₄)₃, RbCaVO₄, and CsCaVO₄ are identified for the first time. Structural data are summarized for all of the mixed vanadates: the space group and lattice parameters are indicated for 14 compounds (for 6 compounds, such data are obtained for the first time), and I and d data are presented for 8 compounds. Partial series of Ca₃(VO₄)₂-based solid solutions with the general formula Ca_{3 – x} M_2x (VO₄)₂ (M = Na, K, Rb, Cs) are identified in the range 0 < x 0.14. Six phase diagrams (M⁺ = Li, Rb, Cs; M²⁺ = Mg, Ca) are investigated and are compared with the phase diagrams of the other ternary systems in question. The key features of the ternary phase diagrams and, hence, the reactivity of the constituent oxides are shown to vary systematically in going from Li₂O to Cs₂O and from MgO to SrO, which is interpreted in terms of the variation in the ionic radius of the alkali and alkaline-earth metals.     

Al2O3—Coated Nano—SiC Particles Reinforced Al2O3 Matrix Composites

Properties of Al2O3-coated nano-SiC have been compared with those of as-received SiC.The isoelectric point(IEP) of SiC changed from pH3.4 to pH7.3 after coating with the alumina precursor,which is close to that of alumina.Because both surfaces of coated SiC and Al2O3 possess higher positive charge at pH=4.5-5.0 ,they are uniformly dispersed in the two-phase aqueous suspensions.Then a mixed powder containing nano-SiC dispersed homogeneously into the Al2O3 matrix was achieved from flocculating the two-phase suspension.Finally,Al2O3/SiC nanocomposited were obtained by coating nano-SiC with Al2O3 ,in which the majority of SiC particles were located within the Al2O3 grains.The observation by transmission electron microscopy(TEM) and the analysis by the X-ray photoelectron spectroscopy(XPS) showed that cracks propagated towards the intragranular SiC rather than along prain boundaries.     

硼的含量对SrAl2O4：Eu^2＋,Dy^3＋发光性能的影响

采用高温固相法制备SrAl2O4：Eu^2＋，Dy^3＋长余辉发光材料。借助材料的激发光谱、发射光谱和X射线衍射，分析研究掺杂B对SrAl2O4：Eu^2＋，Dy^3＋发光材料发光性能的影响及合适的加入量。结果表明：B的加入量影响着发光材料的发光性质，B的最佳加入量为58％。     

SiO2在ZnO—Bi2O3—Sb2O3—BaO系压敏陶瓷中的作用

ＳｉＯ２添加剂对ＺｎＯ－Ｂｉ２Ｏ３－Ｓｂ２Ｏ３－ＢａＯ系和通常的ＺｎＯ－Ｂｉ２Ｏ３－Ｓｂ２Ｏ３系压敏陶瓷电性能的作用和影响有很大不同。通过小电流区伏安特性，交变电压下复阻抗特性，以及对复电容平面图中半弧特性的分析可知，ＳｉＯ２对ＺｎＯ－Ｂｉ２Ｏ３－Ｓｂ２Ｏ３－ＢａＯ系压敏陶瓷中电性能影响是晶界组分及微结构变化造成的。     

Methane decomposition into COx-free hydrogen and carbon nanomaterials over ZrO2–M (M = MgO,Al2O3, SiO2, La2O3 or CeO2) binary oxides supported cobalt catalysts

Hydrogen production via methane decomposition has attracted great attention as a source of clean energy. In this work, the catalytic decomposition of undiluted methane into CO_x-free hydrogen and carbon nanomaterial over ZrO₂–M (M?=?MgO, Al₂O₃, SiO₂, La₂O₃ and CeO₂) binary oxides supported Co catalysts was studied. The fresh and spent catalysts were characterized by XRD, H₂-TPR, N₂ adsorption–desorption, TEM and Raman spectroscopy. The results revealed that the incorporation of secondary oxide to ZrO₂ support played a vital role in the activity and stability of cobalt metal. The activity results illustrated that Co/Zr–Mg exhibited better activity in terms of hydrogen yield compared with the other Zr–M supported catalysts. This is ascribed to the moderate cobalt oxide-support interaction and forming CoMgO_x species which enhance the Co₃O₄ dispersion and prevent its aggregation on the catalyst surface. On the other hand, the Co/Zr–Si catalyst showed the lowest activity due to the agglomeration of Co₃O₄ on the surface of the SiO₂ support. High-resolution TEM images illustrated that almost the deposited carbon on the surface of spent catalysts was in the form of multi-walled carbon nanotubes.     

Wetting behaviour of SiC ceramics: Part II—Y2O3/Al2O3 and Sm2O3/Al2O3

Wettability is the most significant phenomenon in SiC liquid phase sintering. The wetting of Y₂O₃/Al₂O₃ and Sm₂O₃/Al₂O₃ on SiC was analysed by the “Sessil drop” method. The wetting of liquid on solid during liquid phase sintering is very important. The behaviour of the additive on the SiC plate was observed using an imaging system with a CCD camera, and the contact angle measurements were analysed by Qwin Leica software. The samples were cut transversally and characterized by scanning electron microscopy and X-ray spectrometry (SEM/EDS). The wetting was found to be strongly influenced by the temperature; the SiC/additive contact angle decreased with increasing temperature. The YA and SA additives presented low contact angle values, indicating their good wetting on SiC in the argon atmosphere. The contact angle could not be measured when the test was performed in the nitrogen atmosphere because bubbles formed in the liquid during the test. The best atmosphere for this sintering was found to be argon, which allows uniform spreading.