光波导用硅基SiO2-ZrO2二元系统玻璃薄膜的制备

以正硅酸乙酯(TEOS)和丙醇锆Zr(Ⅳ)-propoxide为先驱体,HAc作为螯合剂,采用溶胶-凝胶工艺制备了不同锆含量(XZr)的一系列SiO2-ZrO2块材,用旋涂法制备了硅基薄膜,并经FTIR表征.折射率测试表明,当XZr≤20%时,Zr能够进入Si-O-Si网络,有效的调控材料的折射率.当XZr＞20%时,由于HAc对Zr的螯合作用使丙醇锆无法充分水解,而主要以配合物的形式存在于材料中,导致了薄膜严重龟裂,折射率偏离线性变化;研究获得了旋涂工艺参数对硅基SiO2-ZrO2薄膜厚度的调控规律.     

钛掺杂介孔二氧化硅薄膜的制备与表征

采用溶胶-凝胶工艺,选用表面活性剂十六烷基三甲基溴化铵(CTAB)为模板剂,通过正硅酸乙酯(TEOS)和钛酸丁酯(TPOT)的分步水解得到均匀的SiO2-TiO2复合溶胶,制备了具有介孔结构的钛掺杂的二氧化硅薄膜.薄膜的折射率在1.20～1.236之间可调,介电常数在2.54～2.817之间.随着钛含量的增加,折射率和介电常数增大,而孔洞率降低.结果分析表明钛离子均匀的分散在SiO2-TiO2网络中形成了Si-O-Ti键的孤立四配位形态.     

TiO2包覆单分散SiO2球的制备

分别采用钛酸异丙酯和钛酸丁酯为先驱体,对所制备的单分散氧化硅球(Ф≈400 nm)进行了1次和2次包覆TiO2层,获得了单分散的SiO2-TiO2芯-壳结构的球;采用TEM,SEM和EDS对所得SiO2-TiO2的球的大小、形貌和球中硅、钛含量进行了表征.研究结果表明采用钛酸异丙酯作为先驱体可获得氧化钛层较薄但无粘结的SiO2-TiO2芯-壳结构的球(φ可达500 nm);而采用钛酸丁酯作为先驱体时,则可获得较厚但粘结的SiO2-TiO2芯-壳结构的球(φ可达600nm).     

无水溶胶-凝胶法制备SiO2,SiO2-ZrO2凝胶玻璃

采用无水溶胶-凝胶工艺制备了SiO2,SiO2-ZrO2凝胶玻璃,用红外光谱对其结构进行了表征,并且估算了SiO2凝胶玻璃中的Si-OH含量,结果发现通过无水溶胶-凝胶工艺制备的凝胶玻璃比有水工艺具有更低的Si-OH含量.经150℃热处理的SiO2-ZrO2二元系统凝胶玻璃,其折射率可因ZrO2含量的改变,在1.445～1.614范围内调控.     

溶胶-凝胶ZrO_2/SiO_2双层减反膜(英文)

以锆酸丙酯[Zr(OPr)4]、正硅酸乙酯(TEOS)为原料,用溶胶-凝胶提拉法涂膜,制备了高透过的λ/4-λ/4型ZrO2/SiO2双层减反膜。以锆酸丙酯为前驱体,乙酰丙酮为络合剂,在盐酸的催化条件下,于乙醇溶剂中水解制备ZrO2溶胶。ZrO2溶胶具有很好的稳定性。制备的双层减反膜具有很好的减反效果,在石英玻璃基片二面涂膜,在激光三倍频波长351nm处透过率达到99.41%,在BK-7光学玻璃基片上涂制的双减反层膜在基频波长1053nm处透过率达到99.63%。该减反膜的均方根粗糙度(RMS)为1.038nm。膜层具有较高的激光损伤阈值,在激光波长为1064nm,脉冲宽度为1ns时,ZrO2膜的激光损伤阈值为19.6J/cm2,双层减反膜的激光损伤阈值为16.8J/cm2。     

Zn2SiO4微波陶溶胶-凝胶法制备及性能研究

以Zn(NO3)2·6H2O和正硅酸乙酯为前驱体,乙醇作为溶剂,采用溶胶-凝胶法制备了ZnzSiO4微波陶瓷粉体,并研究了粉体的烧结特性和微波介电性能.干凝胶在800℃热处理后得到的ZnO和Zn2SiO4纳米级混合粉体.溶胶凝胶法制各的粉体具有更大的比表面积,使作为粉体烧结驱动力的表面能剧增,促使陶瓷在1200～1350℃实现致密烧结,比固相法合成粉体的烧结温度降低近200℃,并具有优异的介电性能:εr=6.14,Qf=67,500 GHz(12 GHz).     

ZnO-B2O3-SiO2溶胶-凝胶制备及表征

研究了ZnO-B2O3-SiO2溶胶-凝胶的制备过程,分析了凝胶的形成机理,探讨了干凝胶的析晶过程.结果表明随着SiO2/(ZnO+B2O3)比值的增大,样品胶凝时间逐渐延长,凝胶从浑浊转为清亮,而对应干凝胶的析晶温度升高.析出主晶相为Zn2SiO4,并存在少量的石英相.物相分析和红外能谱分析表明,在热处理过程前后,始终有B2O3-SiO2玻璃相存在于样品中.微观分析表明,经800℃高温热处理的干凝胶中存在着大量0.4μm左右的圆形气孔.     

混合溶剂对氧化铬基气凝胶微结构的影响

采用环氧化物法和无机分散溶胶凝胶法,通过改变甲苯/乙醇混合溶剂比例制备了氧化铬基气凝胶和干凝胶。当甲苯/乙醇体积比由1:3增大至3:1时,环氧化物添加法制备的氧化铬基气凝胶的平均孔径从14nm变为21nm,比表面积从66m2/g升为244m2/g,总孔体积容量由0.2339cm3/g增至1.296cm3/g。无机分散溶胶凝胶法制备的气凝胶(添加聚丙烯酸PolyAcrylicAcid,PAA),比表面积则由276m2/g降至66m2/g,总孔体积容量从0.9601cm3/g降至0.2339cm3/g。结果表明,采用混合溶剂和和添加PAA的方法可能实现对气凝胶微结构的连续调控。     

溶胶-凝胶法制备SiO2减反射薄膜及其耐久性

目的 增加太阳光在太阳能电池玻璃盖板的透过率,以期提高太阳能电池的转换效率。方法 以正硅酸乙酯为原料、乙醇为溶剂、氨水为催化剂,采用碱催化溶胶-凝胶浸渍提拉法,在玻璃表面制备了SiO2减反射薄膜,研究了溶胶中正硅酸乙酯与乙醇物质的量比和提拉镀膜速度对SiO2薄膜光学性质的影响,分析了减反射薄膜的耐久性。结果 碱性溶胶制备的SiO2为非晶相,采用浸渍提拉法在玻璃表面制备的薄膜结构疏松,且存在微裂纹。采用正硅酸乙酯与乙醇物质的量比为1∶20、提拉速度为500 μm/s及正硅酸乙酯与乙醇物质的量比为1∶30、提拉速度为1 000 μm/s制备的SiO2薄膜,折射率分别为1.35和1.33,厚度分别为101.11、102.63 nm,最大透过率分别高于未镀膜玻璃6.57%和6.94%,在400~1 100 nm波长范围内的平均透过率分别高于未镀膜玻璃5.01%和5.34%,表明该薄膜具有优异的减反射性能。玻璃表面制备SiO2薄膜后,水接触角约为5°,具有超亲水性。将未镀膜玻璃及镀膜样品在实验室放置5个月后,采用正硅酸乙酯与乙醇物质的量比为1∶20、提拉速度为500 μm/s及正硅酸乙酯与乙醇物质的量比为1∶30、提拉速度为1 000 μm/s的制备SiO2薄膜的最大透过率分别高于未镀膜玻璃7.50%和6.71%,在400~1 100 nm波长范围内的平均透过率分别高于未镀膜玻璃5.94%和5.59%,表明SiO2薄膜的减反射性能具有较好的耐久性。结论 采用碱催化溶胶-凝胶法在玻璃上制备的SiO2减反射薄膜具有超亲水性及优异的减反射耐久性,在太阳能电池玻璃盖板上具有潜在的应用价值。     

镁合金表面SiO2-ZrO2溶胶凝胶膜的耐蚀性

采用溶胶-凝胶法在AZ91D镁合金表面制备SiO2-ZrO2复合溶胶凝胶膜.研究膜层制备工艺中的干燥、固化过程对膜层耐腐蚀性能的影响,从而确定了SiO2-ZrO2复合溶胶凝胶膜在镁合金表面的最佳沉积工艺.通过全浸腐蚀试验和电化学测试方法评价了膜层的耐腐蚀性能.试验确定最佳沉积工艺参数:干燥温度为80℃、干燥时间为9 h、固化温度为250℃、固化时间为1 h.在优化工艺条件下制备的溶胶凝胶膜层对镁合金基体有一定的防护作用,提高了镁合金的耐蚀性.     

Thermodynamics and phase diagrams in the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3

We applied our model to the enthalpy of mixing data of the binary systems Na₂O-SiO₂, Na₂O-GeO₂, Na₂O-B₂O₃, Li₂O-B₂O₃, CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates. The same applies to the CaO-SiO₂, CaO-Al₂O₃, PbO-B₂O₃, PbO-SiO₂, ZnO-B₂O₃, and ZnO-SiO₂ systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure of the liquid. Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct solid-solid calorimetry.     

Fe2+-Ni2+-NH3-NH4+-C2O42-H2O体系的沉淀配合平衡热力学

针对草酸盐配位共沉淀热分解还原法制备超细铁镍合金粉过程中Fe2+-Ni2+-NH3-NH4+-C2O42--H2O体系的溶液平衡建立热力学分析模型,并根据模型进行相关计算,揭示反应体系中各物质随pH值、氨及草酸浓度的变化关系。结果表明:溶液中的Fe主要以[Fe(C2O4)n]2 2n络合物形式存在,而铁氨络合物含量很低。当氨含量较低时,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在;氨含量较高时,在酸性条件下,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在,在碱性条件下,则主要以[Ni(NH3)n]2+存在。低pH值下,Ni的沉淀率较Fe的高,而高pH值下,Ni的沉淀率则较Fe的低。     

Al2O3-Sm2O3-CeO2电解质的性能（英文）

采用溶胶-凝胶法和低温燃烧技术制备Ce1-xSmxO2（x=0,0.1,0.2,0.3）和掺杂Sm和（2%-8%）Al2O3的二氧化铈;研究其合成、结构、致密化、导电性和热膨胀等性能,并利用XRD研究其结构和相组成。结果表明,于1300°C烧结球团,获得致密的陶瓷,于1250°C在Ce0.8Sm0.2O0.2中加入2%和4%的Al2O3以促进烧结。利用扫描电子显微镜观察烧结后球团的表面形貌,使用双探针交流阻抗谱研究总离子电导率。     

Al2O3包覆改善P2型Na2/3Fe1/2Mn1/2O2正极材料的存储性能

采用超声喷雾热解与高温固相烧结相结合的方法合成P2型Na_2/3Fe_1/2Mn_1/2O₂材料。通过X射线衍射仪、扫描电子显微镜和电化学充放电设备对材料的结构、形貌和电化学性能进行全面的表征。此外,在Na_2/3Fe_1/2Mn_1/2O₂表面包覆Al₂O₃薄层,该包覆层可以抑制Na₂CO₃·H₂O的形成,提高Na_2/3Fe_1/2Mn_1/2O₂材料的存储性能,从而改善其电化学性能。这种简单的表面改性方法为合成高性能钠离子电池正极材料提供了新思路。     

Synthesis and properties of CaCd2Sb2 and EuCd2Sb2

High density polycrystalline CaCd₂Sb₂ and EuCd₂Sb₂ intermetallics are synthesized by Spark Plasma Sintering and their thermoelectric properties are investigated. X-ray diffraction measurements reveal both materials have a structure in space group, containing a small amount of CdSb as a second phase. Thermoelectric measurements indicate both are p-type conductive materials. The figure of merit value of CaCd₂Sb₂ is 0.04 at 600 K and that of EuCd₂Sb₂ is 0.60 at 617 K. Theoretical calculations show that CaCd₂Sb₂ is a degenerate semiconductor with a band gap of 0.63 eV, while EuCd₂Sb₂ is metallic with DOS of 13.02 electrons/eV. For deeper understanding of the better thermoelectric properties of EuCd₂Sb₂, its low temperature magnetic, transport and heat capacity properties are investigated. Its Nèel temperature is 7.22 K, convinced by heat capacity anomaly at 7.13 K. Hall effect convinced that it is a p-type conductive material. It has high Hall coefficient, high carrier concentration and high carrier mobility of +1.426 cm³/C, 4.38 × 10¹⁸/cm³ and 182.40 cm²/Vs, respectively. They are all in the magnitude of good thermoelectric materials. The Eu 4f level around Fermi energy and antiferromagnetic order may count for the better thermoelectric properties of EuCd₂Sb₂ than that of CaCd₂Sb₂.     

Y2O3-BaO-SiO2-B2O3-Al2O3 glass sealant for solid oxide fuel cells

A glass based on Y₂O₃-BaO-SiO₂-B₂O₃-Al₂O₃ (named YBA) has been investigated as sealant for planar solid oxide fuel cells (SOFCs). The YBA glass has been systematically characterized by differential thermal analysis, dilatometer, scanning electron microscopy, impedance analysis, and open circuit voltage to examine their suitability as sealant. The coefficient of thermal expansion of YBA is 11.64 × 10⁻⁶ K⁻¹ between 323 and 873 K. The resistivity is 9.1 × 10⁴ Ω cm at 800 °C. The glass sealant is found to be well adhered with other cell components, such as electrolytes and stainless steels, at an optimum sealing temperature of 800 °C. All measured results showed that the YBA glass appears to be a promising sealant for SOFCs.     

New Zr6CoAs2-type compounds: Y6CoBi2, Ho6CoBi2 and Tm6CoBi2

Results of a powder X-ray diffraction investigation of new ternary compounds are reported. The compounds Y₆CoBi₂ [a=0.8312(1) nm, c=0.4144(1) nm], Ho₆CoBi₂ [a=0.8246(2) nm, c=0.4095(1) nm], and Tm₆CoBi₂ [a=0.8155(2) nm, c=0.4066(1) nm] crystallize in the hexagonal Zr₆CoAs₂-type structure (space group P6b2m No. 189). The Zr₆CoAs₂-type structure is a superstructure of the Fe₂P-type structure.     

Phase equilibria in the system La2O3-BaO-P2O5: The partial system LaPO4-Ba2P2O7-Ba(PO3)2

The LaPO₄-Ba₂P₂O₇-Ba(PO₃)₂ portion of the oxide La₂O₃-BaO-P₂O₅ system has been investigated. Important parts of this investigation were the determination of equilibria in the LaPO₄-Ba(PO₃)₂ subsystem and the addition of liquidus data to the partially known LaPO₄-Ba(PO₃)₂-Ba₂P₂O₇ subsystem. These data were combined with known data from the LaPO₄-Ba₂P₂O₇ subsystem and with measurements of the equilibria within the LaPO₄-Ba₃P₄O₁₃ isopleth to determine the nature of the phase equilibria in the quasi-ternary LaPO₄-Ba₂P₂O₇-Ba(PO₃)₂ system.     

载体中ZrO2/Al2O3比对Pt/ZrO2-Al2O3催化剂性能的影响

相比汽油车而言,柴油车具有高效、低油耗的优势已得到广泛应用。本实验以ZrO₂作为改性剂,探究了ZrO₂与Al₂O₃的质量比对催化剂的影响。研究结果表明：随着ZrO₂的加入,Pt粒子先减小后增大;Pt粒子与载体的交互作用先增大后减小。活性实验数据分析表明,ZrO₂的最佳添加量为40 wt%,CO和C₃H₆完全氧化温度分别降低20 _oC 、25 _oC。贵金属在催化剂的分散度以及贵金属与载体的相互作用随着ZrO₂与Al₂O₃质量比的变化而变化。Pt粒子越小,其与载体的交互作用越强,这表明催化剂性能越强。     

Electronic structures and Eu photoluminescence behaviors in Y2Si2O7 and La2Si2O7

The electronic structures and linear optical properties of Y₂Si₂O₇ (YSO) and La₂Si₂O₇ (LSO) are calculated by LDA method based on the theory of DFT. Both YSO and LSO are direct-gap materials with the direct band gap of 5.89 and 6.06 eV, respectively. The calculated total and partial density of states indicate that in both YSO and LSO the valence band (VB) is mainly constructed from O 2p and the conduction band (CB) is mostly formed from Y 4d or La 5d. Both the calculated VB and CB of YSO exhibit relatively wider dispersion than that of LSO. In addition, the CB of YSO presents more electronic states. Meanwhile, the VB of LSO shows narrower energy distribution with higher electronic states density. The theoretical absorption of YSO shows larger bandwidth and higher intensity than that of LSO. The results are compared with the experimental host excitations and impurity photoluminescence in Eu³⁺-doped YSO and LSO.