从P-Mo(Ⅴ)杂多化合物合成多形貌Al13基钼酸盐晶体

以H₃PMo₁₂O₄0·nH₂O、H₄PMo₁₁VO₄₀·nH₂O和(NH₄)₆P₂Mo₁₈O₆₂·nH₂O 3种杂多化合物为钼源，采用直接混合后陈化的方法合成了多形貌Al₁₃基钼酸盐晶体，相应Al₁₃基钼酸盐晶体的形貌和尺寸分别是斜方三棱柱形(80 μm × 30 μm)、星形(30 μm × 10 μm)和叶片形(500 μm × 150 μm)。粉末X射线衍射结果表明这3种多形貌Al₁₃基钼酸盐晶体结晶较好，在2θ为6.65°、8.00°和14.16°处都有强而尖锐的衍射峰。而以Na₂MoO₄·2H₂O为钼源时只能制得无定形簇合物。根据ICP、FTIR和TG/DTG结果给出多形貌的Al₁₃基钼酸盐晶体的化学简式为Na[AlO₄Al₁₂(OH)₂₄(H₂O)₁₂][MoO₄]₄·8H₂O。初步探讨了Al₁₃基钼酸盐晶体的形成机理。     

高浓度高Al13含量聚合氯化铝溶液的制备

通过快速加碱在82 ℃下合成0.2 mol·L^-1、Al_b为60%～70%的低浓度高Al_b聚合氯化铝(L-PAC)，在热侧温度为50～95 ℃，冷侧温度约9～12 ℃的条件下进行膜蒸馏浓缩，制备出总铝浓度在2 mol·L^-1以上，Al_b含量大于90%，Al₁₃含量约为70%的高浓度高Al_b含量的聚合氯化铝溶液。对膜蒸馏浓缩过程中热侧温度、PAC的碱化度和初始pH值等因素对最终聚合氯化铝溶液产品中聚铝形态分布、总铝浓度的影响进行了初步研究，发现在热侧温度低于70 ℃、碱化度为2.47、初始pH值为5.0 ± 0.2的条件下，可以得到高浓度、高Al_b含量的聚合氯化铝溶液，纳米Al₁₃形态在较高的浓度下可以存在；低温贮存条件下，高浓度PAC中Al_b相当稳定。     

聚合氯化铝中Al13形态的分离纯化方法及特性

采用柱层析法、沉淀置换法和乙醇-丙酮混合溶剂法对聚合氯化铝(PAC)中的Al₁₃形态进行了分离提纯, 采用Al-Ferron逐时络合比色法, ²⁷Al NMR, TEM, SEM, 电位测定法, 粒度测定法等多种现代分析仪器和方法对不同分离提纯方法得到的Al₁₃形态进行了分析表征和比较, 并初步比较研究了Al₁₃形态的水处理效果. 实验结果表明, 不同分离纯化方法得到的 Al₁₃形态具有不同的结构形貌、粒度分布、电性和水处理效果. 乙醇-丙酮混合溶剂法得到的Al₁₃形态具有良好的纯度和水处理效果. 该研究初步证实了Al₁₃是PAC中的最佳絮凝形态.     

聚合氯化铝中Al13形态的分离纯化方法及特性

采用柱层析法、沉淀置换法和乙醇-丙酮混合溶剂法对聚合氯化铝(PAC)中的Al₁₃形态进行了分离提纯, 采用Al-Ferron逐时络合比色法, ²⁷Al NMR, TEM, SEM, 电位测定法, 粒度测定法等多种现代分析仪器和方法对不同分离提纯方法得到的Al₁₃形态进行了分析表征和比较, 并初步比较研究了Al₁₃形态的水处理效果. 实验结果表明, 不同分离纯化方法得到的 Al₁₃形态具有不同的结构形貌、粒度分布、电性和水处理效果. 乙醇-丙酮混合溶剂法得到的Al₁₃形态具有良好的纯度和水处理效果. 该研究初步证实了Al₁₃是PAC中的最佳絮凝形态.     

AlmN2和AlmN2＋ (m＝1～8)团簇结构与稳定性的量子化学研究

用密度泛函理论(DFT)的B3LYP方法, 在6-311G*水平上对Al_mN₂和Al_mN₂^＋ (m＝1～8)团簇的几何构型、电子结构、振动频率和分子轨道进行了理论研究. 结果表明, Al_mN₂类团簇的基态结构有两种基本构型, 一种是以N—N键为核心周围与Al原子相配位形成的, 一种是由两个Al_nN (n≤m/2)分子碎片通过共用Al原子或Al—Al键相互结合形成的. 对Al_nN分子碎片相互结合形成结构的绝热电离能讨论得到, m为偶数的团簇比m为奇数的稳定.     

片状纳米结构CeO2晶体的制备及其吸附CO2性能

在室温下,将CeCl₃溶液与CO₂储存材料（CO₂SM）混合、搅拌0.5 h制备了片状碳酸铈前驱体（CCPs）,并在500℃下煅烧CCPs 4 h,制得平均尺寸为4.94 μm×0.92 μm,厚度为0.04~0.08 μm纳米结构片状CeO₂晶体。在此过程中,CO₂SM不但可以提供CO₃^2-,还能起到分散剂和结构导向剂的作用。反应过程中,系统地研究了CO₂SM用量、Ce³⁺浓度和搅拌时间3个因素对CCPs形态和大小的影响,得到最优制备条件：0.1 g CO₂SM和50 mL 0.03 mol·L^-1 Ce³⁺水溶液以1 000 r·min^-1转速在室温下搅拌0.5 h。煅烧CCPs后,所制备的片状CeO₂晶体在室温下CO₂吸附量可达0.554 mmol·g^-1。     

Ba2SbInO6双钙钛矿的水热合成和表征

利用水热晶化法制备了Ba₂SbInO₆纯相，并通过XRD、SEM、IR、XPS和ICP等方法，对产物的物相、形貌、结构和组成进行了表征。初步结构表征结果表明，产物可能为B位离子无序排列的立方钙钛矿结构，空间群为Pm3m，晶胞参数为a=0.4132 mm。产物粉末呈现立方晶型，粒度约为0.5～2 μm。     

固相燃烧法制备去顶角八面体LiZn0.08Al0.01Mn1.91O4正极材料及其电化学性能

通过固相燃烧法快速合成了包含{111}、{100}和{110}晶面的单晶去顶角八面体形貌LiZn_0.08Al_0.01Mn_1.91O₄正极材料。结果表明,Zn-Al共掺促进了尖晶石型LiMn₂O₄材料的晶体发育和晶面择优生长,形成了单晶去顶角八面体形貌晶粒,有效抑制了Jahn-Teller效应,减缓了Mn溶解,增强了其晶体结构稳定性,显著提升了合成材料的电化学性能。LiZn_0.08Al_0.01Mn_1.91O₄在5C和10C下的首次放电比容量分别为92.6和76.5 mAh·g^-1,经过2 000次循环后的容量保持率分别为70.4%和74.8%。即使在15C高倍率下,仍有64.2 mAh·g^-1的首次放电比容量,循环800次后容量保持率达到82.2%。与LiZn_0.08Mn_1.92O₄相比,LiZn_0.08Al_0.01Mn_1.91O₄正极材料具有较大的Li+扩散系数(1.02×10^-11 cm²·s^-1)和较小的表观活化能(25.60 kJ·mol^-1),表明Zn-Al共掺和单晶形貌调控策略能够降低Li+在脱/嵌过程的能垒和增大Li+在电极材料中的扩散速率。     

固相燃烧法制备去顶角八面体LiZn0.08Al0.01Mn1.91O4正极材料及其电化学性能

通过固相燃烧法快速合成了包含{111}、{100}和{110}晶面的单晶去顶角八面体形貌LiZn_0.08Al_0.01Mn_1.91O₄正极材料。结果表明,Zn-Al共掺促进了尖晶石型LiMn₂O₄材料的晶体发育和晶面择优生长,形成了单晶去顶角八面体形貌晶粒,有效抑制了Jahn-Teller效应,减缓了Mn溶解,增强了其晶体结构稳定性,显著提升了合成材料的电化学性能。LiZn_0.08Al_0.01Mn_1.91O₄在5C和10C下的首次放电比容量分别为92.6和76.5 mAh·g^-1,经过2 000次循环后的容量保持率分别为70.4%和74.8%。即使在15C高倍率下,仍有64.2 mAh·g^-1的首次放电比容量,循环800次后容量保持率达到82.2%。与LiZn_0.08Mn_1.92O₄相比,LiZn_0.08Al_0.01Mn_1.91O₄正极材料具有较大的Li+扩散系数(1.02×10^-11 cm²·s^-1)和较小的表观活化能(25.60 kJ·mol^-1),表明Zn-Al共掺和单晶形貌调控策略能够降低Li+在脱/嵌过程的能垒和增大Li+在电极材料中的扩散速率。     

氧化铝-g-聚丙烯酰胺复合磨粒的制备及表征

为提高α-Al₂O₃磨粒在水基介质中的分散稳定性，采用接枝聚合方法制备了Al₂O₃-g-聚丙烯酰胺复合粒子。采用FTIR、XPS、TOF-SIMS、激光粒度仪、SEM、沉降试验等对氧化铝复合粒子结构及分散性能等进行了表征。结果表明，聚丙烯酰胺以化学键形式接枝到Al₂O₃粒子表面，形成聚丙烯酰胺为壳，Al₂O₃为核的复合磨粒;接枝改性后的Al₂O₃粒子分散性明显提高，并且其分散性与Al₂O₃表面接枝量密切相关。     

Spherulite morphology studies of N‐alkyl chitosan films cast from formic acid solutions

The films of N‐ethyl chitosan were prepared via the solution‐casting technique with formic acid as a solvent. The solutions with different concentrations (35 and 40 wt %) were prepared previously from dilute solution (1 wt %) via evaporating process. The crystalline morphology of these films was investigated by means of polarized optical microscopy and scanning electron microscopy. Normal spherulites with a low growth rate formed in the casting films. The different morphologies of spherulite appeared in the films cast from the solutions with different concentrations. After further crystallizing for a few days, the spherulites were decorated by thousands of needlelike extended‐chain crystals, which had a typical size of ～50 μm (length) × 2～5 μm (width) × 1～2 μm (height) in the central part of the spherulite, but a typical size of ～5 μm (lenght)× 1～2 μm (width) × 1～2 μm (height) in the fringe part of the spherulite. The real concentration for crystallization was determined to be 65–82 wt%. Thus, the crystallization actually appeared in supersaturated solution. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2033–2038, 2003     

Theoretical study on activation mechanism of fluorine substitution reactions of Keggin-MAl12 in aqueous solutions

The fluorine substitution reactions of Keggin polymeric aluminum species K-MAl₁₂ (M = Al, Ga, Ge) were investigated using density functional theory. Two substitution pathways (associative and dissociative) were simulated. The results show that the replacement of charged tetrahedral center metals causes the change in energy barrier either for associative mechanism or dissociative mechanism. The preferred activation mechanisms are proposed by comparing associative and dissociative barriers for fluorine substitution reactions of three Keggin Al species. The fluorine substitution reactions of Al₁₃ and GaAl₁₂ are inclined to dissociative mechanism and GeAl₁₂ follows an associative mode, indicating a mechanistic variation induced by the alteration of tetrahedral metals.     

聚合Al13晶体的制备及表征

近几十年来 , 环境污染的日益严重使人们对健康问题和全球生态系统越来越关注 ?由于一个元素的生物可给性在很大程度上取决于它存在的物理化学形态和浓度 , 准确测定环境和生物体系中的痕量元素的不同形态是研究这些元素的生物毒性 ? 生物有效性和传输机理的关键 ?形态分析成了     

Cation distribution in co-doped ZnAl2O4 nanoparticles studied by X-ray photoelectron spectroscopy and 27Al solid-state NMR spectroscopy

Co(x)Zn(1-x)Al(2)O(4) (x = 0.01-0.6) nanoparticles were synthesized by the citrate sol-gel method and were characterized by X-ray powder diffraction and transmission electron microscopy to identify the crystalline phase and determine the particle size. X-ray photoelectron spectroscopy and (27)Al solid-state NMR spectroscopy were used to study the distribution of the cations in the tetrahedral and octahedral sites in Co(x)Zn(1-x)Al(2)O(4) nanoparticles as a function of particle size and composition. The results show that all of the as-synthesized samples exhibit spinel-type single phase; the crystallite size of the samples is about 20-50 nm and increases with increasing annealing temperature and decreases with Co-enrichment. Zn(2+) ions are located in large proportions in the tetrahedral sites and in small proportions in the octahedral sites in Co(x)Zn(1-x)Al(2)O(4) nanoparticles. The fraction of octahedral Zn(2+) increases with increasing Co concentration and decreases with increasing particle size. Besides the tetrahedral and octahedral coordinations, the presence of the second octahedrally coordinated Al(3+) ions is observed in the nanoparticles. The change of the inversion parameter (2 times the fraction of Al(3+) ions in tetrahedral sites) with Co concentration and particle size is consistent with that of the Zn fraction in octahedral sites. Analysis of the absorption properties indicates that Co(2+) ions are located in the tetrahedral sites as well as in the octahedral sites in the nanoparticles. The inversion degree of Co(2+) decreases with increasing particle size.     

Studies on the Stability of On-top Al13Inm (n = 1～12,m =-1,0,+1) Clusters

Energetic and electronic structures of the on-top Al13Inm (n = 1 ～12,m = -1,0,+1)clusters have been investigated by employing a first-principles pseudo-potential plane wave method.Several parameters such as binding energies,second differences of energy and vertical-electron detachment energies have been adopted to characterize and evaluate the structure stability of Al13In (n = 1 ～ 12) clusters.The optimized models show that the Al13 moieties in the clusters can not retain the original regular icosahedron structure.Results from binding energy and second difference of energy show that Al13In and Al13In- clusters with even n are more stable than those with odd n in contrast with Al13In+ clusters.The calculation of vertical-electron detachment energies (VDE) of Al13In clusters indicates that Al13In and Al13In- clusters with even n are closer to the closed shell of the Jellium model.Further analysis of electron density of states and electron density differences reveals that the enhanced stability of Al13In- clusters is not only associated with the closed shell of valence electrons but also with the bonding type between I and associated Al atoms.     

Dip-coating crystallization on a superhydrophobic surface: a million mounted crystals in a 1 cm2 array

Silicon wafers (silicon dioxide surfaces) were patterned by photolithograpy to contain 3 μm (width) × 6 μm (length) × 40 μm (height) staggered rhombus posts in a square array (20 μm center-to-center spacing). These surfaces were hydrophobized using a vapor phase reaction with tridecafluorooctyldimethylchlorosilane and exhibit "superhydrophobicity" (water contact angles of θ(A)/θ(R) = 169°/156°). When a section of a wafer is submerged in and withdrawn from water, the superhydrophobic surface emerges, apparently completely dry. If the same procedure is performed using aqueous sodium chloride as the liquid bath, individual crystals of the salt can be observed on the top of each of the posts. "Dip-coating crystallization" using an aqueous sodium chloride solution of 4.3 M produces crystals with ～1 μm dimensions. A less concentrated solution, 1 M NaCl, renders crystals with ～500 nm dimensions. These experiments suggest that superhydrophobic surfaces that emerge from water and are "apparently completely dry" are, in fact, decorated with micrometer-size (several femtoliters) sessile water drops that rapidly evaporate. This simple technique is useful for preparation of very small liquid drops or puddles (of controlled composition) and for preparation of arrays of controlled size, crystalline substances (dip-coating crystallization).     

层柱人工水热合成皂石的制备与表征(英)

利用具有理想皂石结构的人工水热合成蒙皂石为层原料，通过与羟基聚合铝离子（[Al₁₃O₄(OH)₂₄(H₂O)₁₂]⁷⁺）交换反应合成得到了一种层柱粘土。实验对于该铝柱皂石进行了粉末XRD，FT-IR和TG-DTA表征。氮气吸附实验说明其高温活化（773K，2 h）产物具有很高的BET比表面（360 m²·g^-1）。相对于层柱蒙脱土，层柱皂石显示了更高的催化裂解性能和热稳定性。层柱皂石的异丙苯裂解转化率达到了65%；而层柱蒙脱土的转化率只有4%。这说明层材料的四面体取代对于层柱粘土Br?nsted酸位的形成具有重要的决定作用。氨程序升温脱附实验发现铝柱皂石在350～650 ℃区间具有较强的氨脱附量，表明层柱皂石具有层柱蒙脱土所没有的强酸中心。     

低密度薄水铝石晶体的水热生长过程

对Al2(SO4)3-CO(NH2)2-H2O体系在[Al3＋]=0.2 mol•L－1、[CO(NH2)2]:[Al3＋]=2∶1和反应2 h的水热条件下,不同反应温度的晶体生长过程进行了研究,得到呈多孔、针状团簇体状的微米级低密度薄水铝石晶体.采用ICP-AES、XRD、FT-IR、SEM、BET和粒径分布等手段对反应液和产物进行了分析和表征.结果表明,140 ℃时氢氧化铝凝胶或无定形粉体的析出已大部分完成,温度升高到180 ℃后,产物的结晶度变好,堆密度从117.2 kg•m－3相应增加到158.2 kg•m－3,比表面也从75.3 m2•g－1增加到88.3 m2•g－1,但平均粒径有所下降.晶体前驱体在550 ℃焙烧2 h后完全转化为形貌相似并且比表面增加的γ-Al2O3.     

动力学因素对热诱导相分离法制备亲水性乙烯-丙烯酸共聚物微孔膜结构的影响

选择 3种不同丙烯酸含量的乙烯 丙烯酸共聚物 (EAA)为原材料 ,二苯醚 (DPE)为稀释剂 ,研究了淬冷温度、粗化时间等影响液滴生长的动力学因素对热诱导相分离法 (TIPS)制备EAA DPE亲水性高分子微孔膜结构的影响 .淬冷温度的高低决定了EAA DPE体系是发生液 液相分离还是固 液相分离 ,而产生相分离的机理不同将影响稀释剂液滴的生长 ,最终影响微孔膜的孔径 .实验结果表明 ,在相同粗化时间的条件下 ,随着EAA1 41 0 DPE、EAA3 0 0 2 DPE、EAA3 0 0 3 DPE三体系冷却温度的逐渐升高 ,孔径逐渐变大 .在结晶温度以下 ( 0℃、3 0℃、60℃ )粗化时间相同时 ,温度对微孔膜的孔径影响较小 ,例如 0℃和 3 0℃的恒温条件粗化 1 0min,微孔膜的孔径在 1～ 3 μm之间 ;在 60℃的恒温条件粗化 1 0min ,微孔膜的孔径在 3～ 5 μm之间 .而在 90℃的恒温条件粗化相同的时间 ,由于体系始终处于结晶温度线以上 ,体系始终处在液 液相分离区域 ,最终得到微孔膜的孔径达到了 6～8μm .在结晶温度以下 ( 3 0℃ )进行恒温粗化 ,由于体系的过冷程度很大 ,液滴相的粗化过程被抑制住 ,所以粗化时间对微孔膜的孔径影响不大 ;而在结晶温度以上 ( 90℃ )进行恒温粗化时 ,则是随着粗化时间的延长 ,微孔膜的孔径逐渐变大     

纳米片组装的Zn_2SnO_4空心八面体分级结构的制备与发光性能(英文)

以乙酸锌、四氯化锡、氢氧化钠为原料,在200℃用L-赖氨酸辅助合成纳米片组装的锡酸锌(Zn2SnO4)空心八面体分级结构。采用XRD、FESEM、TEM、HRTEM等对样品进行了表征,结果表明产物为立方相的Zn2SnO4,单个八面体的棱长在1～2μm,并且表面以及棱上长有许多尺寸在200～400nm的纳米片。此外,结果还表明,氢氧化钠和L-赖氨酸的加入量对八面体形状的形成起到了决定性的作用。产物的室温光致发光谱图说明所制备的产物在500～600nm有很强的发光性能。