绿色荧光体CaSe2O4:Ce3+的共沉淀合成与表征

以草酸为沉淀剂,用共沉淀法合成前驱体粉末,然后将前驱体粉末在5%H2+95%N2的还原气氛下煅烧,得到发光性能良好的CaSe2O4:Ce3+荧光粉.应用X射线粉末衍射(XRD)、荧光光谱(FS)、综合热分析(TC-DSC)和扫描电镜(SEM)等测试手段对前驱物及煅烧后的粉体进行表征.结果表明:烧结温度于800℃以上时,都町以得到正交结构的纯相CaSc2O4:Ce3+荧光体;其最大激发和发射波长分别在450和510 nm,与高温固相法所得产品的发射波长相同.荧光粉优化的合成条件为:Ce3+的最件掺杂浓度为1%(摩尔分数),最佳煅烧条件为1100℃煅烧6 h.最佳煅烧温度较传统的高温固相法(1600℃)低了约500℃,所得产品的发光强度接近高温固相法的产品.     

喷雾-胶凝法制备超细莫来石粉末

以水玻璃和硝酸铝为原料 ,通过喷雾 -胶凝法和共沸蒸馏技术制备莫来石前驱粉体 ,然后煅烧得到超细莫来石粉末 .用TG -DTA、XRD、TEM及BET研究了莫来石前驱粉体在煅烧过程中的热学性质、物相与比表面变化及颗粒大小与形貌变化 ,并对所制得的莫来石粉进行了表征 .结果表明 ,莫来石前驱粉体经 130 0℃煅烧 1h可制得粒径为 2 5nm～ 4 0nm ,比表面积为 4 2 5m2 /g的莫来石超细粉 ;煅烧过程中的物相变化次序为 :勃姆石 +非晶态SiO2 →非晶态Al2 O3 +非晶态SiO2 →γ -Al2 O3 +非晶态SiO2 → 3Al2 O3 ·2SiO2 .     

碳包覆CaSnO3纳米纤维作为高性能锂离子电池负极材料

采用静电纺丝技术制备出CaSnO3纳米纤维(CaSnO3 NFs)并作为模板,再经表面原位聚合酚醛树脂和碳化处理制得碳包覆CaSnO3纳米纤维(CaSnO3@C NFs)。使用X射线衍射、扫描电子显微镜、透射电子显微镜和X射线光电子能谱对材料的物相组成、形貌和微观结构进行了表征,通过循环伏安、恒电流充放电和交流阻抗谱研究了碳包覆及碳化温度对CaSnO3 NFs负极材料电化学性能的影响。结果显示,碳包覆改性使CaSnO3 NFs的电化学性能得到较大程度的提高,而且随着碳化温度的升高,CaSnO3@C NFs复合电极的比容量先增加后下降,600℃碳化获得的CaSnO3@C NFs?600复合材料具有最好的电化学性能。在0.1 A·g^-1的电流密度下,CaSnO3@C NFs?600电极的首圈放电比容量达到1102.2 mAh·g^-1,充放电循环100圈后比容量为548.8 mAh·g^-1,当电流密度提高到2 A·g^-1时,其比容量仍保持在333.5 mAh·g^-1。     

无机溶胶凝胶法制取Y2O3纳米微粒

以廉价无机盐为原料，采用溶胶凝胶法制备出尺度均匀，一次颗粒尺寸平均为60nm，颗粒呈球形的高纯Y2O3，纳米微粒。研究发现适量SO4^2-离子的添加对生成前驱物溶胶及煅烧得到球形的Y2O3纳米微粒起关键作用。对前驱物在煅烧过程中的物相变化进行了研究，分析了煅烧温度对产物粒度和纯度的影响，结果表明在不使生成物颗粒过分长大的前提下，升高煅烧温度有助于制取高纯和晶化完全的Y2O3微粉。     

聚合物前驱体方法低温合成LiTaO3纳米粉体

采用聚合物前驱体方法,以柠檬酸为配位剂,乙二醇为酯化剂,低温合成纳米LiTaO3粉体.以红外光谱和拉曼光谱研究了柠檬酸与金属离子的配位情况.当柠檬酸和金属离子物质的量的比为2.5:1、柠檬酸和乙二醇的物质的量比为1:2时可形成稳定的Li-Ta前驱体溶胶.用差热.热重对凝胶前驱体的热分解历程进行分析,采用X射线衍射和红外光谱对Li-Ta凝胶前驱体及不同温度下煅烧所得粉体的相组成进行分析.结果表明,凝胶前驱体经600℃下煅烧2 h可以得到纯钙钛矿型纳米LiTaO3粉体.平均粒径为60～80 nm.     

CMC辅助纳米ZnO粒子的制备及表征

以离子型纤维素醚羧甲基纤维素(CMC)的水溶液为反应介质,制备[Zn4CO3(OH)6]CMC水凝胶,洗涤、干燥后经不同温度煅烧前驱物得到ZnO纳米粒子。通过XRD、SEM、TEM、TG-DSC及FT-IR等测试技术对产物的组成、粒径及形态进行表征,研究了CMC对前驱物及ZnO形态和尺寸的影响。结果表明,由于CMC加入对煅烧前驱物产生的空间位阻作用,所制得纳米ZnO粒子粒度分布均匀、分散性好、不易团聚、粒子的平均粒径<20 nm。利用UV-V is测试了纳米ZnO的光吸收性能,所得的纳米ZnO在200~400 nm具有较强的吸收性。     

静电纺丝法制备Mn2O3纳米纤维及其磁性研究

采用溶胶-凝胶过程和静电纺丝技术相结合方法, 以聚丙烯腈和醋酸锰为前驱物, 制得了PAN/Mn(CH₃COO)₂复合纳米纤维. 将该复合纤维高温煅烧, 获得了Mn₂O₃纳米纤维. 采用扫描电镜(SEM)、红外光谱(FTIR)、差热-热重(TG-DTA)和X射线衍射(XRD)分析等对样品进行了表征. 结果表明, Mn₂O₃纳米纤维为规则的一维结构, 直径分布均匀, 具有铁磁性-反铁磁性-顺磁性相互转化的特性.     

炭黑吸附法制备掺杂镨TiO2纳米粉体及其光催化性能

以硝酸镨为掺杂的前驱物,钛酸异丙酯为TiO2的前驱物,通过炭黑吸附高温水热法制得掺杂镨的量为0.07%的纳米Pr3+/TiO2粉体。分别采用热重/差热分析(TG-DTA)、X射线衍射(XRD)、扫描电镜(SEM)、紫外可见分析(UV-VIS)和比表面积吸附(BET)对不同焙烧温度下所得粉体的物相、颗粒度、分散性及光吸收性能进行表征和分析。实验结果表明:炭黑的吸附阻止了粉体在干燥和煅烧阶段的团聚和烧结,制得的Pr3+/TiO2纳米粉体团聚较少,呈现良好的分散性,颗粒均匀,经500℃焙烧,得到纳米粉体平均颗粒直径为18 nm,比表面积为78.08 g.m-2。光催化降解实验表明,炭黑吸附后TiO2的光催化活性在一定时间内比没有炭黑的提高了将近2倍,在紫外灯照射下Pr3+/TiO2能在60 min内对亚甲基蓝的降解率达到93%。     

β-MnO_2和α-Mn_2O_3纳米棒的自牺牲模板法制备、表征和应用

在150℃下,仅以高锰酸钾溶液和无水乙醇为原料,通过水热反应合成前驱体γ-Mn OOH纳米棒.以γ-Mn OOH纳米棒为自牺牲模板,分别在350和600℃下煅烧90 min,制备出高纯度的β-Mn O2和α-Mn2O3纳米棒.采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)及热重分析(TGA)等对所制备的样品进行表征.结果表明,前驱物γ-Mn OOH为高纯度的纳米棒状晶体,直径约100~300 nm,长度可达数微米,且终产物β-Mn O2和α-Mn2O3均具有较高的纯度,也很好地保持了前驱物的纳米棒状结构.以二者为锰源,通过固相反应合成出尖晶石Li Mn2O4正极材料.当充放电倍率为0.5 C时,其首次放电比容量分别可达到120.4和123.9 m A·h/g,而且表现出良好的循环性能和倍率性能.     

三维多孔锌钨氧化物异质结的制备、组分调控与光催化性能

采用真空冷冻干燥技术, 通过调控前驱体溶液的组成, 实现了锌钨氧化物异质结材料的可控制备. 前驱物中高分子的引入使煅烧后的氧化物材料很好地保持了三维连通的多孔结构. 光催化实验结果表明, 获得的系列材料均能够实现对罗丹明B的脱色降解, 并表现出组分依赖的光催化活性. 氧化锌/钨酸锌三维多孔异质结材料相比于其它样品具有更高的光催化活性, 可在180 min内将罗丹明B完全脱色.     

微纳米钙钛矿型羟基锡酸钙的合成及对环氧树脂的阻燃性能

钙钛矿型羟基锡酸盐是近年来出现的新型高效阻燃消烟剂. 本文采用化学共沉淀法合成了微纳米钙钛矿型羟基锡酸钙[CaSn(OH)₆, CSH], 并利用扫描电子显微镜、 透射电子显微镜、 X射线衍射仪、 红外光谱仪和X射线光电子能谱仪等对其形貌和结构进行表征. 结果表明合成的CaSn(OH)₆为平均粒径500 nm的纯净正六面体, 粒径均一且分散性良好. 将CaSn(OH)₆应用于环氧树脂(EP)复合阻燃体系(CSH/EP), 并分别采用热重分析、 极限氧指数和锥形量热测试表征了其热降解行为和燃烧性能. 采用扫描电子显微镜、 红外光谱、 X射线衍射和拉曼光谱对EP复合材料的阻燃成炭机制进行探索. 结果表明, CaSn(OH)₆能显著提高EP复合材料的高温稳定性、 热释放速率、 热释放量、 烟释放量和极限氧指数数值. 特别是在很低添加量(0.5%, 质量分数)下, 阻燃消烟性能即得到极大提升, 热释放速率、 总放热量和一氧化碳释放量分别降低45.8%, 25.1%和31.3%. 此外, 由于CaSn(OH)₆在EP基体中的良好分散及较强的界面作用, CaSn(OH)₆在提升EP复合材料阻燃消烟性的同时还提升了EP复合材料的力学强度. 本文合成的CaSn(OH)₆可作为一种多功能的高效阻燃、 消烟和增强剂.     

光促进温和条件下烯烃与二氧化碳的羰基化反应

羰基化反应是有机合成化学中常用的方法之一,但常规的羰基化反应大多要求高温(150～200℃)、高压(10～20 M Pa)或使用贵金属催化剂(如钌、铑、铱等),并且C₁源多用一氧化碳^[1].开发和利用CO₂这一丰富的C₁资源,并最大限度地降低其排放量具有挑战意义.但CO₂活化比较困难,在通常条件下难以转化成其它化学品^[2].在光促进下的羰基化反应可克服上述困难,使反应在温和条件及非贵金属催化下完成,同时可用CO₂代替CO作为C₁源,因此这是一个对环境友好的工艺^[3].本文报道烯烃在光促进常温常压和非贵金属钴配合物催化下与二氧化碳的羰基化反应,同时通过¹³CO₂和¹³CH₃OH同位素实验,对反应产物的结构进行了分析.     

Water-soluble hydroxyalkylated phosphines: examples of their differing behaviour toward ruthenium and rhodium

The reaction of P(CH2OH)3 (I) and P(C6H5)(CH2OH)2 (II) with RuCl3 in methanol eliminates two equivalents of formaldehyde to yield the mixed tertiary and secondary phosphine complexes all-trans-[RuCl2(P(CH2OH)3)2(P(CH2OH)2H)2] (1) and [RuCl2(P(C6H5)(CH2OH)2)2(P(C6H5)(CH2OH)H)2] (2), respectively. There is a high degree of hydrogen-bonding interactions between the hydroxymethyl groups in 1 and 2, although the phenyl groups of the latter reduce the extent of the network compared to 1. The generation of these mixed secondary and tertiary phosphine complexes is unprecedented. Under the same reaction conditions, the tris(hydroxypropyl)phosphine III formed no ruthenium complex. The reaction of P(CH2OH)3, P(C6H5)(CH2OH)2 and P{(CH2)3OH}3 with [RhCl(1,5-cod)]2 in an aqueous/dichloromethane biphasic medium yielded [RhH2(P(CH2OH)3)4]+ (3), [RhH2(P(C6H5)(CH2OH)2)4]+ (4) and [Rh(P(C6H5)(CH2OH)2)4]+ (5) and [Rh(P{(CH2)3OH}3)4]+ (6), respectively. Treating 5 with dihydrogen rapidly gave 4. The hydroxypropyl compound 6 formed the corresponding dihydride much more slowly in aqueous solution, although [RhH2(P{(CH2)3OH}3)4]+ (7) was readily formed by reaction with dihydrogen. Two separate reaction pathways are therefore involved; for P(CH2OH)3 and to a lesser extent P(C6H5)(CH2OH)2, the hydride source in the product is likely to be the aqueous solvent or the hydroxyl protons, whilst for P{(CH2)3OH}3 an oxidative addition of H2 is favoured. The protic nature of and was illustrated by the H-D exchange observed in d2-water. Dihydrides 3 and 4 reacted with carbon monoxide to yield the dicarbonyl cations [Rh(CO)2(P(CH2OH)3)3]+ (8) and [Rh(CO)2(P(C6H5)(CH2OH)2)3]+ (9). The analogous experiment with [RhH2(P{(CH2)3OH}3)4]+ resulted in phosphine exchange, although our experimental evidence points to the possibility of more than one fluxional process in solution.     

Low-energy paths for the unimolecular decomposition of CH3OH: a G2M/statistical theory study

The potential energy surface (PES) of the CH3OH system has been characterized by ab initio molecular orbital theory calculations at the G2M level of theory. The mechanisms for the decomposition of CH3OH and the related bimolecular reactions, CH3 + OH and 1CH2 + H2O, have been elucidated. The rate constants for these processes have been calculated using variational RRKM theory and compared with available experimental data. The total decomposition rate constants of CH3OH at the high- and low-pressure limits can be represented by k infinity = 1.56 x 10(16) exp(-44,310/T) s-1 and kAr0 = 1.60 x 10(36) T-12.2 exp(-48,140/T) cm3 molecule-1 s-1, respectively, covering the temperature range 1000-3000 K, in reasonable agreement with the experimental values. Our results indicate that the product branching ratios are strongly pressure dependent, with the production of CH3 + OH and 1CH2 + H2O dominant under high (P > 10(3) Torr) and low (P < 1 atm) pressures, respectively. For the bimolecular reaction of CH3 and OH, the total rate constant and the yields of 1CH2 + H2O and H2 + HCOH at lower pressures (P < 5 Torr) could be reasonably accounted for by the theory. For the reaction of 1CH2 with H2O, both the yield of CH3 + OH and the total rate constant could also be satisfactorily predicted theoretically. The production of 3CH2 + H2O by the singlet to triplet surface crossing, predicted to occur at 4.3 kcal mol-1 above the H2C...OH2 van der Waals complex (which lies 82.7 kcal mol-1 above CH3OH), was neglected in our calculations.     

Reactions of Laser Ablation-magnesium Plasma with Methanol Clusters

IntroductionReactions of metal ions with neutral molecules orclusters produce a variety of metal complex ions andother new series of cluster ions including cations andanions.The laser ablation-molecular beam(LA-MB)method has marked its relevance in the st…     

Experimental and computational investigation of gas-phase reaction of chlorine with n-propanol: observation of chloropropanol conformational isomerization at room temperature

FTIR smog chamber techniques were used to measure k(Cl+n-C3H7OH) = (1.74 +/- 0.15) x 10-10 and k(Cl+CH2ClCH2CH2OH) = (7.54 +/- 0.73) x 10-11 cm3 molecule-1 s-1 in 700 Torr of N2 at 296 K. The reaction of Cl with n-C3H7OH gives CH3CH2CHOH, CH3CHCH2OH, and CH2CH2CH2OH radicals in yields of 60 +/- 5, 25 +/- 8, and 15 +/- 3%, respectively. Neither CH3CH2CHClOH nor CH3CHClCH2OH is available commercially, and infrared spectra for the three chlorides CH3CH2CHClOH, CH3CHClCH2OH, and CH2ClCH2CH2OH were calibrated experimentally. MP2/6-31G(d,p) calculations were used to corroborate the experimental vibrational assignments. Analysis reveals that each geometric isomer possesses several structurally and spectroscopically distinct conformers arising from intramolecular hydrogen bonding and, in the case of CH3CH2CHClOH, negative hyperconjugation. These conformers interchange slowly enough to be distinguished within the room-temperature vibrational spectrum. The experimentally observed vibrational spectra are well described by a Boltzmann-weighted superposition of the conformer spectra. As is typical of alpha-halogenated alcohols, CH3CH2CHClOH readily decomposes heterogeneously to propanal and HCl.     

光促进下环己烯与二氧化碳羰基化反应中副产物的气相色谱-质谱分析

应用气相色谱-质谱法（GC-MS）研究了光促进温和条件下环己烯与CO2羰基化反应中与丙酮有关的副产物,这有助于对反应进行深入的研究和优化。在光促进温和条件下环己烯与CO2进行羰基化反应的同时,环己烯也可以与反应体系中的CH3COCH3发生光化学反应,生成副产物。分别用CH3COCH3和CD3COCD3进行实验,对反应产物进行GC-MS分析,通过对不同反应情况下的MS图中同位素效应的比较,可以分析出副产物中是否有来自CH3COCH3中的—CH3。研究表明丙酮与底物环己烯之间生成了环氧丁烷衍生物、cyclo-C6H9-C(CH3)2OH和cyclo-C6H11-C(CH3)2OH等3种副产物。     

芳香叔胺引发丙烯腈光聚合的引发机理

芳香叔胺引发丙烯腈(AN)光聚合是通过形成激基复合物(exciPlex)进行的。紫外光谱和荧光光谱表明,芳香叔胺在基态可以和AN形成电荷转移复合物(CTC),而在激发态可和AN形成exciplc(称定域激发)。CTC经光照亦可激发(称CTC激发)。 定域激发引起光聚合速率为CH_3C_6H_4N(CH_3)_2>C_6H_5N(CH_3)_2>HOCH_2·C_6H_4N(CH_3)_2>CH_3C_6H_4N(CH_2CH_2OH)_2,与芳胺荧光被AN淬灭的Stern-Vo-lmer常数顺序一致。CTC激发引起的光聚合顺序为:CH_3C_6H_4N(CH_3)_2>CH_3C_6H_4N(CH_2CH_2OH)_2>HOCH_2C_6H_4N(CH_3)_2>C_6H_5N(CH_3)_2,与芳胺上取代基推电子能力一致。端基分析表明聚合物有芳胺端基。     

Synthesis of ruthenium(II) complexes containing hydroxymethylphosphines and their catalytic activities for hydrogenation of supercritical carbon dioxide

Ligand substitution of RuCl2[P(C6H5)3]3 and Cp*RuCl(isoprene) (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) complexes with hydroxymethylphosphines was investigated to develop new catalyst systems for CO2 hydrogenation. A reaction of P(C6H5)2CH2OH with RuCl2[P(C6H5)3]3 in CH2Cl2 gave Ru(H)Cl(CO)[P(C6H5)2CH2OH]3 (1), which was characterized by NMR spectroscopy and X-ray crystallographic analysis. An isotope labeling experiment using P(C6H5)213CH2OH indicated that the carbonyl moiety in complex 1 originated from formaldehyde formed by degradation of the hydroxymethylphosphine. Elimination of formaldehyde from PCy2CH2OH (Cy=cyclohexyl) was also promoted by treatment of RuCl2[P(C6H5)3]3 in ethanol to give RuCl2(PHCy2)4 under mild conditions. On the other hand, the substitution reaction using Cp*RuCl(isoprene) with the hydroxymethylphosphine ligands proceeded smoothly with formation of Cp*RuCl(L)2 [2a-2c; L=P(C6H5)2CH2OH, PCy(CH2OH)2, and P(CH2OH)3] in good yields. The isolable hydroxymethylphosphine complexes 1 and 2 efficiently catalyzed the hydrogenative amidation of supercritical carbon dioxide (scCO2) to N,N-dimethylformamide (DMF).     

Electron paramagnetic resonance structure investigation of copper complexation in a hemicarcerand

The double-bridged hemicarcerand [A,B-(CH2OH)2-cavitand]-(CH2NHCH2)2-[A,B-(CH2OH)2-cavitand] 23 (and several other related compounds) was synthesized by the condensation of the two complementary precursors A,B-(CH2NH2)2(CH2OH)2-cavitand and A,B-(CH2Br)2(CH2OAc)2-cavitand followed by hydrolysis of the acetate groups. This hemicarcerand has nitrogen and oxygen donor atoms located on the interior of the spherical cavity and thus allows endohedral coordination of metal ions. The cavity has a volume of approximately 0.12 nm3, a value obtained by calculating a Connolly-type contact surface and the molecular electrostatic potential. The Cu2+ complex of hemicarcerand 23 was studied in detail by EPR and DFT calculations at the UB3LYP/6-31G level to verify the anticipated endohedral nature of the metal complex. It could be shown that the copper ion is coordinated to four oxygen donor atoms and no deviation from axial symmetry at the copper site could be detected. No direct coordination to nitrogen atoms of the hemicarcerand could be observed; however, complexation with DMF solvent molecules was detected by ESEEM and HYSCORE experiments. The closed structure of the hemicarcerand was also confirmed by an evaluation of proton-copper distances. Results from DFT calculations are in accord with the EPR results, and further support suggested coordination of the Cu(II) within the hemicarcerand cavity by four oxygen donor atoms.