上转换纳米粒子的Y(OH)CO3壳层包覆及壳层转化

Along with the promising applications of lanthanide doped upconversion nanomaterials in diverse fields such as biology, anti-counterfeiting, and lasering, the demand for multifunctional upconversion nanomaterials is increasing. One effective means of obtaining these nanomaterials is to fabricate upconversion nanomaterial-based heterostructures, which may provide superior properties as compared to the sum of the parts. However, obtaining heterostructured upconversion nanomaterials remains challenging mainly because of the crystal lattice mismatch between upconversion nanomaterials and other materials. Typically used strategies for synthesizing upconversion nanomaterial-based heterostructures are applicable only to limited types of materials. Alternatively, transformation of the intermediate layer is a promising strategy used to obtain these heterostructures. Nevertheless, this method remains in its infancy and, to date, only a few intermediate layers have been developed. New types of intermediate layers are therefore highly desirable. In this study, we show that amorphous Y(OH)CO₃ can be a promising candidate as an intermediate layer for fabricating upconversion nanoparticle-based heterostructures. As a proof-of-concept experiment, ligand-free NaGdF₄:Yb/Tm upconversion nanoparticles were first prepared as core nanoparticles. The Y(OH)CO₃ shell was then directly coated on the NaGdF₄:Yb/Tm upconversion nanoparticles in an aqueous solution using urea and Y(NO₃)₃, by a homogeneous precipitation approach. The thickness of the resulting Y(OH)CO₃ shell could be tuned by adjusting the amounts of either urea or Y(NO₃)₃. The as-coated Y(OH)CO₃ shell could be easily converted to YOF by heating at 300 ℃, yielding NaGdF₄:Yb/Tm@YOF core-shell heterostructured nanoparticles. In addition, we found that the NaGdF₄ core could be transformed to lanthanide oxide fluoride if the NaGdF₄:Yb/Tm@Y(OH)CO₃ core-shell nanoparticles were heated at 350 ℃. We also observed that treating the NaGdF₄:Yb/Tm@Y(OH)CO₃ core-shell nanoparticles at even higher temperatures (e.g., 400 ℃) produced aggregations of nanoparticles without regular morphologies. The transformation of the shell can be attributed to the decomposition of Y(OH)CO₃ and reactions between the Y(OH)CO₃ shell and NaGdF₄ core. Meanwhile, the transformation of the NaGdF₄ core at relatively high temperatures could be primarily due to the reactions between Y(OH)CO₃ and NaGdF₄. Notably, in this study, the core-shell structured nanoparticles, with either a Y(OH)CO₃ or YOF shell, maintained the photon upconversion properties of NaGdF₄:Yb/Tm upconversion nanoparticles. In addition, the method used here could be extended to the coating of other shells such as Tb(OH)CO₃ and Yb(OH)CO₃ on upconversion nanoparticles. Moreover, the NaGdF₄:Yb/Tm@Y(OH)CO₃ core-shell nanoparticles could be transformed to other nanoparticles with novel structures such as yolk-shell nanoparticles. These results can pave the way for preparing upconversion nanoparticle-based heterostructures and multifunctional composites, thus promoting new applications of upconversion nanoparticles.     

三核铁苯甲酸配合物[Fe3O(OBz)6(CH3OH)3](NO3)(CH3OH)2的电子光谱及其理论分析

测定了三核苯甲酸铁配合物[Fe₃O(OBz)₆(CH₃OH)₃](NO₃)(CH₃OH)₂(OBz^-=苯甲酸根)的电子光谱,应用配体场理论和T-S图求得配体场参数10Dq=12457cm^-1.用CNDO/2方法对其简化模型进行了计算。     

负载型Sn2(OMe)4/SiO2催化剂的制备及其催化CO2和CH3OH直接合成碳酸二甲酯的性能

 采用表面改性法制备了负载型Sn2（OMe）4／SiO2双核桥联配合物催化剂，用IR，TPD和微反技术对催化剂的表面结构、化学吸附性质和催化活性进行了研究．结果表明，双核桥联Sn2（OMe）4／SiO2配合物中存在Sn－O－Si双齿配位形式，甲氧基以桥基形式联结两个Sn4＋离子；CO2在催化剂表面以桥式吸附态和甲氧碳酸酯基吸附态存在，而CH3OH只以分子吸附态存在．在反应温度413K，压力0．5MPa，反应空速1500h－1以及CH3OH与CO2的摩尔比为2～2．5的反应条件下，CO2和CH3OH在Sn2（OMe）4／SiO2催化剂上生成碳酸二甲酯的选择性达到近100％．根据实验结果，提出了CO2与CH3OH在Sn2（OMe）4／SiO2催化剂表面上的反应机理，反应物分子共吸附于催化剂表面同一活性位上及CO2的甲氧碳酸酯基吸附态的形成是反应顺利进行的关键因素．     

Ni2(OCH3)2/SiO2催化剂上CO2和CH3 OH的吸附和反应性能

采用表面改性和离子交换相结合的方法制备了Ni2(OCH3)2/SiO2负载型双核金属甲氧基配合物催化剂,利用红外光谱(IR)、程序升温脱附(TPD)、程序升温表面反应(TPSR)和微反技术考察了催化剂的表面结构以及CO2和CH3OH的化学吸附和反应性能.结果表明:Ni2(OCH3)2/SiO2中Ni2+与载体SiO2表面O2-以双齿配位形式键合,甲氧基以桥基形式联结双金属离子形成双核物种Ni2(OCH3)2;CO2在催化剂表面存在甲氧碳酸酯基物种和桥式两种吸附态,CH3OH则只有一种分子吸附态;在100～200℃条件下,CO2和CH3OH在催化剂上的反应产物主要是DMC和H2O;根据反应结果,讨论了催化反应机理.     

三核锰配合物[Mn3O(O2CCH=CHCH3)6(py)3]ClO4·py的合成,晶体结构及磁性

The reaction of N-n-Bu4MnO4 with Mn(Oac) 2 · 4H2O and butenoic acid in nonaqueous solvents leads to the formation of the complex [Mn3O(O2CCH = CHCH3) 6(py) 3] ClO4 · py (1). The crystal structure was determined.The complex crystallizes in hexagonal, space group P63/m, unit cell parameters, a = 1. 2456(1)nm, b = 1. 2456(1) nm, c = 1. 8741(1) nm, V=2. 5181(3) nm3, Z =2, and final R1 =0. 0565, wR2 =0. 1465. Variable tem-perature solid tate magnetic susceptibility study shows that the complex [Mn3O(O2CCH = CHCH3)6(py)3] ClO4 (2) has an antiferromagnetic exchange interaction.     

稀土纳米复合氧化物RE_2O_3∶Eu(RE=Y,Gd)的制备及特性

以甘氨酸辅助的燃烧法和非晶态稀土DTPA配合物前驱体热分解法制备了Y2 O3 ∶Eu和Gd2 O3 ∶Eu纳米材料。X射线衍射表明燃烧法和配合物前驱体热分解法制备的纳米Y2 O3 ∶Eu均为立方相 ,而Gd2 O3 ∶Eu纳米材料则随制备条件不同可得到立方相或单斜相两种产物 ,发射光谱证实了这一结论。通过透射电子显微镜、扫描电子显微镜对不同方法制备的纳米材料的尺寸、形貌也进行了表征     

乳液聚合法制备P(St/BA)-KAl(OH)2CO3纳米复合物

利用乳液聚合法制备了一种含KAl(OH)2CO3纳米粒子的聚苯乙烯／丙烯酸丁酯复合物．Zeta电位、粒径分布、扫描电镜(SEM)和透射电镜(TEM)等分析表明KAl(OH)2CO3粒子能够稳定地分散于苯丙乳液的乳胶粒中,形成核一壳结构．热失重(TG)分析表明KAl(OH)2CO3粒子的加入能提高复合物的热稳定性,使其在阻燃涂料领域有着潜在的应用前景．     

不同阳离子Y分子筛上金属络合物吸附和分解Ⅰ.Co(CO)3NO吸附性质表征

Ｃｏ（ＣＯ）３ＮＯ吸附进入Ｙ分子筛超笼，笼中不同交换阳离子对其吸附和分解起不同作用。研究不同交换阳离子Ｙ分子筛上Ｃｏ（ＣＯ）３ＮＯ的吸附和热分解发现，吸附金属络合物部分脱羰基或脱亚硝基，并伴有少量吸附物种的脱附。ＮａＹ上的热分解产物主要为金属钴；ＮｉＹ，尤其是ＣｕＹ上，阳离子和吸附物种作用较强，甚至发生电子转移，热分解产物为Ｃｏ（０）和Ｃｏ（Ⅱ）混合物。     

三核锰配合物[Mn_3O(O_2CCH=CHCH_3)_6(py)_3]ClO_4·py的合成,晶体结构及磁性(英文)

0 Introduction Molecular-based magnetic materials have attractedmuch attention in designing and synthesizing a newclass of magnetic clusters with high spin ground stateand high critical temperature. The synthesis andmagnetic properties of oxo-centered trinuclear man-ganese complexes have been a focus of intense research     

配合物Ni(Pybox) (SCN)2(CH3OH)的合成、表征与晶体结构

本文合成了含N原子的三齿配体2,6-吡啶二噁唑啉(Pybox),由Pybox与NiCl2·6H2O和KSCN在甲醇溶液中反应制得标题配合物Ni(Pybox)(SCN)2(CH3OH),并进行了元素分析、红外光谱、电子光谱、X-射线衍射等表征.结果表明:此配合物属单斜晶系,空间群为P2(1)/n,晶体学参数为:a=7.9...     

球型Ni(OH)2表面包覆Y(OH)3及其高温充放电性能

应用共沉淀的方法在球型Ni(OH)₂的表面包覆了一层Y(OH)₃,并研究了包覆不同含钇量后的球型Ni(OH)₂的高温充放电性能。研究结果表明:包覆Y(OH)₃的球型Ni(OH)₂具有良好的高温充放电性能。其中1C充放电条件下,包覆量为0.3%的Ni(OH)₂较好,0.2C充放电条件下,包覆量为1%的Ni(OH)₂较好。     

La1-x-yBaxREyMnO3(RE:Dy,Y)超细粒子的制备和其对CH4燃烧的催化性能

使用Na2CO3·10H2O和NaOH为沉淀剂,采用共沉淀法制备了钙钛矿型结构的La1-x-yBaxREyMnO3 (RE=Dy,Y)超细粒子,具有较大的比表面积(经700,1000 ℃ 2 h 分别焙烧后,其比表面积能达到47和16.9 m2*g-1;颗粒尺寸为17和68 nm).该超细粒子随LaMnO3中A位的La3 被Ba2 及稀土元素(Dy3 ,Y3 )部分取代后,显示出良好的热稳定性及对CH4完全燃烧的高活性.     

嵌入(或载在)Y型分子筛上Pd粒子的XPS研究

1前言早在70年代末80年代初，就有文献报道在载体上的金属Pd的某些性能，并注意到将其作为催化剂在甲醇合成上有很高的活性和选择性[1~3]，然而并没有继续进行系统研究．80年代末，Sachtler等人开始在这一领域进行更广泛、更细致、更深入的研究[4~8]．他们不仅研究了载在分子筛上的Pd，也研究了Pd与其他过渡金属所形成的合金的性能．它们的催化性质研究包括对CO加氢、新戊烷和氢解和异构化以及甲基环戊烷的开环和扩环反应[4~9]．对Pd的其他性质的研究，还包括采用TPR、TPD、TPO和TPMS等技术，分析了Pd或其合金等金属原子在NaY分子…     

Observation of Confinement-Free Neutral Group Three Transition Metal Carbonyls Sc(CO)7 and TM(CO)8 (TM=Y,La)

Spectroscopic characterization of neutral highly-coordinated compounds is essential in fundamental and applied research, but has been proven to be a challenging experimental target because of the difficulty in mass selection. Here, we report the preparation and size-specific infrared-vacuum ultraviolet (IR-VUV) spectroscopic identification of group-3 transition metal carbonyls Sc(CO)₇ and TM(CO)₈ (TM=Y, La) in the gas phase, which are the first confinement-free neutral heptacarbonyl and octacarbonyl complexes. The results indicate that Sc(CO)₇ has a C_2v structure and TM(CO)₈ (TM=Y, La) have a D_4h structure. Theoretical calculations predict that the formation of Sc(CO)₇ and TM(CO)₈ (TM=Y, La) is both thermodynamically exothermic and kinetically facile in the gas phase. These highly-coordinated carbonyls are 17-electron complexes when only those valence electrons that occupy metal−CO bonding orbitals are considered, in which the ligand-only 4b_1u molecular orbital is ignored. This work opens new avenues toward the design and chemical control of a large variety of compounds with unique structures and properties.     

包覆Y(OH)3的球形Ni(OH)2的电化学性能

利用软嵌式粉末电极技术研究了Y(OH)3包覆对球形Ni(OH)2电化学性能的影响. 循环伏安结果表明, 在球形Ni(OH)2的氧化过程中存在Ni(Ⅲ)和Ni(Ⅳ)的两步氧化反应, 产生的Ni(Ⅳ)不稳定, 能分解产生NiOOH和氧气, 所以可将Ni(Ⅲ)→Ni(Ⅳ)看作副反应. Y(OH)3包覆层对Ni(OH)2氧化过程后期的副反应, 特别是Ni(Ⅲ)→Ni(Ⅳ)具有较好的抑制作用. 由包覆后的Ni(OH)2制成的模拟电池表现出很好的高温性能, 在1C充放电条件下, 当Y的摩尔分数为1.61%时, 在60 ℃时所对应的容量保持率可达到25 ℃的92.7％; 当Y的摩尔分数仅为0.55 %时, 在60 ℃时所对应的质量比容量也可达到241.3 mA·h/g.     

A comparative computational study of FKrCCH...Y, FCCKrH...Y, and FCCH...Y complexes (Y = BF, CO, N2, OH2, OH(CH3), O(CH3)2)

The structural and spectroscopic changes in complexes of FCCKrH...Y and FKrCCH...Y (Y = BF, CO, N(2), OH(2), OH(CH(3)), O(CH(3))(2)) were computed at the MP2∕6-31++G(d,p) level of theory and compared with the corresponding properties for FCCH...Y. The computed bond length changes and frequency shifts on complexation were rationalized by comparing with a perturbation model, which gives quantitative agreement with the standard ab initio results. A recently proposed model also gives a reasonable qualitative account of the observed trends in these complexes.     

碳酸镉@二氧化硅菱形体核壳结构以及二氧化硅菱形体空心结构微粒的制备

利用Stöber种子生长法, 第一次在尺寸为2 μm左右的碳酸镉菱形微粒表面直接包覆二氧化硅层, 得到碳酸镉@二氧化硅核壳结构的胶体粒子. 作为核壳结构的壳层部分, 二氧化硅层的厚度可以通过加入体系中的正硅酸乙酯的量来控制. 作为核层的碳酸镉胶体部分可以被盐酸刻蚀掉, 进而得到具有菱形体空心结构的二氧化硅微粒.