制备条件及添加稀土对SO_4~(2-)/ZrO_2-Al_2O_3固体超强酸酸性影响的研究

用共沉淀法制备了SO4 2 -/ZrO2 -Al2 O3 固体超强酸 ,并采用低温陈化和添加稀土La对其制备方法进行改进 .通过样品催化正丁烷异构化反应考察了该固体超强酸中nZr和nAl的最佳配比为 1∶2 .该法制备的样品的IR显示 ,在 1393cm-1处的吸收峰强度较常温陈化样品大大增加 .XRD分析表明 ,低温陈化和加入稀土添加剂的样品在6 5 0℃焙烧温度下 ,出现了亚稳态的ZrO2 四方晶相的晶体是表面酸性和催化活性增加的微观原因 .样品催化合成八乙酸蔗糖酯反应结果同样证明 ,在相同的时间内 ,低温陈化和添加稀土添加剂的样品具有较好的催化活性     

Optical Characterization of Eu3+ Ions in CdSe Nanocrystal Containing Silica Glass

Silica glass samples containing CdSe/Eu3+ ions were prepared by sol-gel route. Size distribution and optical band gap of the nanoparticles were calculated from absorption spectrum. It is observed that the presence of CdSe nanocrystallites enhances the fluorescence of europium in silica glass. The phonon sideband spectrum associated with the excitation transition 7F0-5D2 is used to analyze the electron-phonon coupling and nonradiative deexcitiation of the rare earth ions in the glass host, The observed fluorescence enhancement is discussed on the basis of phonon assisted energy transfer from electron-hole recombination of the CdSe nanocrystallites to the rare earth ion and multiphonon relaxation.     

制备条件及添加稀土对SO42- /ZrO2 -Al2O3固体超强酸酸性影响的研究

用共沉淀法制备了SO4^2-/ZrO2-Al2O3固体超强酸，并采用低温陈化和 添加稀土La对其制备方法进行改进，通过样品催化正丁烷异构化反应考察了该固体超强酸中nZr和nAl的最佳配比为1：2，该法制备的样品的IR显示，在1393cm^-1处的吸收峰强度较常温陈化样品大大增加，XRD分析表明，低温陈化和加入稀土添加剂的样品在650℃焙烧温度下，出现了亚稳态的ZrO2四方晶相的晶体是表面酸性和催化活性增加的微观原因，样品催化合成八乙酸蔗糖酯反应结果同样证明，在相同的时间内，低温陈化和添加稀土添加剂的样品具有较好的催化活性。     

稀土掺杂氧化物纳米发光材料研究

综述了稀土掺杂纳米发光材料方面的研究进展;主要介绍稀土掺杂氧化物纳米晶与体相材料相比所具有的一些特有的光谱学性质,包括光谱的移动与谱线的展宽、4fN电子的跃迁与弛豫过程、表面局域环境和格位对称性、电子-声子耦合、能量传递、浓度猝灭、温度猝灭以及光诱导发光强度变化等光谱现象,同时也探寻了其中的物理实质。主要对上转换纳米发光材料和一维纳米线/管的发光性质进行了介绍。     

Temperature of the Magnetic Ordering of the Trivalent Iron Oxide ε-Fe2O3

Physics of the Solid State - The trivalent iron oxide ε-Fe2O3 is a fairly rare polymorphic iron oxide modification, which only exists in the form of nanoparticles. This magnetically ordered...     

Fe3O4@SiO2@An磁性纳米荧光粒子的制备及对锌离子的识别

通过微乳法一步合成了SiO2包覆Fe3O4的磁性纳米颗粒(MNP)并通过硅烷偶联剂将表面氨基化,进一步通过化学成键将荧光分子蒽修饰到氨基化的纳米粒子表面,制得Fe3O4@SiO2@An磁性纳米荧光粒子.采用XRD、TEM、FTIR等实验方法对该粒子进行一系列的表征,其直径约为9nm,常温时具有超顺磁性,通过外加磁场,能够使粒子从溶液中简单有效地分离.该粒子在溶剂中具有较好的分散性,荧光实验表明,对锌离子具有较好的选择性,在锌离子存在下基于光诱导电子转移( PET,PhotoinducedElectron Transfer)机理,粒子荧光强度显著增强,检出限为2.8571×10-5mol/L.     

NaYF_4∶Yb,Er上转换荧光纳米颗粒的共沉淀法合成及表征

以二乙二胺五乙酸(DTPA)为络合剂,采用共沉淀法合成了单分散的NaYF_4:Yb,Er上转换荧光纳米颗粒.通过X射线衍射(XRD)、透射电子显微镜(TEM)、荧光(FL)光谱、热重-差示扫描量热分析(TG-DSC)对合成的样品进行了表征.所合成纳米颗粒的粒径均一,通过改变络合剂DTPA的用最可使颗粒的平均粒径在20～120 nm范围内可调.纳米颗粒经煅烧后发生了由立方品型向六方晶型的转变,并伴随着荧光强度的大幅提升.还探讨了络合剂DTPA的用量、煅烧温度对纳米颗粒粒径、晶型及荧光性能的影响.研究结果表明:络合剂DTPA的加入虽然在一定程度上阻碍纳米颗粒由立方晶型向六方晶型的转变,但可获得单分散的小粒径纳米颗粒,其荧光强度仍能满足生物标记的要求.     

Iron-carbon nanoparticles prepared by CO2 laser pyrolysis of toluene and iron pentacarbonyl

CO₂ laser induced co-pyrolysis of toluene and iron pentacarbonyl in the presence of an ethylene sensitizer was used to produce iron-carbon nanostructures containing cementite Fe₃C as the major component. The passivated Fe-C nanocomposites were characterized by several complementary analytical methods. Good agreement is found between the results of X-ray diffraction, Mössbauer spectroscopy and high-resolution transmission electron microscopy techniques which show that besides cementite, iron, and iron oxides, traces of other carbides are also present. Specific morphological aspects of the nanograins encased in a mostly disordered and quasi-amorphous carbon matrix are revealed. The simultaneous presence of rather small crystallites (mean diameter between 3–6 nm), identified as possible Fe₃C/α-Fe and iron oxide (maghemite/magnetite) phases and of single-phase larger crystallites (10–13 nm mean diameter), identified as Fe₃C is illustrated. Raman spectroscopy seems to confirm maghemite as the iron oxide phase present in the iron-carbon nanopowders. The level of oxidation mainly induced by powder passivation is roughly estimated by FTIR spectroscopy and leads to iron oxide contents between 11–17 wt.?%. The catalytic role of iron nanoparticles in the pyrolyzed system is addressed in connection with nanocarbon samples obtained in the absence of an iron donor.     

Effect of mechanical milling on the magnetic properties of garnets

Rare earth garnets after milling to nanosizes are found to decompose into rare earth orthoferrite and other rare earth and iron oxide phases. The magnetization for the yttrium iron garnet decreases in the nano state due to the formation of antiferromagnetic phases. But for the gadolinium iron garnet when milled up to 25 h, the room temperature magnetization increases despite the formation of antiferromagnetic and non-magnetic phases. This is attributed to the uncompensated moments of the sublattices because of the weakening of the superexchange interaction due to change in bond angles and the breaking of some superexchange bonds on account of the defects and oxygen vacancies introduced on milling. For the 10 h milled gadolinium iron garnet at 5 K, after correcting for the non-magnetic phases present, there is an increase in the magnetic moment of about 10% as compared to the value for the as-prepared garnet. The magnetic hyperfine fields corresponding to the various phases were measured using ⁵⁷Fe Mössbauer spectroscopy at 16 K. The isomer shift values indicate the loss of oxygen for the samples milled for larger duration.     

Energy-loss near-edge fine structures of iron nanoparticles

Body centered cubic (bcc) Fe nanoparticles were fabricated by in situ decomposition of iron fluoride films in a transmission electron microscope. Electron energy-loss near edge structure (ELNES) was used to characterize this exposure process. In particular, the L(3)/L(2) white-line intensity ratio (WLR) was used to monitor the iron valence state during exposure, and as an indicator of other properties of the iron nanoparticles. Iron nanoparticles with sizes between 2 and 20nm exhibit a constant WLR, whose value is same as that for a continuous bcc iron film, suggesting little or no dependence of the local magnetic moment or structure on the particle size. A broad but prominent peak which occurs 40eV after the L(3)-ionization threshold in the iron fluoride, is absent for a metallic iron film but reappears when the iron is converted to an oxide. Long-range ferromagnetic coupling was observed in samples densely populated with iron nanoparticles. Because there is little interaction between particles and the supporting carbon substrate, these samples provide an ideal model system for studying the influence of particle size and interparticle distance on magnetic properties.     

Determination of the oxidation state for iron oxide minerals by energy-filtering TEM

The oxidation state of iron oxide nanoparticles was determined using the two principally different technical realisations of energy filtering TEM, in one case using the JEOL 3010 equipped with a LaB6 cathode and a post-column GIF and in the second, the newly designed LIBRA 200FE equipped with an corrected in-column 90 degrees energy filter and a field emission gun (Schottky emitter). The samples studied were oxide-coated iron nanoparticles, and iron oxide inclusions in feldspars in granites. Five possible candidates exist for the iron-oxide phases: FeO, alpha-Fe2O3 (hematite), gamma-Fe2O3 (maghemite), Fe3O4 (magnetite) or alpha-FeO(OH) (goethite). Fingerprinting the O K-edge ELNES allows to distinguish between oxide phases with the same stochiometry and enables to make a first selection of possible candidates. The additional determination of the chemical composition allows unique identification of the phase present. For the oxide coated iron nanoparticles the most probable iron oxide phase of the shell is maghemite, which was additionally confirmed by HRTEM studies. The second studied system were iron oxide needles in alkali feldspar, where we obtained hematite as the most probable phase. There we additionally demonstrated the drastic changes of the ELNES of the O K-edge for the alkali feldspar and iron oxide needle by spatially resolved EELS.     

含稀土化合物透明树脂的合成与光学性质

我们采用三种不同方法制备了含稀土化合物的光学树脂。第一种是含稀土甲基丙烯酸盐的透明树脂,第二种是采用直接掺杂法制备的含稀土配合物透明树脂,第三种是采用原位复合法制备的含稀土配合物透明树脂。通过对三种透明树脂的热稳定性、抗冲击性、紫外-可见吸收光谱、红外光谱、荧光光谱及核磁等方面的表征,结果表明获得的第二、第三种透明树脂具有非常好的透明性、发光性和相关物理机械性能,进一步比较三种透明树脂的发光性质发现第三种采用原位复合法制备的含稀土配合物透明树脂最好,这说明原位复合法是一种简便快捷合成透明荧光高分子材料的好方法。     

Electrical and dielectric properties of rare earth oxides coated LiCoO2 particles

Pure and rare earth oxides (Sm₂O₃, La₂O₃) coated LiCoO₂ nanoparticles were prepared by acrylamide-assisted polymeric citrate and resin-coating processes, respectively. The prepared powders were characterized by X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and impedance spectroscopy. Powder X-ray diffraction patterns confirmed the formation of phase pure LiCoO₂ with nanocrystallite size. X-ray fluorescence spectra confirm the presence of Sm₂O₃ and La₂O₃ in coated samples. The conductivity, dielectric and electric modulus studies of the samples were carried out at room temperature. Dielectric spectra of the samples show the decrease in dielectric constant with an increase in frequency of the applied field. The modulus studies indicate the non-Debye behavior of the samples, which is due to long-time slow polarization and relaxation of hopping charges.     

Preparation of composite with silica-coated nanoparticles of iron oxide spinels for applications based on magnetically induced hyperthermia

It is reported a novel method to prepare magnetic core (iron oxide spinels)–shell (silica) composites containing well-dispersed magnetic nanoparticles in aqueous solution. The synthetic process consists of two steps. In a first step, iron oxide nanoparticles obtained through co-precipitation are dispersed in an aqueous solution containing tetramethylammonium hydroxide; in a second step, particles of this sample are coated with silica, through hydrolyzation of tetraethyl orthosilicate. The intrinsic atomic structure and essential properties of the core–shell system were assessed with powder X-ray diffraction, Fourier transform infrared spectrometry, Mössbauer spectroscopy and transmission electron microscopy. The heat released by this ferrofluid under an AC-generated magnetic field was evaluated by following the temperature evolution under increasing magnetic field strengths. Results strongly indicate that this ferrofluid based on silica-coated iron oxide spinels is technologically a very promising material to be used in medical practices, in oncology.     

Size-dependent cytotoxicity of yttrium oxide nanoparticles on primary osteoblasts in vitro

Yttrium oxide nanoparticles are an excellent host material for the rare earth metals and have high luminescence efficiency providing a potential application in photodynamic therapy and biological imaging. In this study, the effects of yttrium oxide nanoparticles with four different sizes were investigated using primary osteoblasts in vitro. The results demonstrated that the cytotoxicity generated by yttrium oxide nanoparticles depended on the particle size, and smaller particles possessed higher toxicological effects. For the purpose to elucidate the relationship between reactive oxygen species generation and cell damage, cytomembrane integrity, intracellular reactive oxygen species level, mitochondrial membrane potential, cell apoptosis rate, and activity of caspase-3 in cells were then measured. Increased reactive oxygen species level was also observed in a size-dependent way. Thus, our data demonstrated that exposure to yttrium oxide nanoparticles resulted in a size-dependent cytotoxicity in cultured primary osteoblasts, and reactive oxygen species generation should be one possible damage pathway for the toxicological effects produced by yttrium oxide particles. The results may provide useful information for more rational applications of yttrium oxide nanoparticles in the future.     

The effect of carboxylic acids on the oxidation of coated iron oxide nanoparticles

⁵⁷Fe Mössbauer spectroscopy, XRD, and TEM were used to investigate the effect of mandelic- and salicylic acid coatings on the iron oxide nanoparticles. These two carboxylic acids have similar molecules size and stoichiometry, but different structure and acidity. Significant differences were observed between the Mössbauer spectra of samples coated with mandelic acid and salicylic acid. These results indicate that the occurrence of iron microenvironments in the mandelic- and salicylic acid-coated iron oxide nanoparticles is different. The results can be interpreted in terms of the influence of the acidity of carboxylic acids on the formation, core/shell structure, and oxidation of coated iron oxide nanocomposites.     

电感耦合等离子体法测定高纯氧化铕中14个稀土和20个非稀土杂质

本文提出了用ICP-AES直接同时测定高纯氧化铕中14个稀土和20个非稀土杂质元素的分析方法。着重考察了铕基体对分析元素的基体效应,谱线干扰及背景影响等情况,同时对仪器的工作条件进行了优化。在标准溶液中改变了以往对高纯物质进行分析时常常忽略基准物质中的含量,而用标准加入法测出氧化铕基准中的各稀土微量杂质元素的含量作为低标值,有效的消除了由于忽略基准中的杂质元素的含量给分析测定带来的误差。在本工作所选定的条件下,各稀土元素、非稀土元素的回收率在90％-112％之间,稀土元素的精密度实验显示相对标准偏差为1.12％-9.5％。对不同稀土分离厂家的样品进行了检测,结果令人满意。     

应用XRF与ICP-MS研究陨石样品的元素分布

分别采用X射线荧光光谱无标样全定量分析法(XRF)和微波消解/电感耦合等离子体质谱法(ICP-MS)对铁陨石和石陨石样品进行了元素分析。XRF法检测陨石样品中的常量元素,ICP-MS检测陨石中的微量元素。实验结果表明：XRF法可以检测出陨石样品中含量在10 μg·g-1以上的所有金属和非金属元素,得出两类陨石中共同含有的6种常量元素是Fe,Mg,Si,Na,Al和Ca。不同地区的铁陨石中均含有大量的Fe,石陨石中含有大量的Si。ICP-MS法检测陨石中的24种元素,选出共同存在的9种元素V,Ni,Mo,Ag,Sn,La,Gd,Hg和Pb进行对比分析,得出铁陨石中的重金属元素和稀土元素的含量远高于石陨石。所有的铁陨石样品中Sn元素的含量大约是石陨石的10～25倍,铁陨石中稀土元素La和Gd的含量大约是石陨石的6倍,新疆的5A号和6A号铁陨石中Pb的含量比来自山东的铁陨石(1A, 2A, 3A, 4A)多5～13倍,来自内蒙古的石陨石(9B,10B)比来自新疆的石陨石(7B,8B)多了三种元素La,Mo和Gd。     

Radiation induced synthesis of gold/iron-oxide composite nanoparticles using high-energy electron beam

Composite nanoparticles consisting of gold and iron oxide were synthesized in aqueous solution systems by using a high-energy electron beam. The electron irradiation induces radiation-chemical reaction to form metallic gold nanoparticles. These gold nanoparticles were firmly immobilized on the surface of the support iron oxide nanoparticles. Surface of the support iron oxide nanoparticles are almost fully coated with fine gold nanoparticles. The size of these gold nanoparticles depended on the concentrations of gold ions, polymers and iron oxide nanoparticles in the solutions before the irradiation.     

GOSs-稀土配合物紫外增强材料的光谱分析与稳定性研究

氧化石墨烯薄片(GOSs)作为一种新型的二维片状材料,具有较高的比表面积、丰富的表面含氧官能团以及良好的光热稳定性。而稀土配合物通过无机稀土元素与有机配体的结合表现出优异的荧光特性。为了将两类材料具有的物化特性结合起来应用于紫外光谱探测领域。选取了合适的有机配体啉菲罗啉(1,10-邻二氮杂菲,phen)、2’2-联嘧啶(bpm)作为桥联分子,把氧化石墨烯(GOSs)与稀土配合物通过氢键自组装作用进行复合,制备了高效稳定可调的GOSs-稀土配合物复合荧光材料GOSs-Eu(BA)3phen和GOSs-Eu(TTA)3bpm,并且制备了相应的聚乙烯醇(PVA)共混紫外增强薄膜,对其光谱特性与稳定性进行了深入的研究。采用红外光谱、扫描电镜和金相显微镜等方法,对紫外增强材料进行了性能表征。采用吸收光谱,荧光光谱等方法,对紫外增强薄膜进行了性能表征。此外,通过热重测试(TGA)表征了GOSs氢键复合前后紫外增强材料的热稳定性,通过荧光强度-紫外光照次数表征了GOSs氢键复合前后紫外增强薄膜的光稳定性。红外光谱分析发现,进行配位前后有机配体的特征峰产生了频移,表明稀土配合物中Eu 3+与配体之间存在着明显的配位作用。在进行复合之后,桥联配体的特征峰也产生了偏移,表明GOSs与稀土配合物通过桥联分子的氢键作用进行了进行复合。吸收光谱与荧光光谱测定结果表明增强薄膜吸收峰在200~400 nm,荧光主峰在612 nm左右,为Eu 3+特征红色荧光峰,且不同配体可以实现不同范围的吸收产生差异化的荧光表现。扫描电镜和金相显微镜清晰地展示了稀土配合物复合前后的微观形貌,即颗粒状稀土配合物附着在石墨烯薄片上。光稳定性测试表明经过GOSs氢键复合之后,Eu(BA)3phen和Eu(TTA)3bpm稀土配合物荧光材料在进行25次荧光强度测试后光漂白程度分别下降了4.26%和6.41%,提高了其光稳定性。热重测试也表明在经过GOSs氢键复合之后,稀土配合物的热稳定性有了很大提高。总之,得益于GOSs和稀土配合物的特性结合,所制备的紫外增强材料表现出优异的荧光特性与稳定性,必将在紫外探测方面有着广阔的应用前景。