ICP-OES用于锂/钠离子电池三元正极材料及其前驱体中Li/Na元素含量的测定

在锂/钠离子电池三元正极材料及其前驱体的研究中,Li/Na元素的测定对于电化学性能的探索具有重要意义[1,4]。对于利用共沉淀法得到的前驱体,前驱体中Na的残留量将直接影响后续高温煅烧过程中烧结原料的用量。本文提出了一种利用电感耦合等离子体发射光谱(ICP-OES)测定锂/钠离子电池三元正极材料前驱体中Na及其烧结的三元正极材料中Li/Na含量的方法,在研究样品的溶解方法、称样量、测定介质浓度、仪器参数基础上,实现三元正极材料及其前驱体中Li/Na含量的准确测定。这种方法操作简单,化学干扰小,无需基体匹配即可精确测定前驱体中的Li/Na残留和三元材料中的Li/Na含量,结果重现性好,样品分析结果测量精度(RSD)小于2.0%,对于电池中Li/Na离子脱嵌量的研究具有指导意义。     

高质量镍基超晶格薄膜的制备及表征

自发现镍基超导薄膜之后, 镍基材料体系已成为当前人们的研究热点. 而在相关报道中, 普遍认为高质量的镍基超导前驱体薄膜的制备对其拓扑还原后超导电性的实现具有重要影响. 前期研究表明高质量的前驱体薄膜只生长在SrTiO3 衬底附近, 这与我们的实验结果一致. 为了可控制备高质量的镍基超导前驱体薄膜, 本文利用脉冲激光沉积(PLD) 技术在SrTiO3 (001) 衬底上生长不同厚度的可层选择性还原的[SrTiO3 ]m/[ Nd0 .8Sr0 .2 NiO3 ]n[(STO)m/(NSNO)n ]超晶格薄膜. 采用反射高能电子衍射仪(RHEED) 及透射电子显微镜(STEM) 和 X 射线衍射(XRD) 技术对超晶格薄膜的结构进行原位检测及结构表征, 然后利用综合物性测量系统(PPMS) 测试薄膜的电磁输运性质. 结果表明, 超晶格薄膜的结构质量良好, 超晶格薄膜和高质量单层前驱体薄膜表现出类似的电阻和磁阻现象. 该研究为后续镍基超导薄膜的可重复制备提供了重要的参考.     

Co掺杂量对Ti1-xCoxO2纳米颗粒结构及磁性的影响

以钛酸丁酯、六水硝酸钴等为原料,采用溶胶凝胶法合成Ti1-xCoxO2干凝胶前驱体,将前驱体在500℃空气氛围下进行退火处理,得到一系列Ti1-xCoxO2纳米颗粒样品.采用差热/热重综合热分析仪(TG-DTA)、X射线衍射仪(XRD)、拉曼光谱(Raman)和振动样品磁场计(VSM)对样品的结构和磁性进行研究.结果表...     

钴前驱体对掺杂TiO2微结构和可见光催化性能的影响

为发展可见光下破坏污染物的钴掺杂TiO2光催化剂,以CoCl2、Co(NO3)2和CoSO4为钴前驱体,采用溶胶-凝胶法制备了钴掺杂TiO2,通过X射线衍射、扫描电镜、BET表面积测试和紫外-可见吸收光谱对比研究了钴前驱体对样品的微观结构和吸光性能的影响．同时,以苯胺为降解目标物,比较了样品在可见光下的催化活性．结果表明,样品的TiO2晶相、形貌、比表面积和吸光性能都随着钴前驱体的不同而不同,其中以Co(NO3)2为前驱体制备得到的样品其光催化活性最高,特别是1％掺杂且400℃烧结得到的样品,并简要讨论了其可能原因．     

RbVO_3的光谱分析及能带结构研究

采用杂化前驱体的湿化学合成法制备了偏钒酸铷(RbVO3)发光材料。利用粉末X射线衍射(XRD)、红外光谱仪(IR)等对RbVO3的结构进行了表征,利用紫外-可见(UV-Vis)吸收光谱、光致发光光谱等研究了该发光材料的光致发光性能,并采用基于密度泛函理论的CASTEP程序计算了RbVO3的能带。结果表明,在357 nm紫外光的激发下,RbVO3产生发光峰在525 nm附近、色坐标为(0.318 0,0.430 9)的绿白光发射,发光亮度高;RbVO3计算的光学带隙为2.67 eV,与实验值较为吻合。     

二茂铁质量对气相爆轰法合成碳纳米管的影响

以甲烷和氧气作为爆源,二茂铁为前驱体,探究了不同前驱体质量对所合成的碳纳米管的影响。利用X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)等手段对碳纳米管的形貌和结构进行表征,结果发现:当二茂铁量较少时,只有碳包覆铁纳米颗粒存在;随着二茂铁质量的增加,逐渐有碳纳米管生成,其管径大多分布在10~50nm之间,为多壁碳纳米短管。随着前驱体质量的增加,碳纳米管的石墨化程度提高,结构缺陷也变少。通过对合成产物的热重分析可得,气相爆轰法所制备的碳纳米管具有强烈吸氧性,所得样品中碳纳米管的质量分数为26%左右。     

烧绿石型富氧相Ce_2Zr_2O_8与缺氧相Nd_2Zr_2O_7的振动光谱及XPS对比研究

采用石墨还原法成功制备了富氧相Ce2Zr2O8,选用缺氧相Nd2Zr2O7替代其前驱体CeZrO3.5+δ进行结构对比分析,利用X射线衍射(XRD)、拉曼光谱(Raman)、红外光谱(IR)及X射线光电子能谱(XPS)对样品体、表晶体结构进行表征。XRD结果表明,Ce2Zr2O8相具有典型烧绿石结构特征,表征Ce/Zr阳离子有序排列的超结构峰非常明显,但其Zr—O配位体由前驱体中的[ZrO6]八面体转变为[ZrO8]立方体,[ZrO8]配位体形成大大降低了Ce2Zr2O8的结构稳定性。Raman和IR结果表明,Ce2Zr2O8相的振动光谱谱带比其前驱体替代物Nd2Zr2O7显著增多,说明氧离子的富集导致Ce2Zr2O8相中某些振动简并峰消除简并,该结果进一步证实了其结构对称性较前驱体更低。XPS结果表明,Ce2Zr2O8相表面Ce(Ⅳ)特征峰(916.3eV)非常明显,没有Ce(Ⅲ)特征峰(885eV)出现,说明该相前驱体中的Ce3+已被完全氧化成Ce4+;Ce2Zr2O8相中Zr(3d)结合能与萤石相Gd1.2U0.8Zr2O7+y接近证实其表面形成了与体相一致的[ZrO8]配体;O(1s)低位结合能升高表明Ce2Zr2O8体相氧种介于晶格氧和吸附氧之间,高位氧峰出现说明其表面含有吸附氧,吸附氧与Ce2Zr2O8体相结合强度介于CeO2和Nd2Zr2O7之间。     

光学材料 光学塑料、光学陶瓷

TQ174．758．23 2005043091 Na:YAG激光透明陶瓷超细粉体的合成及其性能表征= Preparation and characteristics of Nd:YAG super-fined powders for laser transparent ceramics[刊,中]／卢利平(长春理工大学材料与化工学院．吉林,长春(130022)),刘景和…／／光学技术,-2005,31(2),-306-308 以Al(NO3)3·9H2O和Y2O3为原料,按YAG化学计量比配成相应的硝酸盐混合液,并用一定量的Nd取代 Y,加入尿素沉淀剂,利用无机体系均相沉淀法制备了 YAG前驱体。对前驱体进行适当处理,并采用高温热解法在1200℃时制备出Nd:YAG透明陶瓷超细粉体。通     

改进型前驱液对化学溶液法制备YBCO薄膜的影响

传统全三氟乙酸前驱液对涂敷环境湿度、低温预分解过程中的升温速率和水汽分压等因素具有敏感性,采用改进型前驱液可以降低其敏感性,从而有利于涂层导体的连续制备.我们提出的改进型前驱液中,三氟乙酸钇、三氟乙酸钡和苯甲酸铜是前驱体,甲醇和丙酸的为溶剂.采用化学溶液法在铝酸镧单晶衬底上制备YBCO,低温分解阶段以1～5℃/min快速升温,可以获得低温后的前驱膜光滑完整,无裂纹.通过X衍射分析和扫描电镜分析了薄膜的织构和表面微结构,四引线法测试薄膜超导电性.采用改进型前驱液制备的薄膜超导转变温度(Tc)为90K,在77K、自场下临界电流密度(Jc)为1MA/cm2.     

Mn掺杂ZnSe前驱体纳米带的制备及其磁光性质

采用了改进的水热途径制备稀磁半导体Mn掺杂ZnSe前驱体纳米带MnxZn1-xSe?en3 (en=ethylenediamine). 与先前方法相比， 具有省时高效的优势. 并通过电子能谱仪、热重分析仪、场发射扫描电子显微镜表征这种前聚体的形态与组成. 在有关电子顺磁共振波谱(ESR)和发光光谱(PL)的实验中，ESR和PL用来研究和表征Mn2+掺杂效率及ZnSe前驱体纳米带中Mn2+-Mn2+的相互作用.Mn掺杂ZnSe前驱体纳米带的ESR谱出现Mn2+特征超精细分裂六重峰，表明了Mn2+-Mn2+的     

Adsorption and structural properties of soft-templated mesoporous carbons obtained by carbonization at different temperatures and KOH activation

Two series of phenolic resin-based mesoporous carbons were prepared by soft-templating strategy, which involves the formation of thermosetting carbon precursor by polymerization of phloroglucinol and formaldehyde in hydrophilic mesodomains of a thermally decomposable triblock copolymer used as a soft-template. It was shown that the volumes of mesopores and micropores in the resulting carbons can be tuned by varying carbonization temperature of phenolic resins in the range from 400 to 1000 °C followed by the post-synthesis KOH activation at 700 °C. The highly microporous carbons were obtained by KOH activation of phenolic resins pyrolyzed at lower temperature (∼500 °C), while high temperature KOH activation (∼800 °C) afforded microporous carbons with preserved mesoporosity.     

Poly(sodium-p-styrenesulfonate) assisted microwave synthesis of ordered mesoporous carbon supported Pd nanoparticles for formic acid electro-oxidation

Pd nanoparticles highly dispersed onto the surface of ordered mesoporous carbons (OMCs) were synthesized successfully by poly(sodium-p-styrenesulfonate) (PSS) assisted microwave synthesis. Here, PSS served as a bifunctional molecule both for solubilizing and dispersing OMCs into aqueous solution and for jointing Pd²⁺ to facilitate the subsequent uniform formation of Pd nanoparticles on their surfaces. The effects of PSS on structural and electrochemical properties of Pd/OMCs were investigated. It was found that the addition of PSS facilitated Pd nanoparticles to disperse on the carbon surface. Electrochemical properties showed that Pd catalysts prepared with addition of PSS displayed better electrochemical activity and stability for formic acid electro-oxidation than those without PSS.     

Synthesis and microwave absorbing properties of FeNi alloy incorporated ordered mesoporous carbon–silica nanocomposite

Ordered mesoporous carbon–silica/FeNi nanocomposite were prepared by a sol–gel method and following sintering process. The electromagnetic parameters were measured in the 0.5–18 GHz range. Compared with ordered mesoporous carbon–silica composite, the permittivity of ordered mesoporous carbon–silica/FeNi nanocomposite decreases, while the permeability almost remains unchanged. The optimal reflection loss of ordered mesoporous carbon–silica/FeNi nanocomposite can reach ?45.6 dB at 11.1 GHz for a layer thickness of 3.0 mm. The enhanced microwave absorption of the mesoporous carbon–silica/FeNi nanocomposite is due to better balance between the complex permittivity and permeability, geometrical effect, as well as multiple reflections by the ordered mesoporous structure.     

Analysis of structure and properties of active carbons and their copolymeric precursors

The relations between chemical structures of BM-DVB copolymers obtained with various monomer molar ratios and their carbonization products were studied. Three porous copolymers 1:4, 1:1, and 4:1 of BM to DVB were the starting materials for preparation of active carbons. Two activation agents were employed: air and phosphoric acid. The carbonization process was performed in the same way in these two cases. To characterize the obtained materials FTIR spectroscopy, thermal and elemental analyses were applied. Porous structure parameters were obtained by means of nitrogen sorption. The results proved that differences in the molar ratio of monomers used in the syntheses of polymeric precursor play a key role for structure and properties of copolymers but have rather small influence on properties of the obtained carbons. Preliminary treatment is more effective during the activation process. The carbons obtained by activation with phosphoric acid are microporous and have well developed porous structures. The air activated carbons are mesoporous with specific surface areas similar to those of polymeric precursors.     

Dual roles of amphiphilic triblock copolymer P123 in synthesis of α-Fe nanoparticle/ordered mesoporous silica composites

A simple and effective method for in situ synthesis of α-Fe nanoparticle/ordered mesoporous silica (OMS) composites is reported. Evaporation induced self-assembly (EISA) and carbothermal reduction (CR) are strategically combined by using amphiphilic triblock copolymer P123 as not only a template and but also a precursor of carbon material. P123 plays dual roles in assembly of mesostructure and reduction of ferric species. Thermogravimetric analysis-mass spectrometer was used to investigate the pyrolysis process of the wet gels. The synthesized composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS) and N₂ adsorption. The results showed that the composites possess ordered hexagonal mesoporous structure and the α-Fe nanoparticles with about 16 nm were well dispersed in mesoporous matrix. The carbon material resulting from P123 can reduce ferric species to α-Fe nanoparticles at 800 °C. Moreover, the formation mechanism for Fe nanoparticles in OMS matrix is proposed.     

Comparative studies of Zr-based MCM-41 and MCM-48 mesoporous molecular sieves: Synthesis and physicochemical properties

Two surfactant-templated synthetic routes are developed for the preparation of new types of mesoporous molecular sieves, Zr-MCM-41 and Zr-MCM-48, using different Si sources but keeping the same zirconium precursor (zirconium-n-propoxide). When fumed silica was used as Si precursor, a Zr-MCM-48 material of cubic structure was formed with a surface area of 654.8 m²/g and an unimodal pore diameter distribution. It shows low stability: after calcination at 600 °C, the ordered structure was transformed into a relatively disordered worm-like mesostructure with many defects and silanol groups. The use of tetraethyl orthosilicate as Si source led to the formation of a Zr-MCM-41 mesoporous solid, which had good thermal stability and a highly ordered hexagonal arrangement, with a surface area 677.9 m²/g and an uniform pore diameter distribution. Fourier transform infrared (FT-IR) characterization and ²⁹Si NMR analysis confirm that zirconium ions indeed incorporated into the framework of the solid. The in situ FT-IR spectroscopy of pyridine adsorption reveals that both, Lewis and Brönsted acid sites, were formed on the surface of these mesoporous materials. The strength and number of the Brönsted acid sites of the Zr-MCM-48 solid were greater than those of the Zr-MCM-41, due to a lower degree of condensation reaction during the synthesis that led to more structural defects in the framework and more silanol groups stretching from the solid surface.     

A fluorescent probe for zinc detection based on organically functionalized SBA-15

In this study, highly ordered mesoporous silica material (SBA-15) functionalized with N-(quinoline-8-yl)-2-(3-triethoxysilyl-propylamino)-acetamide (QTPA) as zinc probe has been reported. The anchoring to the surface of the SBA-15 was carried out by the reaction between the precursor and the hydroxyl groups available on the inner surface of the support. The primary ordered mesoporous structure of SBA-15 was well preserved after the grafting procedure. Fluorescence characterization showed that the obtained organic-inorganic hybrid composite displayed highly selective and sensitive to Zn²⁺ ion over other cations such as Cd²⁺, Pb²⁺, Ni²⁺ and Co²⁺. And the hybrid material has ideal chemical and spectroscopic properties for further biological and environmental applications.     

有序介孔SBA-15复合稀土Tb络合物的制备和发光特性

以三嵌段化合物P123为模板剂、正硅酸乙酯(TEOS)为硅源,利用水热法制备出有序介孔二氧化硅SBA-15,随后利用3-氨丙基三乙氧基硅烷(APTES)、乙酰丙酮(ACAC)分步对该有序介孔材料进行改性,再将其置于乙醇溶液中,加入三价稀土Tb的盐溶液进行络合,制备出具有强发光性能的有序介孔纳米复合稀土材料。采用XRD、FTIR和荧光光谱等分析方法对复合材料的结构与性能进行了研究。发现有序介孔材料、第二配体(邻菲口罗啉Phen)对稀土络合物发光强度有重要影响,并对其机理进行了解释。另外,发现其热稳定性也有所提高。     

Ordered mesoporous silica materials (SBA-15) with good heat-resistant magnetism

A series of highly ordered mesoporous materials (CF-SBA-15) with heat-resistant magnetism have been successfully prepared from impregnation of cobalt salt, iron salt, and citric acid with as-synthesized SBA-15. XRD and N₂ isotherms indicate that these materials have highly ordered hexagonal mesoporous symmetry and open pore systems. The measurement of magnetic property shows that these materials are ferromagnetic even if calcined at 550 °C for 10 h in air, indicating their good heat-resistant magnetism. These results would be very important for recycle and regeneration of adsorbents and catalysts in practical applications. Moreover, this method may be useful for other mesoporous materials with thermally stable magnetism from a combination of other mesoporous materials such as MCM-41 with magnetic nanoparticles of MnFe₂O₄ and NiFe₂O₄.     

A study on the structural and mechanical properties of ordered mesoporous Al2O3 film

Ordered mesoporous aluminum oxide films with a porosity range of 40-48% were synthesized by an evaporation-induced self-assembly (EISA) process using surfactant templating. To investigate the role of the hydrolysis reaction in the formation of a mesoporous structure, the changes of pore structure properties according to a variation of aging time and water molar ratio were monitored. From the tendencies of pore structure properties, the optimized condition for a high porosity and a highly ordered pore structure in ordered mesoporous alumina film was determined. This alumina film maintained the mesoporous structure even though it annealed at high temperatures, up to 1200 °C. Therefore, the ordered mesoporous alumina films synthesized in this study could be applicable as a material used at high temperature.