有机-无机杂化凝胶法合成YAG∶Ce~(3+)荧光粉的包膜及其稳定性

本文以金属硝酸盐为原料,柠檬酸为配位剂的有机-无机杂化凝胶法来合成掺杂三价铈离子的钇铝石榴石荧光粉,采用X-射线衍射法研究了杂化凝胶在煅烧过程中的相转变机制。结果表明:杂化凝胶在煅烧过程中可以通过两条途径形成Y3Al5O12(YAG)相:一是由无定形Y2O3和Al2O3直接向YAG相的一步相转变;二是由无定型Y2O3和Al2O3经由YAlO3(YAP)和γ-Al2O3向YAG相的两阶段相转变,在900℃得到结晶性好的纯YAG∶Ce3 荧光粉,其最大激发波长为459nm,最大发射峰波长为550nm;在荧光粉表面包覆氧化铝和氧化镧,将使荧光粉的荧光强度稍有降低,但对荧光粉的稳定性有很好的改进作用。     

常见饮料中痕量铝的分光光度法研究

新试剂5-溴水杨基荧光酮可在pH5.5～6.8的六次甲基四胺缓冲溶液中,与铝,溴化十六烷基吡啶形成稳定的红色三元配合物。最大吸收波长约为568nm,摩尔吸光系数高达1.7×10~5L mol~(-1)·cm~1,常见金属离子很少干扰。据此,建立了测定微量铝的方法。其线性范围为0～6μg/25ml回收率在96％～103％之间。本文测定了常见饮茶,饮料及饮水中的微量铝。     

壳聚糖／聚丙烯酸聚电解质复合物膜对水／有机液体系的渗透汽化性能

以壳聚糖和聚丙烯酸为原料制备了聚电解质复合物膜，并对其分离水／乙醇体系的渗透汽化特性和浓度，温度，化学组成等因素的影响进行了研究，发现后处理方法对复合物膜的分离性能影响很大。同时对其它水／有机液体系，该膜也具备优异的分离性能。     

Reduction and reconstruction of Co3O4 nanocubes upon carbon deposition

We describe a synthetic investigation on the formation of carbon nanofibers using a preshaped free-standing metal-oxide catalyst (single-crystal cobalt oxide (Co(3)O(4)) nanocubes). In reacting with acetylene (C(2)H(2)) vapor, Co(3)O(4) nanocubes are reduced and reconstructed into metallic cobalt. The resultant metal catalyst with a 2-fold symmetry leads to a bilateral base growth for carbon nanofibers. Our findings indicate that an understanding of catalyst-assisted chemical vapor deposition (CVD) mechanisms can be acquired, when the shape, size, and crystal orientation of pristine metal catalysts are made known to the CVD process. By tracing their evolutional changes in structure and composition, the shape-designed model catalysts may offer new opportunities for mechanistic investigations on the chemical reactivity of nanoparticles, general catalyst-assisted material synthesis, and metal intercalation chemistry.     

Fe-Co-Ni合金纳米线有序阵列的模板合成与磁性

以二次阳极氧化的氧化铝膜为模板，用电化学沉积的方法成功地合成了Fe-Co-Ni三组份有序纳米线阵列.扫描电子显微镜（SEM）和透射电子显微镜(TEM)观察表明纳米线表面光滑、有序、高长径比；磁性测量表明,其矫顽力较同组份的膜材料有较大的提高.将样品在惰性气体氛围中不同温度下退火，随着退火温度增加，其纵向矫顽力有一个极值，而对应的横向矫顽力没有类似的变化，关于这一现象的机理,本文进行了初步的讨论. 图5参15     

A facile electrochemical synthesis of caffeic acid derivatives in the presence of acetylacetone or methyl acetoacetate in aqueous medium

The anodic oxidation of caffeic acid in the presence of acetylacetone or methyl acetoacetate in aqueous solution has been studied by cyclic voltammetry and controlled-potential electrolysis techniques. The result showed that caffeic acid was oxidized to the corresponding o-benzoquinone, which underwent further Michael-addition with acetylacetone or methyl acetoacetate to produce caffeic acid derivative 3,4-dihydroxy-6-(1-acetylacetone)-yl cinnamic acid 4a or 3,4-dihydroxy-6-(1-acetyl-methylacetate)-yl cinnamic acid 4b.     

基于芘的荧光熄灭的单质碘荧光敏感膜的研究

单质碘熄灭固定于增塑的ＰＶＣ膜中的芘的荧光，且这种熄灭作用可逆。本据此研制了用于测定单质碘浓度的荧光敏感膜，最佳膜组成为２～４ｍｇ芘、５０ｍｇＰＶＣ粉、１００ｍｇ邻苯二甲酸二异辛酯，测定碘的浓度范围为２．２６×１０＾－５～１．０４×１０＾－３ｍｏｌ／Ｌ。此膜测定单质碘的重现性好，响应时间小于４０ｓ。除Ｆｅ＾３＋、Ｂｉ＾３＋外，其它常见离子均无干扰。将此膜用于食盐中碘的测定，结果令人满意。     

Preparation ,Structural Characterization and Luminescent Property of Binucleasr Silver（Ⅰ）Complex Formed by Benzotriazole and 1—Hydroxymethyl Benzotriazole

Dinuclear silver (I) six‐membered ring complex [Ag₂ (bta)₂ ‐(hmbta)₂] (ClO₄)₂ (3) has been synthesized by the reaction of benzotriazole (bta) (1) and 1‐hydroxymethyl benzotriazole (hmbta) (2) with Ag (CH₃CN)₄ClO₄. The structures of compound 2 and Complex 3 have been studied by single crystal X‐ray diffraction analysis. The change of luminescent intensity of 1, 2 and 3 was reported. Compound 2 crystallizes in the monoclinic system with space group P2 (1)/c, a = 0.7655 (10) nm, b = 1.0126 (14) nm, c =0.9502 (13) nm, β = 95.07 (2)°, V = 0.7337 (17) nm³ and Z = 4. Complex 3 crystallizes in the triclinic system with space group P1, a = 0.73611 (18) nm, b = 0.9152 (2) nm, c = 1.2277 (3) nm, β = 87.170 (5)°, V = 0.8221 (3) nm³ and Z = 1. The main structural feature of complex 3 is a symmetric dinuclear six‐membered ring formed by two silver (I) atoms and four N‐atoms from two benzotriazoles. The second structural feature of complex 3 is the τ‐τ stacking interaction between two adjacent molecular planes, which forms the two‐dimentional layer structure. Besides, compared with 2, the luminescent intensity of complex 3 shows a remarkable enhancement.     

流动注射—在线分离富集与原子光谱检测联用技术

现代分析化学发展的重要特征之一是分析方法从离线/手动操作向在线/自动操作方向转化。流动注射(FI)作为非均匀和非平衡状态下的溶液处理和微量进样技术,是实现上述转化的有力工具。FI可与不同的分离富集和检测手段结合,具有很强适应性和实用性。在众多联用技术中,FI—在线分离富集与原子光谱检测联用技术特别受到分析化学界的青睐。这种联用不仅可以克服常规离线操作费时、污染环境和试样/试剂消耗大的缺点,而且可大大提高分析效率,显著改善分析方法的灵敏度与选择性,进行多种成分同时检测(对ICP—AES,DCP—AES     

To improve the key properties of nonlinear optical crystals assembled with tetrahedral functional building units

Nonlinear optical (NLO) crystals assembled with conventional non-π-conjugated tetrahedral functional building units (FBUs), generally referring to [PO₄] and [BO₄], usually exhibit weak nonlinearity and poor birefringence. It is currently proposed that partially substituting oxygen atoms with fluoride atoms in these FBUs could enhance these crucial properties. Hence, we investigated for the first time the NLO-related properties of NH₄BAsO₄F (ABAF), which was constructed from tetrahedral [BO₃F] and [AsO₄] FBUs, and enhancements of these properties were observed in this material, that is large second-harmonic generation (SHG) response (2 × KDP) and improved birefringence (0.03 at 1064 nm). Notably, both SHG coefficient and birefringence of ABAF exceeded those of a great majority of phosphates, sulfates, or boron phosphates and achieved a preferable balance. It is interesting that ABAF shows vast structural similarities to the typical NLO crystals Sr₂Be₂B₂O₇ (SBBO) and KBe₂BO₃F₂ (KBBF), which might be the partial reason why it showed improvement in these vital properties. This work may afford some inspiration for enhancing the key performances of NLO crystals assembled with non-π-conjugated tetrahedra.

We report a new nonlinear optical crystal assembled exclusively with tetrahedral functional building units in which enhanced birefringence (Δn) and second-harmonic generation (d_eff) were observed.