β-Ga_2O_3∶Cr~(3+)近红外长余辉纳米颗粒的制备及发光性能

以三乙二醇为表面配体,利用沉淀法制备了β-Ga_2O_3∶Cr~(3+)近红外(NIR)长余辉纳米颗粒.考察了反应条件对β-Ga_2O_3∶Cr~(3+)的发光性能和晶体结构的影响,并初步探讨了其NIR余辉发光机理.结果表明,当溶液的p H值为7,煅烧温度为700℃时,可获得高纯度的β-Ga_2O_3∶Cr~(3+)纳米颗粒,其平均粒径为30 nm,最大余辉发射波长可调控为750 nm,NIR余辉发光时间长于384 h.本方法得到的β-Ga_2O_3∶Cr~(3+)长余辉纳米颗粒不仅尺寸小,而且NIR余辉时间长,发射波长可调控,在低背景噪音的深组织活体成像中具有潜在的应用前景.     

Synthesis,Single Crystal Growth and Crystal Structure of Ta7Cu10Ga34 – a 8 × 4 × 2 Super Structure of CsCl

Single crystals of Ta₇Cu₁₀Ga₃₄ were grown from the elements in a Cu/Ga melt. Ta₇Cu₁₀Ga₃₄ represents the first ternary compound of the system Ta/Cu/Ga. The crystal structure (Cmmm, oC102, Z = 2, a = 23.803(1), b = 12.2087(4), c = 5.7487(2) Å, 1291 refl. 78 parameters, R₁ = 0.037, wR₂ = 0.070). The crystal structure is characterized by rods of pentagonal prisms MGa₁₀, which are alternatingly occupied by Ta and Cu. Four of these rods are connected to columns running in direction (001). These columns are linked by cubic units TaGa₈, CuGa₈, and GaGa₈. According to the characteristic structural elements and the size of the unit cell Ta₇Cu₁₀Ga₃₄ represents a 8 × 4 × 2 super structure of CsCl or bcc. With respect to the underlying CsCl structure the formula can be written as [Ta₇Cu₁₀Ga₂□₁₃]Ga₃₂, i.e. a cubic primitive packing of 32 Ga atoms with Ta, Cu, and Ga in cubic voids and 13 vacancies. The pentagonal‐prismatic coordination of Ta and Cu can formally be obtained from the cubic primitive packing of Ga atoms by a 45° rotation of a part of the Ga₈ cubes. There is a close similarity to the binary compounds Ta₈Ga₄₁ and Ta_2–xGa_5+x. The first one is also related to a CsCl‐like structure, the latter one contains rods of pentagonal prisms, which form the same columns. There are also relations to the ternaries V₂Cu₃Ga₈ and V₁₁Cu₉Ga₄₆, whose cubic structures are more or less complex variants of CsCl.     

Synthesis and Characterization of GaIII,YIII, and LuIII Complexes with Etifenin and Analogues

Complexes of etifenin ( 1a ), disofenin ( 1b ), and mebrofenin ( 1c ) with Ga^III, Y^III, and Lu^III were synthesized and characterized by NMR spectroscopy and UV/Vis spectroscopy. Stability and protonation constants of the complexes of 1a were determined by potentiometry and distribution diagrams were calculated. It was shown that the Y^III and Lu^III species are most stable as bis chelates at higher pH, whereas the Ga^III complex degrades at pH < 4.5.     

Metalated diphosphanylsiloxanes with polycyclic and polymeric structures

The reactions of the diphosphanylsiloxane O(SiiPr₂PH₂)₂ (1) with MiPr₃ (M = Ga, In) produced the polycyclic compounds [O{SiiPr₂(PH)MiPr₂}{SiiPr₂(P)MiPr}] ₂ (2, 3). Compounds 2 and 3 are composed of three M₂P₂ rings forming a ladder structure and two OSi₂P₂M rings. By reactions of 1 with n-BuLi the polymeric compound [O(SiiPr₂PHLi)₂(THF)(TMEDA)] · THF (4) was obtained.     

镓-荧光镓极谱络合吸附波的研究

在荧光法中用荧光镓(LMG)测定镓已有报道,但有关的电分析研究和应用尚未见报道。我们在研究LMG伏安行为和稀土-LMG极谱络合吸附波的基础上,于一氯乙酸缓冲底液中得到了高选择性和高灵敏度的Ga(Ⅲ)-LMG的络合吸附波,检出限为 8.0×10~(-9)mol/L,可不经分离在酸性溶液中直接测定以SiO_2和Al_2O_3为基体的催化剂中的镓,并研究了反应过程机理。     

镓-水杨基荧光酮伏安络合吸附波的研究

在pH为3.0的0.2mol/L邻苯二甲酸氢钾-HCI和5.0×10^-6mol/L水杨基荧光酮底液中,线性扫描可得灵敏的Ga-SAF络合物吸附波,峰电位为-0.93V(vsSCE).镓在7.5×10^-9～3.8×10^-7mol/L浓度范围内与峰高成正比关系.     

n-GaAs为基的光电化学电池输出特性

GaAs 的禁带宽度为1.428eV,而且是直接跃迁,是光电化学电池中很好的电极材料.一些作者研究了 n-GaAs 为基的光电化学电池^[1,2].本文讨论了光强,化学刻蚀、氧化还原对浓度及离子修饰对 n-GaAs 光电化学电池输出特性的影响.所用的电极为低阻 n-GaAs[(100)面],N_D=5.1×10¹⁷cm^-3,试验前通高纯氮20分钟.测光强用的辐照计经上海计量局校正,其它测试方法同前文^[3].     

Determination of gallium by graphite furnace atomic absorption spectrometry with combined use of a tungsten-coated L'vov platform tube and a chemical modification technique

Tungsten-coated non-pyrolytic graphite (NPG), pyrolytic graphite (PG) and pyrolytic L'vov platform graphite (PPG) tubes were prepared, and their analytical performances were compared. The coating process simply involved injecting 100 μl of a sodium tungstate solution (0.01 mol l⁻¹) into each graphite tube, followed by heating according to a temperature programme similar to an atomisation cycle for the determination of gallium. This procedure for coating was repeated at least 12, 25, and 7 times towards NPG, PG, and PPG tubes, respectively. Among these tubes, the tungsten-coated PPG tube showed excellent performance for the determination of gallium. By combined use of a chemical modifier such as aluminium(III) or nickel(II) a detection limit (3σ) of 6 pg and sensitivity (1% absorption) of 3–4 pg were achieved. The practical potential of the proposed technique was demonstrated for the determination of gallium in several samples of alloys and fresh water.     

From crystalline to glassy gallium fluoride materials: an NMR study of Ga and Ga quadrupolar nuclei

Owing to the implementation of acquisition techniques specific for nuclei with very large quadrupolar interaction (full shifted echo and variable offset cumulative spectra (VOCS)), NMR spectra of ⁶⁹Ga and ⁷¹Ga are obtained in crystallised (PbGaF₅, Pb₃Ga₂F₁₂, Pb₉Ga₂F₂₄ and CsZnGaF₆) and glassy (PbF₂–ZnF₂–GaF₃) gallium fluorides. Simulations of both static (full echo or VOCS) and 15 kHz MAS spectra allow to obtain consistent determinations of isotropic chemical shifts and very large quadrupolar parameters (ν_Q up to 14 MHz). In the crystalline compounds whose structures are unknown, the number and the local symmetry of the different gallium sites are tentatively worked out. For the glassy systems, a continuous Czjzek's distribution of the NMR quadrupolar parameters accounts for the particular shape of the NMR spectrum.