Trace analysis of impurities in sol-gel prepared BaTiO3-powders with ICP-MS

An ICP-MS method for the determination of ultra-trace impurities of 21 elements (Be, Al, Ca, Cr, Mn, Co, Ni, Sr, Zr, Ag Cd, In, Sn, La, Ce, Er, Hf, W, Pb, Bi, U) at pg/g to ng/g level in BaTiO₃-powders and precursors prepared by different sol-gel-methods was developed. The non-spectral matrix effects like suppression of the analyte signal and spectral effects like the formation of polyatomic ions like MO⁺, MAr⁺, MCl⁺ and M²⁺ which interfere with isotopes in isobar overlaps was investigated. To correct for these polyatomic ions a “blank solution” with the composition of the sample matrix was measured and the data were subtracted from the results of the sample; a standard addition method for calibration and ⁴⁵Sc, ⁸⁹Y, ¹⁰³Rh and ¹⁴¹Pr as internal standards to compensate the matrix effects were used and improvements in accuracy and precision were shown. The stability of the instrument and the detection limits in the presence of the barium and titanium matrix were established. In BaTiO₃ different amounts of trace impurities were detected in the μg/g to ng/g range. The main impurities are strontium and calcium. The source of the impurities are mainly the educts but it is shown that contamination during the synthesis process is also possible.     

溶胶-凝胶法制备钛酸钡超细粉体的研究

钛酸钡是一种非常重要的铁电材料 ,其合成方法主要分为固相反应法和液相反应法。传统的固相反应法是以ＴｉＯ2 和ＢａＣＯ3 经高温反应制取钛酸钡粉体 ,该法产品杂质含量高 ,颗粒粗 ,均匀性差 ,粉体烧结温度高。与高温固相反应相比 ,液相法合成的钛酸钡粉体具有化学纯度高 ,颗粒细小 ,粒度分布均匀等优点。特别是以醇盐为原料 ,采用溶胶 凝胶法制备的钛酸钡粉体 ,其性能非常优异 ,已为许多研究者所关注[1,2 ] 。文献[3 ] 报道了以异丙醇钛和醋酸钡为原料 ,采用溶胶 凝胶法制备钛酸钡物体的研究 ,但未见有以钛酸丁酯及醋酸钡为原料制备钛酸钡…     

Green up-conversion emission in Er3+:BaTiO3 sol-gel powders

Bright green emissions at 549 and 526 nm have been observed from sol-gel derived Er3+:BaTiO3 powders upon excitations at two near infrared (NIR) wavelengths of 973 and 816 nm. The decay characteristics were measured and studied. It was found that the predominant emission at 549 nm has very different lifetimes upon excitation at 973 and 816 nm, which was explained by the mechanisms of excited state absorption (ESA) of individual Er3+ ion and cooperative energy transfer (CET) between two near Er3+ ions for the up-conversion emission. Analysis also showed that 973-nm excitation is more effective for the green up-conversion emission.     

Trace metal impurities in catalysis

Metal-catalysed transformations are a powerful tool in organic chemistry and the enormous progress, which has been made in the last few decades, was one more time honoured by the Nobel Prize in Chemistry in 2010. Many metal-containing compounds have been applied in carbon-carbon and carbon-heteroatom bond formations. However, not every component originally claimed as catalyst turned out to be the active ingredient in the end. Sometimes trace metal impurities were the actual catalytic species. In this tutorial review, we will highlight recent findings in transition metal-catalysed cross-coupling reactions and detail several reports from the past, which illustrate that "trace metal catalysis" is not a newly discovered phenomenon.     

Bluish-white emission from radical carbonyl impurities in amorphous Al(2)O(3) prepared via the Pechini-type sol-gel process

Many efforts have been devoted to exploring novel luminescent materials that do not contain expensive or toxic elements, or do not need mercury vapor plasma as the excitation source. In this paper, amorphous Al2O3 powder samples were prepared via the Pechini-type sol-gel process. The resulting samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), photoluminescence (PL) excitation and emission spectra, kinetic decay, and electron paramagnetic resonance (EPR). The obtained amorphous Al2O3 powder samples annealed at 500 and 600 degrees C exhibit bright bluish-white emission centered at 430 and 407 nm, respectively. The luminescent mechanisms of the amorphous Al2O3 powder samples can be ascribed to the carbon-related impurities such as radical carbonyl species. The calculated band structure of the defective amorphous Al2O3 agrees well with the results of spectral analysis and the proposed luminescent mechanism.     

液相色谱/大气压化学电离飞行时间质谱分析氢化可的松中微量杂质

采用液相色谱/大气压化学电离飞行时间质谱测定氢化可的松对照品中微量杂 质，并采用源内碰撞诱导解离质谱进行了结构定性分析。方法简单，可靠，重现性 好。     

ICP-MS法测定金属镝中的非稀土杂质

用ICP-MS法对高纯金属镝中10种非稀土杂质Al、Fe、Ni、Ti、Co、Cd、Mn、Pb、Cu、Ba、Mg的测定进行了研究。估算了元素的测定下限;研究了酸度影响;并进行了不同方法的结果对照实验;采用In作内标,方法的加标回收率在80.5%-110.2%之间,相对标准偏差低于12%。     

A water-soluble precursor of BaTiO3 and transparent BaTiO3 thin-films prepared from the solution by a water-based dip-coating technique

A new water-soluble precursor of BaTiO₃ was prepared from citratoperoxotitanate and barium citrate as the Ti and Ba sources, respectively. The water-soluble precursor was easily solved in water to form a stable solution, which produced BaTiO₃ by heat-treatment at 500 °C and above. A water-based dip-coating technique demonstrated a potential application as the coating solution of BaTiO₃. Transparent BaTiO₃ films were formed on the quartz-glass substrates with an increment of typically 9 nm per coating with 0.05 mol dm^?3 solution. The transmittance of the 180 nm-thick film attained almost 90 % at the maximum and the overall transmittance was above 60 % over the visible region. The polycrystalline film was composed of BaTiO₃ grains smaller than 200 nm. Although the film was an insulator, it was not suited for the dielectric application because of the structural problems due to the relatively low density and the thinness of the BaTiO₃ layer. The BaTiO₃ pellet obtained from the water soluble precursor by condensation, pyrolysis and sintering showed the good dielectric properties with ε_r = 3,500 and tan δ = 0.027 with a sintering temperature of 1,375 °C.     

微波消解ICP-MS快速测定生物样品中的多种元素

建立了微波辅助HNO3消解样品,ICP-MS快速测定生物样品中Ti、Cr、Mn、Fe、Co、Ni、Cu、Zn、Ge、As、Se、Sr、Mo、Ag、Cd、I、Ba、Hg、Tl、Pb、Bi共21种微量及痕量元素。通过在线加入内标来校正基体效应和信号漂移对测量所造成的影响。各元素线性相关系数在0.9990以上,RSD小于6.0%。用本方法对国家标准样品GBW07601a(头发),GBW10010(大米),GBW10016(茶叶),GBW10023(紫菜)进行分析,结果满意。方法能满足生物样品痕量分析的要求。     

LiNbO3-based piezoelectric ceramics prepared from sol-gel derived powders

Pure and sodium-modified lithium niobates were synthesized using a “mixed alkoxide-acetate” sol-gel route from niobium pentaethoxide, lithium and sodium acetates. Calcination conditions of the gels were studied by XRD, TG-DTA, specific area measurements and SEM observations. Sintering experiments were carried out in air and appropriate thermal profiles were determined by dilatometry and density measurements. High final densities (up to 96–97%) were obtained. Lithium rich ceramics show piezoelectric activity up to 850 °C.     

电感耦合等离子体质谱法测定土壤中痕量铊的方法研究

采用电感耦合等离子质谱法(ICP-MS)测定土壤中的痕量铊,并对前处理方法进行研究,建立了一种使用HNO_3-H_2O_2-HF酸消解体系测量土壤中痕量铊的方法。该方法在0.00~5.00μg/L范围内线性良好,相关系数为0.999 8,方法检出限为0.1 ng/kg,对4份铊土壤标准样品测定的结果均在保证值范围内,RSD为1.8%~6.6%,2份土壤实际样品的加标回收率为95.4%~102.4%。     

电感耦合等离子体质谱法测定原油中微量元素

原油样品用硝酸和过氧化氢经高压密闭消解罐消解处理,采用电感耦合等离子体质谱法测定其中镁、铝、钒、铬、镍、铜、锌、钼、镉和铅等10种微量元素的含量。10种元素的检出限(3s)在0.012～0.300μg·g~(-1)之间。方法用于S-21油标准样品分析,测定值与认定值相吻合,相对标准偏差(n=5)在0.5%～5.0%之间。10种元素的回收率在93.3%～116.0%之间。     

Trace analysis and leaching dynamics of volcanic ash using NAA and ICP-MS

In 2010, Mt Merapi in Indonesia erupted releasing approximately 160 million tonnes of ash, roughly 75 % of which fell on or near Indonesia. With this extreme amount of a substance, even tract elements can become relevant. We have identified a variety of trace and major elements in this ash using instrumental neutron activation analysis. We have used a variety of techniques to improve our measurements, such as the use of epithermal neutrons and a Compton suppression system that resulted in accurate measurements of a wide range of trace elements including heavy metals. In order to better understand the leaching dynamics at which various elements can enter the local waters and have either enriching or toxic effects on the local ecosystem, we used a modified US Environmental Protection Agency Toxicity Characterization Leaching Procedure (TCLP) employing simulated rainwater.     

Titanium vacancy defects in sol-gel prepared anatase

Rietveld refinement of powder X-ray diffraction data for nanocrystalline anatase samples prepared by different sol-gel methods shows that the samples contain high concentrations (? 20%) of titanium vacancies, the levels of which decrease with increasing crystallite size. Debye function modelling of anatase clusters with different well-defined sizes, shapes and stoichiometries confirmed that the titanium vacancy concentrations obtained from the Rietveld refinements are correct. However, the Debye modelling showed that for nanocrystals smaller than ∼4 nm, the Rietveld modelling gives artificially high cell parameters. Density function theory calculations show that the titanium vacancies are stable defects when the vacancy sites are charge-balanced by incorporation of protons.     

碰撞反应池-电感耦合等离子体质谱法测定锆基合金中痕量镉

用电感耦合等离子体质谱法测定锆基合金中痕量镉。以氧气作为碰撞反应气,消除锆基体中多原子离子ZrOH对镉测定的影响。镉元素的质量浓度在5.0μg·L-1以内与其峰面积呈线性关系,检出限(3σ)为0.122μg·L-1。在0.5μg·L-1镉(Ⅱ)的水平上进行精密度试验,测定值的相对标准偏差(n=11)为2.8%。     

施主掺杂微量的Y_2O_3对BaTiO_3基样品的电性能及PTC效应的影响

为了适应市场对过热保护作用的PTC热敏陶瓷应用需求,采用了固相法的烧结工艺来制备PTC热敏陶瓷样品。主要研究了施主掺杂微量Y_2O_3的BaTiO_3基陶瓷在空气中1 340~1 360℃烧结0.5~1 h后其室温电阻率与升阻比(ρ_(max)/ρ_(min))随施主掺杂含量的变化关系。在实验中我们详细地阐述了BYT陶瓷样品的室温电阻率随施主掺杂含量(0.1≤x≤0.3 mol%)的变化曲线呈现类似"U"形曲线的半导化机理;根据Heywang-Jonker模型成功地解释了该样品的PTC效应随施主掺杂量的增加而呈现出先增加后减小的变化趋势的原因;讨论了烧结助剂SiO_2对BYT样品微观结构以及电性能的影响。     

Electrochemistry in solids prepared by sol-gel processes

Sol-gel chemistry provides a route to preparing inorganic polymers with ionically conducting properties by room temperature synthetic routes. The products, which are rigid solids, are well-suited as media for conventional electrochemical techniques such as cyclic voltammetry. This property, when combined with their ability to host a wide variety of species, has allowed development of a variety of devices of interest in electrochemistry and analytical chemistry. Examples include cathodes for fuels cells, electrochromic devices, biosensors, and amperometric sensors for analytes in the gas phase. In this review, the emphasis will be on reported applications to analytical chemistry; however, studies on the general properties of these materials and on their use in electrochemical science also will be summarized because they may provide the basis for further development of sensors.     

Trace element determination in vitamin E using ICP-MS

Vitamin E supplements are either isolated from plants sources or prepared synthetically. Isolation from plants includes eight different tocopherol structures. Vitamin E synthesis includes seven different stereoisomers, which involves the use of several catalysts that may lead to trace element contamination in the vitamin. The use of ICP-MS is an ideal technique for detecting these trace elements. However, the oily nature of the samples requires the development of a sample preparation methodology. This study was done upon the request of synthetic vitamin E manufacturers to test the trace metal purity of their samples. In this work, the comparison of an acid microwave digestion and emulsion preparation is discussed. Cromium, nickel, tin and lead were found in the synthetic vitamin E analyzed and 200, 60, 9 and 45 ppb were the concentrations found respectively for these elements.Digesting the samples gives slightly lower detection limits compared to the emulsion preparation.     

微波消解-ICP/MS测定烤烟中微量元素含量

以3 mL HNO3和2 mL H2O2的混合消解液对烟草样品进行微波消解,采用电感耦合等离子体质谱测定了烤烟中的Mn、Zn、Cu、Se、N i、Co、Cr、As、Cd、Pb 10种微量元素的含量.结果表明：方法的检出限均低于0.02μg/g,各元素测定的RSD（n=5）均小于3%,样品加标回收率为97.35%-101.30%.方法消耗试剂少,快速准确,适合烟草中多种微量元素的同时测定.     

Thermal behaviour of amorphous Li2ZrO3 prepared by sol-gel technique

The results of the investigations of thermal behaviour of Li₂ZrO₃, prepared in the amorphous state by means of sol-gel technique are demonstrated. The thermal treatment was carried out in air under constant heating rate of 5 deg·min^–1 and cooling rate of 2.5 deg·min^–1. The methods of DTA, TG, Emanation Thermal Analysis (ETA) and dilatometry were used, for characterization of the thermal behaviour in dynamic conditions. The X-ray diffraction patterns were used for characterization of the phase changes observed by TA Methods.

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Zusammenfassung Ergebnisse aus Untersuchungen des thermischen Verhaltens von Li₂ZrO₃, hergestellt mittels einer Sol-Gel-Technik im amorphen Zustand werden dargelegt. Die thermische Behandlung wurde in Luft bei einer konstanten Aufheizgeschwindigkeit von 5 Grad·min^–1 und einer Abkühlgeschwindigkeit von 2,5Grad·min^–1 durchgeführt. Zur Beschreibung des thermischen Verhaltens unter dynamischen Verhältnissen wurden DTA, TG, Emanationsthermoanalyse und Dilatometrie angewendet. Zur näheren Charakterisierung der bei TG beobachteten Phasenumwandlungen wurde Röntgendiffraktion verwendet.