复合熔剂熔融-ICP-AES法测定萤石中钾钠硅铁磷

采用四硼酸锂偏硼酸锂复合熔剂高频熔融炉熔融硝酸浸取方式溶解萤石,用已知含量萤石标准物质制作标准工作曲线,应用ICP-AES法联合测定萤石中硅、磷、钾、钠、铁组分含量。选择两条谱线进行分析,方法检出限在0.025～8.7mg/g之间,样品检测5次的相对标准偏差小于17.98％,测定值与证书值相吻合。     

X-射线荧光光谱法分析硅质耐火材料的主次成分

采用硅石标准样品作为校准样品,建立了熔融制样X-射线荧光光谱法测定硅质耐火材料中SiO2、Al2O3、CaO、MgO、P2O5、Fe2O3、TiO2、K2O、Na2O的方法.采用熔融法为样品片和校准片的制备方法,选择四硼酸锂-偏硼酸锂(质量比为67∶33)为助熔剂,1.00mL LiBr溶液为脱模剂,熔融温度1100℃...     

复合熔剂熔融-电感耦合等离子体原子发射光谱(ICP-AES)法测定萤石中钾、钠、硅、铁、磷

采用四硼酸锂+偏硼酸锂复合熔剂,高频熔融炉熔融,硝酸浸取方式溶解萤石,用已知含量萤石标准物质制作标准工作曲线,用ICP-AES法联合测定萤石中钾、钠、硅、铁、磷组分含量。选择两条谱线进行分析,方法检出限在0.001～0.22mg/L,样品检测5次的相对标准偏差小于9.3%,测定值与证书值相吻合。     

一体化碰撞反应(iCRC)-电感耦合等离子体质谱(ICP-MS)法测定地质样品中痕量稀土元素

钡以及轻稀土元素氧化物对中、重稀土元素的干扰一直是质谱测试中存在的问题。建立了石墨粉垫底碳酸钠-硼酸混合熔剂熔融前处理样品,以103 Rh为内标校正,一体化碰撞反应-电感耦合等离子体质谱(ICP-MS)法测定地质样品中稀土元素含量的方法。探讨了碳酸钠-硼酸混合熔剂熔融前处理样品注意事项、碰撞模式下碰撞气流量和离子透镜的参数优化、干扰校正实验等问题,采用国家标准物质GBW07403、GBW07405、GBW07427、GBW07429验证,实验结果表明,各元素线性关系良好,相关系数均大于0.999,方法检出限在0.01～0.03mg/kg,相对误差为0.13%～7.1%,相对标准偏差为0.79%～6.6%,测定结果与标准值相吻合。对实际样品分析,得到平滑的球粒陨石归一化的稀土元素配分曲线,证明测定结果是合理可信的。方法熔剂用量少,过程空白低,对器皿的侵蚀小,直接加热浸取,简化了操作过程,适用于大批量地质样品中稀土元素的测定。     

火焰原子吸收法测定铬质引流砂中铁镁含量

建立了火焰原子吸收光谱法连续测定铬质引流砂中铁、镁含量的分析方法。试样以碳酸钠-硼酸混合熔剂熔融,以盐酸浸取,在校准溶液中加入重铬酸钾和二氧化硅进行基体匹配,抵消基体影响。对熔剂、熔融温度等进行讨论,确立了最佳分析条件,对样品多次测定,其测定结果与国家标准测定方法测定的结果基本一致,相对标准偏差(RSD,n=11)小于0.3%,加标回收率在98.7%~101%。方法具有操作简便、准确性好、速度快、成本低等特点。     

火焰原子吸收光谱法测定铬质引流砂中铁镁含量

建立了火焰原子吸收光谱法连续测定铬质引流砂中铁、镁含量的分析方法。试样以碳酸钠-硼酸混合熔剂熔融,以盐酸浸取,在校准溶液中加入重铬酸钾和二氧化硅进行基体匹配,抵消基体影响。对熔剂、熔融温度等进行讨论,确立了最佳分析条件,对样品多次测定,其测定结果与国家标准测定方法测定的结果基本一致,相对标准偏差(RSD,n=11)小于0.3%,加标回收率在98.7%~101%。方法具有操作简便、准确性好、速度快、成本低等特点。     

X射线荧光光谱法分析镁砂的主次成分

采用镁砂标准样品作为校准样品,建立了熔融制样X射线荧光光谱法测定镁砂中MgO,Al2O3,SiO2,CaO,P2O5,Fe2O3的方法。采用熔融法为样品片和校准片的制备方法,选择四硼酸锂-偏硼酸锂（67＋33）为助熔剂,1.00mL LiBr溶液为脱模剂,熔融温度为1 100℃,熔融时间20min。对镁砂样品测定的相对标准偏差（RSD）小于3%,对不同镁砂标准样品进行测定,方法的测定结果与认证值相吻合。     

熔融制样-X射线荧光光谱法测定锆钛矿中主次成分

锆钛矿是一种稀缺资源,也是一种战略性矿产,准确分析锆、钛及其共伴生有用有害元素含量对综合评价锆钛矿资源具有重要意义。本文采用稀释比1:20的四硼酸锂-偏硼酸锂混合熔剂,先700℃预氧化7min,再1050℃熔融19min制样,建立了熔融制样-X射线荧光光谱法测定锆钛矿中SiO2、Al2O3、Fe2O3、CaO、MgO、MnO、TiO2、K2O、Na2O、P2O5、ZrO211种主次成分的分析方法。该方法解决了锆钛矿石前处理过程中锆钛易水解,分析周期长的问题。采用标准样品加入光谱纯的方式配制锆钛矿的标准系列样品解决锆钛矿石标准样品不足的问题。本方法各组分的检出限在0.004~0.13%之间,各组分测定结果的相对标准偏差(RSD,n=12)在0.060~2.6%之间。采用本方法对实际样品进行测定,测定值与传统方法测定值一致,并具有操作简便,分析周期短的优点。     

一体化碰撞反应 (iCRC)-电感耦合等离子体质谱法测定地质样品中痕量稀土元素

钡以及轻稀土元素氧化物对中、重稀土元素的干扰一直是质谱测试中存在的问题。建立了石墨粉垫底碳酸钠-硼酸混合熔剂熔融前处理样品,以_¹⁰³Rh为内标校正,一体化碰撞反应-电感耦合等离子体质谱仪法测定地质样品中稀土元素含量的方法。探讨了碳酸钠-硼酸混合熔剂熔融前处理样品注意事项、碰撞模式下碰撞气流量和离子透镜的参数的优化、干扰校正试验等问题,采用国家标准物质GBW07403、GBW07405、GBW07427、GBW07429验证,实验结果表明,各元素线性关系良好,相关系数均大于0.999,方法检出限在0.01～0.03mg/kg之间,相对误差为0.13%～7.1%,相对标准偏差为0.79%～6.59%,测试结果与标准值相吻合。对实际样品分析,得到平滑的球粒陨石归一化的稀土元素配分曲线,证明测定结果是合理可信的。该方法熔剂用量少,过程空白低,对器皿的侵蚀小,直接加热浸取,简化了操作过程,适用于大批量地质样品中稀土元素的测定。     

X射线荧光光谱法分析镁砂中的主次成分

采用镁砂标准样品作为校准样品,建立了熔融制样X射线荧光光谱法测定镁砂中MgO,Al2O3,SiO2,CaO,P2O5,Fe2O3的方法。采用熔融法为样品片和校准片的制备方法,选择四硼酸锂-偏硼酸锂(67+33)为助熔剂,1.00mL LiBr溶液为脱模剂,熔融温度为1 100℃,熔融时间20min。对镁砂样品测定的相对标准偏差(RSD)小于3%,对不同镁砂标准样品进行测定,方法的测定结果与认证值相吻合。     

Higher hydrates of lithium chloride,lithium bromide and lithium iodide

For lithium halides, LiX (X = Cl, Br and I), hydrates with a water content of 1, 2, 3 and 5 moles of water per formula unit are known as phases in aqueous solid–liquid equilibria. The crystal structures of the monohydrates of LiCl and LiBr are known, but no crystal structures have been reported so far for the higher hydrates, apart from LiI·3H₂O. In this study, the crystal structures of the di‐ and trihydrates of lithium chloride, lithium bromide and lithium iodide, and the pentahydrates of lithium chloride and lithium bromide have been determined. In each hydrate, the lithium cation is coordinated octahedrally. The dihydrates crystallize in the NaCl·2H₂O or NaI·2H₂O type structure. Surprisingly, in the tri‐ and pentahydrates of LiCl and LiBr, one water molecule per Li⁺ ion remains uncoordinated. For LiI·3H₂O, the LiClO₄·3H₂O structure type was confirmed and the H‐atom positions have been fixed. The hydrogen‐bond networks in the various structures are discussed in detail. Contrary to the monohydrates, the structures of the higher hydrates show no disorder.     

Multiple lithium exchange under lithium cationization of cyclodextrins

Multiple lithium exchange is observed during electrospray ionization of alpha-, beta- and gamma-cyclodextrins from aqueous methanolic solution containing LiOH. Apart from [M + Li](+) and [M + nLi - (n - 1)H](+) ions, abundant multiply lithiated doubly charged ions corresponding to [M + nLi - (n - 2)H](2+) ions were observed. At least six lithium exchanges in alpha-cyclodextrin, seven in beta-cyclodextrin and eight in gamma-cyclodextrin were noted. The propensity of multiply lithiated doubly charged ions is much less in the open-ended maltoheptaose. It appears that during droplet or cluster formation and subsequent desolvation, LiOH trapped in the cavity of cyclodextrin reacts to form multiply lithiated ions. The singly charged [M + Li](+) and doubly charged [M + 2Li](2+) ions fragment by glycosidic cleavages, giving B series of ions, whereas the multiply lithiated ions fragment by cross ring cleavages ((2, 4)A or (O, 2)X) followed by glycosidic cleavage. From the tandem mass spectra, it appears that a maximum of two lithium exchanges occur in one sugar unit in these cyclodextrins.     

Electrochemistry of a lithium electrode in lithium polysulfide solutions

The effect of lithium polysulfides on the cycling of a lithium electrode and the corrosion rate of lithium cathodic deposits in sulfolane electrolytes is studied. Lithium polysulfides are found to affect the shape of polarization curves, the overpotential of electrode processes, and the cycling time. The presence of lithium polysulfides in electrolyte systems increases the cycling time of a lithium electrode and positively affects the quality of lithium cathodic deposits. A suggested reason for the positive effect of lithium polysulfides is the appearance of a surface film on metallic lithium: this film has quite high protective properties but does not inhibit electrochemical processes.     

Synthesis of lithium metal silicates for lithium ion batteries

Synthesis strategies, nanostructures, and different electrochemical performances are prominent features of rechargeable batteries. Three types Li₂MSiO₄ cathode metarials for lithium ion batteries:Li₂FeSiO₄, Li₂MnSiO₄, and Li₂CoSiO₄ are scientifically discussed, and the comprehensive summaries and evaluations are given in this review.     

Volumetric determination of lithium in lithium carbonate and nitrate and in lithium ferrites in non-aqueous media

Summary Lithium carbonate was titrated after dissolution in a glacial acetic acid/carbon tetrachloride mixture with 0.05 N perchloric acid in glacial acetic acid in the presence of gentian violet indicator. In the case of lithium nitrate the nitrate was firts reduced with ascorbic acid and the lithium titrated in an acetic anhydride/glacial acetic acid medium with the same measuring solution and indicator. The lithium content of lithium ferrites and lithium-nickel-zinc ferrites was measured after the extraction of iron and nickel by means of methyl-isobutyl ketone in a glacial acetic acid/carbon tetrachloride solution in the presence of tropeoline OO/methylene blue indicator mixture.

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Volumetrische Bestimmung von Lithium in Lithiumcarbonat und -nitrat sowie in Lithiumferriten in nichtwärigem Medium

Zusammenfassung Lithiumcarbonat wird nach Auflösung in Eisessig/Tetrachlorkohlenstoff mit 0,05 N Perchlorsäure in Eisessig titriert, wobei Gentianaviolett als Indicator dient. Bei der Analyse von Lithiumnitrat wird zunächst das Nitrat mit Ascorbinsäure reduziert und dann die Titration mit Perchlorsäure gegen Gentianaviolett durchgeführt. Im Falle von Lithium- und Lithium-Nickel-Zink-Ferriten werden Eisen und Nickel durch Extraktion mit Isobutylmethylketon abgetrennt und anschließend wird mit Perchlorsäure in Eisessig/Tetrachlorkohlenstoff gegen ein Indicatorgemisch aus Tropäolin OO und Methylenblau titriert. Die Fehler liegen bei ± 0,5% für Carbonat und Nitrat und 0,5–1% für Ferrite.

     

Blue-shifted lithium bonds

A number of lithium bonding systems (X-LiY) have been found in which the X-Li bond is shortened due to the lithium bond formation.     

Electrochemical investigation of lithium intercalation into graphite from molten lithium chloride

Lithium reduction at a graphite electrode in molten lithium chloride was studied at temperatures from 650 to 900 °C using cyclic voltammetry and chronoamperometry. It was found that, during cathodic polarization, lithium intercalation into graphite occurred before deposition of metallic lithium started. This process was confirmed to be rate-controlled by the diffusion of lithium in the graphite. When the cathodic polarization potential was more negative than that for metallic lithium deposition, exfoliation of graphite particles from the electrode surface was observed. This was caused by fast and excessive accumulation of lithium intercalated into the graphite, which produced mechanical stress too high for the graphite matrix to accommodate. The erosion process was abated once the graphite surface was covered by a continuous layer of liquid lithium. These results are of relevance to the mechanism of carbon nanotube and nanoparticle formation by electrochemical synthesis in molten lithium chloride.     

The lithium intercalation into graphite from electrolyte and from solid lithium

The values of diffusion coefficient (D) of lithium in thermoexpanded graphite during cathodic intercalation from aprotic electrolyte, and upon direct contact with lithium metal, are measured. In the first case galvanostatic switch-on curves were registered, in the second case the method of x-ray diffraction was used. In the both cases D was close to 10^-10 cm²/s.Presented at the 3rd International Meeting "Advanced Batteries and Accumulators," June 16th–20th 2002, Brno, Czech Republic