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Abstract  

Pressureless sintering of CaCO3 was carried out, with Li2CO3 (from 0.5 to 8 wt%) as an additive, under different pressures of CO2. Densification occurs between 600 and 700°C. Sintering above the eutectic temperature (T>662°C) leads to the decomposition of calcium carbonate and the materials become expanded. At 620° under 1 kPa of CO2, a relative density of 96% is reached. Li2CO3 enhances the densification process and grain growth of calcium carbonate. CO2 pressure slows down densification and grain growth kinetics. These results are explained by the influence of carbonate and calcium ion vacancies on the sintering mechanisms.

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Abstract  

The kinetics of the interaction between lithium carbonate and silica with various degrees of dispersion was investigated by TG and DTA methods. It was found that the utilization of pyrogenic silica with a specific surface area of about 300 m2g-1 instead of aerosil with one of 175 m2g-1 leads to an increase of the reaction rate between lithium carbonate and silica, which depends on the formation and growth of lithium orthosilicate crystals in the first stage, and is conditioned by the diffusion of lithium and oxygen ions through the lithium orthosilicate layer formed at temperatures above 800 K. This supposition is supported by the kinetic analysis results obtained with the use of the different models. The optimal regime of heating is recommended.

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Abstract  

The binary system Li2CO3–BaCO3 was studied by means of differential thermal analysis (DTA), thermogravimetry (TG) and X-ray phase analysis. The composition of carbonate and CO2 partial pressure influence on the thermal behavior of carbonate were examined. It was shown that lithium carbonate does not form the substitutional solid solution with barium carbonate, however the possible formation of diluted interstitial solid solutions is discussed. Above the melting temperature the mass loss is observed on TG curves. This loss is the result of both decomposition of lithium carbonate and evaporation of lithium in Li2CO3–BaCO3 system. Increase of CO2 concentration in surrounding gas atmosphere leads to slower decomposition of lithium carbonate and to increase the melting point.

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Abstract  

The mutual reactivity in mixtures containing Nasicon (Na3Zr2Si2PO12) or YSZ (ZrO2:Y2O3) solid electrolytes with Li2CO3 or Li2CO3:BaCO3 sensing electrode materials was investigated using simultaneous DTA and TG and ex situ XRD techniques. The uncontrolled chemical reaction is suspected to be responsible for the instability of electrochemical gas sensors constructed from these materials. DTA and TG results obtained for Nasicon-carbonate mixtures indicate the possibility of reaction in the temperature range from about 470 to 650C, which overlaps the sensor operating temperature range (300–525C). The results obtained for YSZ-carbonate mixtures indicate that reaction between carbonate and the ZrO2 takes place at higher temperatures and cannot explain the instability drift of investigated sensors. The mechanism of observed reactions in systems studied is also discussed.

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Abstract  

The reactivity of recoil tritium in the T-for-H substitution was studied in mixtures of benzene, hexane, cyclohexane or cyclohexane-d12 with lithium carbonate which were irradiated in a reactor. The relative rates per C–H bond of hexane and cyclohexane to benzene were somewhat less than one third. The H/D isotope effect in cyclohexane was given as 1.14.

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Abstract  

LiFe5O8 solid-phase synthesis at radiation-thermal (RT) annealing of lithium carbonate and iron oxide mechanical mixture was studied using thermal analysis (TG/DSC) and X-ray powder diffraction (XRD) techniques. The RT annealing was proceeded with high-power pulsing beam of 2.4 MeV electrons. It was shown that RT synthesis of the precursors considerably enhances the reactivity of the solid system within temperatures range 600–800 °C. In particular, lithium ferrite can be obtained at lower temperatures than those necessary in the absence of RT annealing.

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Lithium salts are efficiently used for treatment of psychiatric disorders. However, prolonged treatment frequently involves adverse side-effects. In the present work, effects of lithium carbonate administration on some biochemical parameters were studied in male mice. Lithium carbonate (20, 40 or 80 mg/kg body weight, corresponding to 3.77, 7.54 or 15.08 mg Li element/kg body weight, respectively) was injected daily for 14 or 28 days. The following parameters were recorded: water consumption, body weight, lithium and testosterone serum concentrations, activities of catalase (CAT), superoxide-dismutase (SOD) and glutathione-peroxidase (GPX) and level of lipid peroxidation (expressed as TBARS) in liver was performed. Lithium treatment, especially at the highest dose for 28 days, was found to induce weight gain, polydipsia and a significant decrease of plasma testosterone level. Lipid peroxidation level and activities of SOD and GPX were increased in liver which suggests a perturbation of the antioxidative status. Our results indicate that subchronic exposure to lithium, which induces weight gain and polydipsia under our experimental conditions, also damages the male reproductive system and triggers an oxidative stress in the liver.

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Abstract

36 kinds of mixed carbonate molten salts were prepared by mixing potassium carbonate, lithium carbonate, sodium carbonate in accordance with different proportions. The data of melting point and latent heat are measured by the analysis of DSC curves of 36 kinds of salts, which show that the majority of ternary carbonate’s melting points are close at around 400 °C. 24 kinds of eutectic molten salts were selected among 36 kinds of molten salts. With high latent heat, ternary carbonate salt has the potential to be employed for phase change thermal storage. The costs for phase change thermal storage of 24 kinds of carbonate salts are calculated. Finally, 13 kinds of ternary carbonate salts with lower cost for phase change thermal storage are recommended, where there are 6 kinds of mixed carbonates have the considerably larger latent heat of melting.

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Abstract  

By spiking the sample and analyte standard with a compound containing a common non-analyte element, to which a relative deceleration property for 5 MeV protons has been ascribed, relative deceleration values for these target materials could be obtained by PIGE. These values are used to correct for matrix effects in elemental analysis using PIGE techniques. Following this approach, the determination of magnesium in the reference standards BSC 308, Cr XXXI, SARM 8 and SARM 9 was investigated by measuring the yield of the 390 keV25Mg p(2,1) and 585 keV25Mg p(1,0) -rays. Lithium carbonate was employed as the non-analyte spike and magnesium oxide as the analyte comparator.

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The thermal decomposition of iron(II) sulphate heptahydrate was carried out in air under dynamic conditions in the presence of lithium, sodium, potassium and rubidium carbonates. The decomposition path in the presence of lithium carbonate differs from that in the presence of the other carbonates. In the presence of lithium carbonate, the heptahydrate loses all the water molecules before entering into reaction with the carbonate. The anhydrous sulphate then reacts with the carbonate, presumably to form iron(II) carbonate, which in turn undergoes decomposition — oxidation via magnetic oxide to ferric oxide. In the case of the other carbonates, iron(II) sulphate enters into reaction with the carbonate in question even before dehydration is complete, to form ferrous carbonate, which in turn reacts with the moisture still present to form green iron(II) hydroxide. This compound then undergoes decomposition — oxidation reactions via magnetic oxide to ferric oxide.

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