Authors:F. Tétard, D. Bernache-Assollant, and E. Champion
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.
Authors:G. Zagorowsky, G. Prikhod'ko, V. Ogenko, and G. Koval'chuk
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.
Authors:P. Pasierb, R. Gajerski, S. Komornicki, and M. Rękas
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
Authors:P. Pasierb, R. Gajerski, S. Komornicki, and M. Rękas
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.
Authors:K. Oohashi, N. Nogawa, Y. Tanno, and N. Morikawa
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.
Authors:A. Surzhikov, A. Pritulov, E. Lysenko, A. Sokolovskiy, V. Vlasov, and E. Vasendina
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.
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.
Authors:Nan Ren, Yu-ting Wu, Tao Wang, and Chong-fang Ma
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.
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.
Authors:K. Shikano, A. Mori, M. Shimizu, T. Ohtsuki, H. Yuki, and K. Masumoto
We have studied the photon activation analysis of carbon in InF3-based fluoride, chalcogenide and tellurite glasses for fiber amplifiers, and especially the nuclear interference from a matrix
produced by (γ,n), (γ,2n), (γ,p) and (n,γ) reactions and a flow method for the rapid and simple separation of 11C. A chemical separation technique is indispensable for determining carbon, because seventeen radionuclides are observed in
these glasses. The flow method can sequentially be undertaken, the fusion of an irradiated sample with an oxidizer, the conversion
of 11C into 11CO2, and the absorption of 11C in ethanolamine solution. We used a mixture of Pb3O4 and B2O3 as the oxidizer. There is interference with the 11C measurement because 18F and 68Ga are produced in fluoride and chalcogenide glasses by the 19F(γ,n), 23Na(γ,αn) and 69Ga(γ,n) reactions, respectively, and also absorbed in ethanolamine solution. Therefore, this flow method can only be applied
to tellurite glasses. The chemical yield provided by the flow method was close to 100% when determining carbon in Japanese
Iron and Steel Certified Reference Materials (JSS) by using lithium carbonate as a standard sample. We determined that the
carbon concentrations in four kinds of tellurite glass were 7 to 14 ppm.