Thermogravimetry and X-ray diffraction study of the thermal decomposition processes in Li2CO3-MnCO3 mixtures

The thermal decomposition processes taking place in solid state mixtures Li2CO3–MnCO3 (xLi=0.10–0.50, xLi=lithium cathionic fraction) have been studied (both in air and nitrogen flow) by thermogravimetric analysis (TGA), in order to get a better understanding of the different possible by-products, and by X-ray powder diffractometry (XRD) to assess the equilibrium compounds. As concerns the measurements performed in air, LiMn2O4 and excess Mn2O3 are the equilibrium products obtained for xLi up to 0.33. By 0.33xLi0.50 a mixture of LiMn2O4 and Li2MnO3 is obtained. In this case the TGA data show that an excess lithiated spinel phase (Li1+xMn2O4) is obtained as an intermediate phase. The measurements performed in nitrogen (xLi up to 0.33) show, when examined by TGA, the formation reaction of LiMn2O4 and Mn3O4 which is completed within about 720°C. At higher temperatures a rather complex reaction takes place between LiMn2O4 and the excess Li2O present at 720°C, leading to the formation of the compounds Li2Mn2O4 and LiMnO2 again with excess of Mn3O4. At higher mixture lithium content (0.33xLi0.50) LiMn2O4, Li2MnO3 and Mn3O4 form up to about 720°C. At higher temperatures LiMnO2 is by far the majority phase present which is formed by solid state reactions occurring between LiMn2O4 and Li2MnO3 and between Li2MnO3 and Mn3O4

TG/FT-IR: An Analysis of the Conditions Affecting the Combined TG/Spectral Response

The results of TG/FT-IR measurements performed on hydrated beta-cyclodextrin at different heating rates and with different carrier gas fluxes are reported. It is shown that the shape of the spectral curve and the its degree of matching with the DTG curves depend on both the TG heating rate and the carrier gas flow rate

Anatomia di una scatola nera. Quanto e come si finanzia l'alta formazione in Italia

The article provides a high-resolution picture of the allocation model that funds Italian academic institutions. It describes its technical aspects and analyzes in detail the 'standard cost', on which the 'basic quota' - the larger share of the budget - of funding is determined (or better, will be determined). This article sheds lights on some critical aspects of the overall theoretical model. Particular attention is devoted to the analysis of the nature and the functioning of the so-called 'perequative model' (aimed to balance major funding fluctuations), on which we express doubts. Moreover, through a detailed analysis of the 2016 and 2017 funds allocation, we illustrate its substantial distributive political failure. Our opinion is that the failure of the model is due also to its original unsustainability: its introduction in 2014 took place in a context of high underfunding of the system, that has till now remained unchanged

Solid state hydrogen storage in alanates and alanate-based compounds: a review

The safest way to store hydrogen is in solid form, physically entrapped in molecular form in highly porous materials, or chemically bound in atomic form in hydrides. Among the different families of these compounds, alkaline and alkaline earth metals alumino-hydrides (alanates) have been regarded as promising storing media and have been extensively studied since 1997, when Bogdanovic and Schwickardi reported that Ti-doped sodium alanate could be reversibly dehydrogenated under moderate conditions. In this review, the preparative methods; the crystal structure; the physico-chemical and hydrogen absorption-desorption properties of the alanates of Li, Na, K, Ca, Mg, Y, Eu, and Sr; and of some of the most interesting multi-cation alanates will be summarized and discussed. The most promising alanate-based reactive hydride composite (RHC) systems developed in the last few years will also be described and commented on concerning their hydrogen absorption and desorption performanc

Fundamental material properties of the 2LiBH4-MgH2 reactive hydride composite for hydrogen storage: (II) Kinetic properties

Reaction kinetic behaviour and cycling stability of the 2LiBH4-MgH2 reactive hydride composite (Li-RHC) are experimentally determined and analysed as a basis for the design and development of hydrogen storage tanks. In addition to the determination and discussion about the properties; different measurement methods are applied and compared. The activation energies for both hydrogenation and dehydrogenation are determined by the Kissinger method and via the fitting of solid-state reaction kinetic models to isothermal volumetric measurements. Furthermore, the hydrogen absorption-desorption cycling stability is assessed by titration measurements. Finally, the kinetic behaviour and the reversible hydrogen storage capacity of the Li-RHC are discussed.Fil: Jepsen, Julian. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Milanese, Chiara. Università degli Studi di Pavia; ItaliaFil: Puszkiel, Julián Atilio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Girella, Alessandro. Università degli Studi di Pavia; ItaliaFil: Schiavo, Benedetto. Università degli Studi di Palermo; ItaliaFil: Lozano, Gustavo A.. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Capurso, Giovanni. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Von Colbe, José M. Bellosta. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Marini, Amedeo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Kabelac, Stephan. Leibniz Universität Hannover; AlemaniaFil: Dornheim, Martin. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; AlemaniaFil: Klassen, Thomas. Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung; Alemani

Fundamental material properties of the 2LiBH4-MgH2 reactive hydride composite for hydrogen storage: (I) Thermodynamic and heat transfer properties

Thermodynamic and heat transfer properties of the 2LiBH4-MgH2 composite (Li-RHC) system are experimentally determined and studied as a basis for the design and development of hydrogen storage tanks. Besides the determination and discussion of the properties, different measurement methods are applied and compared to each other. Regarding thermodynamics, reaction enthalpy and entropy are determined by pressure-concentration-isotherms and coupled manometric-calorimetric measurements. For thermal diffusivity calculation, the specific heat capacity is measured by high-pressure differential scanning calorimetry and the effective thermal conductivity is determined by the transient plane source technique and in situ thermocell. Based on the results obtained from the thermodynamics and the assessment of the heat transfer properties, the reaction mechanism of the Li-RHC and the issues related to the scale-up for larger hydrogen storage systems are discussed in detail.Fil: Jepsen, Julian. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Milanese, Chiara. University of Pavia; ItaliaFil: Puszkiel, Julián Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Girella, Alessandro. University of Pavia; ItaliaFil: Schiavo, Benedetto. Universidad de Palermo; Argentina. Istituto per le Tecnologie Avanzate; ItaliaFil: Lozano, Gustavo A.. Helmholtz-Zentrum Geesthacht; Alemania. BASF; AlemaniaFil: Capurso, Giovanni. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Von Colbe, José M. Bellosta. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Marini, Amedeo. University of Pavia; ItaliaFil: Kabelac, Stephan. Leibniz Universität Hannover; AlemaniaFil: Dornheim, Martin. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Klassen, Thomas. Helmholtz-Zentrum Geesthacht; Alemani

Optimal hydrogen storage in sodium substituted lithium fullerides

A relevant improvement in the hydrogen storage capability of lithium fullerides is obtained by the co-intercalation of a small amount of sodium

Mechanothermal Solid-state Synthesis of Cobalt(II) Ferrite and Determination of its Heat Capacity by MTDSC

Cobalt ferrite (CoFe2O4) has been synthesized by a solid-state mechanothermal process, and its molar heat capacity has been determined. A stoichiometric mixture of CoC2O4 ・ 2H2O and FeC2O4 ・ 2H2O was subjected to a combination of mechanical activation (by high-energy milling) and thermal activation (by annealing at temperatures between 300 and 700 °C). The process was followed by thermogravimetric analysis and high-temperature X-ray powder diffraction. It has been shown that CoFe2O4 forms at all temperatures, though with different degrees of crystallization, while Co3O4 and Fe2O3 are the only products formed when starting from unmilled mixtures. The molar heat capacity of CoFe2O4 has been determined in the temperature range 60 - 400 °C by MTDSC. It has been shown that the molar CP values of CoFe2O4 samples produced at T ≥ 500 °C are close to each other while those of the samples produced at 300 and 400 °C are lower. Furthermore the CoFe2O4 samples prepared at T ≥ 500 °C show very similar microstructures

Solid State Synthesis of CaMnO3 from CaCO3-MnCO3 Mixtures by Mechanical Energy

Abstract A solid state synthesis of calcium manganite (CaMnO3) is described where equimolecular mixtures CaCO3:MnCO3 have been subjected to mechanical stress (high energy milling) so yielding CaCO3-MnCO3 solid solutions of nanometric particle size. TG measurements have shown that a link exists between milling time, the extent of non-stoichiometry and the milling-induced decomposition of MnCO3 to Mn3O4. A short (2 h) annealing at 850 °C performed on a sample mixture milled for 25 h leads to non-stoichiometric CaMnO3−x. No sure conclusion could be drawn for the stoichiometry of CaMnO3 obtained, under the same annealing conditions, from a mixture milled for longer time (150 h). No synthesis of CaMnO3 could be effected by long (48 h) annealing at 1200 °C of mixtures that had not been subjected to mechanical stress

Nanoconfined 2LiBH4eMgH2eTiCl3 in carbon aerogel scaffold for reversible hydrogen storage

Nanoconfinement of 2LiBH4–MgH2–TiCl3 in resorcinol–formaldehyde carbon aerogel scaffold (RF–CAS) for reversible hydrogen storage applications is proposed. RF–CAS is encapsulated with approximately 1.6 wt. % TiCl3 by solution impregnation technique, and it is further nanoconfined with bulk 2LiBH4–MgH2 via melt infiltration. Faster dehydrogenation kinetics is obtained after TiCl3 impregnation, for example, nanoconfined 2LiBH4–MgH2–TiCl3 requires ∼1 and 4.5 h, respectively, to release 95% of the total hydrogen content during the 1st and 2nd cycles, while nanoconfined 2LiBH4–MgH2 (∼2.5 and 7 h, respectively) and bulk material (∼23 and 22 h, respectively) take considerably longer. Moreover, 95–98.6% of the theoretical H2 storage capacity (3.6–3.75 wt. % H2) is reproduced after four hydrogen release and uptake cycles of the nanoconfined 2LiBH4–MgH2–TiCl3. The reversibility of this hydrogen storage material is confirmed by the formation of LiBH4 and MgH2 after rehydrogenation using FTIR and SR-PXD techniques, respectively.Fil: Gosalawit Utke, Rapee. Helmholtz-Zentrum Geesthacht; Alemania. Suranaree University of Technology; TailandiaFil: Milanese, Chiara. Università degli studi di Pavia; ItaliaFil: Javadian, Payam. University Aarhus; DinamarcaFil: Jepsen, Julian. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Laipple, Daniel. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Karmi, Fahim. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Puszkiel, Julián Atilio. Helmholtz-Zentrum Geesthacht; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Jensen, Torben R.. University Aarhus; DinamarcaFil: Marini, Amedeo. Università degli studi di Pavia; ItaliaFil: Klassen, Thomas. Helmholtz-Zentrum Geesthacht; AlemaniaFil: Dornheim, Martin. Helmholtz-Zentrum Geesthacht; Alemani