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The Zaltoprofen/4,4′-Bipyridine system gives rise to two co-crystals of different compositions both endowed - in water and in buffer solution at pH 4.5 - with considerably higher solubility and dissolution rate than the pure drug. The qualitative and quantitative analysis of the DSC measurements, carried out on samples made up of mixtures prepared according to different methodologies, allows us to elaborate and propose an accurate thermodynamic model that fully takes into account the qualitative aspects of the complex experimental framework and which provides quantitative predictions (reaction enthalpies and compositions of the co-crystals) in excellent agreement with the experimental results. Co-crystal formation and cocrystal compositions were confirmed by X-ray diffraction measurements as well as by FT-IR and NMR spectroscopy measurements. The quantitative processing of DSC measurements rationalizes and deepens the scientific aspects underlying the so-called Tammann's triangle and constitutes a model of general validity. The work shows that DSC has enormous potential, which however can be fully exploited only by paying adequate attention to the experimental aspects and the quantitative processing of the measurements.

The eco-friendly method of kneading was here used to synthesize a cocrystal of probenecid, an uricosuric drug used in treating gout and hyperuricemia, with the aim to improve its pharmaceutical behavior. Benzamide was selected as a co-former showing functional groups favorable to the formation of supramolecular synthons with the active principle. The kneading product was characterized by a range of experimental techniques (microscopic, spectroscopic, thermal and diffractometric) all proving the formation of the new multicomponent crystal. In particular, the FT-IR and NMR techniques showed that an important change of hydrogen bonds network takes place in the kneading product and that the acid–acid interaction in the pristine drug is replaced with the related acid-amide one in the cocrystal. The cocrystal solubility and dissolution rate measured in several biorelevant fluids showed an actual improvement with respect to the pure drug.

A detailed characterization of the polymorphs constituting cathode materials, both before and after cell cycling, is mandatory to develop more stable and powerful lithium batteries. In many cases, e.g., for transition metal lithium silicates, standard diffraction techniques cannot give a clear-cut response. Here we show that broadband adiabatic fast MAS NMR can give unique information in the case of model Li2(Mn,Fe)SiO4 high-capacity cathode materials. By coupling 7Li and 29Si 1D and 2D spectra, we are able to address polymorphs speciation also in the mixed Mn/Fe compositions, which is a nearly impossible task for X-rays and neutrons diffraction. We finally discuss the conditions under which this approach is useful when applied to rare nuclei such as 29Si.

To improve the electrochemical performance of the LiNi0.5Mn1.5O4 high voltage cathode for Lithium Ion Batteries, silicon-doped LiNi0.5Mn1.5−xSixO4 samples (0.00≤x≤0.35) were prepared by different synthesis routes (solid-state reaction and ball milling) and characterized. The X-ray diffraction investigation and structural and profile Rietveld refinement put into evidence that effective spinel doping is obtained by the ball milling route: a solubility limit is achieved for x=0.10 and silicon preferentially occupies the 8a tetrahedral site of the spinel structure, thus causing lithium to occupy both the tetrahedral and octahedral sites. In contrast, segregation of lithium silicates in the solid-state synthesis is observed. SEM images show that, independent on the synthesis method, silicon controls the particles morphology and grain size. The doped samples show improved electrochemical performances, which can be ascribed to the role of silicon in increasing cations disorder and controlling particles size

Rechargeable all solid-state lithium batteries are a promising technology for the next generation of safer batteries. In this context, strict requirements are placed on the electrolytes, among which is emerging the Li7La3Zr2O12 garnet, chiefly for the relationships among synthesis conditions and phase stability. Here, the structural modifications of the low temperature (LT) Li7La3Zr2O12 cubic form were investigated by using in situ X-Rays diffraction analysis. In particular, we studied the role of both temperature and atmosphere (air or argon) on phase stabilization. In argon flow, the LT phase is stable under 750 C, and it transforms into the tetragonal one at lower temperature. In air, it partially decomposes to La2Zr2O7 due to Li loss above 250 C. ICP-OES analysis confirmed that garnet stoichiometry was maintained in argon, whereas in air lithium loss occurred. The structural transformations are driven by the CO2 absorbed in the LT structure that can form Li2CO3 and/or La2(CO3)3 so causing stoichiometry changes responsible of the structural evolution

Organosulfonic modified SBA-15 silicas are promising catalysts for a wide spectrum of organic reactions. In particular, their catalytic activity seems to be effective only when large amounts of functional groups are anchored to the silica skeleton. However, there is evidence that the ordered mesostructure is retained only for contents of sulfonic units not exceeding 20 mol%. In this paper, for the first time to our knowledge, we fully address the gradual structural disordering mechanisms of the SBA-15 silica functionalised with increasing amounts of propylsulfonic groups in the compositional range 0-70 mol%. This investigation was carried out by means of a multi-technique wide approach including thermal analysis, TEM, XRD, N2 adsorption, FTIR/Raman and solid-state multinuclear NMR. We obtained detailed information on the structural modifications of these hybrid systems as a consequence of the sulfonation process. In particular, we showed that high functionalization degrees lead to inhomogeneous materials made of inorganic or low-functionalized clusters where the SBA-15 structure is likely retained, and hybrid clusters where the hexagonal mesoporous structure is destroyed. Moreover, full conversion of -SH into -SO3H groups is efficient until 20 mol% functionalization. In fact for higher sulfonation degrees, the formation of S-S bridges becomes a competitive mechanism, which is predominant in the sample SO3H70%, where only about 20% of the introduced organic moieties are actually oxidized. Therefore, to push sulfonic functionalization above 20 mol% is not necessarily useful, at least for applications where ordered mesoporous structure is mandatory, such as in catalysis or in membranes for polymer fuel cells.

Li-air batteries are considered one of the future systems of choice for massive energy storage in automotive and smart grids. In this chapter, we will describe the cell designs developed up to now, with emphasis on aqueous and nonaqueous aprotic electrolyte architectures. Then, we will focus the attention on the cathode compartment, and the carbon-based nanomaterials (including nanotubes and graphene) employed will be critically discussed.

Electron paramagnetic resonance (EPR) and static magnetic susceptibility measurements were carried out on lanthanum-manganese substituted (up to 10 mol%) strontium titanate polycrystalline samples. X-ray diffraction (XRD) analysis revealed in each sample a single cubic perovskite phase with a different lattice parameter. Only weak and narrow EPR signals from a small fraction of Mn2+ and Mn4+ ions were observed when the La and Mn content did not exceed 5 mol%, indicating the nearly complete stabilisation of the Mn3+ oxidation state. Heavily substituted samples showed another EPR signal, very broad and with intensity and resonance field strongly temperature dependent. For these samples, a complex dynamics of Mn3+ stabilisation is suggested, supported by micro-Raman data. (C) 2000 Published by Elsevier Science Ltd.

Electron paramagnetic resonance (EPR) and static magnetization data on manganese substituted (up to 3 mol%) strontium tintanate (Mn:SrTiO3) samples are presented. Four EPR signals are observed from different Mn4+ and Mn2+ sites. The behavior of their intensity vs. temperature is discussed. It suggests the presence of antiferromagnetic interactions in heavily Mn doped grain boundaries. X-ray diffraction analysis shows two coexisting perovskite-type phases, whose abundance depends on the Mn content. (C) 2000 Elsevier Science Ltd. All rights reserved.

Magnetic susceptibility measurements and electron paramagnetic resonance spectra of samples prepared from the reactive system MnO/Li2CO3 with different starting Li cationic fraction cursive Greek chi are analyzed, taking into account the structural and compositional information provided by x-ray diffraction. Parent phases, as Mn2O3, Mn3O4 and Li2MnO3, arise together with the lithium-manganese spinel as a result of Li-deficiency or Li-excess with respect to the cursive Greek chi = 0.33 composition pertinent to the stoichiometric LiMn2O4 spinel. The data show that the spinel phase can sustain a partial Li-Mn substitution in the cation sites, according to compositional models described, for cursive Greek chi > 0.33, by Li1+yMn3+1-3yMn4+1+2yO4 (Li-rich spinel) and, for cursive Greek chi < 0.33, by Li1-|y|Mn2+|y|Mn3+1+|y|Mn4+1-|y|O4 (Li-poor spinel). Paramagnetic resonance data of the Li-poor spinel phase are analyzed to discuss the possible oxidation state of Mn in the tetrahedral site.

EPR data of ordered solid solutions of lithium nickel oxides are reported as a function of the lithium content. The features of the signal and the EPR centre density are analysed by a model of dynamical trapping of holes in [Ni2+-O-Ni2+)-h+] complexes. The possible origin of the interactions responsible for the magnetic ordering and some features of the transport properties are also discussed.

One of the most relevant negative characteristics of high-capacity cathodes for lithium batteries is indeed non-flat voltage-time (V-t) or voltage-capacity (V-C) behaviour during charge-discharge. A clear rationale for this behaviour has not yet been addressed in the literature. Here, by means of density functional theory (DFT) calculations corroborated by basic experimental electrochemical characterization, we investigated both the thermodynamic and the kinetic aspects relevant to voltage variations during charge-discharge of Li2FeSiO4 intended as a model case. A simple physical model allowed us to take into account all the experimental evidence. We suggested that voltage deviations from its theoretical value are due to the formation of undesired delithiated structures caused by concentration gradients. We also related voltage behaviour to relevant quantities such as reaction energies, lithium diffusion coefficients, and particle size, so suggesting some strategies for optimization of materials

In this work we reported, for the first time, the preparation by radio frequency sputtering and the electrochemical characterization of Li/M/Si/O thin films (M 1⁄4 Fe, Mn), as positive electrodes for lithium microbatteries. The deposited films were amorphous both in case of pure iron and mixed iron/manganese compositions. The electrochemical performances, in terms of capacity values and coulombic efficiency, were comparable to those currently reported for the corresponding crystalline bulk materials. In particular, capacities of the order of 50 mAh g1 were obtained at 2.5 C with coulombic efficiency near 90% by using a standard liquid electrolyte. Our preliminary electrochemical results, together with the easiness of preparation, suggested that Li/M/Si/O thin films could be interesting candidates as cathodes in lithium microbatteries