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In the present study, metronidazole was crystallized in several solvents, according to both the “cooling crystallization” and the “crystallization by non-solvent addition”. Particle properties, such as crystal habit, elongation ratio, and mean particle size, were determined by SEM analysis. Structural changes and development of polymorphic forms were excluded by both Differential Scanning Calorimetry (DSC) and X-Ray Powder Diffractometry (XRPD). Crystal habit (and thus elongation ratio) was typically influenced by both the solvent polarity index and the crystallization method: solvents with higher polarity index tended to promote acicular or stick-shaped crystals with a high elongation ratio, while isodimensional crystals were promoted by decreasing the polarity index, as was particle aggregation. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Ca2Fe2O5 powder samples, undoped and doped with Na+, Mg2+, Al3+, Ti4+, Ge4+, were prepared with different synthesis routes to investigate the origin of the weak ferromagnetic component reported in literature for calcium ferrite single crystals. XRPD and EPR measurements have shown the presence of Fe3O4 magnetite as impurity phase in all the samples. This ferrimagnetic phase deeply influences the magnetic behavior with features very similar to those reported in literature for Ca2Fe2O5, both powders and single crystals. Our results support the hypothesis that the weak ferromagnetic component observed in Ca2Fe2O5 can be also due to the presence of magnetite impurity traces in the samples.

Structural, microstructural, and spectroscopic properties of Ba6Zr2Ta8O30 (BZT) and Ba6Zr1.94M0.06Ta8O30 (M = Ni, Co, Fe, Mn, Cr) related doped compounds are reported. The distribution of Zr, Ta, and M dopant ions on the cationic sites and the M valence states are discussed on the basis of the results obtained by the application of the Rietveld method on X-ray powder diffraction (XRPD) patterns and by electron paramagnetic resonance. The micro-Raman spectra of pure and doped BZT, reported and discussed for the first time, confirm the capability of the lattice to host transition cations in a glasslike matrix. The particle size effects of the samples are investigated by analyzing XRPD line broadening and scanning electron microscopy observations. Comparisons with the isostructural pure and doped Ba6Ti2Nb8O30 compounds are also reported.

Lithium-ion batteries are by far the most important storage devices available on the market. At present, they dominate the sector of portable electronics and are the solution of choice in the automotive sector. Other important applications are also foreseen, including storage in electric grids. However, these future markets do require energy density higher than lithium-ion batteries could reasonably deliver in the near future. To this end, other lithium-based chemistries are currently under study, including lithium–air (oxygen) and lithium–sulfur. In this chapter, we will briefly discuss the state-of-the-art and the major scientific and technological challenges underlying the development of lithium-ion and, chiefly, post lithium-ion batteries.

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.

Pure and doped Ba 6 Ti 2 Nb 8 O 30 (BTN), obtained by substituting M = Cr, Mn, or Fe on the Ti site (Ba 6 Ti 2-x M x Nb 8 O 30 , x = 0.06 and 0.18) and Y and Fe on the Ba and Ti sites, respectively (Ba 6-x Y x Ti 2-x Fe x Nb 8 O 30 , x = 0.18), are synthesized. The influence of cation doping on the local structure, the cation oxidation state, and the possible defect formation able to maintain the charge neutrality are investigated by spectroscopic (electron paramagnetic resonance (EPR) and micro-Raman), structural (X-ray powder diffraction) and transport (impedance spectroscopy, thermoelectric power) measurements, in the temperature range of 300-1200 K in air and N 2 flow. Starting from the valence state of the doping ions (Fe 3+ , Cr 3+ , and Mn 2+ ), determined by EPR, and from thermoelectric power measurements, evidencing a negative charge transport, different charge-compensating defect equilibria, based on the creation of positive electron holes or oxygen vacancies and electrons, are discussed to interpret the conductivity results.

The synthesis of pure and Cr-doped nanosized LiMn 2 O 4 particles has been carried out by solid-state process on high-energy ground mixtures. In situ X-ray analysis demonstrates the spinel forms as single phase at 623 K passing through the Mn 3 O 4 precursor at temperatures as low as 573 K. In the doped high-energy ground mixture Li-rich spinel phase forms at 623 K and Cr ions insert in the spinel octahedral site only at 723 K. A mean particle size value of 60 A, quite independent of the reaction time, is obtained for T

The dopant role on the electric and dielectric properties of the perovskite-type CaCu3Ti4O12 (CCTO) compound is evidenced. Impedance spectroscopy measurements show that the relevant permittivity value attributed to sintered CCTO is due to grain boundary (g.b.) effects. The g.b. permittivity value of the pure CCTO can be increased of 1–2 orders of magnitude by cation substitution on Ti site and/or segregation of CuO phase, while the bulk permittivity keeps values 90 e r 180 . Bulk and g.b. conductivity contributions are discussed: electrons are responsible for the charge transport and a mean bulk activation energy of 0.07 eV is obtained at room temperature for all the examined samples. The g.b. activation energy ranges between 0.54 and 0.76 eV. Defect models related to the transport properties are proposed, supported by electron paramagnetic resonance measurements.

AC impedance spectroscopy (IS) measurements were performed in the 15–700 K temperature range on pure and Ni, Fe and Co doped CaCu3Ti4O12 (CCTO) materials. Capacitance values were also confirmed by direct current measurements at room temperature. Thermoelectric power measurements showed that the electrons are involved in the conduction process of the semiconducting bulk region. The IS results evidenced a dielectric behaviour in the grain boundary region, giving a permittivity of about 3400 for the pure sample, so CCTO can be considered an internal barrier layer capacitance (IBLC) material. The giant permittivity of CCTO can be strongly increased to values of w150 000 by Co doping on Ti site. The IBLC behaviour, together with the giant permittivity and the opportunity to combine capacitance and resistance values in an R//C circuit, evidence the applicability of this material as an integrated resonant element for the electronic industry. q 2004 Elsevier Ltd. All rights reserved. PACS: 77.22.Gm; 77.22Kd

We present results from Raman scattering, EPR and static magnetization measurements in CaCu 3 Ti 4 O 12 , a perovskite-related material characterized by a colossal dielectric permittivity e 0 . The investigated samples were pure and partially substituted in the octahedral Ti sites by other transition metals. The results from the pure material are interpreted in terms of the presence of delocalized Copper-holes. Substitutions in the Ti sites drastically change the magnetic properties and, most evidently in the case of Cr, also affect the Raman spectra. These effects correlate with the known suppression of the colossal e 0 after the same kind of substitutions.

Two metastable polymorphs of paracetamol (forms II and III) were prepared by appropriate thermal methods from binary mixtures containing 10% (w/w) of hydroxypropylmethylcellulose. By controlling the reheating step, it was possible to address the recrystallization of the drug either into form II or III. Moreover, it was observed that form III transforms either into form II or I depending on the preparation method. The physical characterization of the polymorphs was performed by means of micro-Fourier transform infrared spectroscopy (MFTIR) and powder X-ray diffractometry (PXRD), both temperature controlled.

Electron paramagnetic resonance (EPR) measurements on pure polycrystalline CaCu3Ti4O12 have been performed and are discussed within a crystal-field approach. A symmetric signal centred at g = 2.15 is observed for T>25 K, with no evidence of hyperfine structure. At this temperature an antiferromagnetic transition is observed as confirmed by static magnetization data. Cu defective and 2% doped (V, Cr, Mn, La) samples were also prepared and considered, mainly to understand the nature of the observed paramagnetic centre. Substitutions in the octahedral sites, causing variations of the configuration in CuO4–TiO6–CuO4 complexes, change the magnetic and EPR features. To justify the EPR response a strong copper-hole delocalization is suggested.

The charge distribution in the Mg-doped lithium manganese spinel Li 1.02 Mg x Mn 1.98− x O 4 with 0.00 x ≤0.20 is discussed and compared to those pertinent to other M-doped samples (M=Ni 2+ , Co 3+ , Cr 3+ , Al 3+ and Ga 3+ ). EPR spectra, low temperature X-ray diffraction and conductivity data are related to the cooperative Jahn–Teller (J–T) transition occurring at about 280 K in the undoped sample. The sensitivity of the cationic sublattice in displaying electronic and magnetic changes after substitution is remarked. The inhibition of the J–T transition is related to the ratio r =|Mn 4+ |/|Mn 3+ | as deduced from the charge distribution model [Li 1− x t + Mg x t 2+ ] tetr [Li y + x t + Mg x o 2+ Mn 1−3 y −2 x 3+ Mn 1+2 y + x 4+ ] octa where x = x o + x t . For y =0.02 and x =0.02, a value r =1.177 is obtained, very close to r lim =1.18, the limit value beyond which the transition is inhibited.

Ga-doped Li−Mn-spinels Li1.02GaxMn1.98-xO4 with 0.00 ≤ x ≤ 0.20 are investigated to verify the lattice capability to allocate the Ga3+ ions on both tetrahedral and octahedral sites and to determine the lowest amount of dopant that prevents the occurrence of the Jahn−Teller (J−T) transition observed near room temperature in LiMn2O4. XRPD, NMR, and EPR spectra and static magnetic susceptibility and conductivity data are related to the site occupancy, the Mn valence state and the homogeneous distribution of the dopant. The electronic and magnetic features of the spinel framework are strongly dependent on substitution in its cationic sublattice: dopant amounts as low as 1% significantly modify the temperature of the conductivity drop associated with the J−T distortion. Ga3+ ions substitute chiefly in the octahedral sites, Mn4+ ions occupy regular and distorted octahedral sites and, at the same time, the value of lattice parameter remains unchanged. Mn2+ ions are present in the tetrahedral site and Li+ increa...

The Y2BaNiO5 compound, prototypical Haldane system characterized by anti-ferromagnetic behaviour, and its analogs Y2BaNi12xMxO5 (M ¼ Mg, Zn; 0:05 # x # 0:65) are investigated by X-ray diffraction and Raman spectroscopy. Structural features and phase stability ranges of the doped samples are first determined. The first order Raman scattering for the different solid solutions is measured at room temperature in order to gain new insight on lattice dynamics of the Y2BaNiO5 compound when Zn 2þ or Mg 2þ ions progressively substitute into Ni site.

We investigate the reversible and irreversible transformations, the Li, Mn spinel undergoes under different atmospheres (air, O2, and N2) when heated up to 1050 °C. In air and O2, a substantial reversible cation exchange occurs. For T≥800 °C, Mn2+ ions substitute Li+ at the tetrahedral (8a) position, and Li+ shifts to interstitial octahedral (16c) site. Charge balance is achieved by a decrease in the Mn3+ fraction, which is partially reduced to Mn2+ in the regular octahedral (16d) site, according to the charge distribution (Li1−2y+Mn2y2+)8a[Li3y+]16c[Mn5y2+Mn1−5y3+Mn14+]16dO4 (y increases with T). Under N2 flow, a first decomposition occurs between 600 and 800 °C and yields Mn3O4, orthorhombic LiMnO2 and O2. A minor O2 release occurs when heating above 900 °C, which is accompanied by the transformation of o-LiMnO2 into a cubic LixMn1−xO solid solution (x≤0.5), consistent with a decrease in the average oxidation state of Mn ions. This cubic phase is stable at high temperature and decomposes upon cooling (T≤800 ° C ) leaving just the Mn3O4 and o-LiMnO2 phases.

Y2BaNiO5, along with its Ca-substituted analog Y2−xCaxBaNiO5 (0 The electron density map ρ(r) is derived from powder X-ray diffraction patterns with a novel procedure based upon a correlative use of two methods: Maximum Entropy Method (MEM) and Whole Powder Profile Fitting (WPPF). We compute the Laplacian ∇2ρ(r) at the Bader critical point of the M–O bond; this quantity is shown to be directly related to structural parameters and their dependence upon composition. In particular, the substantial contraction of NiO6 octahedra with increasing Ca content is related to an Ni–O bond which becomes more ionic as x increases up to x=0.24. On the other hand, covalency becomes stronger above x=0.24, particularly along some Ba–O bonds. Computation of the Shannon entropies confirms the existence of a singularity of the x=0.24 composition, which is a threshold for the re-arrangement of the crystal structure.

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 = 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 g −1 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.

The polymorphism of rac-5,6-diisobutyryloxy-2-methylamino-1,2,3,4-tetrahydro-naphthalene hydrochloride (CHF 1035) was investigated. Three different crystal forms (Form I, Form II, and Form III) were obtained by recrystallization procedures from common organic solvents. The polymorphs were characterized by Raman and carbon-13 nuclear magnetic resonance (13C NMR) spectroscopy, in solution and in solid state (cross polarization-magic angle spinning), powder X-ray diffractometry, and thermal methods (differential scanning calorimetry, hot stage microscopy, and thermogravimetry). Moreover, the diffraction patterns of Form I, collected at controlled temperatures, gave evidence of the presence of two reversible structural rearrangements at ∼60 and ∼75 °C. These structural variations were confirmed by the results obtained by differential scanning calorimetry and hot stage microscopy techniques. The analysis of the Raman spectra allowed the identification of peculiar absorption bands for each polymorph. Form III was the stable crystal form at room temperature as determined by the basis of slurry conversion method. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1154–1163, 2001

The aim of this study is to determine the minimum amount of dopant that prevents the occurrence, near room temperature, of a Jahn–Teller (J–T) transition in the M-doped lithium manganese spinel of composition Li1.02MxMn1.98−xO4 with 0.00

By means of89Y nuclear magnetic resonance (NMR) spectra direct evidence of staggered magnetization induced by a uniform field has been obtained in the Heisenberg antiferromagneticS = 1 chain Y2BaNi1−xMgxO5. A correspondence between the resonance lines and the lattice positions is established, providing an image of the alternating magnetic moments that develop around the Mg impurities at the chain boundaries. The amplitude of these moments is found to decrease exponentially from the edges, with a characteristic decay distance equal to the magnetic correlation length numerically evaluated for an infinite chain. While the magnetization pertaining to ions far from the boundaries behaves as in typical gapped systems, the edge spins exhibit anS = 1/2 Curie-like deviation. These results promote the NMR approach to access the spin-spin correlation function in antiferro-magnetic quantum spin systems at finite temperatures.

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.

The structural evolution of LiMn2O4spinel was followed from 320 K down to 10 K. The structural transformation, recently studied down to 230 K [Rodriguez-Carvajal, Rousse, Masquelier & Hervieu (1998).Phys. Rev. Lett.81, 4660–4663], takes place near room temperature with a significant hysteresis: the high-temperature cubic phase transforms to a superstructure orthorhombic cell. The present study indicates that the nuclear structure is stable down to 10 K, while neutron diffraction patterns below 80 K show the rise of a magnetic ordering in the spinel phase. From Mn—O bond-length analysis of the MnO6octahedra, a temperature-independent charge ordering in the structure can be deduced.

The electrical conductivity of lithium-manganese spinels is analyzed in samples with different starting Li cationic fraction x. Li-rich spinels, resulting from Li-Mn substitution around the stoi-chiometric value (x= 0.333), show conductivity values higher than that observed in stoichiometric LiMn2O4 . Besides, a conductivity drop, associated with a structural phase transition at about 290 K in LiMn2O4 , progressively disappears by decreasing x, while it is absent in Li-rich samples. Stoi-chiometry effects on the concentration of charge carriers and on the available sites for the hopping transport process are evaluated, as well as the effects due to coexisting insulating phases. The role of the Jahn-Teller effect on the conductivity behaviour of stoichiometric and Li-poor spinels is also considered.

In order to test the new EXPO program, an ab initio structure determination from conventional X-ray powder diffraction data has been performed on Y2BaO4, a stable compound that can form during the synthesis of mixed oxides belonging to the Y–Ba–Cu–O and Y–Ba–Ni–O systems. An orthorhombic cell (Pnma space group) with a = 10.3955(1) Å, b = 3.4503(1) Å, c = 12.1157(1) Å, Z = 4 and D c = 5.795 g/cm3 has been obtained, in agreement with the hypothesis that Y2BaO4 is isotypic with Y2SrO4, as reported by Costa, Ferretti, Fornasini, Franceschi, Olcese, 1989. The Pnca space group (60) related to the Pnab proposed by Kwestroo, van Hal, Langereis, 1974 can be rejected. On the basis of accurate atomic fractional coordinates determined by direct methods application and Rietveld refinement, bond lengths and angles have been estimated and discussed with respect to the data of the isotypic Y2SrO4 structure.

The procedure of ab initio structure solution from conventional X-ray powder diffraction data is successfully applied to a series of Y2–x Ca x BaNiO5 compounds (0 ≤ x ≤ 0.33). The study aimed at understanding if the presence of dopants in polycrystalline Y2BaNiO5 compound can influence the success of the structure determination process and at quantifying the substitutional defect. The new code EXPO has been used to obtain the most accurate set of structure factor moduli and to perform the direct methods procedure. It is demonstrated that the substitution on a crystallographic site, as for the above mentioned compound, does not compromise the performance of direct methods. The structural parameters obtained for samples with different x values are compared with those reported in the literature. It is pointed out that the knowledge of the dependence of lattice parameter and cell volume values on the cation site occupancy factors allows the direct determination of the degree of substitution of calcium on yttrium site of the sample.

A thermoanalytical (TGA/DSC) and diffractometric (XRD) study has been performed on the solid state reaction system Li2CO3 -Fe2O3 in the x Li range 0.10±0.50. A detailed analysis of the results shows that the data are in agreement with a reaction model where the carbonate decomposition is regulated by the formation of both LiFeO2 and LiFe5O8 , and the relative amount of the two phases depends on the initial composition. The DSC evidence offers the possibility to directly quantify the LiFe5Ox phase. Furthermore it allows one to obtain the enthalpies of formation of both LiFeO2 and LiFe5O8 .

The results of an ab initio structure determination of a series of CuO powder samples are reported. It is shown that the thermal treatment affects the peak broadening and overlapping and determines the possibility to get the cell size and the atomic positions. It is also demonstrated that the highest level of sintering not always assures the best results in the ab initio procedure as can be seen from the CuO sample prepared at 1273 K. This study suggests that, when possible, it is better to apply the ab initio procedure to a series of samples differently annealed than to use directly the highest sintered powder.

X-ray diffraction (XRD) and $^{7}\mathrm{MAS}$ measurements have been performed on ${\mathrm{LiMn}}_{2}$${\mathrm{O}}_{4}$ (lithium cationic fraction, x=0.333), ${\mathrm{Li}}_{2}$${\mathrm{MnO}}_{3}$ (x=0.667), and the intermediate composition with x=0.40. The use of magic angle spinning produces complex manifolds of the spinning sidebands. The predominant interaction affecting the NMR spectrum is the transferred hyperfine coupling (TFHI) between the Mn ions and the Li spins. TFHI parameters are extracted from MAS-NMR spectra of oxides containing a large quantity of manganese. We obtained a full spectral assignment for the spinel ${\mathrm{LiMn}}_{2}$${\mathrm{O}}_{4}$, for the rocksalt ${\mathrm{Li}}_{2}$${\mathrm{MnO}}_{3}$, and for the x=0.40 sample, which contains the rocksalt and both stoichiometric and nonstoichiometric spinel phases. According to XRD data, the rocksalt phase contains three nonequivalent lithium sites whose NMR peaks are shifted upfield from x=0.667 to 0.40 because of the cell volume expansion.mThe ${\mathrm{Li}}^{+}$ ions belonging to the two spinel phases of x=0.40 are quite mobile and give origin by motional narrowing to a single peak, which is slightly shifted upfield with respect to that of ${\mathrm{LiMn}}_{2}$${\mathrm{O}}_{4}$.

The results of the structural determination of Li 2 MnO 3 from X-ray powder diffraction data and the refinement by the Rietveld technique are presented. The Li 2 MnO 3 structure has a monoclinic cell with space group C2/m (Z = 4) and cell parameters a = 4.9246(1), b= 8.5216 (1), c = 5.0245 (1) A, β=109.398 (1)°; the refinement with 14 structural parameters for 165 reflections in the pattern leads to R wp = 17.61%, R p = 13.25%, R B = 7.07% and S = 3.52. Such a solution agrees with a single-crystal structure determination previously reported in the literature and allows other hypotheses to be rejected.

The coexistence of LiMn 2 O 4 and Li 2 MnO 3 phases from MnO/Li 2 CO 3 mixtures with lithium cationic fraction 0.33≤ x ≤0.53 was studied by X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) measurements. XRD quantitative phase analysis was carried out using the Rietveld profile refinement procedure, while the Li 2 MnO 3 percentage was determined directly by comparing the EPR intensities with the intensity of the pure Li 2 MnO 3 spectrum. The experimental results show the presence of an Li-rich spinel phase and allow an estimation of the lithium excess, since the structural analysis of pure Li 2 MnO 3 samples evidenced a nearly stoichiometric composition ( x =0.663) with very limited cationic disorder.

International audience; Transition metal-based lithium orthosilicates (Li2MSiO4, M=Fe, Ni, Co, Mn) are gaining a wide interest as cathode materials for lithium-ion batteries. These materials present a very complex polymorphism that could affect their physical properties. In this work, we synthesized the Li2FeSiO4 and Li2MnSiO4 compounds by a sol-gel method at different temperatures. The samples were investigated by XRPD, TEM, Li-7 MAS NMR, and magnetization measurements, in order to characterize the relationships between crystal structure and magnetic properties. High-quality Li-7 MAS NMR spectra were used to determine the silicate structure, which can otherwise be hard to study due to possible mixtures of different polymorphs. The magnetization study revealed that the Neel temperature does not depend on the polymorph structure for both iron and manganese lithium orthosilicates.

Transition metal lithium orthosilicates are promising cathode materials for lithium-ion batteries. Here we report a combined experimental (in situ X-ray diffraction) and computational (static lattice and molecular dynamics) study of the thermal behavior of the Li 2 Fe 0.5 Mn 0.5 SiO 4 orthosilicate from room temperature to 950 °C. Our X-ray results showed that Pmnb polymorph is the most stable all over the explored temperature range. A significant cation disorder up to 80%, based on the anti-site defect, was found. The defect concentration depends on the synthesis route and temperature, and is completely reversible after the thermal treatments. Moreover, a careful analysis of the impurity phases allowed us to identify Li 2 SiO 3 , Fe 3 O 4 and Li 3 Fe 5 O 8 , the last one never reported before. The minimization of defects by opportunely tuning the synthetic parameters would be of great importance in view of potential applications of these materials in lithium batteries.

The LiMn2O4 formation from MnO and Li2CO3 mixtures with lithium cationic fraction 0.31 ̲ 0.37. In the former range only the stoichiometric spinel phase was obtained, in the latter, in addition to the Li2MnO3 compound, two spinel phases could be considered: I) LiMn2O4 stoichiometric spinel; II) Li1 + yMn2-yO4 (0.11

X-ray diffraction, magnetic susceptibility, and electron paramagnetic resonance (EPR) measurements have been carried out on mixed nickel-lithium oxides as a function of the lithium content. The experimental results allow us to analyze the cationic order and the magnetic interactions. All the data are consistent with a model that admits coexistence of different structural phases in a wide composition range, previously not accounted for in the discussion of the physical properties of these mixed oxides. \textcopyright{} 1996 The American Physical Society.

Mixed Li-Ni oxides, LixNi1-xO, are prepared by solid state reaction in the range 0.2≤x≤0.46 by annealing around 1000 K for various times. As reported in literature, above x=0.31 an ordered solid solution (OSS) is formed in which planes of pure Ni alternate with Li-Ni planes, whereas below x=0.2 only a fully disordered solid state solution (SSS) exists. We analyze the intermediate composition region 0.22≤x≤0.31 by fitting the X-ray patterns with a two-phases model using the Rietveld method: a SSS phase and an OSS phase where partial occupancy of the Ni-planes by lithium is allowed. The two phases coexist in the intermediate region, and no lithium is allowed in the Ni planes of the OSS phase; furthermore, the lithium contents of the OSS and SSS phases are approximately x ∼ 0.4 and x ∼ 0.2, respectively, and loss of lithium is associated with transformation of the OSS phase into SSS.7Li NMR data find evidence of a common magnetic behaviour of the samples containing the OSS phase which agrees with the X-ray findings.

Co and Li{sub 2}CO{sub 3} were used as starting materials to obtain cobalt-based plaques of potential use in molten carbonate fuel cell technology. Samples were prepared by thermal treatments in the temperature range 800-1300{degrees}C. Their composition and microstructure have been investigated at room temperature by X-ray diffraction analysis (Rietveld refinement), weight change and density data, porosimetry, and scanning electron microscopy. It is shown that a highly nonstoichiometric Co{sub 3}O{sub 4} forms on lithium-containing samples in the entire temperature range investigated, while a stoichiometric Co{sub 3}O{sub 4} is always obtained in the absence of Li. Moreover, clear evidence has been obtained that sinterization starts at lower temperatures on lithiated samples than on pure Co ones and that it causes the formation of consistent amounts of stoichiometric CoO in both types of sample. It is argued that the increased sinterization rate shown by Li-containing samples is due to the highly defective structure of their Co{sub 3}O{sub 4} phase.

The stability of ordered solid solutions (OSS) with LiNiO2 structure has been studied in a wide range of the lithium cationic fraction (0.22< xt < 0.42). The OSS is obtained from the reactive system Ni0/Li2CO3 at 800 °C starting with high nominal lithium content (xt = 0.5). By analysis of the decrease of x, observed after annealing, during which evaporation and a contact reaction occurs, structure-composition relationships can be obtained. The transformation of the ordered phase, due to a cation exchange process, is observed for xt < 0.31 by accurate X-Ray powder pattern analysis (Rietveld method). By increasing the annealing time (decreasing lithium content), the data can be explained on the basis of progressive formation of the simple solid solution (SSS) with only one cation site and halved c axis value. The variations of structural parameters during the transformation are compared with those reported in the literature. The coherence domains of the OSS become smaller and the phase percentage decreases, while the SSS percentage increases. The rate of such a process can be well described on the basis of a two dimensional diffusion mechanism.

We discuss situations where thermogravimetric/Fourier transform infrared (TG/FT-IR) plots are obtained which differ substantially from the expected ones. The most common of these situations involves samples that release atmospheric components (H2O, CO2) at low temperatures. It is shown that the phenomena are mainly related to the purging action of the carrier gas, which strongly influences the spectroscopic portion of the TG/FT-IR plot. Such an influence, as well as the different situations originating from it, is discussed and explained on the basis of an analogy with the operational mode of a conventional dispersive spectrometer.

DSC measurements in the 25–240°C temperature range have been performed on sulphur—selenium physical mixtures (1.99–95.06 mass% of Se) in order to clarify the interaction mechanism. The experimental results can be interpreted on the basis of an interaction model according to which a S/Se copolymerization process takes place in mixtures with Se contents up to 55 mass%. Beyond the 55 mass% Se content the interaction mechanism appears to shift towards an “anomalous melting” behaviour of the two components.

The optical properties of sol–gel prepared Cerium doped Lutetium and Yttrium oxyorthosilicates are investigated in the vacuum ultraviolet energy range by means of synchrotron radiation. The excitation and emission properties are compared to commercial samples grown by Czochralski method. The sol gel polycrystals do show emission features comparable to the ones of the monocrystals but with a slightly smaller decay time. Preliminary radioluminescence measurements indicate the possibility to apply the sol gel synthesized polycrystals as scintillating materials in the low X-ray energy range.

Commercial and recrystallized polycrystalline samples of carprofen, a nonsteroidal anti-inflammatory drug, were studied by thermal, spectroscopic, and structural techniques. Our investigations demonstrated that recrystallized sample, stable at room temperature (RT), is a single polymorphic form of carprofen (polymorph I) that undergoes an isostructural polymorphic transformation by heating (polymorph II). Polymorph II remains then metastable at ambient conditions. Commercial sample is instead a mixture of polymorphs I and II. The thermodynamic relationships between the two polymorphs were determined through the construction of an energy/temperature diagram. The ab initio structural determination performed on synchrotron X-Ray powder diffraction patterns recorded at RT on both polymorphs allowed us to elucidate, for the first time, their crystal structure. Both crystallize in the monoclinic space group type P 2 1 / c , and the unit cell similarity index and the volumetric isostructurality index indicate that the temperature-induced polymorphic transformation I→II is isostructural. Polymorphs I and II are conformational polymorphs, sharing a very similar hydrogen bond network, but with different conformation of the propanoic skeleton, which produces two different packing. The small conformational change agrees with the low value of transition enthalpy obtained by differential scanning calorimetry measurements and the small internal energy computed with density functional methods.

The study of the ionic conducting material LiTi2(PO 4)3 and of its Mn-substituted derivate reveals that the Mn distribution is strictly related to the synthetic method. The results of the structural refinement of X-ray and neutron (ToF) powder diffraction data and of XPS analysis demonstrate that Mn2+ ions are located on the lithium octahedral site, while Mn3+ and Mn4+ ions occupy the titanium ones. The Mn2+ amount on the lithium site seems to be the main factor responsible for the conductivity decrease observed in doped samples. The EPR spectra evidence clustering effects of Mn on both Li and Ti sites and the presence of more insulated Mn2+ ions. The effect of the major Mn amount on Ti site in the case of the sol-gel synthesis is consistent with the different EPR line shape of the related sample. The neutron diffraction and 7Li MAS NMR results do reveal that lithium occupies the M1 site of the rhombohedral LiTi2(PO4)3 structure.

We investigate the influence of particle size and crystal orientation on the electrochemical behavior of carbon-coated LiFePO4 prepared by a hydrothermal synthesis in the presence of a polymeric surfactant and a source of carbon. We evaluated the charge/discharge profiles of two samples, one constituted by particles in the micrometer range with a platelet-like shape (large ac facet and (020) crystal orientation) and another made of sub-micrometer-rounded particles with a random crystal orientation. At low current rates the crystal orientation seems to be the prevailing factor, whereas at high current rates smaller particles can allow a shorter electronic conduction path, so reducing the resistance experienced by Li ions during diffusion.

Gravimetric, dilatometric, diffractometric and microscopic measurements have been used to study the role of thermal treatment in the preparation of lithiated nickel oxide cathodes for molten carbonate fuel cells. Clear evidence has been obtained that both the nominal composition of the reactive system and the thermal treatment during solid solution formation appreciably affect the cathodes microstructure. Starting from a careful analysis of the X-ray data, a reaction model is proposed which quite satisfactorily explains the microstructural aspects of the reaction. It is shown that there are three different processes at the origin of the cathodes microstructure and that the effect of the thermal treatment is to affect their relative weights.

Bioactive glasses and glass-ceramics of the system SiO2-P2O5-CaO with and without zinc were synthesized by sol-gel with the aim to address the influence of both the chemical composition and the microstructure on the growth of hydroxycarbonate apatite (HCA) following soaking in simulated body fluid (SBF). In the standard compositions 58S, 70S, and 80S the silica precursor was also partially replaced with a nanoscale silica powder (HiSil) in order to separate the contributions of porosity and composition. The combined use of XRPD, N2 absorption measurements, and SEM allowed us to establish quantitative correlations among the above-mentioned quantities. We found that the HCA formation rate increases with the silica content and that an important role is played by the specific surface area of the samples. Notably, the addition of even small quantities (0.4 wt%) of ZnO at the expenses of both CaO and P2O5 in the 58S glass leads to the increase, with respect to the 58S sample, of both the HCA formation rate and the HCA content after 8 days of treatment in SBF. A preliminary result revealed that sample with 0.4 wt % ZnO displayed good in vitro biocompatibility as shown by LDH assay