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Nanometric ceria powders doped with 30 mol % samaria are consolidated by a high‐pressure spark plasma sintering (HP‐SPS) method to form > 99 % dense samples with a crystallite size as small as 16.5 nm. A conductivity dependence on grain size was noted: when the grain size was less than 20 nm, only one semicircle in the AC impedance spectra was observed and was attributed to bulk conductivity. In contrast to previous observations on pure ceria, the disappearance of the grain‐boundary blocking effect is not associated with mixed conductivity. With annealing and concomitant grain growth, the samples show the presence of a grain‐boundary effect.

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⁺ increases in the octahedral site as a consequence of Li−Mn/Ga inversion. Such a mechanism increases the efficiency of J−T inhibition by Ga doping, in comparison with transition cations having the same valence.

Lithium manganese spinel Li1+yMn2−yO4(0.0≤y≤0.07) synthesized by the sol–gel process is studied with a focus on the effects of the changes of formation conditions which can sensibly determine the mean crystallite size from a few nanometers to several hundred nanometers. Changes of stoichiometry and abundance of the spinel phase can be observed in the 573≤TA(K)≤1073 range of annealing temperature (TA). Comparing spinel phases obtained by sol–gel and solid state synthesis evidences the correlation among composition, structure, and electric and magnetic properties.

DC conductivity measurements between 15 and 300 K are reported for SmBa2Cu3O6+xsamples with different oxygen doping amounts (x) produced by annealing under appropriate high temperature and oxygen pressure conditions and quenching. Samples with x≥0.5 are superconductors: Tc ~60 K at x=0.7, Tc >80 K at ; x=0.9. The transition from superconduction to non-superconduction corresponds to the tetragonal to orthorhombic structural tran-sition and to the transition from semiconducting to metallic temperature dependence of the resistivity. Oxygen doping causes a sudden increase of hole mobility near x=0.5. Below this threshold, the be-havior of the carrier mobility is in agreement with an Anderson localization.

Among the family of solid electrolytes obtained from AgI and Ag oxysalts, new materials exhibiting high electric conductivity have been identified. The investigation is extended to the study of their behaviour at temperatures higher than 25° C.

Yttria-stabilized zirconia films, 100 to 200 µm thick, were prepared by plasma spraying. The electrical properties were investigated by complex impedance spectroscopy. The results are compared with those obtained on sintered pellets prepared with the same powders used for spraying and on commercial single crystals. The ionic conductivity and the activation energies of sprayed films and single crystals are found to be very similar, and no grain-boundary effect is observed in the film complex impedance plots. These results are explained by the high density and purity of the sprayed films.

A study of the polymer electrolyte system containing poly(ethylene oxide), P(EO), with lead perchlorate is presented. The phase diagram, examined over a Pb(ClO4)2concentration of 0-0.24 mol% by means of differential scanning calorimetry, thermomicroscopy, thermogravimetric analysis, is of the eutectic type. A polymer-salt compound is formed (x≈0.09), which melts incongruently at T∼420 K. The ionic conductivity in the elastomeric phase reaches 10−4Ω−1. The dielectric relaxation technique is used to investigate the relaxation phenomena at low temperatures, below the glass transition. The results are compared with those previously obtained on P(EO)-based systems containing different perchlorates and other Pb salts.

The electric conductivity and the initial thermoelectric power are determined for the solid solutions (Ag, Na)X (X = Cl, Br) over the whole composition range.

The homogeneity range of Bi-Sr-Ca-Cu oxides with two-layers ("2212") structure has been investigated with X-ray powder diffraction and electron microprobe determination on materials with nominal Bi2Sr3-xCaxCu2O8+y) , (x = 1÷ 2 in 0.1 steps) composition and being prepared at two different oxygen partial pressures. The results show Bi over-stoichiometry and a wide range of Sr/Ca substitution.

Two families with hereditary neuropathy with liability to pressure palsies (HNPP) were evaluated clinically, electrophysiologically and pathologically (2 index cases). Familial patterns suggest autosomal dominant inheritance. The clinical presentation is characteristic, with recurrent painless transitory mononeuropathy, without evident triggering factors, or caused by trivial trauma or pressure. In affected members neurophysiological studies showed diffuse slowing in nerve conduction, more evident at common sites of entrapment. Somatosensory evoked potentials (SEPs) showed bilateral peripheral abnormalities with proximal nerve incolvement more pronounced in older patients. 40 to 75% of teased fibers displayed sausage-shaped swellings. Ultrastructurally some sausages showed redundant myelin loops and excessive number of myelin lamellae that seem to cause axonal constriction.

Electrical resistance measurements as a function of water vapor pressure and temperature were carried out, by complex impedance method, on polycrystalline samples of HTaWO6·xH2O (0<-x≤1) pyrochlore. Models for conduction mechanisms in anhydrous and hydrated phases are discussed.

A multi-center survey of antepileptic treatment was conducted in Italy on 245 previously untreated (“new”) patients with epilepsy and 355 patients treated for more than three months (“old” patients). Therapeutic drug monitoring (TDM) of antiepileptic drugs was evaluated in the context of routine clinical conditions, in relation to individual therapeutic problems and mode of treatment. Plasma levels (PL) were determined in 75% of “new” patients and 78% of “old” patients, with wide intercenter variability. TDM was done at 69% of the follow-up attendences for “new” patients and at 34% for “old” patients, but was apparently unrelated to specific therapeutic problems, such as poor disease control or adverse drug reactions. Plasma drug concentration measurements were made more often among patients on polytherapy. The age of the patient and the time elapsing since diagnosis did not seem to affect request patterns significantly. From these findings it appears that TDM is largerly influenced by factors unrelated to the common recommendations in the literature. In addition, the use of TDM in clinical practice reflects the limitations of the available techniques.

XRD measurements proved the coexistence of spinel, lithium-rich spinel, and rock-salt phases in the Li–Mn–O system. An investigation of the electrical properties, carried out on polycrystalline samples, shows that Li2MnO3has insulating behavior while the spinel phases provide an example of hopping conduction mechanism. The negative Seebeck coefficient suggests that electrons constitute the charge carriers and their number is consistent with the fraction of Mn3+over the total number of Mn3+and Mn4+sites in the spinel structure. The static magnetic susceptibility results agree with the presence of the Mn3+ions in high spin configuration.

The charge transport properties of "BaCuO2" with 88:90 (Ba :Cu) cation ratio were characterized by thermopower, electrical conductivity and ionic transport number measurements in a wide range of temperature and oxygen partial pressure conditions.

Electrical resistivity measurements were carried out on polycrystalline YBa2Cu3O7-xat temperatures 300 < T < 1023 K and oxygen partial pressures 5 ·10-7≤ po2≤ 1 atm. The samples, equilibrated in the range from 5 ·10-4to 1 atm, show metallic behaviour, the one equilibrated at po2= 2 ·10-5shows a transition between metallic and semiconducting behaviour at 920 K, and that equilibrated at po2= 5 ·10-7shows semiconducting behaviour: for the latter the relevant resistivity is due to the oxygen-ion migration. The isotherms log σ vs. log po2(in the temperature range from 723 to 1023 K) show slopes of about 1/6 at 723 K (orthorhombic phase) and about 1/2 at 1023 K (tetragonal phase). These results are discussed in terms of appropriate defect models.

This paper studies the thermal stability and the glass formation region the Agl-Ag2O-B2O3 system. The miscibility range of the components has been investigated by direct visual observation at 1000°C, i.e. where the system is liquid over the entire compositional range. By combining X-ray and differential thermal analysis (DTA) measurements, the large region of glass formation of the system has been determined. The dependence of the glass transition temperature upon the glass composition is discussed. Series of glasses have been annealed over extended time intervals above the glass transition temperature in order to characterize the “equilibrium” phase diagram for the system. Analysis of the annealed materials shows that several crystalline compounds form upon annealing.

Most optimized vitreous electrolytes are obtained by doping an oxide glass with a salt (MX); the resulting substance has an increased ionic conductivity, but a reduced thermal stability. On the other hand, this paper shows that it is possible to obtain vitreous electrolytes with enhanced electrical and thermal performances by mixing two glass formers. This phenomenon may be called the “mixed anion effect”. The Ag2O∶B2O3∶P2O5 system is shown to offer a very interesting example of such a phenomenon.

The electrical behaviour of La2-xSrxCuO4-ysolid solutions (with x = 0, x = 0.025, x = 0.05, and x = 0.15) at temperatures between 10 and 900 K and under different oxygen partial pressure pO2= 1 ÷ 10-6atm) has been investigated. The samples prepared and measured under an O2flux (i.e., with y = 0) show a superconducting transition with Tc= 46, 29. 37 K for x = 0. 0.05 and 0.15, respectively. The samples with x = 0.025, y = 0, and x = 0, y ≠ 0 exhibit no sign of superconductivity. In the temperature range 100-900 K. La2CuO4is semiconducting, whereas the electrical resistivity is independent of temperature for the x =0.025 sample, and the x = 0.05 and x = 0.15 are metallic.

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is performed at temp. in the range 10‐900 K under different oxygen partial pressures.

Resistivity measurements in the temp. range 300‐1023 K under oxygen partial pressures of 5·10‐7‐1 atm indicate a metallic behavior for polycrystalline YBa2Cu3O7‐xequilibrated in the p(O2) range 5·10‐4‐1 atm, a transition between metallic and semiconducting behavior at 920 K for the sample equilibrated at p(O2) = 2·10‐5atm, and semiconducting behavior for the sample equilibrated at p(O2) = 5·10‐7atm.