Composition dependence of polymorphism and electrical conductivity in Ce(IV)-doped Bi4V2O11

For the first time, a new member of the BIMEVOX family, namely BICEVOX, has been synthesized by the partial solid-state substitution of Ce(IV) for vanadium in parent Bi₄V₂O₁₁ solid electrolyte. The electrical conductivity in Bi₄Ce _x V_{2? x} O_{11?( x /2)? δ} has been investigated in the compositional range 0 ≤ x ≤ 0.30, using FT-IR, X-ray powder diffraction, differential thermal analysis and ac impedance spectroscopy. Owing to the long-term stabilization of α- and β-polymorphs compared to other members of the BIMEVOX family, the BICEVOX system may be a prospective solid electrolyte for intermediate temperature solid oxide fuel cells due to the significantly increased conductivity at lower temperatures observed for the compositions x > 0.20.     

Effect of Ni(II) substitution on phase stabilization electrical properties of BICo(III)VOX.20 oxide-ion conductor

The BICO_0.20–xNI_xVOX solid electrolyte was synthesized by the standard solid-state reaction. The effect of Ni(II) substitution for Co(III) on phase stabilization and oxide-ion performance has been investigated in the compositional range 0?≤?x?≤?0.20 using X-ray powder diffraction, differential thermal analysis and AC impedance spectroscopy. The highly conductive γ′-phase was effectively stabilized at room temperature for compositions with x?≥?0.13 whose thermal stability increases with Ni content. The complex plane plots of impedance were typically represented at temperatures below 380?°C, suggesting a major contribution of polycrystalline grains to the overall electrical conductivity. The dielectric permittivity measurements revealed the fact that suppression of the ferroelectric transition is compositionally dependent. Interestingly, the maximum ionic conductivity at lower temperatures (~2.56?×?10^?4?S^?cm^?1 at 300?°C) was observed for the composition with x?=?0.13. The variation of low-temperature conductivity with Ni content was accompanied with a general drop in the corresponding values of ΔE_LT. However, the local minimum high-temperature conductivity, σ₆₀₀?°C?~?2.26?×?10^?2?S^?cm^?1 for x?=?0.10, coupled with a local maximum value of ΔE_HT?~?0.48?eV was attributed to an increased defect trapping effect correlated with the V(V)?→?V(IV) reduction at elevated temperatures.     

Fuzzy dissimilarity and distance functions

ε-fuzzy dissimilarity relation is defined by using the concept of ε- fuzzy equivalence relation and a strong negator. It is proved that the ε- fuzzy dissimilarity relation so defined satisfies inequalities resembling to generalized triangle inequality.     

Demonstration of fusion-evaporation and direct-interaction nuclear reactions using high-intensity laser-plasma-accelerated ion beams

Heavy-ion induced nuclear reactions in materials exposed to energetic ions produced from high-intensity (approximately 5 x 10(19) W/cm(2)) laser-solid interactions have been experimentally investigated for the first time. Many of the radionuclides produced result from the creation of "compound nuclei" with the subsequent evaporation of proton, neutron, and alpha particles. Results are compared with previous measurements with monochromatic ion beams from a conventional accelerator. Measured nuclide yields are used to diagnose the acceleration of ions from laser-ablated plasma to energies greater than 100 MeV.     

Propagation instabilities of high-intensity laser-produced electron beams

Measurements of energetic electron beams generated from ultrahigh intensity laser interactions (I>10(19) W/cm(2)) with dense plasmas are discussed. These interactions have been shown to produce very directional beams, although with a broad energy spectrum. In the regime where the beam density approaches the density of the background plasma, we show that these beams are unstable to filamentation and "hosing" instabilities. Particle-in-cell simulations also indicate the development of such instabilities. This is a regime of particular interest for inertial confinement fusion applications of these beams (i.e., "fast ignition").     

Studies with inorganic precipitative membranes: XI. Membrane potential response,characterization and evaluation of effective fixed charge density

Membrane potentials arising across parchment supported nickel and cobalt phosphate membranes when they separete 1:1 electrolyte solutions of concentration c₁ and c₂ such that c₁=10 c₂, have been measured. The membranes in contactwith dilute solutions have been found to carry a negative charge whereas the charge reversal was observed when the membrane was separating concentrated solutions. The membrane potential data have been used according to the procedure prescribed by Teorell-Meyer-Sievers theory (the TMS theory) to derive the value of effective fixed charge density of membranes. The electrical double layer at the membrane-solution interface has been suggested to control the over all rate of diffusion.     

Studies with model membranes. X. Evaluation of the thermodynamically effective fixed charge density and permselectivity of mercuric and cupric iodide parchment-supported membranes

Thermodynamically effective fixed charge densities of mercuric and cupric iodide parchment supported membranes were estimated by methods of Teorell, Meyer, and Sievers; Altug and Hair; and the most recent one of Kobatake and co-workers based on the thermodynamics of irreversible processes. The two limiting forms of Kobatake's equation for dilute and concentrated ranges gave identical values of charge densities. It is interesting to note that these two values of limiting cases are closer to the Teorell-Meyer-Sievers and Altug-Hair values. The theoretical predictions for membrane potential by the Kobatake equation were borne out quite satisfactorily by experimental results obtained with both the membranes.     

Effect of CrO3 addition in ZrO2: Electric and dielectric behavior

The electrical conductivity and dielectric constant of ZrO₂ doped with CrO₃ have been measured at different temperatures for different molar ratios. The electrical conductivity increases due to creation of oxygen vacancies, and the dielectric constant increases due to increase in grain size. X-ray diffraction and IR studies were carried out to confirm the doping effect. Published in Russian in Zhurnal Fizicheskoi Khimii, 2006, Vol. 80, No. 7, pp. 1297–1301. The text was submitted by the authors in English. An erratum to this article is available at .     

Remarks on structure and thermal characterization of Tris-Thallium(III) glycollate

Thermal decarboxylation of Tl (GLA), where GLA stands for glycollic acid anion was reported by Khadikar using TG, DTG and DTA techniques. The various kinetic and thermodynamic parameters were evaluated by him from nonisothermal thermogravimetric curve employing different computational methods. Upon re-estimating his data the reaction order and activation energy were found to be 0.67 and 269 kJ/mol respectively, instead of reported reaction ordern=1 and activation energyE=282 kJ/mol in the paper under comment.Zusammenfassung Unter Anwendung von TG, DTG und DTA beschrieb Khadikar die thermische Decarboxylierung von Tl(GLA) mit GLA=Glykolsäureanion. Mittels verschiedener Rechenmethoden ermittelte er aus der nichtisothermen thermogravimetrischen Kurve verschiedene kinetische und thermodynamische Parameter. In einer Revision seiner Ergebnisse fanden wir anstelle der beschriebenen Reaktionsordnung von 1 und der Aktivierungsenergie vonE=282 kJ/mol Werte von 0.67 bzw. 269 kj/mol.     

Ion-selective characteristics of heavy metal myristate liquid membrane electrodes

Liquid membrane electrodes of myristate soaps of heavy metals, namely copper, cadmium, zinc, nickel, cobalt, strontium and barium in a benzene-n-butanol mixture were prepared. Each electrode showed nernstian response in common metal ion test solution. The range of concentration of the test solution for the Nernstian behaviour lies between 10^?4 and 10^?1M. With a dissimilar metal ion in test solution the metal soap liquid membrane electrode indicates deviations from Nernst's equation depending on the nature of the metal ion, suggesting different selectivities for different ions. The selectivity ratios are therefore calculated.