Ionics

The lead pyrophosphate, Pb2P2O7, compound was prepared by conventional solid-state reaction and identified by X-ray powder diffractometer. Pb2P2O7 has a triclinic structure whose electrical properties were studied using impedance spectroscopy technique. Both impedance and modulus analysis exhibit the grain and grain boundary contribution to the electrical response of the sample. The temperature dependence of the bulk and grain boundary conductivity were found to obey the Arrhenius law with activation energies E g = 0.66 eV and E gb = 0.67 eV, respectively. The scaling behavior of the imaginary part of the complex impedance suggests that the relaxation describes the same mechanism at various temperatures.

Acidic lyotropic liquid crystals (LLCs) have an advantage in constructing continuous proton conduction pathways owing to the well-defined structures, but the contribution of LLC to proton conductivity is hard to determine for the water-dependent nature of LLC. An aqueous 4-(1-ethyldecyl) benzenesulfonic acid solution, exhibiting a lamellar LLC phase at low hydration levels and becoming a micellar solution at high hydration levels, is employed to investigate structure-dependent proton conductivity. Electrochemical impedance spectrum (EIS) characterization reveals that the proton conductivity reaches a maximum of 173 mS cm−1 in the LLC phase. Owing to the self-assembling, the degree of dissociation of -SO3H tends to stabilize at 0.26 with increasing hydration levels. An integrated rate constant Ki is derived to evaluate the effect of self-assembly on proton conductivity, which reaches 1.90 × 107 mS cm5 mol−2 in the LLC but decreases to 1.23 × 107 mS cm5 mol−2 in the micellar solution. The single fuel cell fabricated from the LLC supported membrane exhibits a peak power density of 23.7 mW cm−2, confirming the enhanced proton conductivity under actual working conditions. The results quantitatively unveil the effect of aqueous self-assembly on proton conduction and offer a guide for achieving high conductivities in hydrated electrolytes with well-defined architectures.

The effects of nicotinic acid (NA) on the electrodeposition of Al-Mn alloy have been investigated in aluminum chloride-1-butyl-3-methylimidazolium ionic liquids (AlCl3-BMIC) containing 0.15 mol·L−1 MnCl2 (AlCl3-BMIC-MnCl2). The electrochemical behaviors of the AlCl3-BMIC-MnCl2 electrolyte have been studied here using cyclic voltammetry and potentiodynamic polarization. The addition of NA obviously increased the nucleation overpotential of Al-Mn alloy and inhibited the reduction reaction of Al(III) and Mn(II). The resultant surface morphologies, composition, and roughness of the Al-Mn alloy coating were revealed by scanning electron microscopy (SEM), transmission electron microscope (TEM), and atomic force microscopy (AFM). It was found that these additives strongly affect the morphology, composition, roughness, and crystal structure of the Al-Mn alloy coating. With the addition of NA, the content of Mn decreased, and Al-Mn alloy coatings became more uniform and smoother. The crystal structure of Al-Mn coatings was also examined by X-ray diffraction (XRD), where it was found that the phase composition of the deposits depends on the quantities of additives. For electrolyte containing little or no NA additives, the resulting alloy is amorphous structure. With NA additives up to 6·mmol L−1, the Al-Mn coating changed into a mixture phase of amorphous and crystalline structure.

KTa0.5Nb0.5O3 thin films were synthesized via a metal-organic solution. Characteristics were measured, such as X-ray diffraction pattern, surface morphology and roughness, and electric properties. The synthesized films have a (100) preferential growth orientation on Si (100) substrate. The homogeneous microstructure and smooth surface benefit to the good electric properties of the thin films. The current density-voltage characteristic shows an unexpected feature of the transition from linear to nonlinear, which can be explained by the space-charge-limited mode. Dielectric constant and loss of the thin films decrease with the increase of frequency. The decrease of dielectric loss is related to the decrease of net polarization in material. The decrease of dielectric constant can be explained by Debye formula. The phase transition temperature T c is about 102 °C for KTa0.5Nb0.5O3 materials.