Interface Diffusion and Compatibility of (Ba,La)FeO Perovskite Electrodes in Contact with Barium Zirconate and Ceria.

BaLaFeO perovskites (BLF) capable of conducting electrons, protons, and oxygen ions are promising oxygen electrodes for efficient solid oxide cells (fuel cells or electrolyzers), an integral part of prospected large-scale power-to-gas energy storage systems. We investigated the compatibility of BLF with lanthanum content between 5 and 50%, in contact with oxide-ion-conducting CeGdO and proton-conducting BaZrYO electrolytes, annealing the electrode-electrolyte bilayers at high temperature to simulate thermal stresses of fabrication and prolonged operation. By employing both bulk X-ray diffraction and synchrotron X-ray microspectroscopy, we present a space-resolved picture of the interaction between electrode and electrolyte as what concerns cation interdiffusion, exsolution, and phase stability.

Ion transport mechanism in anhydrous lithium thiocyanate LiSCN part III: charge carrier interactions in the premelting regime.

In lithium thiocyanate Li(SCN), the temperature regime below the melting point (274 °C) is characterized by excess conductivities over the usual Arrhenius behavior (premelting regime). Here, the Schottky defect pair concentration is high, and the point defect chemistry can no longer be considered as dilute. Coulomb interactions of Schottky pairs are expected to occur lowering the formation energy of new carriers and hence leading avalanche-like to a transition into a fully defective superionic state.

Ion transport mechanism in anhydrous lithium thiocyanate LiSCN Part I: ionic conductivity and defect chemistry.

This work reports on the ion transport properties and defect chemistry in anhydrous lithium thiocyanate Li(SCN), which is a -halide Li cation conductor. An extensive doping study was conducted, employing magnesium, zinc and cobalt thiocyanate as donor dopants to systematically vary the conductivity and derive a defect model. The investigations are based on impedance measurements and supported by other analytical techniques such as X-ray powder diffraction (XRPD), infrared (IR) spectroscopy, and density functional theory (DFT) calculations.

Ion transport mechanism in anhydrous lithium thiocyanate LiSCN part II: frequency dependence and slow jump relaxation.

Specific aspects of the Li cation conductivity of anhydrous Li(SCN) are investigated, in particular the high migration enthalpy of lithium vacancies. Close inspection of impedance spectra and conductivity data reveals two bulk relaxation processes, with comparatively fast ion transport at high frequencies and slow ion migration at low frequencies. The impedance results are supported by solid state nuclear magnetic resonance (ssNMR), and pair distribution function (PDF) analysis.

Synthesis, characterization and thermal behaviour of solid phases in the quasi-ternary system Mg(SCN)-HO-THF.

Mg(SCN)2·4H2O can be converted into previously unknown compounds Mg(SCN)2·(4 - x) H2O·xTHF with x = 0, 2 and 4 by multiple recrystallization in tetrahydrofuran (THF). The phases were characterized by infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and their crystal structures were solved from X-ray powder diffraction (XRPD) data. In the crystal structures isolated Mg(NCS)2(H2O)4-x(THF)x units form layered motifs.