Proton Conduction in Grain-Boundary-Free Oxygen-Deficient BaFeO2.5+δ_{2.5+δ} Thin Films

Reduction of the operating temperature to an intermediate temperature range between 350 °C and 600 °C is a necessity for Solid Oxide Fuel/Electrolysis Cells (SOFC/SOECs). In this respect the application of proton-conducting oxides has become a broad area of research. Materials that can conduct protons and electrons at the same time, to be used as electrode catalysts on the air electrode, are especially rare. In this article we report on the proton conduction in expitaxially grown BaFeO2.5+δ (BFO) thin films deposited by pulsed laser deposition on Nb:SrTiO3 substrates. By using Electrochemical Impedance Spectroscopy (EIS) measurements under different wet and dry atmospheres, the bulk proton conductivity of BFO (between 200 °C and 300 °C) could be estimated for the first time (3.6 × 10−6 S cm−1 at 300 °C). The influence of oxidizing measurement atmosphere and hydration revealed a strong dependence of the conductivity, most notably at temperatures above 300 °C, which is in good agreement with the hydration behavior of BaFeO2.5 reported previously

Effects of Size Reduction on the Electrical Transport Properties of 3D Bi Nanowire Networks

3D nanowire networks are fascinating systems for future microelectronic devices. They can be handled like macroscopic objects, while exhibiting properties of nanoscale materials. Here, the fabrication of free‐standing 3D bismuth nanowire networks with well‐controlled and systematically adjusted wire diameter and interconnectivity is presented. The samples are fabricated by pulse electroplating of bismuth into the pores of ion track‐etched membranes using an aqueous electrolyte. By optimizing the growth parameters, homogeneously grown, mechanically self‐supporting and free‐standing networks without a supporting matrix are achieved. Cross‐plane Seebeck coefficient and electrical resistance values are investigated as a function of nanowire diameter and temperature. The unique characteristics of these highly interconnected and mechanically self‐supported Bi 3D nanowire networks offer exciting perspectives for their implementation in, e.g., infrared detection based on thermoelectric effects, sensing, and THz applications

Dual metastability in electroless plating: Complex inertness enabling the deposition of composition‐tunable platinum copper alloy nanostructures

Plasma source ion implantation (PSII) is a technique that is suitable for implantation as well as film deposition. Since it involves a high voltage that is applied to the sample holder to attract ions from the plasma to the sample, an influence can be expected in case that either the whole substrate or a part of it is nonconductive. Diamond-like carbon (DLC) films were deposited by PSII, using C2H2 as precursor. The substrates were silicon samples that were placed on a large, horizontally oriented conductive sample holder in three different ways: 1) directly on the holder, 2) with an alumina block of 5 mm height between holder and sample, and 3) with an alumina block of 12 mm height between holder and sample. A high voltage (pulse or DC) was applied directly to the sample holder. The plasma was generated by this voltage or, in some experiments, by an additional RF signal, which was applied to a plate that was oriented parallel to the sample holder in a distance of 100 mm. The investigation of the effect of the presence of the insulating alumina block on the film properties focused on the deposition rate, the hydrogen content and film structure, the surface roughness, the hardness and the friction coefficient of the films

Interface Behaviour and Work Function Modification of Self-Assembled Monolayers on Sn-Doped In₂O₃

The modification of the work function of Sn-doped In₂O₃ (ITO) by vacuum adsorption of 4-(Dimethylamino)benzoic acid (4-DMABA) has been studied using in situ photoelectron spectroscopy. Adsorption of 4-DMABA is self-limited with an approximate thickness of a single monolayer. The lowest work function obtained is 2.82±0.1 eV, enabling electron injection into many organic materials. In order to identify a potential influence of the ITO substrate surface on the final work function, different ITO surface orientations and treatments have been applied. Despite the expected differences in substrate work function and chemical bonding of 4-DMABA to the substrate, no influence of substrate surface orientation is identified. The resulting work function of ITO/4-DMABA substrates can be described by a constant ionization potential of the adsorbed 4-DMABA of 5.00±0.08 eV, a constant band alignment between ITO and 4-DMABA and a varying Fermi energy in the ITO substrate. This corresponds to the behaviour of a conventional semiconductor heterostructure and deviates from the vacuum level alignment of interfaces between organic compounds. The difference is likely related to a stronger chemical bonding at the ITO/4-DMABA interface compared to the van der Waals bonding at interfaces between organic compounds

Reactive magnetron sputtering of Cu₂O: Dependence on oxygen pressure and interface formation with indium tin oxide

Thin films of copper oxides were prepared by reactive magnetron sputtering and structural, morphological, chemical, and electronic properties were analyzed using x-ray diffraction, atomic force microscopy, in situ photoelectron spectroscopy, and electrical resistance measurements. The deposition conditions for preparation of Cu(I)-oxide (Cu₂O) are identified. In addition, the interface formation between Cu₂O and Sn-doped In2O3 (ITO) was studied by stepwise deposition of Cu₂O onto ITO and vice versa. A type II (staggered) band alignment with a valence band offset