Electrical properties of individual tin oxide nanowires contacted to platinum electrodes

A simple and useful experimental alternative to field-effect transistors for measuring electrical properties free electron concentration nd, electrical mobility , and conductivity in individual nanowires has been developed. A combined model involving thermionic emission and tunneling through interface states is proposed to describe the electrical conduction through the platinum-nanowire contacts, fabricated by focused ion beam techniques. Current-voltage I-V plots of single nanowires measured in both two- and four-probe configurations revealed high contact resistances and rectifying characteristics. The observed electrical behavior was modeled using an equivalent circuit constituted by a resistance placed between two back-to-back Schottky barriers, arising from the metal-semiconductor-metal M-S-M junctions. Temperature-dependent I-V measurements revealed effective Schottky barrier heights up to BE= 0.4 eV

Thin film oxide-ion conducting electrolyte for near room temperature applications

Stabilized bismuth vanadate thin films are presented here as superior oxide ionic conductors, for application in solid state electrochemical devices operating near room temperature. Widely studied in the 90s in bulk form due to their unbeatable ionic conduction, this family of materials was finally discarded due to poor stability above 500 °C. Here, we however unveil the possibility of using BiVCuO at reduced temperatures in thin film-based devices, where the material keeps its unmatched conduction properties and at the same time shows good stability over a wide oxygen partial pressure range

Engineering Transport in Manganites by Tuning Local Non-Stoichiometry in Grain Boundaries

Interface-dominated materials such as nanocrystalline thin films have emerged as an enthralling class of materials able to engineer functional properties of transition metal oxides widely used in energy and information technologies. In particular, it has been proved that strain-induced defects in grain boundaries of manganites deeply impact their functional properties by boosting their oxygen mass transport while abating their electronic and magnetic order. In this work, the origin of these dramatic changes is correlated for the first time with strong modifications of the anionic and cationic composition in the vicinity of strained grain boundary regions. We are also able to alter the grain boundary composition by tuning the overall cationic content in the films, which represents a new and powerful tool, beyond the classical space charge layer effect, for engineering electronic and mass transport properties of metal oxide thin films useful for a collection of relevant solid state devices

Electrophoretic deposition of MnCo2O4 coating on solid oxide cell interconnects manufactured through powder metallurgy

Developing cost-effective and durable interconnects for solid oxide cells is crucial to overcome currently existing barriers for the commercialization of this promising energy technology. A systematic microstructural and electrical characterization of MnCo2O4 spinel coatings processed by electrophoretic deposition on SUS 445 ferritic stainless steel, manufactured through powder metallurgy, is here reviewed and discussed for application in high temperature solid oxide cells stacks. The work presents a successful com- bination of the powder metallurgy processing of metallic interconnects with the electrophoretic deposition as a fast and versatile approach to coat complex interconnect shapes. Therefore, this study assesses the effect of the sintering route of coated steel on the final microstructure. Remarkable results in terms of electrical properties are here presented for EPD coated sample reduced at 1000 °C and re-oxidised at 800 °C in static air, obtaining an area specific resistance degradation rate of 1.2 mΩ cm2/kh together with an effective limitation of Cr outward diffusion despite the prolonged exposure in relevant conditions. This novel approach opens the door for a new class of complex-shaped interconnects with enhanced performance and durability and excellent scalability at a low cost

Isotope Exchange Raman Spectroscopy (IERS): a novel technique to probe physicochemical processes inin situsitu

We have developed a novel in situ methodology for the direct study of mass transport properties in oxides with spatial and unprecedented time resolution, based on Raman spectroscopy coupled to isothermal isotope exchanges. Changes in the isotope concentration, resulting in a Raman frequency shift, can be followed in real time, not accessible by conventional methods, enabling complementary insights for the study of ion transport properties of electrode and electrolyte materials for advanced solid-state electrochemical devices. The proof of concept and strengths of isotope exchange Raman spectroscopy (IERS) are demonstrated by studying the oxygen isotope back-exchange in gadolinium-doped ceria (CGO) thin films. Resulting oxygen self-diffusion and surface exchange coefficients are compared to conventional time-of-flight secondary ion mass spectrometry (ToF-SIMS) characterisation and literature values, showing good agreement, while at the same time providing additional insight, challenging established assumptions. IERS captivates through its rapidity, simple setup, non-destructive nature, cost effectiveness and versatile fields of application and thus can readily be integrated as new standard tool for in situ and operando characterization in many laboratories worldwide. The applicability of this method is expected to consolidate our understanding of elementary physicochemical processes and impact various emerging fields including solid oxide cells, battery research and beyond

SiNERGY, a project on energy harvesting and microstorage empowered by Silicon technologies

Internet of Things and Trillion Sensors are buzzwords illustrating the path towards the next grand paradigm: Smart Everywhere. In many of those realizations long term autonomy of sensor systems is a must to tackle different societal challenges and innovation scenarios. Microenergy autonomy solutions based on energy harvesting offer a promising way in which, KETS mediated, silicon technology and silicon friendly materials may play a decisive role.This work was supported by FP7- NMP-2013-SMALL-7, SiNERGY (Silicon Friendly Materials and Device Solutions for Microenergy Applications), Contract n. 604169Peer reviewe

Synthesis of perovskite-type high-entropy oxides as potential candidates for oxygen evolution

High-entropy materials offer a wide range of possibilities for synthesizing new functional ceramics for different applications. Many synthesis methods have been explored to achieve a single-phase structure incorporating several different elements, yet a comparison between the synthesis methods is crucial to identify the new dimension such complex ceramics bring to material properties. As known for ceramic materials, the synthesis procedure usually has a significant influence on powder morphology, elemental distribution, particle size and powder processability. Properties that need to be tailored according to specific applications. Therefore, in this study perovskite-type high-entropy materials (Gd$_{0.2}$La$_{0.2–x}$Sr$_x$Nd$_{0.2}$Sm$_{0.2}$Y$_{0.2}$) (Co$_{0.2}$Cr$_{0.2}$Fe$_{0.2}$Mn$_{0.2}$Ni$_{0.2}$)O$_3$ (x = 0 and x = 0.2) are synthesized for the first time using mechanochemical synthesis and a modified Pechini method. The comparison of different syntheses allows, not only tailoring of the constituent elements of high-entropy materials, but also to optimize the synthesis method as needed to overcome limitations of conventional ceramics. To exploit the novel materials for a variety of energy applications, their catalytic activity for oxygen evolution reaction was characterized. This paves the way for their integration into, e.g., regenerative fuel cells and metal air batteries

Synthesis of perovskite-type high-entropy oxides as potential candidates for oxygen evolution

High-entropy materials offer a wide range of possibilities for synthesizing new functional ceramics for different applications. Many synthesis methods have been explored to achieve a single-phase structure incorporating several different elements, yet a comparison between the synthesis methods is crucial to identify the new dimension such complex ceramics bring to material properties. As known for ceramic materials, the synthesis procedure usually has a significant influence on powder morphology, elemental distribution, particle size and powder processability. Properties that need to be tailored according to specific applications. Therefore, in this study perovskite-type high-entropy materials (Gd₀.₂La₀.₂₋ₓ SrₓNd₀.₂Sm₀.₂Y₀.₂) (Co₀.₂Cr₀.₂Fe₀.₂Mn₀.₂Ni₀.₂)O₃ (x = 0 and x = 0.2) are synthesized for the first time using mechanochemical synthesis and a modified Pechini method. The comparison of different syntheses allows, not only tailoring of the constituent elements of high-entropy materials, but also to optimize the synthesis method as needed to overcome limitations of conventional ceramics. To exploit the novel materials for a variety of energy applications, their catalytic activity for oxygen evolution reaction was characterized. This paves the way for their integration into, e.g., regenerative fuel cells and metal air batteries