Oxide-based valence-change memristors are promising nonvolatile memories for future electronics that operate on valence-change reactions to modulate their electrical resistance. The memristance is associated with the movement of oxygen ionic carriers through oxygen vacancies at high electric field strength via structural defect modifications that are still poorly understood. This study employs a CeGdO solid solution model to probe the role of oxygen vacancies either set as "free" or as "immobile and clustered" for the resistive switching performance. The experiments, together with the defect chemical model, show that when the vacancies are set as "free", a maximum in memristance is found for 20 mol % of GdO doping, which clearly coincides with the maximum in ionic conductivity. In contrast, for higher gadolinia concentration, the oxide exhibits only minor memristance, which originates from the decrease in structural symmetry, leading to the formation of "immobile" oxygen defect clusters, thereby reducing the density of mobile ionic carriers available for resistive switching. The research demonstrates guidelines for engineering of the oxide's solid solution series to set the configuration of its oxygen vacancy defects and their mobility to tune the resistive switching for nonvolatile memory and logic applications.

Memristive devices are among the most prominent candidates for future computer memory storage and neuromorphic computing. Though promising, the major hurdle for their industrial fabrication is their device-to-device and cycle-to-cycle variability. These occur due to the random nature of nanoionic conductive filaments, whose rupture and formation govern device operation. Changes in filament location, shape, and chemical composition cause cycle-to-cycle variability. This challenge is tackled by spatially confining conductive filaments with Ni nanoparticles. Ni nanoparticles are integrated on the bottom La 0.2 Sr 0.7 Ti 0.9 Ni 0.1 O 3−δ electrode by an exsolution method, in which, at high temperatures under reducing conditions, Ni cations migrate to the perovskite surface, generating metallic nanoparticles. This fabrication method offers fine control over particle size and density and ensures strong particle anchorage in the bottom electrode, preventing movement and agglomeration. In devices based on amorphous SrTiO 3 , it is demonstrated that as the exsolved Ni nanoparticle diameter increases up to ≈50 nm, the ratio between the ON and OFF resistance states increases from single units to 180 and the variability of the low resistance state reaches values below 5%. Exsolution is applied for the first time to engineer solid-solid interfaces extending its realm of application to electronic devices.

The effect of surface functionalities, specific surface area and pore size of activated carbon fibers (ACFs) on the adsorption of toluene and acetaldehyde, two volatile organic compounds (VOC), at low concentrations (*80 ppmv) and short contact time (20 ms) has been studied. Two different types of ACFs characterized by low temperature N 2 adsorption: ultramicroporous (d pore \ 1 nm) and supermicroporous (d pore * 1-2 nm) were tested. Both ACFs were effective for the removal of toluene attaining the adsorption capacity as large as 51 wt%. The surface chemistry of ACFs (O-containing functional groups) was characterized by temperature-programmed desorption monitoring the CO/CO 2 evolved. Oxidative treatment of ACFs by nitric acid increased the surface concentration of O-groups. This resulted in lower adsorption capacity towards toluene but higher one towards acetaldehyde. This result was rationalized based on different type of VOC interactions with the carbon surface.

The field of oxide spintronics can strongly benefit from the establishment of ferromagnetic insulators with near room-temperature Curie temperature. Here, we investigate the structural, electronic, and magnetic properties of epitaxially strained thin films of the double perovskite La2NiMnO6 (LNMO) grown by off-axis radio-frequency magnetron sputtering. We find that the films retain insulating behavior and a bulk-like Curie temperature in the order of 280 K independently of the epitaxial strain conditions. These results suggest a prospective implementation of LNMO films in multi-layer device architectures where a high-temperature ferromagnetic insulating state is a prerequisite.