RESUMEN
Electrical equivalent circuits are a widely applied tool with which electrical processes can be rationalized. There is a wide-ranging selection of fields from bioelectrochemistry to batteries to fuel cells making use of this tool. Enabling meta-analysis on the similarities and differences in the used circuits will help to identify commonly used circuits and aid in evaluating the underlying physics. We present a method and an implementation that enables the conversion of circuits included in scientific publications into a machine-readable form for generating machine learning datasets or circuit simulations.
RESUMEN
Recent advances in perovskite ferroelectrics have fostered a host of exciting sensors and actuators. Defect engineering provides critical control of the performance of ferroelectric materials, especially lead-free ones. However, it remains a challenge to quantitatively study the concentration of defects due to the complexity of measurement techniques. Here, a feasible approach to analyzing the A-site defect and electron in alkali metal niobate is demonstrated. The theoretical relationships among defect concentration, conductivity, and oxygen partial pressure can be established based on the defect chemistry equilibria. The type and concentration of defects are reflected through the conductivity variation with oxygen partial pressure. As a result, the variation of defect concentration gives rise to defect-driven interfacial polarization, which further leads to distinct properties of the ceramics. e.g., abnormal dielectric behavior. Furthermore, this study also suggests a strategy to manipulate defects and charges in perovskite oxides for performance optimization.
RESUMEN
Dislocations are 1D crystallographic line defects and are usually seen as detrimental to the functional properties of classic semiconductors. It is shown here that this not necessarily accounts for oxide semiconductors in which dislocations are capable of boosting the photoconductivity. Strontium titanate single crystals are controllably deformed to generate a high density of ordered dislocations of two slip systems possessing different mesoscopic arrangements. For both slip systems, nanoscale conductive atomic force microscope investigations reveal a strong enhancement of the photoconductivity around the dislocation cores. Macroscopic in-plane measurements indicate that the two dislocation systems result in different global photoconductivity behavior despite the similar local enhancement. Depending on the arrangement, the global photoresponse can be increased by orders of magnitude. Additionally, indications for a bulk photovoltaic effect enabled by dislocation-surrounding strain fields are observed for the first time. This proves that dislocations in oxide semiconductors can be of large interest for tailoring photoelectric functionalities. Direct evidence that electronic transport is confined to the dislocation core points to a new emerging research field.
RESUMEN
For millennia, ceramics have been densified via sintering in a furnace, a time-consuming and energy-intensive process. The need to minimize environmental impact calls for new physical concepts beyond large kilns relying on thermal radiation and insulation. Here, we realize ultrarapid heating with intense blue and UV-light. Thermal management is quantified in experiment and finite element modelling and features a balance between absorbed and radiated energy. With photon energy above the band gap to optimize absorption, bulk ceramics are sintered within seconds and with outstanding efficiency (≈2 kWh kg-1) independent of batch size. Sintering on-the-spot with blacklight as a versatile and widely applicable power source is demonstrated on ceramics needed for energy storage and conversion and in electronic and structural applications foreshadowing economic scalability.
RESUMEN
The introduction of dislocations is a recently proposed strategy to tailor the functional and especially the electrical properties of ceramics. While several works confirm a clear impact of dislocations on electrical conductivity, some studies raise concern in particular when expanding to dislocation arrangements beyond a geometrically tractable bicrystal interface. Moreover, the lack of a complete classification on pertinent dislocation characteristics complicates a systematic discussion and hampers the design of dislocation-modified electrical conductivity. We proceed by mechanically introducing dislocations with three different mesoscopic structures into the model material single-crystal SrTiO3 and extensively characterizing them from both a mechanical as well as an electrical perspective. As a final result, a deconvolution of mesoscopic structure, core structure, and space charge enables us to obtain the complete picture of the effect of dislocations on functional properties, focusing here on electric properties.
RESUMEN
Coupling of magnetic, ferroelectric, or piezoelectric properties with charge transport at oxide interfaces provides the option to revolutionize classical electronics. Here, the modulation of electrostatic potential barriers at tailored ZnO bicrystal interfaces by stress-induced piezoelectric polarization is reported. Specimen design by epitaxial solid-state transformation allows for both optimal polarization vector alignment and tailoring of defect states at a semiconductor-semiconductor interface. Both quantities are probed by transmission electron microscopy. Consequently, uniaxial compressive stress affords a complete reduction of the potential barrier height at interfaces with head-to-head orientation of the piezoelectric polarization vectors and an increase in potential barrier height at interfaces with tail-to-tail orientation. The magnitude of this coupling between mechanical input and electrical transport opens pathways to the design of multifunctional electronic devices like strain triggered transistors, diodes, and stress sensors with feasible applications for human-computer interfacing.