Microstructural impacts on ionic conductivity of oxide solid electrolytes from a combined atomistic-mesoscale approach

Although multiple oxide-based solid electrolyte materials with intrinsically high ionic conductivities have emerged, practical processing and synthesis routes introduce grain boundaries and other interfaces that can perturb primary conduction channels. To directly probe these effects, we demonstrate an efficient and general mesoscopic computational method capable of predicting effective ionic conductivity through a complex polycrystalline oxide-based solid electrolyte microstructure without relying on simplified equivalent circuit description. We parameterize the framework for Li7-xLa3Zr2O12 (LLZO) garnet solid electrolyte by combining synthetic microstructures from phase-field simulations with diffusivities from molecular dynamics simulations of ordered and disordered systems. Systematically designed simulations reveal an interdependence between atomistic and mesoscopic microstructural impacts on the effective ionic conductivity of polycrystalline LLZO, quantified by newly defined metrics that characterize the complex ionic transport mechanism. Our results provide fundamental understanding of the physical origins of the reported variability in ionic conductivities based on an extensive analysis of literature data, while simultaneously outlining practical design guidance for achieving desired ionic transport properties based on conditions for which sensitivity to microstructural features is highest. Additional implications of our results are discussed, including a possible connection between ion conduction behavior and dendrite formation.

Preparation of PSFO and LPSFO Nanofibers by Electrospinning and Their Electronic Transport and Magnetic Properties

In this paper, Pr0.5Sr0.5FeO3 (PSFO) and La0.25Pr0.25Sr0.5FeO3 (LPSFO) nanofibers were prepared by electrospinning and subsequent calcination, and their morphology, microstructure, electronic transport and magnetic properties were studied systematically. The temperature-dependent resistance curves of PSFO and LPSFO nanofibers were measured in the temperature range from 300 K down to 10 K. With the temperature lowering, the resistance increased gradually and the then decreased sharply due to the occurrence of ferromagnetic metal phase. The metal-insulator transition temperature was about 110 K and 180 K for PSFO and LPSFO nanofibers separately. The electronic conduction behavior above the transition temperature can be described by one-dimensional Mott’s variable-range hopping (VRH) model. The hysteresis loops and the field-cooled (FC) and zero-field-cooled (ZFC) curves showed that both PSFO and LPSFO nanofibers exhibit ferromagnetism. Although the doping of La reduces the overall magnetization intensity of the material, it increases the ferromagnetic ratio of the system, which may improve the performance of LPSFO in solid oxide fuel cell.

MAPbI3 Microrods-Based Photo Resistor Switches: Fabrication and Electrical Characterization

The current work proposed the application of methylammonium lead iodide (MAPbI3) perovskite microrods toward photo resistor switches. A metal-semiconductor-metal (MSM) configuration with a structure of silver-MAPbI3(rods)-silver (Ag/MAPbI3/Ag) based photo-resistor was fabricated. The MAPbI3 microrods were prepared by adopting a facile low-temperature solution process, and then an independent MAPbI3 microrod was employed to the two-terminal device. The morphological and elemental compositional studies of the fabricated MAPbI3 microrods were performed using FESEM and EDS, respectively. The voltage-dependent electrical behavior and electronic conduction mechanisms of the fabricated photo-resistors were studied using current–voltage (I–V) characteristics. Different conduction mechanisms were observed at different voltage ranges in dark and under illumination. In dark conditions, the conduction behavior was dominated by typical trap-controlled charge transport mechanisms within the investigated voltage range. However, under illumination, the carrier transport is dominated by the current photogenerated mechanism. This study could extend the promising application of perovskite microrods in photo-induced resistor switches and beyond.

Thermal and electrical conduction of AL/CNT composite

Authors have investigated the thermal and electrical conduction behavior of Al/MWCNT composite fabricated by powder metallurgy method in which CNTs were pre-encapsulated with Ni. The thermal and electrical conductivity values were found proportional to the addition of CNTs. For 2.5% wt. CNTs addition with HIP treatment, the Al/CNT composite showed thermal conductivity of 476 W/m-k which is about 85% higher than the value of pure Al. Also, the resultant electrical conductivity was 0.405 × 10−8 S which is about 14% higher than the value of pure Al. The increased thermal and electrical conductivity can be attributed mainly to the well dispersion of CNTs through Ni-encapsulation and the enhanced interfacial bonding of Ni-coated CNTs with the matrix. Due to having good electrical conductivity of nickel itself, electrical conductivity of the composite was also enhanced which was further confirmed from First Principle study.