Elucidation of the Transport Properties of Calcium-Doped High Entropy Rare Earth Aluminates for Solid Oxide Fuel Cell Applications.

Solid oxide fuel cells (SOFCs) are paving the way to clean energy conversion, relying on efficient oxygen-ion conductors with high ionic conductivity coupled with a negligible electronic contribution. Doped rare earth aluminates are promising candidates for SOFC electrolytes due to their high ionic conductivity. However, they often suffer from p-type electronic conductivity at operating temperatures above 500 °C under oxidizing conditions caused by the incorporation of oxygen into the lattice.

State of Charge-Dependent Impedance Spectroscopy as a Helpful Tool to Identify Reasons for Fast Capacity Fading in All-Solid-State Batteries.

Thiophosphate-based all-solid-state batteries (ASSBs) are considered the most promising candidate for the next generation of energy storage systems. However, thiophosphate-based ASSBs suffer from fast capacity fading with nickel-rich cathode materials. In many reports, this capacity fading is attributed to an increase of the charge transfer resistance of the composite cathode caused by interface degradation and/or chemo-mechanical failure.

Influence of Microstructure on the Material Properties of LLZO Ceramics Derived by Impedance Spectroscopy and Brick Layer Model Analysis.

Variants of garnet-type LiLaZrO are being intensively studied as separator materials in solid-state battery research. The material-specific transport properties, such as bulk and grain boundary conductivity, are of prime interest and are mostly investigated by impedance spectroscopy. Data evaluation is usually based on the one-dimensional (1D) brick layer model, which assumes a homogeneous microstructure of identical grains.

Contribution of Electrolyte Decomposition Products and the Effect of Temperature on the Dissolution of Transition Metals from Cathode Materials.

A fundamental understanding of aging processes in lithium-ion batteries (LIBs) is imperative in the development of future battery architectures for widespread electrification. Herein, dissolution of transition metals from cathode active materials of LIBs is among the most important degradation processes. Research has demonstrated that elevated operating temperatures accelerate battery degradation.

Understanding the Impedance of Mesoporous Oxides: Reliable Determination of the Material-Specific Conductivity.

The unique architecture of ordered mesoporous oxides makes them a promising class of materials for various electrochemical applications, such as gas sensing or energy storage and conversion. The high accessibility of the internal surface allows tailoring of their electrochemical properties, e.g.

Reproducible long-term cycling data of AlO coated LiNiCoMnO cathodes for lithium-ion batteries.

LiNiCoMnO (NCM) based cathodes for Li-ion batteries (LIBs) are of great interest due to their higher energy density and lower costs compared to conventional LiCoO based cathodes. However, NCM based cathodes suffer from instabilities of the cathode-electrolyte interface resulting in faster capacity fading during long-term cycling. Different NCM compositions along with different coatings have been developed to protect the interface.

Design of Ordered Mesoporous CeO-YSZ Nanocomposite Thin Films with Mixed Ionic/Electronic Conductivity via Surface Engineering.

Mixed ionic and electronic conductors represent a technologically relevant materials system for electrochemical device applications in the field of energy storage and conversion. Here, we report about the design of mixed-conducting nanocomposites by facile surface modification using atomic layer deposition (ALD). ALD is the method of choice, as it allows coating of even complex surfaces.

Ordered mesoporous metal oxides for electrochemical applications: correlation between structure, electrical properties and device performance.

Ordered mesoporous metal oxides with a high specific surface area, tailored porosity and engineered interfaces are promising materials for electrochemical applications. In particular, the method of evaporation-induced self-assembly allows the formation of nanocrystalline films of controlled thickness on polar substrates. In general, mesoporous materials have the advantage of benefiting from a unique combination of structural, chemical and physical properties.

Surface Diffusion Control Enables Tailored-Aspect-Ratio Nanostructures in Area-Selective Atomic Layer Deposition.

Area-selective atomic layer deposition is a key technology for modern microelectronics as it eliminates alignment errors inherent to conventional approaches by enabling material deposition only in specific areas. Typically, the selectivity originates from surface modifications of the substrate that allow or block precursor adsorption. The control of the deposition process currently remains a major challenge as the selectivity of the no-growth areas is lost quickly.

Polarization-dependence of the Raman response of free-standing strained CeGdO membranes.

Square-shaped CeGdO (GDC) membranes are prepared by microstructuring techniques from (111)-oriented, polycrystalline GDC thin films. The strain state of the membranes is investigated by micro-Raman mapping using polarized excitation light. Using circularly polarized excitation, the maps of the Raman shifts reveal circular contour lines in concordance with the quadratic shape of the membrane and with optical investigations of the residual strain distribution.

Optimized atomic layer deposition of homogeneous, conductive AlO coatings for high-nickel NCM containing ready-to-use electrodes.

Atomic layer deposition (ALD) derived ultrathin conformal AlO coating has been identified as an effective strategy for enhancing the electrochemical performance of Ni-rich LiNiCoMnO (NCM; 0 ≤x, y, z < 1) based cathode active materials (CAM) in Li-ion batteries. However, there is still a need to better understand the beneficial effect of ALD derived surface coatings on the performance of NCM based composite cathodes. In this work, we applied and optimized a low-temperature ALD derived AlO coating on a series of Ni-rich NCM-based (NCM622, NCM71.

Tailoring the protonic conductivity of porous yttria-stabilized zirconia thin films by surface modification.

Porous yttria-stabilized zirconia (YSZ) thin films were prepared by pulsed laser deposition to investigate the influence of specific surface area on the electronic, oxygen ion, and protonic transport properties. Electrochemical impedance spectroscopy was carried out as a function of temperature, oxygen activity and humidity of the surrounding atmosphere. At high humidity, protons on the surface of the porous YSZ thin films lead to increased conductivity, even for temperatures up to 700 °C.

Bacteriuria and vitamin D deficiency: a cross sectional study of 385 nursing home residents.

Background: Up to half of elderly people at nursing homes have asymptomatic bacteriuria, and concentrations of 25-hydroxyvitamin D (25OHD) are generally low. Vitamin D is a modulator of the immune system and involved in protection of the epithelium in the urinary tract as well. The objective was to determine a possible association between bacteriuria and vitamin D deficiency among elderly people at nursing homes.

Anomalous Angle-Dependent Magnetotransport Properties of Single InAs Nanowires.

We study the magnetotransport properties of single InAs nanowires grown by selective-area metal-organic vapor-phase epitaxy. The semiconducting InAs nanowires exhibit a large positive ordinary magnetoresistance effect. However, a deviation from the corresponding quadratic behavior is observed for an orientation of the applied magnetic field perpendicular to the nanowire axis.

Thermal stability, electrochemical and structural characterization of hydrothermally synthesised cobalt ferrite (CoFeO).

Monophasic nano-crystalline CoFeO (CFO) nanoparticles of high purity have been synthesised through a low temperature hydrothermal route, which does not involve hazardous chemicals, or conditions. The easy, green procedure involves a hydrothermal treatment at 135 °C of an aqueous suspension of the oxalate salts of the precursors. No further purification or annealing procedure was necessary to obtain the crystalline nano-structured oxide.

Platinum microelectrodes on gadolinia doped ceria single crystals - bulk properties and electrode kinetics.

To better understand the electrode kinetics of oxygen reduction and oxidation of gadolinia doped ceria (GDC), the electrochemical properties of platinum electrodes on GDC single crystals and polycrystalline samples were investigated with geometrically well-defined microelectrodes. For comparison measurements were also performed on polycrystalline samples using platinum interdigital electrodes in order to access the effect of the electrode geometry on the electrochemical properties. The transport properties were characterised using impedance spectroscopy, allowing to separate the transport processes of the electrode and the electrolyte.

Is ReO a mixed ionic-electronic conductor? A DFT study of defect formation and migration in a BO perovskite-type oxide.

Density-functional-theory (DFT) calculations within the generalised gradient approximation (GGA) were used to examine the behaviour of point defects in the cubic BO perovskite-type oxide, ReO. Energies of reduction and of hydration were calculated, and the results are compared with literature data for ABO perovskite oxides. The activation energies of migration were determined for O, H, Li, Na, K and HO.

Nanostructured Composites of BiSb Nanoparticles and Carbon Nanotubes and the Characterization of Their Thermoelectric Properties.

The impact of inclusions of carbon nanotubes (CNT) on the thermoelectric properties of nanostructured BiSb alloys with an Sb content between 10 and 20% was investigated for varying amounts of CNT. Three series of BiSb pellets with 0, 0.3, and 0.

Vitamin D deficiency was common among nursing home residents and associated with dementia: a cross sectional study of 545 Swedish nursing home residents.

Background: Residents of nursing homes may have low 25-hydroxyvitamin D (25OHD) concentrations. Associations between vitamin D and cognitive performance, dementia and susceptibility to infections are not clearly established. The aim of this study was to investigate the prevalence of vitamin D deficiency and to identify associated factors among residents of nursing homes for elderly.

Combining two redox active rare earth elements for oxygen storage - electrical properties and defect chemistry of ceria-praseodymia single crystals.

Solid solutions of ceria and praseodymia are highly relevant for electrochemical applications as the incorporation of praseodymium into the ceria lattice shifts the range of mixed ionic electronic conductivity to higher oxygen partial pressures. To better understand the influence of praseodymium substitution on the transport processes and oxygen storage capacity in ceria, single crystals of ceria substituted with 14 mol% praseodymium have been investigated, obtaining the bulk properties without the influence of grain boundaries. Beside the characterization of structural changes caused by the substitution using XRD and Raman spectroscopy, the electrochemical transport properties of ceria-praseodymia single crystals are reported.

Doping-Induced Universal Conductance Fluctuations in GaN Nanowires.

The transport properties of Ge-doped single GaN nanowires are investigated, which exhibit a weak localization effect as well as universal conductance fluctuations at low temperatures. By analyzing these quantum interference effects, the electron phase coherence length was determined. Its temperature dependence indicates that in the case of highly doped nanowires electron-electron scattering is the dominant dephasing mechanism, while for the slightly doped nanowires dephasing originates from Nyquist-scattering.

Correlation of electrochromic properties and oxidation states in nanocrystalline tungsten trioxide.

Although tungsten trioxide (WO3) has been extensively studied since its electrochromic properties were first discovered, the mechanism responsible for the coloration or bleaching effect is still disputed. New insights into the coloration mechanism of electrochromic, nanocrystalline WO3 are provided in this paper by studying thin WO3 films combining the electrochemical and spectroscopic techniques. By employing in situ UV-Vis transmission spectroscopy at a fixed spectral band pass during electrochemical experiments, such as cyclic voltammetry, a two-step insertion process for both protons and lithium ions is identified, of which one step exhibits a significantly higher coloration efficiency than the other.

Ionic Conductivity of Mesostructured Yttria-Stabilized Zirconia Thin Films with Cubic Pore Symmetry—On the Influence of Water on the Surface Oxygen Ion Transport.

Thermally stable, ordered mesoporous thin films of 8 mol % yttria-stabilized zirconia (YSZ) were prepared by solution-phase coassembly of chloride salt precursors with an amphiphilic diblock copolymer using an evaporation-induced self-assembly process. The resulting material is of high quality and exhibits a well-defined three-dimensional network of pores averaging 24 nm in diameter after annealing at 600 °C for several hours. The wall structure is polycrystalline, with grains in the size range of 7 to 10 nm.