Die vorliegende Arbeit beschäftigt sich mit der elektrischen Charakterisierung von Zinkoxid-Nanodrähten, die mittels gepulster Laserablation (PLD) hergestellt wurden. Ausgehend von den so generierten ZnO-Nanodraht-Ensembles werden Methoden zu deren elektrischer Untersuchung diskutiert und auf praktische Anwendbarkeit hin verglichen. Die entwickelten Methoden werden auf Ensembles von auf n-leitenden ZnO- und ZnO:Ga-Dünnschichten aufgewachsenen Phosphor-dotierten ZnO-Nanodrähten angewendet. Deren reproduzierbares, in Strom–Spannungs- (I–U-) Kennlinien beobachtetes diodenartiges Verhalten wird genauer beleuchtet. Im Zusammenhang mit der elektrischen Charakterisierung einzelner ZnO-Nano-drähte werden experimentelle Methoden zur Vereinzelung und zur Kontaktierung der vereinzelten ZnO-Nanodrähte diskutiert. Dabei werden sowohl etablierte Methoden wie Elektronenstrahllithographie (EBL) als auch neue Techniken wie elektronen- und ionenstrahlinduzierte Deposition (EBID/IBID) und Strom–Spannungs-Rastersondenmikroskopie (I-AFM) behandelt und ihre Eignung für eingehende elektrische Untersuchungen und reproduzierbare Messungen analysiert. Die geeignetsten Methoden werden schließlich eingesetzt, um spezifischen Widerstand sowie Ladungsträgermobilität und -dichte sowohl in nominell undotierten als auch in Aluminium-dotierten ZnO-Nanodrähten zu untersuchen und zu vergleichen. In der Ableitung der physikalischen Materialparameter aus den Messdaten wird dabei besonderes Augenmerk auf die Einbeziehung der geometrischen Besonderheiten der Nanodrähte gegenüber Volumenmaterial- und Dünnschichtproben gelegt. Im Zuge dessen wird unter anderem ein Modell für den elektrischen Widerstand in Nanodrähten mit ihrer Länge nach veränderlichem Querschnitt abgeleitet.

Die vorliegende Arbeit beschäftigt sich mit der elektrischen Charakterisierung von Zinkoxid-Nanodrähten, die mittels gepulster Laserablation (PLD) hergestellt wurden. Ausgehend von den so generierten ZnO-Nanodraht-Ensembles werden Methoden zu deren elektrischer Untersuchung diskutiert und auf praktische Anwendbarkeit hin verglichen. Die entwickelten Methoden werden auf Ensembles von auf n-leitenden ZnO- und ZnO:Ga-Dünnschichten aufgewachsenen Phosphor-dotierten ZnO-Nanodrähten angewendet. Deren reproduzierbares, in Strom–Spannungs- (I–U-) Kennlinien beobachtetes diodenartiges Verhalten wird genauer beleuchtet. Im Zusammenhang mit der elektrischen Charakterisierung einzelner ZnO-Nano-drähte werden experimentelle Methoden zur Vereinzelung und zur Kontaktierung der vereinzelten ZnO-Nanodrähte diskutiert. Dabei werden sowohl etablierte Methoden wie Elektronenstrahllithographie (EBL) als auch neue Techniken wie elektronen- und ionenstrahlinduzierte Deposition (EBID/IBID) und Strom–Spannungs-Rastersondenmikroskopie (I-AFM) behandelt und ihre Eignung für eingehende elektrische Untersuchungen und reproduzierbare Messungen analysiert. Die geeignetsten Methoden werden schließlich eingesetzt, um spezifischen Widerstand sowie Ladungsträgermobilität und -dichte sowohl in nominell undotierten als auch in Aluminium-dotierten ZnO-Nanodrähten zu untersuchen und zu vergleichen. In der Ableitung der physikalischen Materialparameter aus den Messdaten wird dabei besonderes Augenmerk auf die Einbeziehung der geometrischen Besonderheiten der Nanodrähte gegenüber Volumenmaterial- und Dünnschichtproben gelegt. Im Zuge dessen wird unter anderem ein Modell für den elektrischen Widerstand in Nanodrähten mit ihrer Länge nach veränderlichem Querschnitt abgeleitet.

Traditionally archaeology has referred to the anthropic sediments accumulated around prehistoric settlements with the blanket term ‘midden’. This is now recognised as an inadequate term to describe the complex formation processes and functions represented in these sediments. This thesis reviewed the body of evidence accumulated over the past century of research into Neolithic and Bronze Age settlements on the islands of the Scottish North Atlantic seaboard and extrapolated the many occurrences of ‘midden’. Several contexts emerged for these sediments including interior floors, hearths, exterior occupational surfaces, dumped deposits, building construction materials and abandonment infill. In addition, ‘midden’ is described added to cultivated soils to form fertile anthrosols. The way in which prehistoric communities exploited this material for agriculture and construction has been described through geoarchaeological research which implied that to past communities ‘midden’ was a valuable resource. This led to the formation of a model based upon a human ecodynamics framework to hypothesise sediment formation pathways. Rescue excavation at the Links of Noltland, Westray provided an opportunity to conduct a holistic landscape and fine resolution based study of Neolithic and Bronze Age settlement to test this model. The research incorporated auger survey, archaeological and geoarchaeological excavation, thin section micromorphology and SEM EDX analyses. Sediments identified in literature review and recovered from the field site were described using this toolkit and set within a cultural and environmental context. Results demonstrate that anthropic materials were incorporated into all contexts examined. Discrete burning and maintenance activities were found to have taken place during the gradual accumulation of open-air anthropic sediments whilst incorporation of fuel residues and hearth waste into floors lead to the gradual formation of ‘living floors’ inside structures. An unexpected discovery was evidence of animal penning within late Neolithic/Early Bronze Age settlement and the in situ burning of stabling waste. Three types iv | P a g e of land management strategy which relied upon the input of anthropic sediments were evidenced and the range and extent of anthropic inclusions in the landscape recorded. Spatial interpolation of auger survey data utilised a new sub-surface modelling technique being developed by the British Geological Survey to explore soil stratigraphic relationships in 3D. SEM EDX analysis supported micromorphological analysis providing chemical data for discrete inclusions and assisting in the identification of herbivore dun ash and the Orcadian funerary product ‘cramp’. SEM EDX analysis was also applied to fine organo-mineral material for statistical testing of nutrient loadings across context groups. It was found that anthropic sediments were enriched in macro and intermediate plant nutrients Mg, P, K, S and Ca compared to geological controls, and the application of anthropic material to cultivated soils improved soil fertility for the three observed land management practices. The versatility of anthropic sediments was explored through discussion of context groups based upon the results of this research and the potential significance of this material to prehistoric communities is explored.

Sr₃Ru₂O₇ is a quasi-two-dimensional metal and has a paramagnetic ground state that is heavily renormalised by electron-electron correlations and magnetic exchange interactions. Inextricably linked to this renormalisation is the metamagnetism of Sr₃Ru₂O₇ - a rapid rise in uniform magnetisation over a narrow range of applied magnetic field. Knowledge of the zero-field physics is essential to any description of the metamagnetism. Light may be shed on the enigmatic ground state of Sr₃Ru₂O₇ by doping the crystal lattice with foreign cations: this is the primary purpose of the original research referred to in this thesis, in which studies of some of the electronic properties of crystals of cation-doped Sr₃Ru₂O₇ are reported. Single crystals of Sr₃(Ru[subscript(1-x)]Ti[subscript(x)])₂O₇ and Sr₃(Ru[subscript(1-x)]Cr[subscript(x)])₂O₇ have been synthesised in an image furnace and some of the properties of these crystals have been measured. Evidence that indicates the emergence of a spin density wave as a function of Ti-doping in Sr₃(Ru[subscript(1-x)]Ti[subscript(x)])₂O₇ is presented. Time-dependent magnetic irreversibility has been observed in samples of Sr₃(Ru[subscript(1-x)]Cr[subscript(x)])₂O₇, thus hinting at the involvement of the RKKY mechanism in these materials. Regarding cation doping out of the conducting RuO₂ planes, samples of (Sr[subscript(1-y)]La[subscript(y)])₃Ru₂O₇ have been grown and investigated. Both the Sommerfeld coefficient and the Fermi liquid A coefficient of (Sr[subscript(1-y)]La[subscript(y)])₃Ru₂O₇ are found to decrease as a function of y (0 ≤ y ≤ 0.02); these observations point towards a reduction in the thermodynamic mass of the Landau quasiparticles. Results from magnetoresistance and magnetisation measurements indicate that the metamagnetism of the (Sr[subscript(1-y)]La[subscript(y)])₃Ru₂O₇ series probably cannot be explained by a rigid band-shift model. Also, some aspects of these data imply that the metamagnetism cannot be fully accounted for by a spin fluctuation extension to the Ginzburg-Landau theory of uniform magnetisation.

The focus of this work is to investigate the dissolution of MW25, a non-radioactive simulant of UK high-level nuclear waste borosilicate glass, and to predict its performance in the near field of a geological repository. A single-pass flow-through (SPFT) experimental system was used to measure the forward dissolution rates of MW25. Experiments were conducted in two parts. Experiment Part 1 considers the dissolution of the waste glass in deionised water at 40 and 90 oC and circum-neutral pH. Experiment Part 2 considers the dissolution of the waste glass in simulant groundwaters, with similar compositions to groundwaters of Callovo-Oxfordian clay (lower-strength sedimentary rock (LSSR)) and Borrowdale Volcanic Group rocks (higher-strength rock (HSR)), at 40 oC and pH 7. The forward dissolution rate measured in deionised water was found to be approximately one order of magnitude higher at 90 oC than at 40 oC. A similar release was observed for Si, Mg and Al at 40 oC and 90 oC, whereas the B, Cs, Na, Li and Mo showed an order of magnitude increase when the temperature was increased from 40 to 90 oC for low q/S values. The activation energy (Ea) of the reactions shows that the dissolution process is a surface phenomenon. At 90 oC the net effect of the processes governing MW25 dissolution led to the preferential release of boron and alkali metals relative to the release of Si during the transient dissolution stage, accompanied by an increase in the concentration of silicic acid. This suggests that the solution activity of silicic acid at a higher temperature has a weak influence on the release of the mobile elements. The forward dissolution rate measured in LSSR simulant groundwater was found to be slightly higher than that measured in HSR simulant groundwater. The dissolution behaviour of MW25 in both groundwaters is consistent with its behaviour in deionised water at 40 oC, with the dissolution rates of elements increasing as flow rates were increased. However, forward dissolution rates measured in the simulant groundwaters were lower than the forward dissolution rates measured in deionised water under these experimental conditions. This is attributable to the interaction of the components of the simulant groundwaters with the glass, as revealed by post-reaction surface analyses, and a consequential lower alkalinity of the leachates collected in the experiments with simulant groundwater than in deionised water. Reactive chemical transport simulations of waste glass dissolution and radionuclide release in a hypothetical near field were conducted over a time span of a million years with GoldSim. The results showed that enclosing the waste glass in a steel canister covered by a copper canister and emplacing the waste package in a granite host rock is optimal for the long-term isolation of the radionuclides. The waste glass was found to play a significant role in the overall performance of the near field. This study features a new method for estimating the surface area of reacted glass powder more accurately than the geometric surface area estimate, which is the preferred standard method among researchers.

Cette thèse porte sur l’évaluation des techniques pour la tomographie chimique par STEM EDX : mise au point des procédures expérimentales, traitement des données, reconstruction des volumes, analyse de la qualité des résultats obtenus et évaluation de la complexité globale. Les performances très limitées de l’analyse STEM EDX font que peu d’études, jusqu’à aujourd’hui, se sont portées sur cette technique. Cependant, les avancées très notables procurées par les nouveaux détecteurs ‘SDD’ ainsi que les sources électroniques X-FEG haute brillance, rendant l’analyse STEM EDX 2D très rapide, ont relancé la possibilité de la tomographie chimique ; la technique demande toutefois à être mise au point et évaluée (performances et complexité). Nous avons travaillé sur un microscope Tecnai Osiris permettant d’acquérir des cartographies chimiques EDX de centaines de milliers de pixels avec une résolution de l’ordre du nanomètre en quelques minutes. Nous avons choisi de préparer par FIB des échantillons en forme de pointe et d’utiliser un porte-objet permettant une exploration angulaire de 180° sans ombrage. Puis, à l’aide d’échantillons modèles (billes de SiO2 dans une résine), nous avons évalué les déformations d’échantillon par l’irradiation du faisceau électronique. Ceci nous a permis de proposer une méthode pour limiter cet effet par déposition d’une couche de 20 nm de chrome. Des simulations d’images ont permis d’évaluer les logiciels et méthodes de reconstruction. La méthodologie de chaque étape d’une analyse de tomographie STEM EDX a ensuite été expliquée, et l’intérêt de la technique démontré grâce à la comparaison de l’analyse 2D et 3D d’un transistor FDSOI 28 nm. La qualité des reconstructions (rapport signal-sur-bruit, résolution spatiale) a été évaluée en fonction des paramètres expérimentaux à l’aide de simulations et d’expériences. Une résolution de 4 nm est démontrée grâce à l’analyse d’une mire et d’un transistor « gate all around ». Pour ce même transistor, la possibilité et l’intérêt d’analyse de défaillance à l’échelle nanométrique est prouvée. Une analyse d’un défaut de grille d’une SRAM ou de trous dans un pilier en cuivre permettent d’expliquer l’intérêt d’une combinaison d’un volume HAADF (morphologie et résolution < 4 nm) et du volume EDX (information chimique). La conclusion est que cette technique, qui reste encore à améliorer du point de vue de sa simplicité, montre déjà son utilité pour l’analyse et la mise au point des technologies avancées (nœud 20 nm et après). / This thesis focuses on the evaluation of the STEM EDX chemical tomography technique: development of experimental procedures, data processing and volumes reconstruction, quality analysis of the results and evaluation of the overall complexity. Until now, STEM EDX analysis performances were very limited, so only few studies about this technique have been realized. However, very significant progress procured by the new SDD detectors as well as by the high brightness electronic sources (X-FEG), making the STEM EDX 2D analysis very fast, have revived the possibility of the chemical tomography, although the technique has to be developed and evaluated (performance and complexity). We have worked on a Tecnai Osiris which acquires EDX chemical mapping of hundreds of thousands of pixels with resolution of one nanometer and in a few minutes. We chose to prepare the rod-shaped samples by FIB and use a sample holder allowing an angle of exploration of 180° without shadowing effects. Then, using model samples (SiO2 balls in resin), we evaluated the sample deformation due to the electron beam irradiation. This allowed us to propose a method to reduce this effect by depositing a 20 nm chromium layer. Images simulations were used to evaluate the software and the reconstruction methods. The methodology of each step of the STEM EDX tomography analysis is then explained and the technique interest is demonstrated by comparing the 2D and the 3D analysis of a transistor 28 nm FDSOI. The quality of the reconstructions (signal-to-noise ratio, spatial resolution) was evaluated, in function of experimental parameters, using simulations and experiments. A resolution of 4 nm is demonstrated through the analysis of a test pattern and a "gate all around” transistor. For the same transistor, the possibility and the interest of a failure analysis at the nanoscale is proven. Analyses of a SRAM gate fail or of the holes in a copper pillar explain the benefits of a combination between a HAADF volume (morphology and resolution < 4 nm) and an EDX volume (chemical information). To conclude, this technique, which still needs to be improved in terms of simplicity, is already showing its usefulness for the analysis and the development of advanced technologies (20nm node and beyond).

The Sámi’s past activities have been documented historically from a European perspective, and more recently from an anthropological viewpoint, giving a generalised observation of the Sámi, during the study period of AD200-AD1800, as semi-nomadic hunter gatherers, with several theories suggesting that interaction with Europeans, through trade, led to the adoption of European activities by certain groups of the Sámi (Eiermann, 1923; Paine, 1957; Manker and Vorren, 1962; Bratrein, 1981; Mathiesen et al, 1981; Meriot, 1984). However, there is almost no information on the impact the Sámi had on the landscape, either before or after any adoption of European activities, and none investigating what cultural footprint or indicators would remain from Sámi or European occupation and/or activity within the typically podzolic soils of Northern Sweden. Consequently the thesis aims to contribute to the gap in knowledge through the formation of a podzol model identifying the links between anthropogenic activity and the alteration of podzol soils, and through the creation of soils based models which identify the cultural indicators associated with both Sámi and European activity; formed from the identification of cultural indicators retained within known Sámi and European sites. The methods used to obtain the information needed to achieve this were the pH and magnetic susceptibility from bulk soil samples and micromorphological and chemical analysis of thin section slides through the use of standard microscopy and X-ray fluorescence from a scanning electron microscope. The analysis revealed that the Sámi had an extremely low impact on the landscape, leaving hard to detect cultural indicators related to reindeer herding in the form of reindeer faecal material with corresponding phosphorous peaks in the thin section slides. The European footprint however, was markedly different and very visible even within the acidic soil environment. The European indicators were cultivation based and included phosphorous and aluminium peaks as well as a deepened, highly homogenised plaggen style anthropogenic topsoil rich in ‘added’ materials. An abandoned European site which visibly and chemically shows the formation of a secondary albic horizon within the anthropogenic topsoil also provides an insight into the delicate balance of cultivated soil in northern Sweden, whilst reinforcing the outputs identified in the podzol model. Due to the almost invisible Sámi footprint on the landscape, areas of overlap were impossible to identify however, there was no evidence of the adoption of European cultivation activities at any of the Sámi sites investigated. The only known area of interaction between the two cultures was an official market place which had been a Sámi winter settlement prior to its use as a market site. This site showed none of the reindeer based Sámi indicators or the cultivation based European indicators, but did contain pottery fragments which could be linked to trade or occupation. Overall, the thesis reinforces the low impact expected of the semi-nomadic Sámi and sheds light on the underlying podzolic processes influencing the anthropogenically modified soils of Northern Sweden. The podzol model is reinforced by several findings throughout the thesis and the soils based cultural indicator models for both Sámi and European activity have been successfully tested against independent entomological and palynological data and therefore provide reliable reference material for future studies.

Soy flour (SF), a by-product of the soybean oil extraction processing, was investigated for its application in soy-polypropylene composites for interior automotive applications. The emphasis of this work was the understanding of this new type of filler material and the contribution of its major constituents to its thermal stability and impact properties. For this reason, reference materials were selected to represent the protein (soy protein isolate (SPI)) and carbohydrate (soy hulls (SH)) constituents of the soy flour. Additional materials were also investigated: the residue obtained after the protein removal from the soy flour which was called insoluble soy (IS), and the remaining liquid solution after acid precipitation of the proteins, containing mostly sugars and minerals, which was called soluble sugar extract (SSE). Two treatments, potassium permanganate and autoclave, were analyzed for their potential to modify the properties of the soy composite materials. An acid treatment with sulfuric acid conducted on soy flour was also considered. The soy materials were studied by thermogravimetric analysis (TGA) under isothermal (in air) and dynamic (in nitrogen) conditions. SPI had the highest thermal stability and SSE the lowest thermal stability for the early stage of the heating process. Those two materials had the highest amount of residual mass at the end of the dynamic TGA in nitrogen. The two treatments showed minimal effect on the isothermal thermal stability of the soy materials at 200 ??C. A minor improvement was observed for the autoclave treated soy materials. Fourier transformed infrared (FTIR) spectroscopy indicated that the chemical surface composition differed according to type of the soy materials but no difference could be observed for the treatments within one type of soy material. Contact angle analysis and surface energy estimation indicated differences of the surface hydrophobicity of the soy materials according to type of material and treatment. The initial water contact angle ranged from 57 ?? for SF to 85 ?? for SH. The rate of water absorption increased dramatically after the autoclave treatment for IS and SPI. Both materials showed the highest increase in the polar surface energy fraction. In general, the major change of the surface energy was associated with change of the polar fraction. After KMnO4 treatment, the polar surface energy of SF, IS and SPI decreased while SH showed a slight increase after KMnO4 treatment. A relationship between protein content and polar surface energy was observed and seen to be more pronounced when high protein containing soy materials were treated with KMnO4 and autoclave. Based on the polar surface energy results, the most suitable soy materials for polypropylene compounding are SPI (KMnO4), SH, and IS (KMnO4) because their polar surface energy are the lowest which should make them more compatible with non-polar polymers such as polypropylene. The soy materials were compounded as 30 wt-% material loading with an injection moulding grade polypropylene blend for different combinations of soy material treatment and coupling agents. Notched Izod impact and flexural strength as well as flexural modulus estimates indicated that the mechanical properties of the autoclaved SF decreased when compared to untreated soy flour while the potassium permanganate treated SF improved in impact and flexural properties. Combinations of the two treatments and two selected (maleic anhydride grafted polypropylene) coupling agents showed improved impact and flexural properties for the autoclaved soy flour but decreased properties for the potassium permanganate treated soy flour. Scanning electron microscopy of the fractured section, obtained after impact testing of the composite material, revealed different crack propagation mechanisms for the treated SF. Autoclaved SF had a poor interface with large gaps between the material and the polypropylene matrix. After the addition of a maleic anhydride coupling agent to the autoclaved SF and polypropylene formulation, the SF was fully embedded in the polymer matrix. Potassium permanganate treated SF showed partial bonding between the material and the polymer matrix but some of the material showed poor bonding to the matrix. The acid treated SF showed cracks through the dispersed phase and completely broken components that did not bind to the polypropylene matrix. In conclusion, the two most promising soy materials in terms of impact and flexural properties improvement of soy polypropylene composites were potassium permanganate treated SF and the autoclaved SF combined with maleic anhydride coupling agent formulation.

The aim of this work was to study the separate effect of fission fragment damage on the structural integrity and matrix dissolution of uranium dioxide in water. Radiation damage similar to fission damage was created by irradiating bulk undoped and doped ‘SIMFUEL’ disks of UO2, undoped bulk CeO2 and thin films of UO2 and CeO2 with high energy Xe and U ions. The UO2 thin films, with thicknesses in the range of 90 – 150 nm, were deposited onto (001), (110) and (111) orientations of single crystal LSAT (Al10La3O51Sr14Ta7) and YSZ (Yttria-Stabilised Zirconia) substrates. The CeO2 thin films were deposited onto single crystal silicon (001) substrates. Part of the bulk UO2 and CeO2 samples, the thin films of UO2 on the LSAT substrates and the thin films of CeO2 were irradiated with 92 MeV 129Xe23+ ions to a fluence of 4.8 × 1015 ions/cm2 to simulate the damage produced by fission fragments in uranium dioxide nuclear fuel. Part of the bulk UO2 and CeO2 samples and the thin films of UO2 on the YSZ substrates were irradiated with 110 MeV 238U31+ ions to a fluence of 5 × 1010, 5 × 1011 and 5 × 1012 ions/cm2 to study the accumulation of the damage induced. The irradiated and unirradiated samples were studied using scanning electron microscopy (SEM), focused ion beam (FIB), atomic force microscopy (AFM), energy dispersive X-ray (EDX) spectroscopy, electron probe microanalysis (EPMA), X-ray diffraction (XRD), electron backscatter diffraction (EBSD), secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) techniques to characterise the as-produced samples and assess the effects of the ion irradiations. Dissolution experiments were conducted to assess the effect of the Xe ion irradiation on the dissolution of the thin film UO2 samples on the LSAT substrates and the bulk and thin film CeO2 samples. The solutions obtained from the leaching of the irradiated and unirradiated samples were analysed using inductively coupled plasma mass spectrometry (ICP-MS). XRD studies of the bulk UO2 samples showed that the ion irradiations resulted in an increased lattice parameter, microstrain and decreased crystallite size, as expected. The irradiated UO2 thin films on the LSAT substrates underwent significant microstructural and crystallographic rearrangements. It was shown that by irradiating thin films of UO2 with high energy, high fluence ions, it is possible to produce a structure that is similar to a thin slice through the high burn-up structure. It is expected that the ion irradiation induced chemical mixing of the UO2 films with the substrate elements (La, Sr, Al, Ta). As a result, a material similar to a doped SIMFUEL with induced radiation damage was produced.

Multi-metallic aerogels have recently emerged as a novel and promising class of unsupported electrocatalyst materials due to their high catalytic activity and improved durability for various electrochemical reactions. Aerogels can be prepared by a spontaneous one-step gelation process, where the chemical co-reduction of metal precursors and the prompt formation of the nanochain-consisting hydrogels, as a preliminary stage for the preparation of aerogels take place. However, detailed knowledge about the homogeneity and chemical distribution of these three-dimensional Pd-Pt aerogels at the nano-scale as well as at the macro-scale is still unclear to date. Therefore, we used a combination of spectroscopic and microscopic techniques to obtain a better insight into the structure and elemental distribution of the various Pd-rich Pd-Pt aerogels prepared by the spontaneous one-step gelation process. Synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy and high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) in combination with energy-dispersive X-ray spectroscopy (EDX) were employed in this work to uncover the structural architecture and chemical composition of the various Pd-rich Pd-Pt aerogels over a broad length range. The Pd80Pt20, Pd60Pt40 and Pd50Pt50 aerogels showed heterogeneity in the chemical distribution of the Pt and Pd atoms inside the macroscopic nanochain-network. Features of monometallic clusters were not detected by EXAFS or STEM-EDX, indicating alloyed nanoparticles. However, the local chemical composition of the Pd-Pt alloys strongly varied along the nanochains and thus within a single aerogel. To determine the electrochemically active surface area (ECSA) of the Pd-Pt aerogels for applications in electrocatalysis, we used the electrochemical CO stripping method. Due to high porosity and extended network structure, the resulting values of the ECSA for the Pd-Pt aerogels were higher than that for a commercially available unsupported Pt black catalyst. We show that the Pd-Pt aerogels possess a high utilization of catalytically active centers for electrocatalytic applications based on the nanostructured bimetallic framework. Knowledge about the homogeneity and chemical distribution of the bimetallic aerogels can help to further optimize their preparation by the spontaneous one-step gelation process and to tune their electrocatalytic reactivity.