In this work we demonstrate the role of grain boundaries and domain walls in the local transport properties of n- and p-doped bismuth ferrites, including the influence of these singularities on the space charge imbalance of the energy band structure. This is mainly due to the charge accumulation at domain walls, which is recognized as the main mechanism responsible for the electrical conductivity in polar thin films and single crystals, while there is an obvious gap in the understanding of the precise mechanism of conductivity in ferroelectric ceramics. The conductivity of the BiCaFeTiO (x = 0, 0.05, 0.1; δ = (0.05 - x)/2) samples was studied using a scanning probe microscopy approach at the nanoscale level as a function of bias voltage and chemical composition. The obtained results reveal a distinct correlation between electrical properties and the type of charged defects when the anion-deficient (x = 0) compound exhibits a three order of magnitude increase in conductivity as compared with the charge-balanced (x = 0.05) and cation-deficient (x = 0.1) samples, which is well described within the band diagram representation. The data provide an approach to control the transport properties of multiferroic bismuth ferrites through aliovalent chemical substitution.
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http://dx.doi.org/10.3390/nano10050940 | DOI Listing |
ACS Appl Bio Mater
January 2025
Department of Chemistry, Indian Institute of Technology Palakkad, Palakkad, Kerala 678 623, India.
The aggregation of proteins, peptides and amino acids has been a keen subject of interest owing to their implications in metabolic disorders. In this work, we investigated the self-aggregation of the unmodified aromatic amino acid l-tryptophan (Trp) into unusual spherical microstructures. Using fluorescence spectroscopy and field emission scanning electron microscopy (FE-SEM), we detail the time-dependent transformation of monomeric tryptophan into spherical aggregates with distinct fluorescence characteristics (λ = 345 nm, λ = 430 nm) compared to the monomer.
View Article and Find Full Text PDFJ Phys Chem C Nanomater Interfaces
January 2025
Institute of Physics, NAWI Graz, University of Graz, Universitätsplatz 5, 8010 Graz, Austria.
For weakly interacting adsorbate/substrate systems, the integer charge transfer (ICT) model describes how charge transfer across interfaces depends on the substrate work function. In particular, work function regimes where no charge transfer occurs (vacuum level alignment) can be distinguished from regions where integer charge transfer by electron tunneling from substrate to adsorbate or vice versa takes place (Fermi level pinning). While the formation of singly integer charged molecular anions and cations of organic semiconductors on various substrates has been well described by this model, the double integer charging regime has so far remained unexplored and experimentally elusive.
View Article and Find Full Text PDFQuant Imaging Med Surg
January 2025
Department of Neurology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Background: Rapid eye movement sleep behavior disorder (RBD) is associated with pathological α-synuclein deposition and may have different damage directions due to α-synuclein spreading orientations. Recent functional imaging studies of Parkinson's disease (PD) with RBD have identified abnormalities in connectivity, but effective connectivity (EC) for this altered orientation is understudied. Here, we aimed to explore altered intrinsic functional connectivity (FC) and EC in PD patients with probable RBD (pRBD).
View Article and Find Full Text PDFQuant Imaging Med Surg
January 2025
Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China.
Background: Magnetic resonance (MR) diffusion-derived 'vessel density' (DDVD) is calculated according to: DDVD = Sb0/ROI - S/ROI, where S and S refer to the tissue signal when -value is 0 or 2 s/mm. S and ROI can also be approximated by other low -values diffusion-weighted imaging (DWI). This study investigates the influence of the second motion probing gradient -value and T2 on DDVD calculations of the liver, spleen, and liver simple cyst.
View Article and Find Full Text PDFSmall
January 2025
Leibniz-Institut für Polymerforschung e. V, Hohe Str. 6, 01069, Dresden, Germany.
Polyelectrolyte brushes (PEBs) undergo conformational transitions due to changes in pH and/or ionic strength, which is leveraged as smart surfaces and on-demand drug-release systems. However, probing conformational transitions of functional PEBs has remained challenging due to low spatiotemporal resolution of characterization methods. Herein, fluorescently-coupled PEBs are devised that give rise to Förster Resonance Energy Transfer (FRET) intrinsically coupled to conformational transitions of chains.
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