A number of grain boundary phenomena in ionic materials, in particular, anomalous (either depressed or enhanced) charge transport, have been attributed to space charge effects. Developing effective strategies to manipulate transport behaviour requires deep knowledge of the origins of the interfacial charge, as well as its variability within a polycrystalline sample with millions of unique grain boundaries. Electron holography is a powerful technique uniquely suited for studying the electric potential profile at individual grain boundaries, whereas atom-probe tomography provides access to the chemical identify of essentially every atom at individual grain boundaries. Using these two techniques, we show here that the space charge potential at grain boundaries in lightly doped, high-purity ceria can vary by almost an order of magnitude. We further find that trace impurities (<25 ppm), rather than inherent thermodynamic factors, may be the ultimate source of grain boundary charge. These insights suggest chemical tunability of grain boundary transport properties.
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http://dx.doi.org/10.1038/s41563-020-0656-1 | DOI Listing |
Nanoscale Adv
December 2024
Department of Mechanical Engineering, IIT Bombay Mumbai Maharashtra India 400076
Using the spectral energy density method, we predict the phonon scattering mean lifetimes of polycrystalline graphene (PC-G) having polycrystallinity only along the -axis with seven different misorientation (tilt) angles at room temperature. Contrary to other studies on PC-G samples, our results indicate a strong dependence of the thermal conductivity (TC) on the tilt angles which we attribute to careful preparation of our grain boundaries-based samples without introducing any local strains and ensuring periodic boundary conditions for the supercells along the and axes. We also show that the square of the group velocity components along and axes and the phonon lifetimes are uncorrelated and the phonon density of states are almost the same for all samples with different tilt angles.
View Article and Find Full Text PDFHeliyon
December 2024
Department of Mechanics, Electrical Power and Computer, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Dissimilar laser welding of martensitic AISI 1060 carbon steel and Duplex Stainless Steel 2205 was performed based on an experimental and numerical study. The experiments were then conducted based on central composite design experiments (CCD) and analyzed via the response surface methodology (RSM) by considering the effect of laser welding process parameters (incident laser power, speed of welding, nozzle distance and deviation of laser beam) on the weld joint characterization. The experimental results showed that the laser power had a remarkable effect on the melt pool depth.
View Article and Find Full Text PDFHeliyon
December 2024
School of Materials Science and Engineering, Inner Mongolia University of Science and Technology, Baotou, 014010, China.
This paper presents the preparation of the parental experimental alloy, featuring a standard composition of TiYZrFeNiMn, via the vacuum induction melting technique. Subsequently, the TiYZrFeNiMn alloy, with an addition of 2 wt% Ni, underwent mechanical ball milling to yield a TiFe-based composite for experimental purposes. The results of the experimental tests indicate that the composite alloy's phase composition comprises the TiFe primary phase, with a minor quantity of ZrMn phase segregated on the surface of the primary TiFe phase, as well as Ni phase.
View Article and Find Full Text PDFSmall
January 2025
Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, 999077, China.
Tin-based halide perovskites represent a highly promising and eco-friendly alternative to lead-based materials with significant potential for optoelectronic applications. However, their advancement is hampered by challenges such as poor film crystallinity and unintended self-doping. Herein, this work reports the fabrication of high-quality CsSnBr perovskite films by plasma-assisted chemical vapor deposition (PACVD), which improves the film quality.
View Article and Find Full Text PDFSci Rep
January 2025
Multifunctional Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India.
The utilization of single crystals is exponentially growing in optoelectronic devices due to their exceptional benefits, including high phase purity and the absence of grain boundaries. However, achieving single crystals with a porous structure poses significant challenges. In this study, we present a method for fabricating porous single crystals (porous-SC) of CsAgBiBr and related halide double perovskites using an infrared-assisted spin coating technique.
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