Sintering

Kang, Suk–Joong L.

doi:10.1002/9783527631957.ch6

Cited by 3 publications

(3 citation statements)

References 89 publications

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“…Correspondingly, we are associating the accelerated pressure relaxation upon temperature increase shown in Figure to a more pronounced particle rearrangement dynamics, where the higher temperature makes it easier for the powder particles to reduce the applied pressure by filling the remaining pores, so that we assume the occurrence of a sintering process. This is clearly supported by the grain growth and disappearance of the primary particle structures and clearer grain boundaries as observed in Figure , which are typical for a sintering process. , …”

Section: Discussionsupporting

confidence: 61%

Impact of Pressure and Temperature on the Compaction Dynamics and Layer Properties of Powder-Pressed Methylammonium Lead Halide Thick Films

Witt

Schmid

Leupold

et al. 2020

ACS Appl. Electron. Mater.

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While halide perovskite X-ray detectors based on single crystals could achieve extraordinary sensitivities, detectors based on polycrystalline thick films lag behind in efficiency. This is unfortunate since the processing methods for producing polycrystalline thick films, especially by pressure treatment of powders, are suitable for upscaling. Here, we investigate in detail the pressing of readily prepared powders of methylammonium lead halide perovskites MAPbI3 and MAPbBr3 to thick layers. By time-dependent pressure measurements, we monitor the occurring compaction dynamics, identifying two relaxation processes with different timescales. When pressing at elevated temperatures from room temperature (RT) to 100 °C, the pressure relaxations change drastically. While the layer properties such as relative density and surface roughness only improve to a certain degree by increasing the pressure at RT, we observe relative densities >97%, considerable reduction in surface roughness, and a significant increase in grain size with tempered pressing. Analyses regarding time-dependent pressure relaxations of tempered pressing allow attributing the dynamics to a sintering process, where we find the sinter onset to be surprisingly low at about 30 °C, mainly independent of the applied pressure (10–100 MPa). Our results will allow for an improved and more targeted powder processing of halide perovskite thick films as they are promising candidates for efficient X-ray detectors.

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Section: Discussionsupporting

confidence: 61%

Impact of Pressure and Temperature on the Compaction Dynamics and Layer Properties of Powder-Pressed Methylammonium Lead Halide Thick Films

Witt

Schmid

Leupold

et al. 2020

ACS Appl. Electron. Mater.

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“…The fact that there are preferential solid–gas interfaces for the attachment/detachment of atoms strongly suggests that the GB and pore surfaces are not perfect sources and sinks of atoms. Thus, our discovery supports the existence of a critical driving force for the attachment/detachment of atoms in nanometric ceramics, suggesting that interfacial reactions related to atomic transportation can also take part or control the sintering process. , …”

supporting

confidence: 75%

“…pointed out, interfacial reactions related to atomic transport can also take part or control the sintering process. The interfacial reactions are related to faceted (atomically ordered and macroscopically straight or zig-zagged) grain boundary and pore surfaces regions. − Experimental results have indicated the existence of a critical driving force for densification in samples with faceted grain boundaries, − supporting the idea that we should consider the interfacial reaction to describe the sintering process. The correlation between the interface faceting and the limit of densification relies on the assumption that the detachment or attachment of atoms in the faceted surface can control the densification kinetics. ,− Identifying the critical driving force for the sintering process in systems that present faceted boundaries implies that the grain boundaries and pore surfaces are not perfect sources and sinks of atoms, without an energy barrier for the attachment/detachment of atoms .…”

mentioning

confidence: 87%

Visualization of the Final Stage of Sintering in Nanoceramics with Atomic Resolution

et al. 2022

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The deep understanding of the sintering mechanism is pivotal to optimizing denser ceramics production. Although several models explain the sintering satisfactorily on the micrometric scale, the extrapolation for nanostructured systems is not trivial. Aiming to provide additional information about the particularities of the sintering at the nanoscale, we performed in situ experiments using high-resolution transmission electron microscopy (HRTEM). We studied the pore elimination process in a ZrO2 thin film and identified a high anisotropic pore elimination. Interestingly, there is a redistribution of the atoms from the rough surface in the solid–gas surface, followed by the atom attachment in a faceted surface. Finally, we found evidence of the pore acting as a pin, reducing the GB mobility. These findings certainly can contribute to enhance the kinetic models to describe the densification process of systems at the nanoscale.

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Current understanding and future research directions at the onset of the next century of sintering science and technology

2017

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Sintering and accompanying microstructural evolution is inarguably the most important step in the processing of ceramics and hard metals. In this process, an ensemble of particles is converted into a coherent object of controlled density and microstructure at an elevated temperature (but below the melting point) due to the thermodynamic tendency of the particle system to decrease its total surface and interfacial energy. Building on a long development history as a major technological process, sintering remains among the most viable methods of fabricating novel ceramics, including high surface area structures, nanopowder-based systems, and tailored structural and functional materials. Developing new and perfecting existing sintering techniques is crucial to meet ever-growing demand for a broad range of technologically significant systems including, for example, fuel and solar cell components, electronic packages and elements for computers and wireless devices, ceramic and metal-based bioimplants, thermoelectric materials, materials for thermal management, and materials for extreme environments.In this study, the current state of the science and technology of sintering is presented. This study is, however, not a comprehensive review of this extremely broad field. Furthermore, it only focuses on the sintering of ceramics. The fundamentals of sintering, including the thermodynamics and kinetics for solid-stateand liquid-phase-sintered systems are described. This study summarizes that the sintering of amorphous ceramics (glasses) is well understood and there is excellent agreement between theory and experiments. For crystalline materials, attention is drawn to the effect of the grain boundary and interface structure on sintering and microstructural evolution, areas that are expected to be significant for future studies. Considerable emphasis is placed on the topics of current research, including the sintering of composites, multilayered systems, microstructure-based models, multiscale models, sintering under external stresses, and innovative and novel sintering approaches, such as field-assisted sintering. This study includes the status of these subfields, the outstanding challenges and opportunities, and the outlook of progress in sintering research. Throughout the manuscript, we highlight the important lessons learned from sintering fundamentals and their implementation in practice.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

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Sintering

Cited by 3 publications

References 89 publications

Impact of Pressure and Temperature on the Compaction Dynamics and Layer Properties of Powder-Pressed Methylammonium Lead Halide Thick Films

Impact of Pressure and Temperature on the Compaction Dynamics and Layer Properties of Powder-Pressed Methylammonium Lead Halide Thick Films

Visualization of the Final Stage of Sintering in Nanoceramics with Atomic Resolution

Current understanding and future research directions at the onset of the next century of sintering science and technology

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