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Abstract The Cold Sintering Process (CSP) can provide opportunities to fabricate high-performance BaTiO3dielectric composites with polymer materials that are typically difficult to impossible to co-process under a conventional sintering process. Therefore, we investigated the preparation process of BaTiO3sintered body by CSP and integrated a well-dispersed intergranular polymer phase. In this study, we focused on preparing BaTiO3and Polytetrafluoroethylene (PTFE) composites. We considered the importance of the particle size of the PTFE phase, and correlated the impact on the composite dielectric properties. Through fitting a general-mixing-law to the dielectric properties as a function of volume fraction, we could deduce more homogeneous composites obtained in using the 200 nm PTFE powders. In addition, the temperature dependent dielectric properties and field dependent conductivity of the composites was investigated. It was found that with the good dispersion of the PTFE can suppress the leakage current density in the dielectric composites.
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Assessment of flaws in cold‐sintered ZnO via acoustic wave speed and attenuation measurements
Abstract The cold sintering process (CSP) is a low temperature processing technique that utilizes a transient phase to synthesize dense ceramics. However, some CSP parts contain microflaws that arise due to inhomogeneities in pressure, temperature, and transient phase. This work uses 20 MHz ultrasound to verify the presence of defects in CSP ZnO samples of varying densities (84%–97%). Acoustic metrics used in this work include wave speed, which is affected by differences in the effective elastic properties of the medium, and attenuation, which quantifies wave energy loss due to scattering from defects. Wave speed maps were inhomogeneous, suggesting density gradients which were verified with scanning electron microscopy. In addition, it was demonstrated that the pores produced by cold sintering are anisometric, which increases the anisotropy in the elastic properties. High attenuation regions (>300 Np/m) are present in all samples independent of relative density and correspond to defects identified in X‐ray computed tomography (XCT) which were as small as 38 µm in effective diameter. However, some high attenuation spots do not correspond to visible defects in XCT, which suggests the presence of features undetectable with XCT such as residual secondary phases at the grain boundaries.
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- PAR ID:
- 10418072
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of the American Ceramic Society
- Volume:
- 106
- Issue:
- 8
- ISSN:
- 0002-7820
- Page Range / eLocation ID:
- p. 4955-4966
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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