| 1. |
- Liu, Jing, et al.
(författare)
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Visible and infrared transparency in lead-free bulk BaTiO3 and SrTiO3 nanoceramics
- 2010
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 21:7
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Tidskriftsartikel (refereegranskat)abstract
- Multifunctional transparent ferroelectric ceramics have widespread applications in electro-optical devices. Unfortunately, almost all currently used electro-optical ceramics contain a high lead concentration. In this work, via coupling of spark plasma sintering with high pressure, we have successfully synthesized bulk lead-free transparent nanostructured BaTiO3 (abbreviated as BTO) and SrTiO3 (STO) ceramics with excellent optical transparency in both visible and infrared wavelength ranges. This success highlights potential ingenious avenues to search for lead-free electro-optical ceramics.
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| 2. |
- Liu, Shih-Chia, et al.
(författare)
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Photonic crystal bandedge membrane lasers on silicon
- 2017
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 56:31, s. H67-H73
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Tidskriftsartikel (refereegranskat)abstract
- We report here the design and experimental demonstration of optically pumped photonic crystal bandedge membrane lasers on silicon-on-insulator (SOI) and on bulk silicon (Si) substrates, based on heterogeneously integrated InGaAsP multi-quantum-well membrane layers transfer printed onto patterned photonic crystal cavities. Singlemode lasing under room-temperature operation was observed at 1542 nm, with excellent side mode suppression ratio greater than 31.5 dB, for the laser built on SOI substrate. For the laser built on bulk Si substrate, single-mode lasing was also achieved at 1452 nm with much lower thermal resistance, as compared to that of the laser built on SOI substrates. Such improved thermal characteristics are favorable for lasers operating potentially at higher temperatures and higher power.
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| 3. |
- Liu, Shih-Chia, et al.
(författare)
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Photonic Crystal Surface-Emitting Lasers on Silicon Substrates
- 2017
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Ingår i: 2017 IEEE PHOTONICS SOCIETY SUMMER TOPICAL MEETING SERIES (SUM). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509065707 ; , s. 77-78
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Konferensbidrag (refereegranskat)abstract
- We report here photonic crystal surface emitting lasers on bulk silicon substrates. Optically pumped lasers were demonstrated with single mode operation. Thermal resistance of such oxide-free cavity was investigated to evaluate the heat dissipation and lasing characteristics.
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| 4. |
- Lu, Yiping, et al.
(författare)
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Directly cast bulk eutectic and near-eutectic high entropy alloys with balanced strength and ductility in a wide temperature range
- 2017
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Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454. ; 124, s. 143-150
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Tidskriftsartikel (refereegranskat)abstract
- High entropy alloys (HEAs) usually possess weak liquidity and castability, and considerable compositional inhomogeneity, mainly because they contain multiple elements with high concentrations. As a result, large-scale production of HEAs by casting is limited. To address the issue, the concept of eutectic high entropy alloys (EHEAs) was proposed, which has led to some promise in achieving good quality industrial scale HEAs ingots, and more importantly also good mechanical properties. In the practical large-scale casting, the actual composition of designed EHEAs could potentially deviate from the eutectic composition. The influence of such deviation on mechanical properties of EHEAs is important for industrial production, which constitutes the topic of the current work. Here we prepared industrial-scale HEAs ingots near the eutectic composition: hypoeutectic alloy, eutectic alloy and hypereutectic alloy. Our results showed that the deviation from eutectic composition does not significantly affect the mechanical properties, castability and the good mechanical properties of EHEAs can be achieved in a wide compositional range, and at both room and cryogenic temperatures. Our results suggested that EHEAs with simultaneous high strength and high ductility, and good liquidity and castability can be readily adapted to large-scale industrial production. The deformation behavior and microstructure evolution of the eutectic and near-eutectic HEAs were thoroughly studied using a combination of techniques, including strain measurement by digital image correlation, in-situ synchrotron X-ray diffraction, and transmission electron microscopy. The wavy strain distribution and the therefore resulted delay of necking in EHEAs were reported for the first time.
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| 5. |
- Lu, Yiping, et al.
(författare)
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Preparing bulk ultrafine-microstructure high-entropy alloys: Via direct solidification
- 2018
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 10:4, s. 1912-1919
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Tidskriftsartikel (refereegranskat)abstract
- In the past three decades, nanostructured (NS) and ultrafine-microstructure (UFM) materials have received extensive attention due to their excellent mechanical properties such as high strength. However, preparing low-cost and bulk NS and UFM materials remains to be a challenge, which limits their industrial applications. Here, we report a new strategy to prepare bulk UFM alloys via the direct solidification of high-entropy alloys (HEAs). As a proof of concept, we designed AlCoCr x FeNi (1.8 ≤ x ≤ 2.0) HEAs and achieved a complete UFM in bulk materials. The compositional requirements for obtaining the formation of the UFM are highly demanding, necessitating the coupling of near eutectic alloy composition and the high temperature decomposition of supersaturated primary and secondary phases. Our strategy provides a low-cost and highly efficient method to prepare bulk UFM alloys, with great potential to accelerate the engineering application of these materials.
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