ORCID Profile
0000-0002-7144-1861
Current Organisation
The Hong Kong Polytechnic University
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Functional Materials | Nanoscale Characterisation | Materials Engineering | Metals and Alloy Materials
Structural Metal Products | Expanding Knowledge in Engineering | Expanding Knowledge in Technology |
Publisher: Elsevier BV
Date: 09-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7TC03123H
Abstract: An in situ dynamic routine is developed to tune the PL peak intensity through piezoelectric strain.
Publisher: Informa UK Limited
Date: 18-12-2020
Publisher: Springer Science and Business Media LLC
Date: 31-05-2023
DOI: 10.1038/S41586-023-05952-6
Abstract: Titanium alloys are advanced lightweight materials, indispensable for many critical applications 1,2 . The mainstay of the titanium industry is the α–β titanium alloys, which are formulated through alloying additions that stabilize the α and β phases 3–5 . Our work focuses on harnessing two of the most powerful stabilizing elements and strengtheners for α–β titanium alloys, oxygen and iron 1–5 , which are readily abundant. However, the embrittling effect of oxygen 6,7 , described colloquially as ‘the kryptonite to titanium’ 8 , and the microsegregation of iron 9 have hindered their combination for the development of strong and ductile α–β titanium–oxygen–iron alloys. Here we integrate alloy design with additive manufacturing (AM) process design to demonstrate a series of titanium–oxygen–iron compositions that exhibit outstanding tensile properties. We explain the atomic-scale origins of these properties using various characterization techniques. The abundance of oxygen and iron and the process simplicity for net-shape or near-net-shape manufacturing by AM make these α–β titanium–oxygen–iron alloys attractive for a erse range of applications. Furthermore, they offer promise for industrial-scale use of off-grade sponge titanium or sponge titanium–oxygen–iron 10,11 , an industrial waste product at present. The economic and environmental potential to reduce the carbon footprint of the energy-intensive sponge titanium production 12 is substantial.
Publisher: Wiley
Date: 03-01-2020
Publisher: Elsevier BV
Date: 03-2018
Publisher: American Physical Society (APS)
Date: 08-07-2016
Publisher: Elsevier BV
Date: 12-2021
Publisher: AIP Publishing
Date: 13-01-2014
DOI: 10.1063/1.4859915
Abstract: Droplet epitaxy is an important method to produce epitaxial semiconductor quantum dots (QDs). Droplet epitaxy of III-V QDs comprises group III elemental droplet deposition and the droplet crystallization through the introduction of group V elements. Here, we report that, in the droplet epitaxy of InAs/GaAs(001) QDs using metal-organic chemical vapor deposition, significant elemental diffusion from the substrate to In droplets occurs, resulting in the formation of In(Ga)As crystals, before As flux is provided. The supply of As flux suppresses the further elemental diffusion from the substrate and promotes surface migration, leading to large island formation with a low island density.
Publisher: AIP Publishing
Date: 09-04-2018
DOI: 10.1063/1.5020534
Abstract: Ferroelectric materials have been extensively explored for applications in electronic devices because of their ferroelectric/ferroelastic domain switching behaviour under electric bias or mechanical stress. Recent findings on applying mechanical loading to manipulate reversible logical signals in non-volatile ferroelectric memory devices make ferroelectric materials more attractive to scientists and engineers. However, the dynamical microscopic structural behaviour of ferroelectric domains under stress is not well understood, which limits the applications of ferroelectric/ferroelastic switching in memory devices. Here, the kinetics of reversible and irreversible ferroelectric domain switching induced by mechanical stress in relaxor-based ferroelectrics was explored. In-situ transmission electron microscopy investigation revealed that 90° ferroelastic and 180° ferroelectric domain switching can be induced by low and high mechanical stresses. The nucleation and growth of nanoscale domains overwhelm the defect-induced pinning effect on the stable micro-domain walls. This study provides deep insights for exploring the mechanical kinetics for ferroelectric/ferroelastic domains and a clear pathway to overcome the domain pinning effect of defects in ferroelectrics.
Publisher: Elsevier BV
Date: 02-2022
Publisher: American Physical Society (APS)
Date: 06-01-2017
Publisher: Elsevier BV
Date: 02-2020
Publisher: American Physical Society (APS)
Date: 06-12-2017
Publisher: Elsevier BV
Date: 10-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7TA06000A
Abstract: Nickel phosphide has a much higher catalytic activity for the hydrogen evolution reaction in strongly acidic and basic electrolytes.
Publisher: Elsevier BV
Date: 08-2022
Publisher: Elsevier BV
Date: 2014
Publisher: Elsevier BV
Date: 03-2023
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 08-2013
DOI: 10.1016/J.MSEC.2013.04.044
Abstract: High strength, low Young's modulus and good biocompatibility are desirable but difficult to simultaneously achieve in metallic implant materials for load bearing applications, and these impose significant challenges in material design. Here we report that a nano-grained β-Ti alloy prepared by high-pressure torsion exhibits remarkable mechanical and biological properties. The hardness and modulus of the nano-grained Ti alloy were respectively 23% higher and 34% lower than those of its coarse-grained counterpart. Fibroblast cell attachment and proliferation were enhanced, demonstrating good in vitro biocompatibility of the nano-grained Ti alloy, consistent with demonstrated increased nano-roughness on the nano-grained Ti alloy. Results suggest that the nano-grained β-Ti alloy may have significant application as an implant material in dental and orthopedic applications.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1NR04300E
Abstract: We show a new way to tune ferroelectric behaviors in ferroelectric nanoplates by electron beam irradiation.
Publisher: Wiley
Date: 30-09-2022
Abstract: Direct data processing in nonvolatile memories can enable area‐ and energy‐efficient computation, unlike independent performance between separate processing and memory units repetitive data transfer between these units represents a fundamental performance limitation in modern computers. Spatially mobile conducting domain walls in ferroelectrics can be redirected between drain, gate, and source electrodes to function as nonvolatile transistors with superior energy efficiency, ultrafast operating and communication speeds, and high logic/storage densities. Here, in‐memory computing is demonstrated using multilevel domain wall diodes at LiNbO 3 interfaces. Ultrathin domains within interfacial layers between each mesa‐like memory cell and the contact electrodes can rectify diode‐like domain wall currents with on/off current ratios exceeding 10 7 at low operating voltages, surpassing the performance of traditional p‐n junctions using built‐in potentials across depletion layers. NOT, NAND, and NOR gate logic functions are demonstrated, providing insights into high‐density integration of multilevel storage and computational units in all‐ferroelectric domain wall devices.
Publisher: Elsevier BV
Date: 10-2023
Publisher: Informa UK Limited
Date: 12-1984
Publisher: Wiley
Date: 12-09-2021
Abstract: The introduction of trace impurities within the doping processes of semiconductors is still a technological challenge for the electronics industries. By taking advantage of the selective enrichment of liquid metal interfaces, and harvesting the doped metal oxide semiconductor layers, the complexity of the process can be mitigated and a high degree of control over the outcomes can be achieved. Here, a mechanism of natural filtering for the preparation of doped 2D semiconducting sheets based on the different migration tendencies of metallic elements in the bulk competing for enriching the interfaces is proposed. As a model, liquid metal alloys with different weight ratios of Sn and Bi in the bulk are employed for harvesting Bi 2 O 3 ‐doped SnO nanosheets. In this model, Sn shows a much stronger tendency than Bi to occupy surface sites of the Bi–Sn alloys, even at the very high concentrations of Bi in the bulk. This provides the opportunity for creating SnO 2D sheets with tightly controlled Bi 2 O 3 dopants. By way of ex le, it is demonstrated how such nanosheets could be made selective to both reducing and oxidizing environmental gases. The process demonstrated here offers significant opportunities for future synthesis and fabrication processes in the electronics industries.
Publisher: American Chemical Society (ACS)
Date: 18-09-2019
Publisher: Elsevier BV
Date: 02-2015
Publisher: Springer Science and Business Media LLC
Date: 19-03-2018
DOI: 10.1038/S41563-018-0034-4
Abstract: Piezoelectric materials, which respond mechanically to applied electric field and vice versa, are essential for electromechanical transducers. Previous theoretical analyses have shown that high piezoelectricity in perovskite oxides is associated with a flat thermodynamic energy landscape connecting two or more ferroelectric phases. Here, guided by phenomenological theories and phase-field simulations, we propose an alternative design strategy to commonly used morphotropic phase boundaries to further flatten the energy landscape, by judiciously introducing local structural heterogeneity to manipulate interfacial energies (that is, extra interaction energies, such as electrostatic and elastic energies associated with the interfaces). To validate this, we synthesize rare-earth-doped Pb(Mg
Publisher: American Chemical Society (ACS)
Date: 07-09-2022
Abstract: Perovskite multiferroics have drawn significant attention in the development of next-generation multifunctional electronic devices. However, the majority of existing multiferroics exhibit ferroelectric and ferromagnetic orderings only at low temperatures. Although interface engineering in complex oxide thin films has triggered many exotic room-temperature functionalities, the desired coupling of charge, spin, orbital and lattice degrees of freedom often imposes stringent requirements on deposition conditions, layer thickness and crystal orientation, greatly hindering their cost-effective large-scale applications. Herein, we report an interface-driven multiferroicity in low-cost and environmentally friendly bulk polycrystalline material, namely cubic BaTiO
Publisher: Elsevier BV
Date: 11-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3TA01995K
Abstract: This work will not only shed some light on understanding the dominant mechanism of piezocatalysis, but also uncover additional degrees of freedom, namely phase ratio within a phase boundary region, to further enhance the piezocatalytic efficiency.
Publisher: Springer Science and Business Media LLC
Date: 31-08-2012
Abstract: InAs/GaAs(001) quantum dots grown by droplet epitaxy were investigated using electron microscopy. Misfit dislocations in relaxed InAs/GaAs(001) islands were found to be located approximately 2 nm above the crystalline s le surface, which provides an impression that the misfit dislocations did not form at the island/substrate interface. However, detailed microscopy data analysis indicates that the observation is in fact an artefact caused by the surface oxidation of the material that resulted in substrate surface moving down about 2 nm. As such, caution is needed in explaining the observed interfacial structure.
Publisher: Elsevier BV
Date: 12-2022
Publisher: Elsevier BV
Date: 03-2022
Publisher: Elsevier BV
Date: 10-2021
Publisher: The American Association of Immunologists
Date: 03-2021
Abstract: Prophylactic human papillomavirus (HPV) vaccines are commercially available for prevention of infection with cancerogenic HPV genotypes but are not able to combat pre-existing HPV-associated disease. In this study, we designed a nanomaterial-based therapeutic HPV vaccine, comprising manganese (Mn4+)-doped silica nanoparticles (Mn4+-SNPs) and the viral neoantigen peptide GF001 derived from the HPV16 E7 oncoprotein. We show in mice that Mn4+-SNPs act as self-adjuvants by activating the inflammatory signaling pathway via generation of reactive oxygen species, resulting in immune cell recruitment to the immunization site and dendritic cell maturation. Mn4+-SNPs further serve as Ag carriers by facilitating endo/lysosomal escape via depletion of protons in acidic endocytic compartments and subsequent Ag delivery to the cytosol for cross-presentation. The Mn4+-SNPs+GF001 nanovaccine induced strong E7-specific CD8+ T cell responses, leading to remission of established murine HPV16 E7-expressing solid TC-1 tumors and E7-expressing transgenic skin grafts. This vaccine construct offers a simple and general strategy for therapeutic HPV and potentially other cancer vaccines.
Publisher: Elsevier BV
Date: 12-2019
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-10-2020
Abstract: Ferroelectricity is engineered by dimension in nanoscale single-crystal ferroelectrics.
Publisher: Elsevier BV
Date: 10-2022
Publisher: Wiley
Date: 18-09-2022
Abstract: The current approach to achieving superior energy storage density in dielectrics is to increase their breakdown strength, which often incurs heat generation and unexpected insulation failures, greatly deteriorating the stability and lifetime of devices. Here, a strategy is proposed for enhancing recoverable energy storage density ( W r ) while maintaining a high energy storage efficiency ( η) in glassy ferroelectrics by creating super tetragonal (super‐T) nanostructures around morphotropic phase boundary (MPB) rather than exploiting the intensely strong electric fields. Accordingly, a giant W r of ≈86 J cm −3 concomitant with a high η of ≈81% is acquired under a moderate electric field (1.7 MV cm −1 ) in thin films having MPB composition, namely, 0.94(Bi, Na)TiO 3 ‐0.06BaTiO 3 (BNBT), where the local super‐T polar clusters (tetragonality ≈1.25) are stabilized by interphase strain. To the knowledge of the authors, the W r of the engineered BNBT thin films represents a new record among all the oxide perovskites under a similar strength of electric field to date. The phase field simulation results ascertain that the improved W r is attributed to the local strain heterogeneity and the large spontaneous polarization primarily is originated from the super‐T polar clusters. The findings in this work present a genuine opportunity to develop ultrahigh‐energy‐density thin‐film capacitors for low‐electric‐field‐driven nano/microelectronics.
Publisher: American Chemical Society (ACS)
Date: 19-12-2022
Publisher: American Chemical Society (ACS)
Date: 16-11-2022
Abstract: Although the solid-state cooling technology based on electrocaloric response has been considered a promising refrigeration solution for microdevices, the mediocre dipolar entropy change Δ
Publisher: American Chemical Society (ACS)
Date: 15-05-2012
DOI: 10.1021/CG201676U
Publisher: OAE Publishing Inc.
Date: 2021
Publisher: AIP Publishing
Date: 19-06-2023
DOI: 10.1063/5.0145118
Abstract: Exploring and revealing the influence of the pyroelectric thin film array element size on its structure and pyroelectric performance is crucial for designing integrated pyroelectric infrared detectors. In this work, the transverse size effect on the piezoelectric, dielectric, and especially the pyroelectric properties for a new-generation relaxor ferroelectric material Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 (PIMNT) was studied by a finite element method. The lateral size-dependent piezoelectric and dielectric properties of the PIMNT thin film indicated that with the decrease in the transverse size, the piezoelectric constant d33 and relative dielectric constant εr increased substantially. The piezoelectric constant d33 and relative dielectric constant εr along ⟨001⟩ and ⟨011⟩ orientation increased faster than those along ⟨111⟩. A critical aspect ratio (in this paper, it was defined as radius/thickness) was found around 1:1 for three directions. We further discovered that the pyroelectric coefficient for PIMNT thin film along the ⟨111⟩ direction (the best crystallographic orientation for pyroelectric performance) decreased from 8.5 × 10−4 to 8.0 × 10−4 C/(m2·K) with the aspect ratio down to 0.01. The variation of the piezoelectric, dielectric, and pyroelectric properties originated from the decl ing of the PIMNT thin film from the substrate. This finding gives insight into the transverse size effect on the electrical properties of new-generation relaxor PIMNT thin film and provides a guidance for designing high-performance infrared array detectors.
Publisher: Elsevier BV
Date: 11-2013
Publisher: MDPI AG
Date: 31-12-2021
Abstract: Numerous investigations on the development of the relaxor-PbTiO3 ferroelectric crystals have been carried out since their extraordinary properties were revealed. Recent developments on these crystals have offered further advances in electromechanical applications. In this review, recent developments on relaxor-PbTiO3 crystals and their practical applications are reviewed. The single crystal growth methods are first discussed. Two different strategies, poling and doping, for piezoelectric improvement are surveyed in the following section. After this, the anisotropic features of the single crystals are discussed. Application perspectives arising from the property improvements for electromechanical devices are finally reviewed.
Publisher: Elsevier BV
Date: 11-2022
Publisher: Springer Science and Business Media LLC
Date: 07-04-2021
DOI: 10.1038/S41467-021-22355-1
Abstract: Failure of polarization reversal, i.e., ferroelectric degradation, induced by cyclic electric loadings in ferroelectric materials, has been a long-standing challenge that negatively impacts the application of ferroelectrics in devices where reliability is critical. It is generally believed that space charges or injected charges dominate the ferroelectric degradation. However, the physics behind the phenomenon remains unclear. Here, using in-situ biasing transmission electron microscopy, we discover change of charge distribution in thin ferroelectrics during cyclic electric loadings. Charge accumulation at domain walls is the main reason of the formation of c domains, which are less responsive to the applied electric field. The rapid growth of the frozen c domains leads to the ferroelectric degradation. This finding gives insights into the nature of ferroelectric degradation in nanodevices, and reveals the role of the injected charges in polarization reversal.
Publisher: Springer Science and Business Media LLC
Date: 09-02-2021
DOI: 10.1038/S41467-021-21202-7
Abstract: (K,Na)NbO 3 based ceramics are considered to be one of the most promising lead-free ferroelectrics replacing Pb(Zr,Ti)O 3 . Despite extensive studies over the last two decades, the mechanism for the enhanced piezoelectricity in multi-elements doped (K,Na)NbO 3 ceramics has not been fully understood. Here, we combine temperature-dependent synchrotron x-ray diffraction and property measurements, atomic-scale scanning transmission electron microscopy, and first-principle and phase-field calculations to establish the dopant–structure–property relationship for multi-elements doped (K,Na)NbO 3 ceramics. Our results indicate that the dopants induced tetragonal phase and the accompanying high-density nanoscale heterostructures with low-angle polar vectors are responsible for the high dielectric and piezoelectric properties. This work explains the mechanism of the high piezoelectricity recently achieved in (K,Na)NbO 3 ceramics and provides guidance for the design of high-performance ferroelectric ceramics, which is expected to benefit numerous functional materials.
Publisher: Elsevier BV
Date: 10-2013
Publisher: Elsevier BV
Date: 08-2013
Start Date: 2021
End Date: 2021
Funder: Australian Research Council
View Funded ActivityStart Date: 04-2021
End Date: 04-2023
Amount: $468,000.00
Funder: Australian Research Council
View Funded Activity