ANSTO :: Browsing by Author "Li, H"

Browsing by Author "Li, H"

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Alumina template-assisted electrodeposition of Bi2Te2.7Se0.3 nanowire arrays
(Elsevier, 2010-06-01) Li, XL; Cai, KF; Li, H; Yu, DH; Wang, X; Wang, HF
Bi2Te2.7Se0.3 nanowire arrays have been fabricated by electrodeposition into the pores of an anodic aluminum oxide (AAO) template followed by annealing at 300°C under Ar atmosphere. The as-prepared nanowires were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. The nanowires are uniform single crystalline with diameter of ~14 nm. © 2010, Elsevier Ltd.
Correlated migration invokes higher Na+‐ion conductivity in NaSICON‐type solid electrolytes
(Wiley, 2019-10-01) Zhang, ZZ; Zou, Z; Kaup, K; Xiao, RJ; Shi, S; Avdeev, M; Hu, YS; Wang, D; He, B; Li, H; Huang, XY; Nazar, LF; Chen, LQ
Na super ion conductor (NaSICON), Na1+nZr2SinP3–nO12 is considered one of the most promising solid electrolytes; however, the underlying mechanism governing ion transport is still not fully understood. Here, the existence of a previously unreported Na5 site in monoclinic Na3Zr2Si2PO12 is unveiled. It is revealed that Na+‐ions tend to migrate in a correlated mechanism, as suggested by a much lower energy barrier compared to the single‐ion migration barrier. Furthermore, computational work uncovers the origin of the improved conductivity in the NaSICON structure, that is, the enhanced correlated migration induced by increasing the Na+‐ion concentration. Systematic impedance studies on doped NaSICON materials bolster this finding. Significant improvements in both the bulk and total ion conductivity (e.g., σbulk = 4.0 mS cm−1, σtotal = 2.4 mS cm−1 at 25 °C) are achieved by increasing the Na content from 3.0 to 3.30–3.55 mol formula unit−1. These improvements stem from the enhanced correlated migration invoked by the increased Coulombic repulsions when more Na+‐ions populate the structure rather than solely from the increased mobile ion carrier concentration. The studies also verify a strategy to enhance ion conductivity, namely, pushing the cations into high energy sites to therefore lower the energy barrier for cation migration. © 2019 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim
Coupled cation–anion dynamics enhances cation mobility in room-temperature superionic solid-state electrolytes
(American Chemical Society, 2019-11-08) Zhang, ZZ; Roy, PN; Li, H; Avdeev, M; Nazar, LF
Single-ion conducting solid electrolytes are gaining tremendous attention as essential materials for solid-state batteries, but a comprehensive understanding of the factors that dictate high ion mobility remains elusive. Here, for the first time, we use a combination of the Maximum Entropy Method analysis of room-temperature neutron powder diffraction data, ab initio molecular dynamics, and joint-time correlation analysis to demonstrate that the dynamic response of the anion framework plays a significant role in the new class of fast ion conductors, Na11Sn2PnX12 (Pn = P, Sb; X = S, Se). Facile [PX4]3– anion rotation exists in superionic Na11Sn2PS12 and Na11Sn2PSe12, but greatly hindered [SbS4]3– rotational dynamics are observed in their less conductive analogue, Na11Sn2SbS12. Along with introducing dynamic frustration in the energy landscape, the fluctuation caused by [PX4]3– anion rotation is firmly proved to couple to and facilitate long-range cation mobility, by transiently widening the bottlenecks for Na+-ion diffusion. The combined analysis described here resolves the role of the long-debated paddle-wheel mechanism, and is the first direct evidence that anion rotation significantly enhances cation migration in rotor phases. The joint-time correlation analysis developed in our work can be broadly applied to analyze coupled cation–anion interplay where traditional transition state theory does not apply. These findings deliver important insights into the fundamentals of ion transport in solid electrolytes. Invoking anion rotational dynamics provides a vital strategy to enhance cation conductivity and serves as an additional and universal design principle for fast ion conductors. © 2019 American Chemical Society
Development of a DC-LSND welding process for GMAW on DH-36 steel
(Australian Institute of Nuclear Science and Engineering (AINSE), 2013-11-02) Paradowska, AM; Law, M; Larkin, N; Holder, R; Li, H; Kuzmikova, L; Pan, Z; Norrish, J; Shen, C
The reduction of weld induced distortion has become an important focus of research for the shipbuilding industry with the continuing trend of using thinner plates in the ship's hull and super structure. This paper investigates the use of an active cooling process known as Dynamically Controlled—Low Stress No Distortion (DC-LSND) Welding on medium thickness (5 to 6 mm) DH-36 steel. Thermal profiles are obtained. Hardness, distortion and residual stress measurements are also achieved. Results show that the application of a localized cryogenic cooling source trailing the welding arc can significantly reduce weld induced distortion and residual stress using the GMAW process. And welds done by DC-LSND process show a hardening and brittle tendency. The effect of forced cooling on the weld microstructure is also observed.
Effects of heat treatment on microstructure and mechanical properties of wire arc additively manufactured Hastelloy C276 alloy
(Materials Australian and The Australian Ceramic Society, 2022-06-01) Qiu, Z; Wu, B; Zhu, H; Wang, Z; Wexler, D; Van Duin, S; Pan, Z; Li, H
Hastelloy C276 is a Ni-Cr-Mo based superalloy which has a high potential for application in high temperature and extreme corrosive environment due to its high corrosion resistance and excellent mechanical properties. In this research, the wire arc additive manufacturing (WAAM) process was successfully used to fabricate the defect-free Hastelloy C276 component. The microstructure of the component was characterized using optical microscopy, scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray diffraction, the mechanical properties were evaluated via tensile and hardness tests. The as-deposited component exhibited anisotropy on both microstructure and mechanical properties. The influences of solid solution heat treatment and stress relief heat treatment on microstructure and mechanical properties were also investigated. It was found that both microstructure and mechanical properties were significantly modified after heat treatment. Preliminary creep tests indicted the texture has a strong influence on the creep performance of the component.
Evaluation on nuclear emergency response strategies in the Asia-Pacific region
(Elsevier B. V., 2021-09) Li, F; Wang, J; Li, H; Hu, Q; Dan, WX; Ge, LQ; Cohen, DD
The safe use of nuclear energy has always been one of the vital factors hindering the development of nuclear energy. Especially after the Chernobyl Disaster in 1986 and the Fukushima nuclear power plant accident in 2011, the attitude of the government and the public towards the safe handling of nuclear power has become increasingly negative. International discussions on the emergency decision of nuclear accidents have never ceased, and the process of dealing with the accidents’ aftermath is still difficult. Therefore, it is worth researching on the trend, effectiveness and perfection of the nuclear emergency response strategies issued by the government. This article selected the Asia-Pacific region as the research object, deeply reviewed the optimization policy and management of Australia, China, Thailand, Russia and other countries since 1953. With the constantly innovation of nuclear technology, this work is of great significance to formulate relevant policies and to improve the global nuclear emergency response strategies in the future. © 2021 Elsevier B.V.
Experimental and modelling approaches to the determination of fatigue crack growth from a structural steel T-butt weld toe
(Engineers Australia, 2017-11-27) Tanulia, V; Prusty, BG; Pearce, GM; Hellier, AK; Li, H; Reid, M; Paradowska, AM
T-butt welded joints are found in many structural steel applications including buildings, bridges and offshore structures and are susceptible to fatigue crack initiation and propagation,which often leads ultimately to fast fracture failure. An example ofthis was the I-35W bridge in Minneapolis, which collapsed in 2007 resulting in 13 fatalities, as shown in Figure 1 [1]. The experimental work for this project was conducted using A350 grade black mild steel plate. An ultrasonic peening treatment was applied to one T-butt specimen to introduce compressive residual stress at the weld toe, in order to reduce the effective fatigue crack propagation rate. The results generated from 3-D FEA modelling plus a FORTRAN program (implementing parametric stress intensity factor and crack propagation equations) will be compared with experimental fatigue test results. © (2017) by Engineers Australia
Magnetotransport and Berry phase tuning in Gd-doped Bi2Se3 topological insulator single crystals
(American Physical Society, 2022-05-01) Chen, L; Li, SS; Zhao, W; Bake, A; Cortie, DL; Wang, XL; Karel, J; Li, H; Zheng, RK
The Berry phase is an important concept in solids, correlated to the band topology, axion electrodynamics, and potential applications of topological materials. Here, we investigate the magnetotransport and Berry phase of rare earth element Gd-doped Bi2Se3 (Gd:Bi2Se3) topological insulators (TIs) at low temperatures and high magnetic fields. Gd:Bi2Se3 single crystals show Shubnikov-de Haas (SdH) oscillations with nontrivial Berry phase, while Bi2Se3 single crystals show zero Berry phase in SdH oscillations. A fitting of the temperature-dependent magnetization curves using the Curie-Weiss law reveals that the Gd dopants in the crystals show paramagnetism in the 3-300 K region, indicating that the origin of the Berry phase is not long-range magnetic ordering. Moreover, Gd doping has limited influence on the quantum oscillation parameters (e.g., frequency of oscillation, area of Fermi surface, effective electron mass, and Fermi wave vectors) but has a significant impact on the Hall mobility, carrier density, and band topology. Our results demonstrate that Gd doping can tune the Berry phase of TIs effectively, which may pave the way for the future realization of many predicted exotic transport phenomena of topological origin. ©2022 American Physical Society
Neutron diffraction residual stress measurements of weldments for shipbuilding application
(Australian Institute of Nuclear Science and Engineering (AINSE), 2012-11-15) Shen, C; Paradowska, AM; Larkin, N; Li, H; Pan, Z; Law, M
Pulsed tandem gas metal arc welding (PT-GMAW) has been identified as a welding process potentially capable of increasing productivity and minimising distortion in ship-building. For this study, the PT-GMAW process was used in pulse-pulse mode to butt-weld DH36 steel in order to determine its suitability as a replacement for standard gas-metal-arc welding and submerged-arc welding in naval shipbuilding. Weld residual stresses often lead to increased distortion, and reduction of fatigue life. Quantitative 3D nondestructive neutron diffraction measurements are vital to fully understand the complexity of this welding procedure and their influence on the weld integrity. This paper presents preliminary study of mechanical properties and residual stresses of the welds and their influence on the distortion and fatigue performance. Residual stress measurements were conducted by neutron diffraction at the OPAL reactor on the strain scanner KOWARI. The challenges of the project will be discussed and future planes will be presented.
Neutron diffraction residual stress measurements of welds made with pulsed tandem gas metal arc welding (PT-GMAW)
(Cambridge University Press, 2014-11-10) Paradowska, AM; Larkin, N; Li, H; Pan, Z; Shen, C; Law, M
Pulsed tandem gas metal arc welding (PT-GMAW) is being developed to increase productivity and minimise weld-induced distortion in ship-building. The PT-GMAW process was used in pulse–pulse mode to butt-weld two different strength and thickness steels; the residual stress and hardness profiles of the welds are reported and correlated. © International Centre for Diffraction Data 2014
Phase behaviour and aggregate structures of the surface-active ionic liquid [BMIm][AOT] in water
(Elsevier B.V., 2023-12-15) Zhang, YX; Marlow, JB; Wood, K; Wang, J; Warr, GG; Li, H; Atkin, R
Hypothesis: The surface-active ionic liquid, 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate ([BMIm][AOT]), has a sponge-like bulk nanostructure consisting of percolating polar and apolar domains formed by the ion charge groups and alkyl chains, respectively. We hypothesise that added water will swell the polar domains and change the liquid nanostructure. Experiments: Small angle X-ray scattering (SAXS), small angle neutron scattering (SANS) and polarizing optical microscopy (POM) were used to investigate the nanostructure of [BMIm][AOT] as a function of water content. Differential scanning calorimetry (DSC) was employed to probe the thermal transitions of [BMIm][AOT]-water mixtures and the mobility of water molecules. Findings: SAXS, SANS and POM show that at lower water contents, [BMIm][AOT]-water mixtures have a sponge-like nanostructure similar to the pure SAIL, at medium water contents a lamellar phase forms, and at high water contents vesicles form. DSC results reveal that water molecules are supercooled in the lamellar phase. For the first time, results reveal a series of transitions from inverse sponge, to lamellar then to vesicles, for [BMIm][AOT] upon dilution with water. © 2023 Elsevier Inc.
Preparation and thermoelectric properties of AgPbmSbSem+2 materials
(Elsevier, 2008-06) Cai, KF; He, XR; Avdeev, M; Yu, DH; Cui, JL; Li, H
Hydrothermally synthesized AgPbmSbSem+2 (m = 10, 12, 16, 18) nanoparticles with diameters of 20-50 nm were compacted by pressureless sintering. The Seebeck coefficient and electrical conductivity of the samples were measured from room temperature up to similar to 750 K. The samples show large and positive values of the Seebeck coefficient and moderate electrical conductivity. The thermoelectric properties of AgxPb18SbSe20 (x = 0.8, 0.85) and AgPb(18)Sbse(20-y)Te(y) (y = 1, 3) samples have also been studied. It has been found that Ag0.85Pb18SbSe20 sample has a higher thermoelectric power factor. A significant difference in thermoelectric properties has also been observed for the AgPb18SbSe20 samples prepared with pressureless sintering and spark plasma sintering. © 2008, Elsevier Ltd.
Residual stress effects on fatigue crack growth from a T-butt weld toe
(University of Wollongong Australia, 2018-11) Hellier, AK; Li, H; Prusty, BG; Pearce, GM; Reid, M; Paradowska, AM
A350 grade black mild steel is one of the most widely used structural materials in the world, being commonly found in buildings, bridges and offshore structures.Welding is commonly used to join two plates of structural steel and this often takes the form of a T-butt.In addition, other more complex geometrical joints are often simplified for stress analysis purposes by approximating them as 2-D T-butt plate models (e.g. skewed T-joints, cruciform welded joints, tubular welded joints, pipe–plate joints, etc.).However, all such welds are potentially susceptible to fatigue crack initiation and slow but accelerating growth arising as a result of fluctuating service loads, often eventually resulting in fast fracture.
Residual stress study of Al/Al laminates processed by accumulative roll bonding
(Materials Research Forum LLC, 2016-07-03) Su, L; Lu, C; Li, H; Luzin, V; Wang, H; Tieu, K
In this work accumulative roll bonding (ARB) was used to combine AA1050 and AA6061 sheets to produce AA1050/AA1050, AA6061/AA6061 and AA1050/AA6061 laminates with ultrafine grained (UFG) structure. Two sheets of starting materials were roll bonded with 200 °C preheating for 180 s before rolling. The through-thickness residual stress distribution of these laminates processed up to two cycles of ARB was determined by neutron diffraction with spatial resolution of 0.2 mm through 1.5 mm thickness. The measurements also required high accuracy of only few MPa since residual stresses in the laminates peaked at only about 15 MPa. The laminates composed of the same material (AA1050/AA1050 and AA6061/AA6061) showed symmetric residual stress profile with tensile stress at the centre of the sheets and compressive stress at the surfaces. The AA1050/AA6061 laminates showed asymmetric distribution with residual tensile stress in the AA1050 layer and compressive stress in the AA6061 layer. A finite element model (FEM) was used to simulate the residual stress distribution and the results were in agreement with the measured results qualitatively. © 2016 The Authors
Residual stresses in titanium aerospace components formed via additive manufacture
(Australian Institute of Nuclear Science and Engineering (AINSE), 2013-12-02) Hoye, N; Li, H; Cuiuri, D; Paradowska, AM
Additive manufacturing (AM) using arc-wire based metal deposition has been suggested as one method to reduce the costs associated with production of titanium components, particularly within the aerospace sector. In the present study gas tungsten arc welding (GTAW) with automated wire addition was used to additively manufacture (AM) a representative thin-walled aerospace component from Ti-6AI-4V in a layer-wise manner. Residual strains, and hence stresses, were analysed quantitatively using neutron diffraction techniques on the KOWARI strain scanner at the OPAL research facility operated by the Australian Nuclear Science and Technology Organisation (ANSTO). Results showed that residual strains within such an AM sample could be measured with relative ease using the neutron diffraction method. Residual stress levels were found to be greatest in the longitudinal direction and concentrated at the interface between the base plate and deposited wall. Difficulties in measurement of lattice strains in some discrete locations were ascribed to the formation of the formation of localised texturing where α-Ti laths form in aligned colonies within prior β-Ti grain boundaries upon cooling. Observations of microstructure reveal 'basket-weave' morphology typical of welds in Ti-6AI-4V. Microhardness measurements show a drop in hardness in the top region of the deposit, indicating a dependence on thermal cycling from sequential welds. Time-of-flight neutron diffraction has been proposed to analyse stresses in both the α-Ti and β-Ti phases simultaneously as well as inter-granular strains. This study forms part of a wider investigation into the suitability of arc-wire based deposition techniques for the additive manufacture of titanium components.
Synthesis and thermoelectric properties of single crystalline and polycrystalline Ba8Ga16Ge30
(Elsevier, 2010-02-18) Wang, HF; Cai, KF; Li, H; Yu, DH; Wang, XC; Zhou, CW; Li, XL; Wang, YY; An, BJ; Du, Y
Large Ba8Ga16Ge30 single crystals were synthesized by a Ga-flux method. The single crystals were characterized by X-ray diffraction and energy-dispersive X-ray spectroscopy. The cubic structure of Ba filled type-I germanium clathrates with lattice parameter of 10.767 Å has been confirmed. The Ba8Ga16Ge30 polycrystalline sample was prepared by melting the synthesized single crystals. Thermoelectric properties of the single crystalline and polycrystalline Ba8Ga16Ge30 samples were measured from room temperature to 773 K. The single crystalline sample shows p-type conduction, while the polycrystalline sample exhibits n-type conduction and typical heavily doped semiconducting behavior. At room temperature, the electrical conductivity of the polycrystalline sample is much higher than that of the single crystalline sample, whereas the absolute value of Seebeck coefficient of the single crystalline sample is higher than that of the polycrystalline sample. The maximum power factor for the single crystalline and polycrystalline samples reaches ~17 μW cm−1 K−2 at 773 K and ~10 μW cm−1 K−2 at 500 K, respectively. © 2010, Elsevier Ltd.

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