ORCID Profile
0000-0001-5096-2046
Current Organisation
UNSW Sydney
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Publisher: Springer Science and Business Media LLC
Date: 17-10-2023
Publisher: Wiley
Date: 26-08-2022
Abstract: In‐sensor computing with visual information, which can integrate photo‐sensing, data storage, and computation functions within the same physical element, has promised a fundamentally different architecture for future machine vision technology with extreme energy and time efficiency. The elementary devices required to fulfil the goal of such a new sensory computation scheme would demand a bold functional variation to the existing sensor and data processing hardware. Here, a van der Waals (vdW) heterostructure‐based optoelectronic transistor that can act as an integrated photoreceptor, memory, and computation unit by exploiting its own physical attributes is demonstrated. It is found that erse photoelectric control of device conductance can lead to versatile photoresponse characteristics, including memristive behaviors, retention‐, polarity‐ and strength‐tunable photoconductance, photoelectric‐coupling effect, etc. Exploiting the photoelectric‐coupling effect, reconfigurable and nonvolatile optoelectronic logic functions are realized in this device, featuring a logic‐in‐sensor unit. With the same device, both short‐ and long‐term synaptic plasticity can be faithfully emulated, rendering it an optoelectronic synaptic transistor. Moreover, a psychologic human memory model is implemented with the device, showing the emulation of memorization and learning processes. This prototypical demonstration provides a promising hardware system for visual information in‐sensor computing capable of addressing complex computation tasks.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-07-2019
Abstract: WTe 2 , a layered crystalline material, displays both ferroelectricity and metallicity.
Publisher: Elsevier BV
Date: 08-2016
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9TC06739F
Abstract: The piezoelectric litude drops by 44.7% and meanwhile the out-of-plane tensile strain rises by 11.0% under reverse magnetic fields in (1–3)-type BFO–CFO thin films.
Publisher: Wiley
Date: 18-03-2019
Publisher: American Chemical Society (ACS)
Date: 09-2023
Publisher: American Chemical Society (ACS)
Date: 23-12-2016
Abstract: Strain-mediated magnetoelectric (ME) coupling effect is expected in self-assembly heterostructures engineered by ferroelectric and ferromagnetic materials, contributing to the enhanced overall magnetoelectric effect. Microstructures as well as the connectivity configuration are considered to play a significant role in achieving efficient magnetoelectric properties. Different from the conventional (1-3) and (2-2) type composite films, we fabricate BiFeO3-CoFe2O4 (BFO-CFO) composite thin films with a novel quasi (0-3) type connectivity via a dual-target pulsed laser deposition process. The self-assembly growth mechanism has been studied, which demonstrates that the perovskite (BFO) matrix segments the connectivity of spinel (CFO) resulting in a quasi (0-3) composite. Direct observation of ferroelectric domain wall motion under external magnetic fields proves a strong magnetoelectric coupling effect in these (0-3) thin films. Our preliminary findings reveal the promising application potential of this new structure as multiferroic domain wall devices.
Publisher: AIP Publishing
Date: 08-09-2014
DOI: 10.1063/1.4895615
Abstract: The electrocaloric effect in lead-free BaTi1−xSnxO3 (BTSn, x = 0.08, 0.105, and 0.14) ferroelectric ceramics was studied by using an indirect method. It was found that the largest electrocaloric response could be achieved in BTSn with x = xQP = 0.105 near room temperature with an adiabatic temperature change ΔT of 0.61 K and an electrocaloric strength ΔT/ΔE of 0.31 K mm kV−1, under a modest electric field ΔE of 20 kV cm−1, which is comparable with the best values reported in lead-free materials. These enhanced values are attributed to the multiphase (four phases) coexistence at x = xQP corresponding to the quasi-quadruple point composition.
Publisher: Wiley
Date: 02-06-2020
Publisher: American Chemical Society (ACS)
Date: 16-08-2022
Publisher: American Chemical Society (ACS)
Date: 28-06-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8TC03965H
Abstract: The structure and elemental distribution of PbZrO 3 thin films are investigated. Defect controlled electrocaloric effects are discussed.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CC02548C
Abstract: We develop a ferroelectric nanohybrid that improves photocatalytic efficiency by reducing the recombination of holes and electron charge carriers.
Publisher: Elsevier BV
Date: 11-2016
Publisher: American Chemical Society (ACS)
Date: 14-04-2021
Publisher: Elsevier BV
Date: 06-2021
Publisher: American Physical Society (APS)
Date: 13-07-2021
Publisher: Wiley
Date: 09-06-2021
Abstract: Developing nano‐ferroelectric materials with excellent piezoelectric performance for piezocatalysts used in water splitting is highly desired but also challenging, especially with respect to reaching large piezo‐potentials that fully align with required redox levels. Herein, heteroepitaxial strain in BaTiO 3 nanoparticles with a designed porous structure is successfully induced by engineering their surface reconstruction to dramatically enhance their piezoelectricity. The strain coherence can be maintained throughout the nanoparticle bulk, resulting in a significant increase of the BaTiO 3 tetragonality and thus its piezoelectricity. Benefiting from high piezoelectricity, the as‐synthesized blue‐colored BaTiO 3 nanoparticles possess a superb overall water‐splitting activity, with H 2 production rates of 159 μmol g −1 h −1 , which is almost 130 times higher than that of the pristine BaTiO 3 nanoparticles. Thus, this work provides a generic approach for designing highly efficient piezoelectric nanomaterials by strain engineering that can be further extended to various other perovskite oxides, including SrTiO 3 , thereby enhancing their potential for piezoelectric catalysis.
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7RA03080K
Abstract: Large activation energy and a different migration path of oxygen vacancy diffusion in Mn-doped SBN ferroelectric ceramics are revealed.
Publisher: American Chemical Society (ACS)
Date: 06-2016
Publisher: Springer Science and Business Media LLC
Date: 22-12-2016
DOI: 10.1038/SREP38354
Abstract: In this work, we report a rapid stability phenomenon of ferroelectric polarization in the Ca, Ce hybrid doped BaTiO 3 ceramics (BCaxT+BTCe8) (x = 10, 20, 24, 30 mol%) prepared by separate doping Ca 2+ and Ce 4+ ions. Double hysteresis loops are identified in the aged BCaxT+BTCe8 s les meanwhile, the polarization of these loops present a rapid decrease within very short aging time (about 1 h), and then the polarization remains almost unchanged over the followed ~1000 h. This phenomenon is not reported in previous researches. Raman scattering spectrum indicates that oxygen vacancies are generated because of Ca 2+ ions entering into Ti sites partly in the BCaxT+BTCe8 s les, and then the oxygen vacancies are quantitatively characterized by half of the Ce 3+ content through the XPS test. The emergence of the aging phenomenon is explained through the "Equation missing" defect dipole reorientation mechanism. The larger radius of Ca 2+ ions is further discussed as a possible reason for the rapid stability phenomenon of ferroelectric polarization. It may provide an effective design method from the viewpoint of the ionic radius to accelerate polarization stability, and thus to facilitate the possible practical applications of the aging effect.
Publisher: Elsevier BV
Date: 2016
Publisher: Wiley
Date: 09-09-2019
Abstract: Piezocatalysis, converting mechanical vibration into chemical energy, has emerged as a promising candidate for water-splitting technology. However, the efficiency of the hydrogen production is quite limited. We herein report well-defined 10 nm BaTiO
Publisher: Wiley
Date: 06-10-2021
Abstract: Topotactic transitions, that is, reversible crystal structure changes due to controllable stoichiometry of material, offer substantial potential to control a wide variety of functionality in transition metal oxides, especially in systems with high ionic mobility and correlated electrons. Here the authors report on topotactic electrochromism with prominent coloration efficiency in SrCo 0.66 Fe 0.34 O 3 −δ associated with changes of electrical conductivity and electronic structure of the material. Changes in electron correlation lead to significant coloration and light absorption, which provides a general approach for utilizing topotactic transitions in electrochromic applications.
Publisher: Wiley
Date: 15-09-2023
Abstract: Reversible control of ferroelectric polarization is essential to overcome the heterocatalytic kinetic limitation. This can be achieved by creating a surface with switchable electron density however, owing to the rigidity of traditional ferroelectric oxides, achieving polarization reversal in piezocatalytic processes remains challenging. Herein, sub‐nanometer sized Hf 0.5 Zr 0.5 O 2 (HZO) nanowires with a polymer‐like flexibility have been synthesized. Oxygen K‐edge X‐ray absorption spectroscopy (XAS) and negative spherical aberration‐corrected transmission electron microscope (NCS‐TEM) reveal an orthorhombic ( Pca2 1 ) ferroelectric phase of the HZO sub‐nanometer wires (SNWs). The ferroelectric polarization of flexible HZO SNWs can be easily switched by slight external vibration, resulting in a dynamic modulation of the binding energy of adsorbates and thus breaking the “scaling relationship” during piezocatalysis. Consequently, the as‐synthesized ultrathin HZO nanowires display superb water‐splitting activity, with a H 2 production rate of 25687 μm ol g −1 h −1 under 40 kHz ultrasonic vibration, which is 235 and 41 times higher than those of non‐ferroelectric hafnium oxides and rigid BaTiO 3 nanoparticles, respectively. More strikingly, the hydrogen production rates can reach 5.2 μm ol g −1 h −1 by addition of stirring exclusively. This article is protected by copyright. All rights reserved
Publisher: American Chemical Society (ACS)
Date: 06-01-2021
Publisher: Elsevier BV
Date: 05-2019
Publisher: Wiley
Date: 12-03-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3QI00571B
Abstract: The epitaxial ferroelectric heterostructure Ti 4 O 5 /BaTiO 3 is constructed by surface reconstruction engineering, which induces the band bending of Ti 4 O 5 and improves the photoexcited electron–hole pair separation and CO 2 reduction performance.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 02-03-2018
Abstract: Machine learning of dynamic responses allows determination of structural phase transitions in relaxor ferroelectrics.
Publisher: AIP Publishing
Date: 04-01-2021
DOI: 10.1063/5.0029620
Abstract: Robust retention of ferroelectric polarization in harsh environments is a requirement for the application of ferroelectric materials in space, liquids, and various chemical conditions. Surface screening of the polarization can significantly alter domain states and usually has a strong influence on domain stability in ferroelectrics, hindering applications that require defined and non-volatile polarization states. Here, we show that designer defects in BiFeO3 can be engineered to strongly pin domain walls, which even in harsh environments such as 100% humidity and elevated temperatures of 175 °C leads to a superior polarization retention of several years for domain sizes well below 100 nm.
Publisher: Elsevier BV
Date: 05-2019
Publisher: Wiley
Date: 03-09-2015
Abstract: Monodispersed ferroelectric BaTiO3 nanoparticles are synthesized as a model system to investigate the effect of ferroelectricity on a photocatalytic process. The results demonstrate that ferroelectricity can directly affect the photocatalytic activity due to promotion of the separation of photo-excited carriers by spontaneous polarization in ferroelectric materials. Moreover, Ag nanoparticles are attached on these BaTiO3 to further improve the photocatalytic property.
Publisher: Springer Science and Business Media LLC
Date: 17-01-2020
DOI: 10.1038/S41467-019-14250-7
Abstract: Ferroelectric materials possess a spontaneous polarization that is switchable by an electric field. Robust retention of switched polarization is critical for non-volatile nanoelectronic devices based on ferroelectrics, however, these materials often suffer from polarization relaxation, typically within days to a few weeks. Here we exploit designer-defect-engineered epitaxial BiFeO 3 films to demonstrate polarization retention with virtually no degradation in switched nanoscale domains for periods longer than 1 year. This represents a more than 2000% improvement over the best values hitherto reported. Scanning probe microscopy-based dynamic switching measurements reveal a significantly increased activation field for domain wall movement. Atomic resolution scanning transmission electron microscopy indicates that nanoscale defect pockets pervade the entire film thickness. These defects act as highly efficient domain wall pinning centres, resulting in anomalous retention. Our findings demonstrate that defects can be exploited in a positive manner to solve reliability issues in ferroelectric films used in functional devices.
Publisher: Wiley
Date: 24-05-2023
Abstract: Mechanical friction leads to wear and energy dissipation, and its control is of high importance in new‐generation miniature electromechanical devices. 2D materials such as graphene are considered to be excellent solid lubricants due to their ultralow friction and have attracted considerable research interest. Unique friction properties are discovered in various other 2D materials. However, the friction of functional van der Waals materials which have potential applications in novel nanoelectronics, like ferroelectric copper indium thiophosphate, has barely been studied. Herein, the study reports on the observation of inhomogeneous friction behavior existing in copper‐deficient CuInP 2 S 6 (Cu 0.2 In 1.26 P 2 S 6 ), which exhibits a nanoscale phase separation of polar and non‐polar crystalline phases. The paraelectric In 4/3 P 2 S 6 phase exhibits higher friction than the ferroelectric CuInP 2 S 6 phase, while phase boundaries between the two phases, interestingly, display the lowest friction. The origin of this phenomenon is attributed to different lattice strains of phases together with the presence of large strains at the nanoscale phase boundaries, which also manifests in the nonuniform tip‐s le adhesion force. The findings provide new insights into nanoscale device design and wear behavior of a phase‐separated van der Waals ferroelectric, which may help to reduce the power consumption of friction‐exhibiting devices and extend their service life.
Publisher: American Chemical Society (ACS)
Date: 11-02-2022
Abstract: In-memory computing featuring a radical departure from the von Neumann architecture is promising to substantially reduce the energy and time consumption for data-intensive computation. With the increasing challenges facing silicon complementary metal-oxide-semiconductor (CMOS) technology, developing in-memory computing hardware would require a different platform to deliver significantly enhanced functionalities at the material and device level. Here, we explore a dual-gate two-dimensional ferroelectric field-effect transistor (2D FeFET) as a basic device to form both nonvolatile logic gates and artificial synapses, addressing in-memory computing simultaneously in digital and analog spaces. Through ersifying the electrostatic behaviors in 2D transistors with the dual-ferroelectric-coupling effect, rich logic functionalities including linear (AND, OR) and nonlinear (XNOR) gates were obtained in unipolar (MoS
Publisher: Springer Science and Business Media LLC
Date: 18-03-2015
DOI: 10.1038/SREP09229
Abstract: Dynamic oxygen vacancies play a significant role in memristive switching materials and memristors can be realized via well controlled doping. Based on this idea we deposite Nb 2 O 5 -NaNbO 3 nanocomposite thin films on SrRuO 3 -buffered LaAlO 3 substrates. Through the spontaneous phase separation and self-assembly growth, two phases form clear vertical heteroepitaxial nanostructures. The interfaces between niobium oxide and sodium niobate full of ion vacancies form the conductive channels. Alternative I-V behavior attributed to dynamic ion migration reveals the memristive switching mechanism under the external bias. We believe that this phenomenon has a great potential in future device applications.
Publisher: American Chemical Society (ACS)
Date: 08-10-2019
Abstract: Control of coupling between electric and elastic orders in ferroelectric bulks is vital to understand their nature and enrich the multifunctionality of polarization manipulation applied in domain-based electronic devices such as ferroelectric memories and data storage ones. Herein, taking (1 -
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6CP05462E
Abstract: The assembled Ba 0.8 Sr 0.2 TiO 3 thin films formed by precisely designed building blocks of ferroelectric nanocubes have a large electrocaloric effect (9.1 K).
No related grants have been discovered for Dawei Zhang.