Browsing by Author "Shaw, Christopher"

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    Advances in test and measurement of the interface adhesion and bond strengths in coating-substrate systems, emphasising blister and bulk techniques
    (Elsevier, 2019-03-11) Chen, Xiaomei; Shaw, Christopher; Gelman, Leonid; Grattan, Kenneth T. V.
    In this paper, recent advances in the minimum-destructive testing of the adhesion of coating-substrate systems are reviewed, focusing on key techniques such as micro- and nano-scale levels of indentation, scratching, laser-induced wave shock, as well as the blister and buckle approach. Along with adhesion failure tests, the latest and most extensive applications of the adhesion test methods in nano-, micro- and bulk-coating technology and the associated techniques to determine the minimum damage defects left on the coatings are discussed and their use reviewed.
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    Electrical and mechanical characterisation of poly(ethylene)oxide-polysulfone blend for composite structural lithium batteries
    (MDPI, 2023-06-05) Gucci, Francesco; Grasso, Marzio; Russo, Stefano; Leighton, Glenn J. T.; Shaw, Christopher; Brighton, James
    In this work, a blend of PEO, polysulfone (PSF), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSi) was prepared at different PEO–PSf weight ratios (70-30, 80-20, and 90-10) and ethylene oxide to lithium (EO/Li) ratios (16/1, 20/1, 30/1, and 50/1). The samples were characterised using FT-IR, DSC, and XRD. Young’s modulus and tensile strength were evaluated at room temperature with micro-tensile testing. The ionic conductivity was measured between 5 °C and 45 °C through electrochemical impedance spectroscopy (EIS). The samples with a ratio of PEO and PSf equal to 70-30 and EO/Li ratio equal to 16/1 have the highest conductivity (1.91 × 10−4 S/cm) at 25 °C, while the PEO–PSf 80-20 EO/Li = 50/1 have the highest averaged Young’s modulus of about 1.5 GPa at 25 °C. The configuration with a good balance between electrical and mechanical properties is the PEO–PSf 70-30 EO/Li = 30/1, which has a conductivity of 1.17 × 10−4 S/cm and a Young’s modulus of 800 MPa, both measured at 25 °C. It was also found that increasing the EO/Li ratio to 16/1 dramatically affects the mechanical properties of the samples with them showing extreme embrittlement.
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    Electrophoretic deposition of LiFePO4 and carbon black: a numerical study to explore longitudinal trends using Taguchi design
    (Elsevier, 2024-11) Russo, Stefano; Grasso, Marzio; Huang, Jian; Pramana, Stevin S; Gucci, Francesco; Shaw, Christopher; Leighton, Glenn J
    Developing Electrophoretic Deposition (EPD) for Composite Structural Batteries (CSBs) could revolutionise energy storage technology. CSBs offer an innovative solution by seamlessly integrating batteries into structures and effectively reducing weight and space constraints. Despite its successful implementation across various fields, EPD method still lacks comprehensive understanding of the underlying physical and chemical processes due to the number of variables involved. In this study the effects of key parameters associated with the process are investigated with a coupled FEM and analytical approach to find correlations with the deposition process. A Taguchi Design of Experiment with five parameters, namely voltage, concentration, relative weight ratio of LiFePO4 – carbon black particles, length and perimeter of the electrodes is implemented to identify the correlations with mass deposited, thickness of the coating and yield rate when LiFePO4 and Carbon Black particles in ethanol suspension are used. In order to capture the variation over time, each parameter is studied at six different time of deposition. A concentration that optimises yield rate resulting in thickness and mass deposition is identified. The resistivity of the suspension dictates the yield rate dynamics, allowing it to be designed within a specific range to meet requirements of different applications.
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    Enhanced energy storage performance of (1-x)(BCT-BMT)-xBFO lead-free relaxor ferroelectric ceramics in a broad temperature range
    (Elsevier, 2019-03-03) Xu, Mengxing; Peng, Biaolin; Zhu, Jinian; Liu, Laijun; Sun, Wenhong; Leighton, Glenn J. T.; Shaw, Christopher; Luo, Nengneng; Zhang, Qi
    Relaxor ferroelectrics with high energy storage performances are very attractive for modern applications in electronic devices and systems. Here, it is demonstrated that large energy densities (0.52e0.58 J/cm3) simultaneously with high efficiencies (76è2%) and thermal stabilities (the minimum variation of efficiency < 4% from 323 K to 423 K at x ¼ 0.04) have been achieved in the (1-x)(BCT-BMT)-xBFO lead-free relaxor ferroelectric ceramics prepared using a conventional solid-state reaction method. Large dielectric breakdown strengths and great relaxor dispersion around the dielectric peaks are responsible for the excellent energy storage performances. The energy storage performances of as-prepared ceramics at high BFO doping amount (x ¼ 0.06 and 0.07) were deteriorated seriously due to low dielectric breakdown strengths. However, they could be greatly improved when aged, since the operable electric field was significantly enhanced from 10 kV/cm of as-prepared samples to 100 kV/cm of aged samples due to the reduced concentration of oxygen vacancies during the aging process. The excellent energy storage performances may make them attractive materials for applications in modern energy storage systems in a broad temperature range.
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    Giant pyroelectric properties achieved at a wide temperature range in lead-free sodium bismuth titanate-based and composite ceramic materials.
    (2017-12) Balakt, Ahmed Muwafaq J.; Zhang, Qi; Shaw, Christopher
    Health and environmental concerns have universally increased in importance during the last several decades. In the material science sphere, researchers are racing to replace poisonous, PZT-based pyroelectric materials with nonhazardous environmentally friendly ones, which simultaneously possess enhanced properties and provide the high performance. Beside environmental issues, the lower pyroelectric response and narrow operating temperature range have been identified as significant drawbacks of presently used lead-free pyroelectric materials for future diverse advanced industrial applications. One of the possible, most challenging and highly promising solutions to those industrial problems is utilizing composite ceramic materials (CCMS). Those materials combine the best raw materials properties and the sophisticated design. Therefore, they provided better performance compared to the original materials. The major aim of this systematic study is to investigate and improve the pyroelectric properties of lead-free sodium bismuth titanate modified by barium titanate ceramics, Na1/2Bi⅟₂TiO₃-0.06BaTiO₃ (NBT-0.06BT), at the morphotropic phase boundary (MPB) over a wide range of frequencies and temperatures. The secondary goal is to control and lower the first phase transition temperature, termed depolarisation temperature (Td), to around room temperature (RT). Three different techniques were used: (1) modifying the composition by altering A-site element contents; (2) doping the A- and/or B-sites with selective elements; and (3) forming composite pyroelectric ceramic material (CPCM). This study confirms that NBT-0.06BT at the MPB regains its critical composition and is sensitive to any compositional modification. These changes in NBT-0.06BT composition can shift its structure slightly away from the MPB area and will considerably change its pyroelectric properties. It was found that the pyroelectric properties at RT and Td were significantly enhanced by tailoring the NBT-0.06BT composition. Likewise, Td was controlled and decreased by implementing the same techniques as used to tailor the material composition. This study succeeded in increasing the range of the pyroelectric coefficient temperature response from one sharp peak at an exact temperature to a broad peak, which extends to around 25 °C with maximum pyroelectric coefficient (7.10 × 10⁻4 C.m⁻².°C⁻¹ at 40 °C) by developing CPCM. This significant achievement can expand considerably the range of the pyroelectric working temperature and is, therefore, both useful and valuable for a wide variety of pyroelectric applications.
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    High-performance La-doped BCZT thin film capacitors on LaNiO3/Pt composite bottom electrodes with ultra-high efficiency and high thermal stability
    (Elsevier, 2019-03-13) He, Shangkai; Peng, Biaolin; Leighton, Glenn J. T.; Shaw, Christopher; Wang, Ningzhang; Sun, Wenhong; Liu, Laijun; Zhang, Qi
    Dielectric capacitors possessing large energy storage density, high efficiency and high thermal stability simultaneously are very attractive in modern electronic devices to be operated in harsh environment. Here, it is demonstrated that large energy storage density (W ∼ 15.5 J/cm3), ultra-high efficiency (η ∼93.7%) and high thermal stability (the variation of both W from 20 °C to 260 °C and η from 20 °C to 140 °C is less than 5%) have been simultaneously achieved in the La-doped (Ba0.904Ca0.096)0.9775+xLa0.015(Zr0.136Ti0.864)O3 (x = 0.0075) lead-free relaxor ferroelectric thin film capacitors deposited on LaNiO3/Pt composite bottom electrodes by using a sol-gel method. The good energy storage property of the thin film capacitors at x = 0.0075 is mainly ascribed to the diversity of the structure of the nano-clusters around the three-phases coexisting component point (Ba0.904Ca0.096)(Zr0.136Ti0.864)O3 where cubic, tetragonal and rhombohedral phases coexisted, as well as the ultra-high quality of thin film due to the utilization of the LaNiO3/Pt composite bottom electrode, making it a promising candidate for dielectric capacitors working in harsh environments.
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    In-situ tuning of catalytic activity by thermoelectric effect for ethylene oxidation
    (American Chemical Society, 2018-09-20) Achour, Abdenour; Liu, Jian; Peng, Ping; Shaw, Christopher; Huang, Zhaorong
    Thermoelectric material BiCuSeO used as a support and promoter for catalytic ethylene oxidation is reported here. The catalytic activity on the continuous and non-continuous catalyst Pt supported on BiCuSeO was observed to be promoted in-situ by a thermoelectric Seebeck voltage generated by the temperature gradient across the material. It is also shown this thermoelectric promotion of catalysis enabled the thermoelectric material BiCuSeO itself to be highly catalytic active for ethylene oxidation. A good linear relationship between the logarithm of the reaction rate and the thermoelectric Seebeck voltage was observed. This thermoelectric promotion of catalysis is attributed to the change of work function of the catalyst surface, accompanied by a charge transfer from the bulk to the surface due to the thermoelectric effect.
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    PEO-based polymer blend electrolyte for composite structural battery
    (Taylor and Francis, 2023-02-22) Gucci, Francesco; Grasso, Marzio; Shaw, Christopher; Leighton, Glenn; Marchante Rodriguez, Veronica
    High mechanical strength and ionic conductivity of solid-state electrolyte (SSE) are currently conflicting targets that are very difficult to achieve. Polyethylene oxide (PEO) is one of the most common polymers adopted for SSE because of its very high ionic conductivity, but its mechanical strength is very low. This work discusses the manufacturing and testing of PEO blends using polysulfone (PSf) and Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to assess the mechanical response under microtensile testing and the ionic conductivity with electrochemical impedance spectroscopy (EIS). Mechanical tests demonstrated a beneficial effect of LiTFSI with significant increase in maximum stress and ductility measured as strain at failure. The blending of PEO and PSf showed promising conductivity values at room temperature with the 90–10 PEO-PSf composition achieving the highest value (1.06 × 10−6 S/cm) and for the 70–30 composition achieving the highest maximum stress (3.5 MPa) with a conductivity of 3.12 × 10−7 S/cm.
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    Phase-transition induced giant negative electrocaloric effect in a lead-free relaxor ferroelectric thin film
    (Royal Society of Chemistry, 2019-05-02) Peng, Biaolin; Zhang, Qi; Gang, Bai; Leighton, Glenn J. T.; Shaw, Christopher; Milne, Steven J.; Zou, Bingsuo; Sun, Wenhong; Huang, Haitao; Wang, Zhonglin
    Ferroelectric/antiferroelectric thin/thick films with large positive or negative electrocaloric (EC) effects could be very useful in designing commercial refrigeration devices. Here, a giant negative EC effect (maximum ΔT ∼ −42.5 K with ΔS ∼ −29.3 J K−1 kg−1) comparable to the best positive EC effects reported so far is demonstrated for 0.5(Ba0.8Ca0.2)TiO3–0.5Bi(Mg0.5Ti0.5)O3 (BCT–BMT) lead-free relaxor ferroelectric thin films prepared on Pt(111)/TiOx/SiO2/Si substrates using a sol–gel method. An electric-field induced structural phase transition (nanoscale tetragonal and orthorhombic to rhombohedral) along the out-of-plane [111] direction plays a very key role in developing the giant negative EC effect. This breakthrough will pave the way for practical applications of next-generation refrigeration devices with high cooling efficiency in one cycle by ingeniously utilizing and combining both the giant negative and positive EC effects. Moreover, a large energy density of 51.7 J cm−3 with a high power density of 1.15 × 1010 W kg−1 at room temperature is also achieved in the thin film, indicating that it is also an attractive multifunctional material for energy storage.
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    Tailoring the electrocaloric effect of Pb0.78Ba0.2La0.02ZrO3 relaxor thin film by GaN substrates
    (Royal Society of Chemistry, 2019-11-06) Peng, Biaolin; Jiang, Jintao; Tang, Silin; Zhang, Miaomiao; Liu, Laijun; Zou, Bingsuo; Leighton, Glenn J. T.; Shaw, Christopher; Luo, Nengneng; Zhang, Qi; Sun, Wenhong
    The electrocaloric (EC) effect in ferroelectric/antiferroelectric thin films has been widely investigated due to its potential applications in solid state cooling devices. It is demonstrated that the EC effect of the Pb0.78Ba0.2La0.02ZrO3 (PBLZ) relaxor thin films prepared by using a sol–gel method strongly depends on the substrates. The maximum ΔT of PBLZ thin films deposited on Pt(111)/TiOx/SiO2/Si(100) (Pt), LaNiO3/Pt(111)/TiOx/SiO2/Si(100) (LaNiO3/Pt), LaNiO3/n-type GaN (LaNiO3/n-GaN) and LaNiO3/p-type GaN (LaNiO3/p-GaN) substrates is ∼13.08 K, 16.46 K, 18.70 K, and 14.64 K, respectively. Moreover, negative EC effects in a broad temperature range (∼340 K to 440 K) could be obtained in the thin films deposited on LaNiO3/n-GaN and LaNiO3/p-GaN substrates, which is ascribed to higher proportions of orthorhombic antiferroelectric phase to rhombohedral ferroelectric phase induced by the GaN substrates. These results indicate that tailoring the EC effects by changing the substrates could provide a new strategy in designing an EC cooling device with high cooling efficiency.
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    Thermal strain induced large electrocaloric effect of relaxor thin film on LaNiO3/Pt composite electrode with the coexistence of nanoscale antiferroelectric and ferroelectric phases in a broad temperature range
    (Elsevier, 2018-03-08) Peng, Biaolin; Zhang, Qi; Lyu, Yinong; Liu, Laijun; Lou, Xiaojie; Shaw, Christopher; Huang, Haitao; Wang, Zhonglin
    Ferroelectric/antiferroelectric thin/thick films with large electrocaloric (EC) effect in a broad operational temperature range are very attractive in solid-state cooling devices. We demonstrated that a large positive electrocaloric (EC) effect (maximum ΔT ~ 20.7 K) in a broad temperature range (~ 110 K) was realized in Pb0.97La0.02(Zr0.65Sn0.3Ti0.05)O3 (PLZST) relaxor antiferroelectric (AFE) thin film prepared using a sol-gel method. The large positive EC effect may be ascribed to the in-plane residual thermal tensile stress during the layer-by-layer annealing process, and the high-quality film structure owing to the utilization of the LaNiO3/Pt composite bottom electrode. The broad EC temperature range may be ascribed to the great dielectric relaxor dispersion around the dielectric peak because of the coexistence of nanoscale multiple FE and AFE phases. Moreover, a large pyroelectric energy density (6.10 Jcm−3) was harvested by using an Olsen cycle, which is much larger than those (usually less than 10− Jcm−3) obtained by using direct thermal-electrical, Stirling and Carnot cycles, etc. These breakthroughs enable the PLZST thin film an attractive multifunctional material for applications in modern solid-state cooling and energy harvesting.