The Department of Electronic and Electrical Engineering is located on Thornton Science Park, a modern expressly-designed site that profits from a recently-completed multi-million pound renovation that has created a state-of-the-art teaching and research facility. The site was home to Shell UK’s exploration and research centre since the 1940s, and its takeover by the University heralded the opportunity to apply its legacy to the continuation of world-class innovation and research in the North West.

Recent Submissions

  • (Ba0.6Sr0.4)TiO3/PEEK composites modified by Polyethersulfone with low dielectric constant and high dielectric tunability under DC bias

    Yang, Bin; Liu, Shuhang; Guo, Yiting; Hu, Guoxin; Wu, Sichen; Xu, Jie; Chen, Jianxin; Bulejak, Weronika; Baxter, Harry; Kong, Jie; et al. (Elsevier, 2023-01-19)
    Ceramic/polyetheretherketone (PEEK) composites show a wide range of applications and have attracted extensive interest in the scientific community due to their outstanding dielectric and mechanical characteristics. However, the interface connection between the ceramic and PEEK is a vital issue that must be addressed to improve their physical and electrical properties. In this work, the polyethersulfone resin (PES) was selected as interface modifier between barium strontium titanate (Ba0.6Sr0.4TiO3, BST) and PEEK. Cold-pressing sintering was used to create BST/PEEK materials with superior dielectric frequency stability and dielectric tunability. The effects of PES content on the morphology and dielectric characteristics of PES modified BST/PEEK materials were investigated. The results showed PES could improve the dispersion of BST particles in polymer. The dielectric constant, dielectric tunability, and breakdown strength increased first, then reduced as PES content increased. The composite had the most homogeneous microstructure and the best dielectric properties when the PES content was 7.5vol%. The frequency dispersion factor F(x) was much smaller than that of other ceramic/polymer composites reported. In addition, the dielectric tunability of the composites could reach a relatively high level (34.18%) while the dielectric constant was as low as 14. The dielectric tunable efficiency (TuE) was proposed to evaluate the property of low dielectric constant and high dielectric tunability under DC bias. The TuE of PES modified BST/PEEK composites show the highest value comparing with reported dielectric tunable composites. This research laid the path for the development of a novel ceramic/polymer composite with good interface bonding and high dielectric tunability.
  • THz probing ferroelectric domain wall dynamics

    Yang, Bin; University of Chester (IEEE, 2022-12-27)
    This work uses THz time domain spectroscopy (THz-TDS) to detect the dynamics of domain walls in a Aurivillius phase ferroelectric ceramic, Ca 0.96 Rb 0.02 Ce 0.02 Bi 2 Nb 2 O 9 . Results show that ferroelectric domain walls are active at the THz band, with lower dielectric permittivity compared with that of the domain. This work has verified that it is feasible to use domain wall engineering method to optimize properties of ferroelectrics at the THz band, which help create new applications for ferroelectric materials at THz frequency.
  • New methodology to reduce power by using smart street lighting system

    Al-khaykan, Ameer; Aziz, Ali Saleh; Al-Kharsan, Ibrahim H.; Counsell, John M. (Walter de Gruyter GmbH, 2022-12-08)
    One of most important things now is to create smart street and smart lighting system to save enormous electrical energy. Especially Iraq is suffering shortage of electrical energy generation up to 45%. Because of this, Iraq needs to save a lot of electrical energy in the entire country so as to meet the electrical demand and reduce the large amount of CO2 emission. However, this work presents a very unique and economic control lighting system (CLS) for main streets and sidewalks, which can control the lighting system to give sufficient illumination to the drivers and the pedestrians simultaneously. And at the same time, the CLS system can reduce a lot of electrical energy consumption and the CO2 emissions together. However, by using these smart systems with the exciting illumination source in the streets, the CLS can minimize the electrical energy consumed for the lighting at the main roads and the footpath by about 60% and can use the surplus energies to fill the shortage of electricity in the country. Also, this system will increase the lifetime of the lighting system which means further decrease in cost. Finally, this work presents new type of illumination source, high-intensity discharge (HID), which can reduce the electrical consumption much more by up to 90%, when using the CLS with HID.
  • Rare earth ion-doped Y2.95R0.05MgAl3SiO12 (R = Yb, Y, Dy, Eu, Sm) garnet-type microwave ceramics for 5G application

    Ye, Zijun; Jiang, Yu; Mao, Minmin; Xiu, Zhiyu; Chi, Mengjiao; Wu, Guofa; Liu, Bing; Wang, Dawei; Yang, Bin; Song, Kaixin; et al. (MDPI, 2022-11-11)
    In this work, Y2.95R0.05MgAl3SiO12 (R=Yb, Y, Dy, Eu, Sm) microwave single-phase dielectric ce-ramics were successfully prepared via conventional ceramic technology by doping a series of rare earth elements with different ionic radius (Yb, Y, Dy, Eu, Sm) for the first time. The effects of A site occupied by rare earth elements on the microwave dielectric properties of Y2.95R0.05MgAl3SiO12 were studied by crystal structure refinement, scanning electron microscope (SEM), bond valence theory, P-V-L theory and infrared reflection spectroscopy. It was found that the ionicity of Y-O bond, the lattice energy, the bond energy and bond valance of Al(Tet)-O bond had important effects on microwave dielectric properties. Particularly, the optimum microwave dielectric properties were obtained for Y2.95Dy0.05MgAl3SiO12 sintered at 1575 °C for 6 h, with εr = 9.68, Q×f = 68,866 GHz, and τf = -35.8 ppm/°C, displaying its potential prospect in the 5G communication.
  • Terahertz Faraday rotation of SrFe12O19 hexaferrites enhanced by Nb-doping

    Hu, Zimeng; Stenning, Gavin B. G.; Koval, Vladimir; Wu, Jiyue; Yang, Bin; Leavesley, Alisa; Wylde, Richard; Reece, Michael J.; Jia, Chenglong; Yan, Haixue; et al. (American Chemical Society, 2022-10-04)
    The magneto-optical and dielectric behaviour of M-type hexaferrites as permanent magnets in the THz band are essential for potential applications like microwave absorbers and antennas, while are rarely reported recent years. In this work, single-phase SrFe12-xNbxO19 hexaferrite ceramics were prepared by conventional solid state sintering method. Temperature-dependent of dielectric parameters were investigated here to search the relationship between dielectric response and magnetic phase transition. The saturated magnetization increases by nearly 12% while the coercive field decreases by 30% in the x = 0.03 composition compared to that of the x = 0.00 sample. Besides, Nb substitution improves the magneto-optical behaviour in the THz band by comparing the Faraday rotation parameter from 0.75 (x = 0.00) to 1.30 (x = 0.03). The changes in the magnetic properties are explained by a composition-driven increase of the net magnetic moment and enhanced ferromagnetic exchange coupling. The substitution of donor dopant Nb on the Fe site is a feasible way to obtain multifunctional M-type hexaferrites, as preferred candidates for permanent magnets, sensors and other electronic devices.
  • FinFET-based non-linear analog signal processing modules

    Sharma, Vipin Kumar; Ansari, Mohammad Samar; Parveen, Tahira; Aligarh Muslim University; University of Chester (Elsevier, 2022-11-08)
    FinFETs exhibit far superior transistor characteristics (better gate control and a lower sub-threshold slope) as compared to the standard MOSFETs, this paper first employs the FinFETs in the design of an operational transconductance amplifier (OTA). The FinFET-based OTA offers a linearity range and - 3 dB bandwidth of 300 mV and 631.81 GHz, respectively. Further, the non-linear applications of the proposed OTA, viz. voltage divider, memristor emulator, and a memristive neuron, are presented. The proposed analog voltage divider circuit contains one OTA and two external N-FinFETs. The maximum bandwidth obtained for the voltage divider is 217.54 GHz. The memristor emulator contains one OTA, two external N-FinFETs, and one grounded capacitor. The proposed emulator circuit follows the signature characteristics of the actual memristor device. The frequency response characteristics of the proposed emulator circuit depict a bandwidth of 22.7 GHz. The proposed emulator shows non-volatile as well as electronically tunable features. Next, Monte-Carlo simulation analysis has been performed on the proposed circuits in order to observe the effects of statistical variation in different operating conditions. Furthermore, we propose a FinFET-based passive memristive neuron model using a memristor emulator circuit. The proposed neuron circuit follows a tangent hyperbolic activation function. All the proposed circuits are suitable for monolithic implementation. The proposed circuits are verified using 20 nm FinFET technology. The simulation results obtained using HSPICE agree well with the theoretical analysis.
  • A Novel Double-Threshold Neural Classifier for Non-Linearly Separable Applications

    Kashif, Mohd; Rahman, Syed Atiqur; Ansari, Mohammad Samar; Aligarh Muslim University; University of Chester
    Classification of data finds applications in various engineering and scientific problems. When real-time operation is desired, hardware solutions tend to be more amenable as compared to algorithmic/heuristic solutions. This paper presents a novel current-mode dual-threshold neuron designed and implemented at 32nm CMOS technology node. Subsequently, a current-mode double-threshold classifier is presented which is capable of classifying input patterns of non-linearly separable problems. Thereafter, application of the current-mode dual-threshold neuron in the realization of the XOR function using only a single neural unit is discussed. The proposed neuron as well as both the applications discussed are capable of operating from sub-1V power supplies. Computer simulations using HSPICE yield promising results with the values of delay and power consumption estimated to be lower than existing circuits.
  • Wasserstein GAN based Chest X-Ray Dataset Augmentation for Deep Learning Models: COVID-19 Detection Use-Case

    Hussain, B. Zahid; Andleeb, Ifrah; Ansari, Mohammad Samar; Joshi, Amit Mahesh; Kanwal, Nadia; Aligarh Muslim University; University of Chester; Malaviya National Institute of Technology Jaipur; Keele University (IEEE, 2022-09-08)
    The novel coronavirus infection (COVID-19) is still continuing to be a concern for the entire globe. Since early detection of COVID-19 is of particular importance, there have been multiple research efforts to supplement the current standard RT-PCR tests. Several deep learning models, with varying effectiveness, using Chest X-Ray images for such diagnosis have also been proposed. While some of the models are quite promising, there still remains a dearth of training data for such deep learning models. The present paper attempts to provide a viable solution to the problem of data deficiency in COVID-19 CXR images. We show that the use of a Wasserstein Generative Adversarial Network (WGAN) could lead to an effective and lightweight solution. It is demonstrated that the WGAN generated images are at par with the original images using inference tests on an already proposed COVID-19 detection model.
  • Low permittivity cordierite-based microwave dielectric ceramics for 5G/6G telecommunications

    Lou, Weichao; Mao, Minmin; Song, Kaixin; Xu, Kuiwen; Liu, Bing; Li, Wenjun; Yang, Bin; Qi, Zeming; Zhao, Jianwei; Sun, Shikuan; et al. (Elsevier, 2022-02-01)
    5G and forthcoming 6G communication systems require dielectric ceramics with low relative permittivity (εr) and near-zero temperature coefficient of resonant frequency (τf) for the lower part of the microwave (MW) band and at sub-Terahertz. Mg2Al4Si5O18 (MAS) ceramics are promising candidates due to their low εr (~6) and high-quality factor (Q×f >40,000 GHz) but have a large f. In this study, 5.5wt% TiO2 (MAS-T5.5) was used to adjust τf of MAS to -2.8 ppm/℃ whilst retaining low εr (5.24) and good Q×f (33,400 GHz), properties consistent with those obtained by infrared reflectance. A demonstrator microstrip patch antenna with gain 4.92dBi and 76.3% efficiency was fabricated from MAS-T5.5.
  • Resolving nanoscopic structuring and interfacial THz dynamics in setting cements

    Song, Fu V.; Yang, Bin; Di Tommaso, Devis; Donnan, Robert S.; Chass, Gregory A.; Yada, Rickey Y.; Farrar, David H.; Tian, Kun V.; Queen Mary University of London; University of Chester; The University of British Columbia; McMaster University; Sapienza University of Rome (Royal Society of Chemistry, 2022-05-16)
    The setting dynamics of two commercial cements have been tracked over >24 hours of setting with non-destructive THz spectroscopy and neutron scattering. Two established glass ionomer cements (GICs) were measured, both exhibiting similar and commercially agreeable non-linear settings associated with changes in interfacial particle dynamics through variations in their collective low-energy vibrations. Structural evolutions in the ∼1–30 nm range were correlated with changes in small angle neutron scattering (SANS) profiles over setting. Accompanying models of the interfacial structures and the amorphous glass components of the cements helped make the dynamic and structural trends comprehensible. The combined observations helped elucidate key temporal features in the setting of the cements, whilst suggesting the functional role played by the THz vibrations, in particular at dynamically coordinated interfacial Al-atom pivots. The insights obtained could help evolve nano-scopic strategies to optimise cements and their eventual properties.
  • Terahertz Characterisation of Lead-Free Dielectrics for Different Applications

    Zhang, Man; Zhang, Hangfeng; Jiang, Qinghui; Gao, Feng; Chen, Riqing; Zhang, Dou; Reece, Michael J.; Yang, Bin; Viola, Giuseppe; Yan, Haixue; et al. (American Chemical Society, 2021-11-02)
    In this Spotlight on Applications, we describe our recent progress on the terahertz (THz) characterization of linear and non-linear dielectrics for broadening their applications in different electrical devices. We begin with a discussion on the behavior of dielectrics over a broadband of frequencies and describe the main characteristics of ferroelectrics, as an important category of non-linear dielectrics. We then move on to look at the influence of point defects, porosity and interfaces, including grain boundaries and domain walls, on the dielectric properties at THz frequencies. Based on our studies on linear dielectrics, we show that THz characterization is able to probe the effect of porosities, point defects, shear planes and grain boundaries to improve dielectric properties for telecommunication applications. Further, we demonstrate that THz measurements on relaxor ferroelectrics can be successfully used to study the reversibility of the electric field-induced phase transitions, providing guidance for improving their energy storage efficiency in capacitors. Finally, we show that THz characterization can be used to characterize the effect of domain walls in ferroelectrics. In particular, our studies indicate that the dipoles located within domain walls provide a lower contribution to the permittivity at THz frequencies than the dipoles present in domains. The new findings could help develop a new memory device based on non-destructive reading operations using a THz beam.
  • Terahertz probing of low temperature degradation in zirconia bioceramics

    Ahmed, Shafique; Zhang, Man; Koval, Vladimir; Zou, Lifong; Shen, Zhijian; Chen, Riqing; Yang, Bin; Yan, Haixue; Queen Mary University of London; Mehran University of Engineering and Technology; Institute of Materials Research; Stockholm University; Fujian Agriculture and Forestry University; University of Chester (Wiley, 2021-09-19)
    ZrO2 based ceramics are widely used in biomedical applications due to its colour, biocompatibility, and excellent mechanical properties. However, low temperature degradation (LTD) introduces a potential risk for long-term reliability of these materials. The development of innovative non-destructive techniques, which can explore LTD in zirconia-derived compounds, is strongly required. Yttria stabilised zirconia, 3Y-TZP, is one of the well-developed ZrO2 based ceramics with the improved resistance to LTD for dental crown and implant applications. Here, 3Y-TZP ceramic powders were pressed and sintered to study the LTD phenomenon by phase transition behaviour. The LTD driven tetragonal-to-monoclinic phase transition was confirmed by XRD. XPS analysis demonstrated the LTD induced the reduction of oxygen vacancies to support these findings. It is proved that after the degradation the 3Y-TZP ceramics show the decreased dielectric permittivity at terahertz frequencies due to the crystallographic phase transformation. Terahertz non-destructive probe is a promising method to investigate LTD in zirconia ceramics.
  • Characterization of microwave and terahertz dielectric properties of single crystal La2Ti2O7 along one single direction

    Zhang, Man; Tang, Zhiyong; Zhang, Hangfeng; Smith, Graham; Jiang, Qinghui; Saunders, Theo; Yang, Bin; Yan, Haixue; Huazhong University of Science and Technology; University of Chester; Queen Mary University of London; Chinese Academy of Sciences (Elsevier, 2021-08-02)
    New generation wireless communication systems require characterisations of dielectric permittivity and loss tangent at microwave and terahertz bands. La2Ti2O7 is a candidate material for microwave application. However, all the reported microwave dielectric data are average value from different directions of a single crystal, which could not reflect its anisotropic nature due to the layered crystal structure. Its dielectric properties at the microwave and terahertz bands in a single crystallographic direction have rarely been reported. In this work, a single crystal ferroelectric La2Ti2O7 was prepared by floating zone method and its dielectric properties were characterized from 1 kHz to 1 THz along one single direction. The decrease in dielectric permittivity with increasing frequency is related to dielectric relaxation from radio frequency to microwave then to terahertz band. The capability of characterizing anisotropic dielectric properties of a single crystal in this work opens the feasibility for its microwave and terahertz applications.
  • Millimeter-Wave Free-Space Dielectric Characterization

    Liu, Xiaoming; Gan, Lu; Yang, Bin; Anhui Normal University; Wuhu CEPREI Information Industry Technology Research Institute; University of Chester (Elsevier, 2021-05-07)
    Millimeter wave technologies have widespread applications, for which dielectric permittivity is a fundamental parameter. The non-resonant free-space measurement techniques for dielectric permittivity using vector network analysis in the millimeter wave range are reviewed. An introductory look at the applications, significance, and properties of dielectric permittivity in the millimeter wave range is addressed first. The principal aspects of free-space millimeter wave measurement methods are then discussed, by assessing a variety of systems, theoretical models, extraction algorithms and calibration methods. In addition to conventional solid dielectric materials, the measurement of artificial metamaterials, liquid, and gaseous-phased samples are separately investigated. The pros of free-space material extraction methods are then compared with resonance and transmission line methods, and their future perspective is presented in the concluding part.
  • Volatile Liquid Detection by Terahertz Technologies

    Baxter, Harry W.; Worrall, Adam A.; Pang, Jie; Chen, Riqing; Yang, Bin; University of Chester; Fujian Agriculture and Forestry University (Frontiers Media, 2021-04-08)
    The prospect of being able to move through security without the inconvenience of separating liquids from bags is an exciting one for passengers, and there are important operational benefits for airports as well. Here, two terahertz (THz) systems, 100 GHz sub-THz line scanner and attenuation total reflection-based THz time domain spectroscopy (TDS), have been used to demonstrate the capability of identifying different liquid samples. Liquid samples’ THz complex permittivities are measured and their differences have contributed to the variation of 100 GHz 2D images of volatile liquids with different volumes inside of cannister bottles. The acquired attenuation images at 100 GHz can easily be used to distinguish highly absorbed liquids (Water, Ethanol, Fuel Treatment Chemicals) and low loss liquids (Petrol, Diesel, Kerosene and Universal Bottle Cleaner). The results give a promising feasibility for mm-wave imager and THz spectroscopy to efficiently identify different volatile liquids.
  • Simulating Topological Robustness of Fano Resonance in Rotated Honeycomb Photonic Crystals

    Hajivandi, J.; Kaya, E.; Edwards, Gerard; Kurt, H.
    The Fano resonance with a distinctive ultra-sharp, asymmetric line shape and high quality factor, is a widely occurring phenomena, that has a large variety of optical, plasmonic and microwave manifestations. In this paper, we explore the characteristic robustness of a Fano resonance mode, which is topologically protected by engineering a band inversion, induced by breaking the mirror symmetry of a two-dimensional honeycomb photonic crystal (HPC), associated with C 6 point group symmetry. Dark and bright topological edge modes appear in the band gap which arise when Dirac cone is opened up. Destructive and constructive interference of the dark and bright modes leads to the asymmetric line shape of the Fano resonance. The Fano resonance is very sensitive to the material changes and structural perturbations. This property can be applied to obtain new sensor designs. Here we demonstrate that the topological Fano resonance mode preserves its asymmetric, ultra-sharp line shape in the presence of the disorder, defects and cavities.The stability of the Fano resonance mode has useful optical device applications such as in low threshold lasers, and extremely precise interferometers.
  • Terahertz reading of ferroelectric domain wall dielectric switching

    Zhang, Man; Chen, Zhe; Yue, Yajun; Chen, Tao; Yan, Zhongna; Jiang, Qinghui; Yang, Bin; Eriksson, Mirva; Tang, Jianhua; Zhang, Dou; et al. (American Chemical Society, 2021-03-08)
    Ferroelectric domain walls (DWs) are important nano scale interfaces between two domains. It is widely accepted that ferroelectric domain walls work idly at terahertz (THz) frequencies, consequently discouraging efforts to engineer the domain walls to create new applications that utilise THz radiation. However, the present work clearly demonstrates the activity of domain walls at THz frequencies in a lead free Aurivillius phase ferroelectric ceramic, Ca0.99Rb0.005Ce0.005Bi2Nb2O9, examined using THz time domain spectroscopy (THz-TDS). The dynamics of domain walls are different at kHz and THz frequencies. At low frequencies, domain walls work as a group to increase dielectric permittivity. At THz frequencies, the defective nature of domain walls serves to lower the overall dielectric permittivity. This is evidenced by higher dielectric permittivity in the THz band after poling, reflecting decreased domain wall density. An elastic vibrational model has also been used to verify that a single frustrated dipole in a domain wall represents a weaker contribution to the permittivity than its counterpart within a domain. The work represents a fundamental breakthrough in understanding dielectric contributions of domain walls at THz frequencies. It also demonstrates that THz probing can be used to read domain wall dielectric switching.
  • Enhanced design of an offgrid PV-battery-methanation hybrid energy system for power/gas supply

    Xu, Xiao; Hu, Weihao; Cao, Di; Liu, Wen; Huang, Qi; Hu, Yanting; Chen, Zhe; University of ESTC; Utrecht University; University of Chester; Aalborg University
    Extensive studies have been carried out on various hybrid energy systems (HESs) for providing electricity to off-grid areas. However, a standalone HES that is capable of providing power and gas, has been less studied. In this paper, a standalone Photovoltaic (PV)-battery-methanation HES is proposed to provide adequate, reliable and cost-effective electricity and gas to the local consumers. Identifying a potential solution to maximize the reliability of the system, asked by consumers, and to minimize costs required by the investors is challenging. Bi-level programming is adopted in this study to tackle the pre-mentioned issue. In the outer layer, an optimal design is obtained by means of particle swarm optimization. In the inner layer, an optimal operation strategy is found under the optimal design of the outer layer using sequential quadratic programming. The results indicate that 1) The bi-level programming used in this study can find the optimal solution; 2) The proposed HES is proved to be able to supply power and gas simultaneously. 3) Compared with the right most and leftmost points on Pareto set, the total costs are reduced by 17.77% and 2.16%.
  • Ultrafast Electric Field-induced Phase Transition in Bulk Bi0.5Na0.5TiO3 under High Intensity Terahertz Irradiation

    Yang, Bin; Zhang, Man; McKinnon, Ruth A.; Viola, Giuseppe; Zhang, Dou; Reece, Michael J.; Abrahams, Isaac; Yan, Haixue; University of Chester; Queen Mary University of London; Central South University (American Chemical Society, 2020-12-22)
    Ultrafast polarization switching is being considered for the next generation of ferroelectric based devices. Recently, the dynamics of the field-induced transitions associated with this switching have been difficult to explore, due to technological limitations. The advent of terahertz (THz) technology has now allowed for the study of these dynamic processes on the picosecond (ps) scale. In this paper, intense terahertz (THz) pulses were used as a high-frequency electric field to investigate ultrafast switching in the relaxor ferroelectric, Bi0.5Na0.5TiO3. Transient atomic-scale responses, which were evident as changes in reflectivity, were captured by THz probing. The high energy THz pulses induce an increase in reflectivity, associated with an ultrafast field-induced phase transition from a weakly polar phase (Cc) to a strongly polar phase (R3c) within 20 ps at 200 K. This phase transition was confirmed using X-ray powder diffraction and by electrical measurements which showed a decrease in the frequency dispersion of relative permittivity at low frequencies.
  • Structure and dielectric properties of double A-site doped bismuth sodium titanate relaxor ferroelectrics for high power energy storage applications

    Yang, Bin; Zhang, Hangfeng; Fortes, Dominic; Yan, Haixue; Abrahams, Isaac; University of Chester; Queen Mary University of London; Rutherford Appleton Laboratory
    The structural and dielectric properties of barium/strontium substituted Bi0.5Na0.5TiO3 were examined in compositions of general formula (Ba0.4Sr0.6TiO3)x(Bi0.5Na0.5TiO3)1-x. An average classic cubic perovskite structure is maintained from x = 0.5 to 1.0. The temperature dependence of dielectric properties of studied compositions shows relaxor-ferroelectric behaviour attributed to the existence of polar nano-regions. Ferroelectric measurements under variable temperature demonstrated two transitions from normal ferroelectric to relaxor-ferroelectric and relaxor-ferroelectric to paraelectric, at the dipole freezing temperature, Tf, and temperature of maximum permittivity, Tm, respectively. The obtained value of Tf coincides with the onset of linear thermal expansion of the cubic unit cell parameter obtained from high resolution powder neutron diffraction data. Careful analysis of the neutron diffraction data revealed no significant change in the average cubic structure from -263 to 150 C. However, changes in the Gaussian variance component of the neutron peak shape, reveal three distinct regions with transitions at about -100 and 100 C corresponding to the beginning and end of the dielectric dispersion seen in the permittivity and loss spectra. This variation in the Gaussian variance parameter is attributed to the activity of the polar nano-regions. The composition (Ba0.4Sr0.6)0.5(Bi0.5Na0.5)0.5TiO3 was found to exhibit the maximum recoverable energy storage density, with a value of 1.618 J cm-3 and 76.9% storage efficiency at a field of 17 kV mm-1.

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