super capacitor electrodes

The Department of Physics is happy to announce that Prof Ranjit Thapa and his PhD Scholar Mr Samadhan Kapse have published a paper titled “Supercapacitor electrodes based on quasi-one-dimensional van der Waals TiS3 nanosheets: experimental findings and theoretical validation” in the Nature indexed journal ‘Applied Physics Letters’ having an impact factor of 3.79. The Paper is published in collaboration with Abhinandan Patra and Chandra Sekhar Rout from Jain University and Dattatray J Late from Amity University.

Abstract of the Research

To cease the ever-increasing energy demand, additional enthusiastic focus has been given to generate more sustainable energy from alternative renewable sources. The storage of these energies for future usage solely depends on the energy storage devices. A diversity of electrode materials based on two-dimensional (2D) transition metals and their derivatives have enticed the whole world owing to their tunable properties. Transition metal trichalcogenides (TMTCs- MX3 type) is the emergent class of 2D materials that gathered a lot of interest because of their quasi-one-dimensional anisotropic properties with the van der Waals force of attraction in between the layers. Herein, TiS3 being an MX3-type of material is preferred as the electrode for supercapacitor application with detailed experimental investigations and theoretical validation. The highest capacitance attained for TiS3 is found to be 235 F/g (105 C/g) at 5 mV/s with a battery type of charge storage mechanism. The asymmetric device is fabricated using Ti3C2Tx MXene nanosheets as negative electrode and a brilliant 91 % of capacitance retention is accomplished with an extensive potential window of 1.5 V. The investigational discoveries are substantiated by theoretical simulation in terms of the quantum capacitance assessment and charge storage mechanisms.

About the Research

In this work, a battery type TMTC material i.e., TiS3 has been synthesized and characterized by different analytical techniques such as Raman spectroscopy, FESEM and TEM to gain information on its structural and morphological aspects. The electrochemical performance was found to be promising by considering its good energy storage performance. High capacitance of 235 F/g (105 C/g) at 5 mV/s was achieved and the asymmetric supercapacitor devices disclosed outstanding cycling stability of 91 % over 6000 GCD cycles. In addition, the theoretical simulations also validated the experimental findings through the evaluation of the quantum capacitance. The higher conductivity, abundant electrochemical active sites, swift faradic redox kinetics and well-connected pathway for ion transfer characteristics pave the way for TiS3 to emerge as an eminent material for energy storage application in the long run.

Social Implications

Energy storage devices come into picture whenever there is a prerequisite of storing renewable energy. Among the numerous energy storage devices, batteries and ultracapacitors have acquired more popularity in nanotechnology and optoelectronics field. The high stability, accuracy, swift functionality, power density and reversibility are the key factors that have positioned ultracapacitors at the forefront of all energy storage devices. On the contrary, the low energy density and high cost of supercapacitor electrodes try to put them in the back seat of the wheels of the energy industry. Henceforth, in recent times the development of supercapattery (abbreviated for supercapacitor and battery) types of materials has become a way out which tie the aces like high specific power of supercapacitors with the high energy density of batteries. These materials exhibit capacitive or battery type behaviour on the basis of materials properties, electrolytic ions, design of the electrochemical cell. Due to these advantages and superior energy storage performance, the demand for this kind of material is growing.

Theoretical quantum capacitance is an important parameter to investigate the supercapacitor performance of low dimensional materials such as electrodes. This approach is highly cost-effective for the rapid screening of various materials for supercapacitor applications.

green urea synthesis

Prof Ranjit Thapa and his PhD scholar, Mr Samadhan Kapse from the Department of Physics have reported their euphoric achievement of discovering an economically viable electrocatalyst for effective green urea synthesis. The paper “Selective Electrocatalytic Co-reduction of N2 and CO2 on Copper Phthalocyanine for Green Urea Production” has been published in the highly prestigious Nature indexed journal, ‘Advanced Functional Materials’, having an Impact Factor of 18.81. It was published in collaboration with Jit Mukherjee, and Uttam Kumar Ghorai, from the Department of Industrial Chemistry & Applied Chemistry, Swami Vivekananda Research Centre.

With global annual production of 100 million tons, urea is one of the important nitrogen sources for the fertilizer industry. Industrial urea is synthesized by the following two consecutive steps. First, the reaction of nitrogen and hydrogen (N2 + H2 → NH3) by the Haber-Bosch process at high temperature and pressure (350–550°C, 150–350 bar); followed by the reaction of NH3 and CO2 [NH3 + CO2 → CO(NH2)2] under mild reaction conditions (170–200°C and 200–250 bar). The sequential reactions are carried out for several cycles to increase the conversion efficiency. For the first step, fixation of N2 is an energy as well as a capital intensive process due to difficulty in cleaving the N≡N bond. Extensive research works have been reported on electrochemical N2 fixation to NH3 in water medium under ambient conditions. In this electrochemical method, isolation of NH3 gas with high purity from electrolyte solution is troublesome. In the second step, CO2 fixation on the substrate and its separation is one of the major challenging tasks for the further reaction with NH3 to end up in urea formation. Overall, the two-step process for large scale production of urea consumes high energy and produces greenhouse gases for the environment.

The research team reported copper-phthalocyanine nanotubes (CuPc NTs) having multiple active sites as an efficient electrocatalyst which exhibits a tremendous yield of urea with good durability and long-term stability. DFT calculation predicts that Pyridinic–N1 in CuPc is responsible for N2 reduction and the metal centre plays an important role for CO2 reduction. This study not only provides us with the co-reduction of N2 and CO2 gases using cost-effective CuPc NTs catalyst but also opens a new pathway to the rational design of other transitional metal-based electrocatalysts having multiple active sites for N2 and CO2 gas fixation applications.

This electrochemical method of urea synthesis by the co-reduction of N2 and CO2 [N2 + CO2 + 6H+ + 6e– → CO(NH2)2 + H2O] using an efficient electrocatalyst in a water medium under ambient conditions would be an alternative way in the upcoming days. All the strategies using alloys and heterostructure for urea synthesis forming C–N bond by the co–reduction of N2 and CO2 have not reached the benchmark in terms of urea yield rate and FE for practical applications. To achieve a high urea yield and FE, various factors are to be considered in this work.

Abstract of the Research

Green synthesis of urea under ambient conditions by electrochemical co-reduction of N2 and CO2 gases using effective electrocatalyst essentially pushes the conventional two steps (N2 + H2 = NH3 & NH3 + CO2 = CO (NH2)2) industrial process at high temperature and high pressure, to the brink. The single-step electrochemical green urea synthesis process has hit a roadblock due to the lack of an efficient and economically viable electrocatalyst with multiple active sites for dual reduction of N2 and CO2 gas molecules to urea. Herein, the research reports copper-phthalocyanine nanotubes (CuPc NTs) having multiple active sites (such as metal centre, Pyrrolic-N3, Pyrrolic-N2, and Pyridinic-N1) as an efficient electrocatalyst which exhibits urea yield of 143.47 µg h-1 mg-1cat and FE of 12.99% at –0.6 V vs RHE by co-reduction of N2 and CO2. Theoretical calculation suggests that Pyridinic-N1 and Cu centres are responsible to form C–N bonds for urea by co-reduction of N2 to NN* and CO2 to *CO respectively. This study provides new mechanistic insight into the successful electro-reduction of dual gases (N2 and CO2) in a single molecule as well as the rational design of an efficient noble metal-free electrocatalyst for the synthesis of green urea.

 

faculty development

The Department of Physics organised a Faculty Development Programme discussing the scopes of implementing sponsored projects. Renowned academicians, Prof Sathish Vadhiyar, IISc Bangalore; Prof Kothandaraman Ramanujam, IIT Madras; and Prof Paromita Chakraborty, SRMIST were the keynote speakers of the session. They shared their views and enlightened the faculty on the scopes and challenges in implementing projects proposed across various disciplines.

Prof V S Rao, Vice-Chancellor SRM-AP, welcomed the gathering. He appreciated the department’s effort in organising programmes on such impactful topics. Reminding the community of the inevitability of emphasising research, he congratulated all the faculty for their influential publications, sponsored projects, patent publications, etc. Prof D Narayana Rao, Pro-Vice-Chancellor, also addressed the gathering and reiterated the need to conduct such crucial discussions among administrators and policymakers. He further highlighted the importance of reorienting the vision of every Indian university by giving a special focus on research and development.

faculty development programme

Prof Sathish Vadhiyar commenced the discussion by providing a brief overview of the National Super Computing Mission (NSM). It is one of the principal ventures funded by DST and MeItY to advance the overall high-performance computing ecosystem. He deliberated on the R&D projects involved in NSM, its objectives, proposal areas, budget, research allocations etc. Prof Ramanujam presided over and shared his experience in collaborating with industries to market the research product. He gave a detailed analysis of the functioning of consultation companies, types of consultancies, stages involved in such projects, and the different ways to attract funding. Prof Paromita Chakraborty was the last speaker of the day. She offered an elaborate outline for designing and developing a project proposal and concluded by imparting a few insights from her successful projects.

 

air filter mechanism

Studies and research on air pollution have sparked worldwide interest in the recent decades to overcome the imminent threat of air pollution. The air filtration mechanism is one of the efficient ways to capture particulate matter (PM) and purify the air. An innovatory air filtration mechanism blending polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) polymer nanofibers has been proposed by Prof Ranjit Thapa and his PhD scholar Deepak S Gavali from the Department of Physics.

The paper “Low Basis Weight Polyacrylonitrile/Polyvinylpyrrolidone Blended Nanofiber Membranes for Efficient Particulate Matter Capture” was published in collaboration with Applied NanoPhysics Laboratory, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur. It was featured in the journal ‘ACS Applied Polymer Materials’ having an Impact Factor of 4.09.

In the twenty-first century, air pollution is a major problem facing human and environmental health. Every year, millions of people die, mostly in developing nations, owing to the aggravating level of air pollution. According to the World Health Organization (WHO), 92 per cent of the people live in places where the air quality level has crossed the WHO limits. Particulate matter (PM) (solid or liquid particles with different aerodynamic diameters), nitrogen dioxide (NO2), ozone (O3), and others are the relevant air contaminants.

In low-income cities, the effect of PM 2.5 pollution is high due to high urban air pollution. Even at very low concentrations, PM 2.5 (particles with an aerodynamic diameter less than 2.5 µm) pollution has health consequences. Air filtration is one of the best remedies to tackle such problems and maintain a clean environment for humans. Among the available air filter materials, fiber-based air filters have proven to be the most potentially effective treatment, due to their high porosity, high surface area, lightweight, etc.

This study relies on a careful design that blends PAN and PVP fibers. The resultant nanofiber material is utilized to overcome the low air pressure resistance issue with high filtration efficiency. Large-scale free-standing nanofibers were obtained by a simple peeling-off process. The morphology, chemical interaction between the filter media and PM pollutant; and filtration properties were investigated. Compared to commercial mask, the semi- high-efficiency particulate air (HEPA) filter media, PAN/PVP filter medium showed superior performance in PM 2.5 filtration. Furthermore, the intermolecular interactions between PMs and nanofibers were analyzed by DFT calculations. With constant optimization of synthesis conditions, the synthesized air filters achieved high filtration efficiency for PM removal and showed great potential for practical application.

Abstract of the Research

Particulate matter (PM) in air frequently poses a serious threat to human health. Smaller PM can easily enter into the alveolus and blood vessels with airflow. This work reports the first polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) polymer blend nanofiber filter media for effectively capturing PM. Density functional theory (DFT) calculations are used to investigate the effect of the blending of two polymers on the dipole moment and the electrostatic potential. Based on the DFT calculations of the intermolecular interactions between nanofibers and PM, the PAN/PVP heteromolecular percentage is considered for experimental synthesis, which can provide better performance in the filtration of pollutants. The composite PAN/PVP fiber network was successfully developed and optimized to cope with complex environments during the actual filtration process. The role of the blending ratio of PAN and PVP in wt % was explored on PM 2.5 capture, and the refined ratio overcame the conflict between high filtration efficiency and low air pressure resistance. The air filter medium PAN/PVP (6:2) possesses an extremely high air filtration efficiency of 92% under a very low pressure drop of 18 Pa for a 0.5 g m–2 basis weight. Both polar and nonpolar functional groups in blend nanofibers promoted significantly the electrostatic attraction and improved the filtration efficiency under static and dynamic airflow. The PAN/PVP nanofiber membranes maintain outstanding air filtration under different temperature and humidity conditions. This study will shed light on the fabrication of high-efficiency low-basis weight nanofiber filter media as an end product.

kinetic model interactions

Dr Soumyajyoti Biswas, Assistant Professor, Department of Physics, had two lucky breaks as he got his article “Kinetic Exchange Models of Societies and Economies” featured in the prestigious journal Philosophical Transactions of the Royal Society A, the theme issue co-edited by Dr Biswas himself, along with Dr Guiseppe Toscani from the University of Pavia, and Dr Parongama Sen from the University of Calcutta. Philosophical Transactions of the Royal Society has the prestige of being the world’s longest-running science journal launched in 1665. Publishing high-quality theme issues on topics of current importance and general interest within the physical, mathematical, and engineering sciences, the journal continues its history of influential scientific publishing.

A kinetic model of binary interaction, with conserving or non-conserving exchange, has been an elegant and powerful tool to explain collective phenomena in myriad human interaction-based problems, where an energy consideration for dynamics is generally inaccessible. Nonetheless, in this age of Big Data, seeking empirical regularities emerging out of collective responses is a prominent and essential approach, much like the empirical thermodynamic principles preceding quantitative foundations of statistical mechanics.

Through this theme issue, the authors intend to bring together the current progress in the applications of kinetic exchange models in various applications of societies (opinion formations, rating, social networks, fake news, etc.) and economies (inequality measures, taxation, trade models, behavioral economics, etc.) using numerical simulations, machine learning techniques, analytical methods, and data analysis, reported by physicists, social scientists, mathematicians and economists through some of the original and reviewed articles.

In human interactions, such as a trade (exchange of money) or, discussions or debates (exchange of opinions), following simple dynamical rules, a collection of agents (a society) shows emergent properties that are widely seen in real data (distributions of wealth, formation of consensus, etc.). Without knowing the complexities that are involved at the individual levels, it is, therefore, possible to understand the average properties of the society as a whole. This is reminiscent of simple elastic collisions of ideal gas molecules that give average thermodynamic properties, such as temperature, pressure, etc. without knowing the complexities of the individual atoms. This has been a widely followed route to formulate statistical physical models of societies and economies.

The kinetic exchange models have been a very successful set of tools to understand the socio-economic emergent properties from simple models. Among other things, these models helped understand the growth of economic inequalities, the effects of taxes as well as the spread of opinions. A close quantitative resemblance with real data from various countries of the world demonstrates its usefulness.

The future prospects of the kinetic exchange models for societies and economies include possible predictions of extreme fluctuations in average measurable quantities by looking at the inequality of time series data. The models can help us in identifying the features of the real data that can mirror the underlying extreme fluctuations.

Assistant professors Dr Sabyasachi Mukhopadhyay and Dr Imran Pancha from the Department of Physics and the Department of Biological Sciences, respectively, along with Ms Ashwini Nawade, a PhD student of the Department of Physics, have developed a method to integrate plant proteins in the solid-state electronic circuits and utilize the biological functionality to produce a thin film, cost-effective photodetector. Their paper entitled Electron Transport across Phycobiliproteins Films and its’ Optoelectronic Properties has been published in the ECS Journal of Solid State Science and Technology with an Impact Factor of 2.07. It is an interdisciplinary research project between the Department of Biotechnology and Physics.

Explanation of the research

Interdisciplinary research paperBiomolecules such as proteins, peptides being the most crucial life-forms, have an intimate relationship with various life activities for biological functions. The contemporary work with biomolecules mainly focuses on its evolving potential associated with nanoscale electronics where proteins and peptides are integrated as sensing materials. The researchers explored the optoelectronics functionality of combined proteins known as phycobiliproteins. They investigated electron transport behavior across the phycobiliproteins films under dark and white light illumination. The research affirms that the photochemical activity of the protein is more stable in a solid-state/ thin-film with tightly bonded water molecules than its presence in a buffer solution. Furthermore, the studies demonstrate that phycobiliproteins films modulate their electrical conductivity within their different conformation states. Researchers speculate that the electrical conductance variation could originate from the chemical alteration of cysteine-conjugated bilin chromophores to protein and the electrostatic environment around the chromophores.

The research explores the photochemical properties and electrical transport efficiency of phycobiliproteins (PBPs) films. In addition, it investigates the optoelectronics functionality of PBPs films by studying electron transport behavior across the protein films under a dark state and white light illumination. The researchers proposed to develop a photodetector with the protein film in the future.

The research at the Department of Physics is currently focusing on developing new theoretical frameworks to revamp the fundamental concepts that describe the origin of the universe. Assistant Professor Dr Amit Chakraborty has published a paper titled Revisiting Jet Clustering Algorithms for New Higgs Boson Searches in the Hadronic Final States in the European Physical Journal C, with an Impact Factor of 4.59.

Abstract

Standard modelDisplaced signatures originating from the pair production of a supersymmetric particle, called sneutrino, at the Large Hadron Collider (LHC) are studied. The theoretical model considered in this work is the Next-to-Minimal Supersymmetric Standard Model supplemented with right-handed neutrinos triggering a Type-I seesaw mechanism. The research has shown how such signatures can be established through a heavy Higgs portal when the sneutrinos are decaying to charged leptons and charginos giving rise to further leptons or hadrons. The research also illustrated how the Yukawa parameters of neutrinos can be extracted by measuring the lifetime of the sneutrino from the displaced vertices, thereby characterising the dynamics of the underlying mechanism of neutrino mass generation.

Explanation of the research

Standard modelThe Standard Model of Particle Physics is currently the remarkably successful theory to describe the basic building blocks of the universe and their interactions with the three fundamental forces of nature. Despite its success at explaining the universe, the Standard Model does have several limitations. For example, how neutrinos get their mass, why the mass spectrum of the different elements of SM fermions, namely quarks and leptons, are so hierarchical, why the Higgs boson mass is so low, etc. The primary research is to understand these issues and then propose theoretical models which circumvent these shortcomings of SM and provide signatures that can be tested in the ongoing or future proposed experiments.

For this research project, Dr Amit Chakraborty have collaborated with Particle Physics Department, STFC Rutherford Appleton Laboratory, UK and School of Physics and Astronomy, University of Southampton, UK. His broad research interest is to perform theoretical studies of physics beyond the Standard Model (BSM) in particular, collider search strategies and prospects of different BSM models at the Large Hadron Collider (LHC) and future proposed collider experiments. He aims to build new theoretical models, develop new techniques/tools, and devise new search strategies to improve our knowledge of the standard model as well as BSM physics processes.

Dr Amit Chakraborty’s future research topics include Higgs Boson Physics and Beyond Standard Model Physics Phenomenology, Dark Matter at the Colliders, Interpretable Machine Learning techniques in BSM Physics, and Ultra-light particles and Physics Beyond the Colliders.

 

soumyajyoti biswas

The Department of Physics is glad to announce that Dr Soumyajyoti Biswas, Assistant Professor, has published a paper titled ” Near universal values of social inequality indices in self-organized critical models” in the journal Physica A: Statistical Mechanics and its Applications having an impact factor of 3.263. This research was done in collaboration with Prof S S Manna of S N Bose National Center for Basic Sciences and Prof B K Chakrabarti of Saha Institute of Nuclear Physics.

It is well known that wealth invariably accumulates only in a few hands while a majority of the world continues to remain poor. In economics, it is quantified in Pareto’s 80-20 law (20% of people possess 80% of wealth) or ‘The Law of the Vital Few’. This research reveals that the implication of this law goes far beyond the socio-economic systems. It is also a crucial indicator of the onset of critical phenomena in a wide class of physical systems.

It has been observed that in the dynamics of disordered systems, such as fracture and breakdown of solids, slowly increasing the external force produces acoustic emissions (crackling noise), the sizes of which follow Pareto-like behaviour (most noises are weak, only a few are strong that results in the breakdown). Quantifications of these “inequalities” in these physical systems reveal some universal characteristics in a wide class of models, known as self-organized critical systems.

The main implication of this observation lies in predicting catastrophic breakdown in disordered systems. Applications of these inequality measures, which are traditionally in the domain of social sciences, have proved to be immensely useful in identifying the approaching breakdown points in the models of disordered systems. Given that the methods are applicable to a wide variety of models, the 80-20 law has the potential for a wide range of applications. Dr Biswas and his PhD student Diksha are currently working with a team in Spain on experimental data and studying these inequalities in real systems.

The potential applications of NdNiO3

Research at the Department of Physics is currently exploring the potential applications of NdNiO3. Recently, Professor Ranjit Thapa, and his Ph D student, Mr Deepak S Gavali published the paper, Low-Temperature Spin-Canted Magnetism and Bipolaron Freezing Electrical Transition in Potential Electron Field Emitter NdNiO3 in the journal ACS Applied Electronic Materials, with an Impact Factor of 3.314. This work is done in collaboration with the Department of Physics and Astronomy, National Institute of Technology Rourkela, Rourkela, Odisha, India.

About the research

NdNiO3.In this work, NdNiO3 nanoparticles are synthesized by sol-gel auto-combustion techniques, and its primary characterization related to structural and surface morphological analysis is carried out by X-Ray Diffraction (XRD), Fourier Transforms Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDX), and Transmission Electron Microscopy (TEM) techniques. The research is focused on magnetic phase transition below Curie temperature (TN) ∼176 K, and the magnetic susceptibility indicates a weak antiferromagnetic ordering at low temperature. Different ac conduction mechanisms, that is, Correlated Barrier Hopping (CBH), Continuous-Time Random Walk (CTRW) conduction model, and Non-overlapping Small Polaron Tunneling (NSPT), are introduced to interpret its electrical transport behavior near, above, and below TMI ∼178 K. Using first principles and Density of States (DOS) calculation, the researchers have characterized the electronic and magnetic ground state of NdNiO3 at room temperature. It exposed the overlapping of conduction and valence band at room temperature, and the degree of hybridization between Ni 3d and O 2p is very high compared to Nd 5d states. The work function is also calculated for a few-layer NdNiO3 to estimate the field enhancement factor (β), which plays a crucial role in the practical application of a field emitter.

Practical implications

The additional novelty of the present work is to explore the potential application of NdNiO3 as an efficient field emitter and controlled electron/X-ray sources in a flat panel display, microwave vacuum electronic devices, electron microscopy/ lithography, and so forth. To eject conducting electrons from the metal/semiconducting surface by a quantum mechanical tunneling process, sufficient energy is required in terms of the applied electric field (∼106 to 107 V/cm) to overcome the potential barrier at the vacuum−metal interface. The potential difference between the Fermi level (Ef ) of the metal surface to vacuum is known as the work function (Φ). It depends on material characteristics and plays an essential role in field enhancement capability. The primary requirement for efficient field emitters is high aspect ratios (i.e., field enhancement factor), inferior turn-in field, low work, function, etc. Researchers have examined various classes of materials for efficient field emitter electrodes, such as (i) carbonaceous materials like graphene and carbon nanotube, (ii) various 1D and 2D metal oxide and transition metal dichalcogenides like ZnO, MnO2, In2O3, WS2, WSe2, MoS2, PdSe2, etc., (iii) inorganic semiconductors like SiC and Si, and (iv) wide band gap semiconducting compounds GaN, AIN, and so on. The field emission properties of rare earth nickelates (RNiO3; R = La, Gd, Nd, Sm, etc.) with an exciting room temperature metallic nature have not been examined.

Dr PranabA paper titled “Study on ferroelectric polarization induced resistive switching characteristics of neodymium-doped bismuth ferrite thin films for random access memory applications” has been published by Dr Pranab Mandal, Assistant Professor of Physics and his PhD student, Ms K N Malleswari in the journal ‘Current Applied Physics’ having an Impact Factor of 2.480.

Doi: https://doi.org/10.1016/j.cap.2022.04.013

Abstract

Resistive random-access memory (ReRAM) devices are based on the resistance switching (RS) effect. Such RS devices have recently attracted significant attention due to their potential application in realizing the next-generation non-volatile memory (NVM) devices. The present work reports on resistive switching (RS) characteristics of Neodymium (Nd)-doped bismuth ferrite (BFO) layers. The Nd (2–10 at%) doped BFO thin film layers were deposited using a spray pyrolysis method. The structural analysis reveals that a higher Nd doping concentration in BFO leads to significant distortion of the prepared Nd: BFO thin films from rhombohedral to tetragonal characteristics. The morphological analysis shows that all the deposited Nd: BFO thin films have regularly arranged grains. The X-ray photoelectron spectroscopy (XPS) analysis reveals that the prepared Nd: BFO thin films have a higher Fe3+/Fe2+ ratio and fewer oxygen vacancy (VO) defects which enrich the ferroelectric characteristics in Nd: BFO layers. The polarization-electric field (P-E) and RS characteristics of the fabricated Nd: BFO-based RS device were examined. It was observed that the Nd (7 at%) doped BFO RS device shows large remnant polarization (P r) of 0.21 μC/cm2 and stable RS characteristics.

Research in brief

Non-volatile resistive random access memory (RRAM) are future generation random access memory device with potential benefits such as high operational speed (nanoseconds read and write time), non-volatility, high endurance scalability and low power consumption [Namnoscale Research Lett., 15, 90, 2020]. Here in this work, we presented the resistive switching characteristics of a multiferroic material namely Nd-doped BiFeO3 material. The device shows stable resistive switching characteristics.

Practical implementation/social implications

Researchers in this field are focusing to overcome challenges of high operation current, lower resistance ratios, and reliability issues [Namnoscale Research Lett., 15, 90, 2020]. While several prototype RRAMs have been developed by other groups, future memory applications would require overcoming the challenges mentioned above.

Collaboration

The work has been conceptualized by Dr Amiruddin at  Crescent Institute of Science and Technology, Chennai; and Dr Pranab Mandal and Ms Malleswari provided inputs on ferroelectric polarization – electric field (P – E) measurement and drafting.