Ambesh Dixit
@iitj.ac.in
Associate Professor, Department of Physics and Center for Solar Energy
Indian Institute of Technology Jodhpur
EDUCATION
Ph.D. WSU, Michigan, USA
RESEARCH INTERESTS
Functional materials and devices for energy, health, water and optolelectronic devices including multistate memories and senors
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Piyush Choudhary, Chandni Tiwari, Ajay Tiwari, Vijay K. Singh, Suvra S. Laha, Bansi D. Malhotra, and Ambesh Dixit
Elsevier BV
Priyambada Sahoo, Chandni Tiwari, Sumit Kukreti, and Ambesh Dixit
Elsevier BV
Priyambada Sahoo and Ambesh Dixit
Royal Society of Chemistry (RSC)
Bismuth ferrite (BiFeO3) multiferroic nanoparticles are synthesized using a low-temperature sol–gel auto-combustion technique.
Rishow Kumar, Sony Priyadershini, Kumar Brajesh, Shashikant Gupta, Ambesh Dixit, and Ashish Garg
AIP Publishing
In this manuscript, we examine the electrical behavior of pulse laser deposition grown epitaxial (111) oriented CuO thin films using impedance spectroscopy to understand the microscopic origin of their relaxor-like characteristics. Temperature (T) dependent variation of the real part of dielectric permittivity (ε′) shows a relaxor ferroelectric-like anomaly with Vogel–Fulcher relation fitting well with the observed dielectric behavior, and thus, pointing toward a relaxor ferroelectric nature of the CuO thin film. However, the loss tangent and frequency-dependent dielectric spectroscopy measurements suggest the need to further explore the different mechanisms to understand the origin of observed relaxor behavior. Deconvolution of the impedance spectra reveals that interfacial contributions dominate in the dielectric response. Moreover, deconvoluted capacitances are temperature-independent within the specified temperature range, thereby excluding the possibility of a ferroelectric transition suggested by ε′ vs T data. The DC bias measurement of dielectric permittivity and I–V measurements reveal the MW (Maxwell–Wagner) nature of the observed dielectric anomaly. The measurements also suggest interface-limited Schottky conduction as the predominant conduction mechanism in the CuO thin films. This work demonstrates that the apparent relaxor behavior observed in the CuO thin film is related to extrinsic, i.e., interfacial polarization effect, instead of the intrinsic ferroelectric nature of the material.
Priyanka Saini, Jitendra Kumar Yadav, Bharti Rani, Anant Prakash Pandey, and Ambesh Dixit
Wiley
AbstractWe investigated Fe3O4 nanoparticles (NPs) for a symmetric supercapacitor (SSC) under ambient conditions from synthesizing material to device fabrication. The prepared Fe3O4 NPs are characterized using different characterization, X‐ray diffraction, Raman and FTIR spectroscopy. The electrochemical performance of supercapacitor (SC) is measured in two electrode systems using coin‐cell assembly at various scan rates varying from 10–100 mV s−1, and cyclic voltammetry measurements are investigated from −0.8 to 0.6 V window. The Fe3O4 NPs based SSC shows an energy density of 24.99 Wh kg−1 with the high specific capacitance of 91.82 F g−1 at 10 mV s−1 scan rate. At a current rate of 4 A g−1, the power density reaches 2000 W kg−1. The Fe3O4 NPs based SSC exhibits a quick charge and discharge mechanism at various current rates and is stable over 500 galvanostatic chargingdischarging cycles at a current rate of 4 A g−1. The fabricated SSC showed >60% capacitance retention even after operating for 1000 cyclic voltammetry cycles at a scan rate of 100 mV s−1. A reasonable choice for SSC electrodes with high power density, and the outstanding resilience of electrodes is further shown by cyclic stability and impedance study exhibiting a negligible change in the different impedance elements. The potential of the fabricated SSC is demonstrated by lightening a light emitting diode (LED) light as a practical aspect for future applications.
Abhijeet J. Kale, Biswajit Pal, and Ambesh Dixit
Wiley
Herein, density functional theory‐based comparative studies on cubic CsMX3 (M‐: Pb, Sn, Ge; X‐: Cl, Br, I) and rhombohedral CsGeI3 perovskites are reported. The structural stability indicator analysis shows that Ge‐based perovskites may exhibit small rhombohedral distortion led by lone pair (4) electrons on off‐centering Ge atom. The role of lone pair on Ge atom in rhombohedral distortion is corroborated by bond length, electronegativity, and charge density distributions. Nearly agreeable bandgap () values are noticed for cubic CsPbX3 (X‐: Cl, Br, I) and rhombohedral CsGeI3, and the corresponding values are 3.04, 2.30, 1.72, and 1.45 eV, respectively. The effect of Jishi et al. reparameteried Tran–Blaha‐modified Becke–Johnson exchange‐correlation (XC) potential is discussed in context of optoelectronic properties. The changes in bandgap are attributed to the lifting of electronic degeneracy either by spin‐orbit coupling or symmetry lowering in rhombohedral distortion. The rhombohedral CsGeI3 is thus further emphasized to account its ferroelectricity with computed total polarization () around 32.75 μC cm−2. The suitable (1.45 eV), high absorption (≈105 cm−1), tolerable reflectivity (19%), and carrier effective masses (0.61 and 0.27) enable rhombohedral CsGeI3 (superior 30.5% spectroscopy‐limited maximum efficiency [SLME] at 1 μm thickness) to outperform conventional CsPbI3 (27.6% SLME at 1 μm) and others which may attract PV community to further address its underexplored promise.
Jeel Swami, Ambesh Dixit, and Brajesh Tiwari
World Scientific Pub Co Pte Ltd
Electronic properties of spin polarized antiferromagnetic ACrO3 (A = La, Y) are explored with Hubbard model using density functional theory (DFT). These two isostructural systems are investigated using the different Hubbard energy and analyzed the hybridization of chromium 3d orbitals and oxygen 2p orbitals and the change in energy bandgaps against the Hubbard energy. The bond length and bond angle affect significantly the orbital contributions of Cr-3d and O-2p electrons for both the system. We noticed that the Cr–O hybridization affects the orbital degeneracy and is substantiated with partial density of states. These results emphasize the contribution of Hubbard energy in correlated electron systems.
Bharti Rani, Jitendra Kumar Yadav, Priyanka Saini, Anant Prakash Pandey, and Ambesh Dixit
Wiley
AbstractWe report the electrochemical performance of aluminum‐air (Al‐Air) cells for three commercially available aluminum alloys, that is, Al 1200, Al 8011, and Al 6061 together with the pure aluminum as anode. The contact angle and Tafel analysis are used to understand the surface adherence and corrosion characteristics. The respective Al‐Air coin cells are fabricated with 1.54 cm2 active electrode area and discharge characteristics are evaluated at different current densities that is, 0.65, 1.3, and 2.6 mA cm−2. The specific capacity, power density, and energy density are calculated, and observed that Al 1200 is less wettable and less corrosive with better discharge performance along with higher specific capacity and energy density with respect to other Al grade anodes including pure aluminum. A detailed electrochemical impedance spectroscopy and post‐mortem analysis of the anodes are also investigated to verify the corrosion at various Al anode materials. The potential of the fabricated battery is shown by glowing an LED light using the optimal Al‐Air cell. Thus, the present work demonstrates that Al 1200 can be used as suitable anode material for efficient Al‐Air electrochemical cells.
Khushbu Meena, Harish Kumar Meena, Sushil Kumar Jain, Ambesh Dixit, Shalini Dixit, K. B. Sharma, and Balram Tripathi
Wiley
AbstractThis manuscript is reporting hydrogen adsorption uptake of PCN‐250(Fe) metal organic framework (MOF) at temperature of 300, 126K, and pressure in between 6 and 10 bar. X‐ray diffraction spectrum of PCN‐250(Fe) confirms crystalline structure, however Fourier transform infrared (FT‐IR) spectrum showing dominant bonding structure of COOH, N = N, and Fe─O functional groups. SEM images confirm surface morphology as an octahedrons of average crystalline size upto 50 µm. Thermogravimetric analysis (TGA) confirms excellent thermal stability upto 450 °C. The hydrogen adsorption uptake of 0.80 wt% has been found at 126 K and pressure of 10 bar attributes adsorption occurs due to the structural and physical properties like topology, porosity, and presence of open metal sites as well as surface area. It is suggested that PCN‐250(Fe) as an adsorbent material offers as an intensive way of storing H2 at low temperature and at ambient pressure.
Anant Prakash Pandey, Bharti Rani, Minakshi Sharma, Jitendra Kumar Yadav, Priyanka Saini, Shalu, and Ambesh Dixit
Wiley
AbstractOne of the greatest alternatives to Li‐ion batteries is an Al‐air battery as it is more economically feasible and less toxic together with relatively better electrochemical performance. The design of the cell and the selection of electrode for improved electrochemical performance are the primary factors influencing the performance of the Al‐air battery. The present study focuses on designing an efficient air cathode host to lengthen the battery's lifespan using highly porous carbon aerogel. Initially, the carbon aerogel (CA) material is synthesized using sol‐gel polymerization process and characterized using XRD, RAMAN, SEM, and BET. The synthesized CA is used to fabricate the electrode stacking using the in‐house‐built Al‐air cell. The performance of carbon aerogel coated on carbon cloth as air cathode has been evaluated using a galvanostatic discharge of the assembly at different current rates, and the specific capacity is recorded. The highest specific capacity observed is ~683 mAh g−1 at 2.551 mA cm−2 current density. The acquired results demonstrate the superiority of the present electrodes material compared to currently used air electrode. The improved electrochemical stability and the robust pore network in CA allow oxygen to pass through the cathode end for chemical reaction. Overall, this enhances kinetics and makes the interactions between oxygen and aluminum easier to generate higher current.
Biswajit Pal, Abhijeet J. Kale, Minakshi Sharma, K. C. Bhamu, Sung Gu Kang, Vijay K. Singh, and Ambesh Dixit
American Chemical Society (ACS)
Priya Khandelwal, Zhiwen Chen, Chandra Prakash, Kriti Shrivastava, Fangqin Guo, Hiroki Miyaoka, Takayuki Ichikawa, Ambesh Dixit, and Ankur Jain
Elsevier BV
Jitendra Kumar Yadav, Bharti Rani, Ajay Tiwari, and Ambesh Dixit
AIP Publishing
The highly porous and binder-free flexible paper electrodes can enhance the specific capacitance of symmetric supercapacitors (SCs) due to their large surface and effective ion diffusion pathways. We synthesized the exfoliated graphite (ExG) by the thermal exfoliation method of chemically treated graphite flakes and compressed it into a paper-like thin sheet (binder-free) of ∼0.15 mm thickness. The coin cell SCs with copper (Cu) and stainless steel (SS) as current collectors have been fabricated for the electrochemical measurement. The cyclic voltammetry and galvanostatic charge/discharge measurements are investigated at various scan rates and current densities. The SCs with Cu foil as a current collector perform better than SS-based SCs. The Cu current collector-based SCs showed a specific capacitance of 37.08 mF cm−2, whereas it was ∼29.98 mF cm−2 for SS-based SCs at a 0.01 V s−1 scan rate across a 0–0.6 V potential window. Approximately no degradation in charge storage capacity for more than 15 000 cycles at 0.1 V s−1 shows the ultra-stability of the flexible ExG-based binder-free electrodes. A digital watch is powered using the fabricated pouch cell supercapacitor with copper-based current collectors to show the potential of SCs.
Ankit Kumar Yadav, Surbhi Ramawat, Sumit Kukreti, and Ambesh Dixit
Springer Science and Business Media LLC
Ashutosh Arora, Prithvi Singh, Chandra Mohan Arora, Sanjay Kumar Bansal, and Ambesh Dixit
AIP Publishing
Ramavtar Jangra, Kiran Ahlawat, Ambesh Dixit, and Ram Prakash
Springer Science and Business Media LLC
AbstractAir pollution is one of the top 5 risks causing chronic diseases according to WHO and airborne transmitted pathogens infection is a huge challenge in the current era. Long living pathogens and small size aerosols are not effectively dealt with by the available indoor air purifiers. In this work, a dielectric barrier discharge (DBD) based portable cold-plasma detergent in environment device is reported and its disinfection efficiency has been analyzed in the indoor environment of sizes up to 3 × 2.4 × 2.4 m3. The deactivation efficiency of total microbial counts (TMCs) and total fungal counts (TFCs) is found to be more than 99% in 90 min of continuous operation of the device at the optimized parameters. The complete inactivation of MS2 phage and Escherichia coli bacteria with more than 5 log reduction (99.999%) has also been achieved in 30 min and 90 min of operation of the device in an enclosed environment. The device is able to produce negative ions predominantly dominated by natural plasma detergent along with positive ions in the environment similar to mother nature. The device comprises a coaxial DBD geometry plasma source with a specially designed wire mesh electrode of mild steel with a thickness of 1 mm. The need for feed gas, pellets and/or differential pressure has been eliminated from the DBD discharge source for efficient air purification. The existence of negative ions for more than 25 s on average is the key advantage, which can also deactivate long living pathogens and small size aerosols.
Ankit Kumar Yadav, Chandra Prakash, Akhilesh Pandey, and Ambesh Dixit
Wiley
AbstractCu2ZnSnS4 (CZTS) active material‐based resistive random‐access memory (RRAM) devices are investigated to understand the impact of three different Cu, Ag, and Al top electrodes. The dual resistance switching (RS) behaviour of spin coated CZTS on ITO/Glass is investigated up to 102 cycles. The stability of all the devices (Cu/CZTS/ITO, Ag/CZTS/ITO, and Al/CZTS/ITO) is investigated up to 103 sec in low‐ (LRS) and high‐ (HRS) resistance states at 0.2 V read voltage. The endurance up to 102 cycles with 30 msec switching width shows stable write and erase current. Weibull cumulative distribution plots suggest that Ag top electrode is relatively more stable for set and reset state with 33.61 and 25.02 shape factors, respectively. The charge carrier transportation is explained by double logarithmic plots, Schottky emission plots, and band diagrams, substantiating that at lower applied electric field intrinsic copper ions dominate in Cu/CZTS/ITO, whereas, at higher electric filed, top electrodes (Cu and Ag) dominate over intrinsic copper ions. Intrinsic Cu+ in CZTS plays a decisive role in resistive switching with Al electrode. Further, the impedance spectroscopy measurements suggest that Cu+ and Ag+ diffusion is the main source for the resistive switching with Cu and Ag electrodes.
Kumar Brajesh, Sudhir Ranjan, Rishow Kumar, Rajeev Gupta, Ambesh Dixit, and Ashish Garg
Wiley
In this manuscript, we report room temperature structural, microstructural, optical, dielectric, and magnetic properties of CuO and Cu0.995La0.005 ceramics, synthesized by solid-state reaction method. La doping in CuO leads to the evolution of compact and dense microstructure with reduced porosity. Due to noticeable differences in the ionic radii of, La doping creates vacancy defects which induce considerable strain in the CuO lattice resulting in a reduction in the lattice parameters and cell volume. However, both ceramics processes a similar monoclinic structure with the C2/c space group. Detailed characterization using XPS, Raman, and FTIR spectroscopy confirmed the incorporation of the La3+ in CuO lattice. Interestingly, La doping enhances the dielectric constant by more than three times and results in a reduced leakage current. The onset of a large dielectric constant is attributed to dense microstructure and strain/distortion in CuO lattice after La doping. Additionally, the band-gap of Cu0.995La0.005 ceramics decreases which is attributed to increased vacancy defect concentration that creates intermediate dopant energy level within bandgap of CuO matrix. Furthermore, improvement in magnetic and dielectric properties is also discussed and correlated with the grain size in La-doped CuO.
Kiran Ahlawat, Ramavtar Jangra, Ambar Ish, Ambesh Dixit, Deepak Fulwani, Neha Jain, and Ram Prakash
AIP Publishing
This work presents a large-scale surface disinfection system, which has a unique lantern arrangement of ultraviolet-C (UV-C) light (254 nm) in conjunction with nanotechnology in a protective biosafety environment. Shadow regions are best dealt in this system by the generation of hydroxyl radicals (•OH) and negative air ions at sites where UV light cannot penetrate. More than 35 000 negative air ions/cm3 along with •OH were produced continuously in the disinfection chamber through the advanced photocatalytic oxidation process [UV-C + titanium dioxide (TiO2)]. The arrangement has been made to provide an optimized UV irradiation (∼2 mW/cm2) throughout the disinfection system. In order to distinguish between effects arising from (i) the action of UV dose alone and (ii) the action of UV dose along with •OH and negative air ions, E. coli and P. aeruginosa were chosen for bacterial testing and two interventions were made. The first intervention involved placing only UV lamps in the disinfection chamber to see the effect of only UV dose on bacterial inactivation efficiency. The second intervention involved placing the TiO2 nanoparticle coated aluminum plates along with UV lamps; this allows for the generation of negative air ions and •OH inside the disinfection chamber and enhanced bacterial inactivation efficiency. More than 95% bacterial inactivation efficiency has been reported in the case of UV-C + TiO2 compared to only 77% in UV only at the same time interval (90 s).
Jeel Swami, Ambesh Dixit, and Brajesh Tiwari
Wiley
The magnetic ground state of LaCrO3 and CaCrO3 solid solution is investigated in the complete miscibility range, that is, La1−xCaxCrO3 with 0 ≤ x ≤ 1 at the interval of x = 0.25 to understand the magnetic phase transitions with Ca substitutional fraction. The density functional theory is used with Hubbard correction to account for Cr exchange interaction. The isostructural La1−xCaxCrO3 system exhibits antiferromagnetic insulator (x = 0, i.e., LaCrO3) to ferromagnetic half metal (x = 0.75, i.e., La0.25Ca0.75CrO3) to antiferromagnetic metal (x = 1, i.e., CaCrO3) phase transitions. Cr changes its oxidation state from 3+ in LaCrO3 to 4+ in CaCrO3, showing both 3+ and 4+ states for intermediate compositions. Interestingly, the introduction of Hubbard energy U and Ca substitution affects Cr–O hybridization, as observed in partial density of states. A compositional phase diagram with magnetic ground state is presented for the La1−xCaxCrO3 (0 ≤ x ≤ 1) system.
Priyambada Sahoo, Piyush Choudhary, Suvra S. Laha, Ambesh Dixit, and O. Thompson Mefford
Royal Society of Chemistry (RSC)
Zinc ferrite based nanostructures for magnetic hyperthermia applications.
Sumit Kukreti, Deep Jyoti Sapkota, and Ambesh Dixit
American Chemical Society (ACS)
Ajay Tiwari, D. Chandrasekhar Kakarla, Bommareddy Poojitha, Priyambada Sahoo, H. L. Liu, A. Dixit, C. W. Wang, T. W. Yen, M.-J. Hsieh, J.-Y. Lin,et al.
American Physical Society (APS)
Surbhi Ramawat, Sumit Kukreti, and Ambesh Dixit
American Physical Society (APS)
Chandra Prakash and Ambesh Dixit
AIP Publishing
Beyond von Neumann’s architecture, artificial neural network-based neuromorphic computing in a simple two-terminal resistive switching device is considered the future potential technology for simultaneous data processing and storage. These are also compatible with low-power consumption nanoelectronic devices and, thus, suitable for applications such as image recognition toward solving complex pattern recognition problems. Herein, motivated by the human biological brain, we successfully synthesized low-cost RRAM devices using the thermal oxidation of Cu, i.e., CuO as the active material together with Cu as the top electrode and FTO as the bottom contact for a two-terminal resistive switching device, and investigated characteristics for neuromorphic computing. Cu/CuO/FTO-based devices showed excellent bipolar analog RRAM characteristics with 150 repeatable cycles, retention for 11 000 s, and DC pulse endurance for 5000 cycles. Moreover, devices exhibit a remarkable mimicking ability, demonstrating spike time-dependent plasticity (STDP), pulse-paired facilitation (PPF), synaptic weight, and learning and forgetting characteristics, substantiating the recognition ability. Furthermore, the artificial neural network synaptic membrane exhibits excellent long-term (LTP) and short-term (STP) potentiation for six consecutive cycles. Thus, the present work on Cu/CuO/FTO-based devices provides a detailed understanding of CuO active material-based resistive switching with a potential for neuromorphic computing beyond the von Neumann architecture.