Asokan Kandasami

Asokan Kandasami
Inter University Accelerator Centre | IUAC · Materials Science Group

PhD

About

732
Publications
121,017
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7,599
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Introduction
Presently working as Senior scientist. His principal areas of research and experience are: (i) Electronic structure of materials; semiconductors, oxides using Synchrotron Radiation based techniques like x-ray absorption spectroscopy and related spectroscopies (ii)Ion beam interaction in materials: energy materials, magnetic systems, polymers etc
Skills and Expertise

Publications

Publications (732)
Article
The tunability of magnetic properties of VO2 has fascinated substantial attention in the first generation of spintronics-related applications such as read head sensors for hard disk drives and magnetic random-access memory. In this work, we focus on Cr doped VO2, V1−xCrxO2(0 ≤ x ≤ 0.3) (VCO) thin films and study the effect of Cr-substitution on the...
Article
In situ current–voltage and capacitance–voltage characteristics were performed on Ni/HfO2/β-Ga2O3 devices using 120 MeV Ag⁷⁺ swift heavy ion (SHI) irradiation. The Poole-Frenkel emission is significant within 2.25–7.50 MV/cm until 5 × 10¹² ions/cm² and covers a full range of 0.01–7.50 MV/cm for the fluences of 1 × 10¹³ and 5 × 10¹³ ions/cm² under g...
Article
In the present study, high quality LaMnO3–δ/La0·7Ca0·3MnO3/LaAlO3 (LMO/LCMO/LAO) manganite – manganite structure was successfully prepared using low cost chemical solution deposition (CSD) method. Temperature dependent resistive switching (RS) was performed across the manganite – manganite structure and various electronic processes have been employ...
Article
The present investigation reports the optical characteristics of the porous Si (PSi) based microcavities before and after energetic He ⁺ and H ⁺ ion irradiations. These PSi microcavities were fabricated by the galvanostatic electrochemical etching process and irradiated with 35 keV He ⁺ and H ⁺ ions with three different ion fluences: 1 × 10 ¹⁵ , 5...
Article
Effect of 120 MeV Ag-ion irradiation at a fluence of 2 × 1012 ions/cm2 was studied on La-doped SrSnO3 thin films. The structural study revealed grain growth with irradiation caused by local crystallization in the films due to the annealing effect below the threshold value of the electronic energy loss. The spectral profile and a shift in the absorp...
Article
The temperature-dependent electrical resistivity of the Ni-doped CoSb3 system (Ni= 0, 1, 3, and 5 at.%) was carried out to identify the conduction mechanism at the different temperatures. The samples were prepared by solid-state reaction and characterized by x-ray diffraction (XRD) and Raman spectroscopy. The XRD pattern confirms the CoSb3 phase fo...
Article
Full-text available
The present work investigates the effect of 100 MeV Ag ions irradiation on pure Fe3O4, zinc- and cobalt-doped Fe3O4 thin films deposited on Silicon (100) substrates by pulsed laser deposition technique (PLD). The study demonstrates that both surface roughness and magnetization of all studied thin-film samples are affected by 100 MeV Ag ions irradia...
Article
High quality indium tin oxide (ITO) thin films (In2−xSnxO3: x = 0.0, 0.1 and 0.2) have been grown by using pulsed laser deposition technique on quartz substrate. The structural, morphological, optical and electrical investigations of deposited films have been studied as a function of substrate deposition temperature and the Sn composition. X-ray di...
Article
Thin film-based thermoelectric materials have attracted enormous research interest due to their potential to exhibit excellent thermoelectric (TE) behavior. Considering the potential of earth-abundant and nontoxic magnesium silicide (Mg2Si) to behave as a mid-temperature TE material, the present study was conducted to assess the structural evolutio...
Book
This book provides an overview of the applications of ion beam techniques in oxide materials. Oxide materials exhibit defect-induced physical properties relevant to applications in sensing, optoelectronics and spintronics. Defects in these oxide materials also lead to magnetism in non-magnetic materials or to a change of magnetic ordering in magnet...
Article
Low energy ion implantation with exquisite control of angle allows manipulating the applications of thin films. Here we present a favourable and efficient strategy of 50 keV Carbon ion implantations on ZnO thin films at three different tilt angles 0°, 30° and 60°. This plays a significant role in tuning of optical absorbance, bandgap, grain size an...
Article
Full-text available
Native defects and unintentional contaminations during growth can strongly influence the optical properties of semiconductors and their applications. The tailoring of these optical properties requires a deep understanding of the role of defects and hence contributes to the improvement of the crystal quality of the epitaxially grown active layer in...
Article
In this work, PMMA-reduced graphene oxide (rGO) films (PrGO) are prepared by solvent evaporation and further, swift heavy ions (100 MeV gold ion) irradiated on them by varying fluences viz. 1×10¹¹, 5×10¹¹ and 1×10¹² ions/cm² (referred as PrGO-111, PrGO-511, PrGO-112). There was a low angle peak shift of rGO and the reduction of crystallinity at hig...
Article
The impacts of electronic excitations with three different ion beams, namely Au, Ag, and O ions at 100–120 MeV and fluences of 5 × 10¹² ions/cm², on the structural, optical, morphological, and electrical properties of spray-deposited CuGaS2 (CGS) thin films have been investigated. Powder X-ray diffraction and micro-Raman spectroscopy measurements h...
Article
The Sr(Zr-Mn)2xFe12-2xO19 (x = 0.0 - 1.0) were synthesized using microwave-hydrothermal method at 200⁰C/60 min. The Rietveld refined X-ray diffraction patterns show single-phase hexagonal structure. The lattice parameter a is increased from 5.886 Å (x = 0.0) to 5.930 Å (x = 1.0) and c from 23.063 Å to 23.339 Å with x. The percentage of increase in...
Article
Titanium dioxide (TiO2) thin films were fabricated via a micro arc oxidized process and its surface was modified using 100 MeV Swift Heavy Si⁷⁺ ion (SHI) irradiation. GIXRD analysis confirmed both the phases of rutile and anatase. Additionally, the analysis showed a gradual decrease in intensity which coincided with a rise in ion fluence at up to 5...
Article
Full-text available
Superconducting fluctuations on electrical conductivity of YBa2Cu3O7-δ + xBaZrO3 (x = 0.0, 2.0, 4.0, 6.0 and 10.0 wt.%.) composites are investigated from electrical resistivity versus temperature measurements in zero and 13 T magnetic field. Aslamazov–Larkin model and Lawrence and Doniach model are used to calculate the dimensions of superconductin...
Article
We report the temperature-dependent emission characteristics of ZnO phosphors in the range of 10 to 300 K measured using the synchrotron-based vacuum ultraviolet (VUV) photoluminescence spectroscopy. The ZnO phosphors with different morphologies: pyramid-like and sheet-like synthesized via co-precipitation and solid-state reaction methods, respecti...
Article
Full-text available
The structural and electrical transport properties of Ge ion-implanted CoSb3 thin films were investigated. These thin films were deposited by pulsed laser deposition on the quartz substrates and 100 keV Ge ions were implanted with the ion fluences ranging from 5 × 1014, 1 × 1015 to 5 × 1015 ions/cm2. Scanning electron microscopy shows an enlargemen...
Article
Conducting polymer PolyAniline (PANI) was implanted with 75 keV Au and 30 keV Ag ions. The projectile ranges were calculated from SRIM analysis prior to implantations; it is found to be 65 nm for Au and 32 nm for Ag. The optical absorption behaviors are remarkably different from the pristine samples due to combined effects of the defects and metal...
Article
Full-text available
We report the evolution of structural distortions on the pulsed laser deposited SrTiO3 (STO) thin films irradiated by 1 MeV Ar ion beam and their response in the electrical and thermoelectric properties correlated with their electronic structures. The structural studies reveal a modification in the crystalline nature resulting in the synergistic en...
Article
The physical properties of nanostructured ZnO thin films have been modified by a pragmatic approach of varying polar angles during low energy ion implantation. The C ions of 50 keV were implanted at three polar angles: 0°, 30° and 60°. Materials characterizations using X-ray diffraction, magnetic force microscopy and vibrating sample magnetometer r...
Article
We report the crystal, magnetic and electronic structures of Cr doped VO2 [i.e., V1−xCrxO2 (VCO), x = 0, 0.05 and 0.10] thin films studied using X-ray diffraction (XRD), Raman, Vibrating sample magnetometer (VSM) and various high energy spectroscopic techniques. These VCO films were deposited on an r-sapphire substrate by pulse laser deposition. XR...
Article
Full-text available
The present study demonstrates the reduction in the dielectric loss at room temperature from 0.149 to 0.027 in the composite of (NdFeO3)0.1−(Ba0.7Sr0.3TiO3)0.9 as compared to the undoped Ba0.7Sr0.3TiO3 and correlates with the charge compensation due to the ionic substitutions for both A site (NdBa) and B (FeTi) site generated excess electrons, loca...
Article
ZnO films grown on Si(100) substrate through radio frequency (RF) sputtering are subjected to 100 keV Ni ion beam at different fluence (1×1016, 2.5×1016 and 5×1016 ions/cm²). High resolution X-ray diffraction revealed the increase in crystallite size and development of stress gradient in the ZnO thin films with the increasing Ni ion fluence. Ni imp...
Article
The incorporation of metallic nanostructures into the active layers of oligomer solar cells is the most promising light trapping approach. The size and relative arrangement of nanostructures are the key factors for enhanced light trapping. The present letter reports the formation of plasmonic silver (Ag)-nanoparticles using low-energy 150 keV argon...
Conference Paper
Full-text available
Co doped ZnO at dilute concentrations were synthesized using low temperature co-precipitation method. XRD measurements indicates the hexagonal wurtzite structure with P63mc phase group. Also, the impurity phases related to Co ions were absent. Further, Williamson-Hall (W-H) analysis was employed to understand the peak broadening observed upon dilut...
Article
The present study demonstrates the tuning of optical characteristics of porous silicon (PSi)-based microcavities by N ion beam interactions. These optical microcavities are prepared by using electrochemical etching of heavily doped p+-type Si. The PSi microcavities were exposed to N ions of 200 keV and 1 MeV at an optimized ion fluence of 1 × 1015...
Article
SrSnO3 is a potential candidate for the perovskite-structured transparent electrode for many optoelectronic devices, especially for recently developed perovskite solar cells. La-doped SrSnO3 thin films were deposited using pulsed laser deposition on SrTiO3 (STO) substrate to study its structural and electrical properties. This study reveals that La...
Article
Atomic defect centers in diamond have been widely exploited in numerous quantum applications like quantum information, sensing, quantum photonics and so on. In this context, there is always a requirement to improve and optimize the preparation procedure to generate the defect centers in controlled fashion, and to explore new defect centers which ca...
Article
Titanium dioxide (TiO2) thin films of thicknesses in the range of 20 to 60 nm were deposited by sol-gel dip coating method, and their structural and morphological properties before and after irradiation with 100 MeV Ni⁵⁺ ions were investigated. A systematic analysis of the hydrolysis reaction in the sol and films showed that complete hydrolysis of...
Article
WO2.72 thin films were deposited on fluorine-doped tin oxide substrates using the e-beam evaporation technique, and 150 keV Ti⁺ ions were implanted at various fluences. The structural studies of these thin films confirm the presence of P21/m monoclinic phase. After implantation, the intensities of X-ray peaks varied significantly, and atomic force...
Article
The present investigation demonstrates an enhancement of the visible photocatalytic activities by C ion implantation in ZnO nanorod arrays (NRAs). Vertically aligned ZnO NRAs were prepared by seed layer assisted solution-phase growth and implanted with 70 keV carbon ions at various fluencies: 1E15, 5E15, 1E16, and 3E16 ions/cm². X-ray diffraction a...
Article
This study demonstrates the tunability of optical properties of porous silicon (PSi) based optical microcavities by energetic oxygen (O) ion irradiation. The PSi microcavities were irradiated with ion beams of energies: 20 keV and 1 MeV with different ion fluences. The dominant resonant cavity peak exhibits significant redshift up to ∼ 20 nm with i...
Article
The effect of swift heavy silicon ion irradiation on hydroxyapatite prepared by hydrothermal technique was analyzed. The physical and biological properties were studied using G1XRD, Micro-Raman, photoluminescence, AFM, SEM, EDX, in vitro bioactivity, antimicrobial activity and drug release. When compared with pristine the crystallinity increases wi...
Article
Defects play an essential role in controlling the phenomena of d0 ferromagnetism in nonmagnetic oxides. Defects can significantly impact on behavior, especially d0 ferromagnetism of oxide materials at room temperature (RT). Defects in magnesium oxide (MgO) can be created by various phenomenons like ion implantation, swift heavy ion/laser/gamma or U...
Article
Present work is focused on the study of physical properties of different phases (α & γ) of Fe2O3 prepared just by varying initial precursors and solvents. Diverse structural and spectroscopic techniques infer growth of α-phase using gelatin (GEL) + deionized water (DI) while γ-phase is obtained with GEL + ethylene glycol (EG) as precursor and solve...
Article
Present study investigates the contribution of defects in the thermoelectric transport properties of Bi2Te3 thin films using 120 keV He⁺ and Ar⁺ ion irradiation. Charge carrier type is converted from n-type to p-type with He⁺ ion irradiation. Upon Ar⁺ ion irradiation, thin film exhibited p-type conductivity at lower ion fluence and n-type conductiv...
Article
Full-text available
Inorganic ZnO modified using rare earth (RE) ions is proposed as an alternative source of energy harvesting over the whole solar spectrum by utilizing the down-and upconversion excitation mechanisms. The present investigation reports the tunability of white/red light possessing excellent color rendering index and color quality scale by employing do...
Article
Damping-like torque (DLT) arising from the spin Hall effect (SHE) in heavy metals and their alloys has been widely explored for applications in spin–orbit torque MRAM, auto-oscillations, spin waves, and domain wall motion. In conventional materials, the DLT efficiency is limited by intrinsic properties, while attaining strong spin–orbit coupling an...
Article
In the present work, KBiFe2O5 (KBFO) films were implanted with 1 MeV N+-ions at different fluencies i.e., 1015, 1016 and 1017 ions cm-2 and their structural, optical and electronic properties were analyzed. From the X-ray diffraction studies, it is evident that the crystal structure of these films belong to that of brownmillerite. Effective bandgap...
Article
Full-text available
In the present study, the role of the Bound Magnetic Polaron (BMP) model is understood in Sm-doped ZnO nanoparticles synthesized via a facile co-precipitation method based on the experimental results from magnetic properties and electronic structures. Experimentally, these compounds exhibit a typical M vs H curve at room temperature depicting ferro...
Article
Full-text available
We investigate the morphological, structural, optical and electrical transport properties of pulsed laser deposited pure and 10% Fe-doped indium oxide nanostructured thin films on the quartz substrates. The crystal structures and morphologies of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and atomic forc...
Article
Full-text available
The synthesis and characterization of high mobility thin films of La-doped SrSnO3 are reported. The mobility for the 7% La-doped sample was found to be 228 cm2V-1s-1. The observed high mobility was associated with the reduced carrier effective mass and scattering centers of various scattering mechanisms. The enhancement in mobility and the increase...
Article
Full-text available
The electronic properties studied using the X-ray absorption near-edge structure (XANES) spectroscopy performed in the vicinity of O K-, Ca L3,2-, Fe L3,2-, and Cu L3,2-edges demonstrate the reversal of orbital symmetry in CaCu3Ti4O12 on Fe³⁺ions substitution. The study of Cu L3,2- and Fe L3,2-edges confirms that the valence states to be +2 and +3...
Article
We study the implications of FeCo underlayer and overlayer on the static and dynamic magnetic properties of FeCo/FePt exchange spring system along with post annealing kinetics. Probing of FePt/FeCo/Si and FeCo/FePt/Si bilayers using high energy synchrotron X-ray diffraction by varying glancing angles unveiled structural variations at the interface,...
Article
We have investigated the bipolar resistive switching of Y0.95Ca0.05MnO3 (YCMO) thin film on Si substrate using pulsed laser deposition. Simulation of Mn L3,2 near-edge X-ray absorption fine structure has been executed by CTM4XAS to corroborate the presence of a mixed-valence state of Mn ions and oxygen vacancies. The charge transport in the film is...
Article
Full-text available
We report the stimulating effects of interfacial charge transfer process between spherical Ag nanoparticles and shuttlecock-shaped ZnO nanostructures observed by UV-visible spectroscopy and X-ray absorption spectroscopy. In specific, ZnO nanorods and shuttlecock-shaped ZnO/Ag nanostructures were developed using a simple chemical colloidal method an...
Article
Full-text available
Engineering the optical bandgap of metal oxides is essential for optoelectronic and photocatalytic applications. The present study reports the application of electronic excitations, induced by 125 MeV Ag ions, in tuning the bandgap of SrTiO3 films in the range of 2.93-3.78 eV and their correlation with the synchrotron-based X-ray diffraction patter...
Article
Full-text available
Zinc tin phosphide (ZTP) has attracted recent research interest as a low-cost light sensing material, alternative to III–V and II–III-based compounds, for photo-detector and solar cell applications. In this study, a versatile chemical route for the synthesis of ZTP nanoparticles starting from commercially available alkyl-zinc and tin, alkyl-phospho...
Article
Full-text available
We study the effect of addition of Ag on normal, paracoherent and superconducting coherent state of YBa2Cu3O7-δ (YBCO). We find that both room temperature resistivity and residual resistivity decrease with the addition of Ag in YBCO. In absence of magnetic field, the addition of Ag in YBCO shift various crossover temperatures of paracoherent state...
Article
We report current–voltage (I–V) device characteristics of pulsed laser deposition (PLD) grown La0.5Gd0.2Ca0.3MnO3 (LGCMO) manganite thin films on single crystalline (100) Nb:SrTiO3 (SNTO) substrates. LGCMO films were irradiated using 100 MeV O⁺⁹ swift heavy ions (SHI). The θ–2θ X–ray diffraction (XRD) and atomic force microscopy (AFM) measurement w...
Preprint
Full-text available
Atomic defect centers in diamond have been widely exploited in numerous quantum applications like quantum information, sensing, quantum photonics and so on. In this context, there is always a requirement to improve and optimize the preparation procedure to generate the defect centers in controlled fashion, and to explore new defect centers which ca...
Article
Full-text available
We report on the formation of n-type ultra-nanocrystalline diamond exhibiting high electrical conductivity, σ R T ∼ 1 0 4 Ω − 1 m − 1 by phosphorus ion implantation. The Raman study confirms the restoration of crystallinity upon high vacuum and high-temperature annealing post-implantation process at 850 ° C. Varying the fluence enabled us to obtain...
Article
In this article, we report the results of the fabrication and studies of Y0.95Ca0.05MnO3/Si device (referred hereafter as YCMO/Si) by pulsed laser deposition (PLD) and its temperature-dependent resistive switching (RS) behaviours measured across the YCMO/Si interface. These temperature (100–300 K)-dependent hysteretic current–voltage (I–V) characte...
Article
Full-text available
The present review provides an overview of the current status and future perspectives of one of the smart manufacturing techniques of Industry 4.0, laser transmission welding (LTW) of semi-crystalline (SC) polymers and their composites. It is one of the most versatile techniques used to join polymeric components with varying thickness and configura...
Article
The 5d-based SrIrO3 represents a prototype example of nonmagnetic correlated metal which mainly originates from a combined effect of spin-orbit coupling, lattice dimensionality, and crystal structure. Therefore tuning of these parameters results in diverse physical properties in this material. Here, we study the structural, magnetic, and electrical...
Preprint
The 5$d$ based SrIrO$_3$ represents prototype example of nonmagnetic correlated metal which mainly originates from a combined effect of spin-orbit coupling, lattice dimensionality and crystal structure. Therefore, tuning of these parameters results in diverse physical properties in this material. Here, we study the structural, magnetic and electric...
Article
Trace level detection of Arsenic in groundwater is one of the major step in the detoxification of drinking water. Accumulation of Arsenic in various parts of the human body through drinking water is a serious health hazard across the world including India. The present experiment describes the template free growth of gold nano island(AuNis) on the I...
Preprint
Full-text available
The synthesis and characterization of high mobility thin films of La-doped SrSnO 3 are reported. The mobility for the 7% La-doped sample is found to be 228 cm 2 V -1 s -1 . The observed high mobility is associated with the reduced carrier effective mass and scattering centers of various scattering mechanisms. The enhancement in mobility and the inc...
Preprint
Investigation of Seebeck coefficient in ultra-wide bandgap materials presents a challenge in measurement, nevertheless, it is essential for understanding fundamental transport mechanisms involved in electrical and thermal conduction. \b{eta}-Ga2O3 is a strategic material for high power optoelectronic applications. Present work reports Seebeck coeff...
Article
The present study investigates the effect of 26 keV N ions implantation on Iron oxide (Fe3O4) thin films of 100 nm deposited on Si (100) substrate by electron beam evaporation method. For this N ions implantation, a fluence of 1×10¹⁶ ions/cm² was used. The cubic spinel phase of Fe3O4 is confirmed by the Raman Spectroscopy. The magnetic properties a...
Article
Full-text available
The present study utilizes synchrotron-based x-ray diffraction (XRD), photoluminescence (PL), and x-ray absorption near edge structure (XANES) spectroscopic techniques to comprehend the evolution of optical intense blue-green emission in 100 keV nitrogen (N) ion implanted SrTiO3 (STO) thin films deposited by RF magnetron sputtering technique. The X...
Article
Defect induced structural, microstructural, resistive switching (RS) characteristics and related responsible charge conduction mechanisms of Y0·95Ca0·05MnO3 (YCMO) manganite films, grown on single crystalline (100) Nb:SrTiO3 (SNTO) substrates (0.2 wt% Nb doped at Ti–site in SrTiO3), are reported in this communication. Films were irradiated by 100 M...
Article
In the present work, extended X-ray absorption fine-structure (EXAFS) investigations of Co 69 Fe x Si 21-x B 10 (x = 3, 5, 7) glassy ribbons were performed at the Co K-edge. The magnitude of the first peak of the Fourier transforms of the EXAFS signals is found to increase monotonically with increasing Si concentrations indicating the formation of...