Dhiraj Kumar Rana
@home.iitd.ac.in
Postdoctoral Fellow, Department of Materials Science and Engineering
Indian Institute of Technology Delhi
RESEARCH, TEACHING, or OTHER INTERESTS
Materials Science, Ceramics and Composites, Polymers and Plastics, Electronic, Optical and Magnetic Materials
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Dhiraj Kumar Rana, Pratip Sankar Banerjee, Soutik Betal, and Shib Shankar Banerjee
Wiley
AbstractConventional charge storage devices made of ceramic materials have limited deformability and configurability due to their extreme stiffness. The high demand for compliant dielectrics has led researchers to look beyond conventional ceramics, despite their very high dielectric properties. In this work, a mechanically robust, highly‐flexible and ultra‐stretchable thermoplastic elastomeric material with dielectric characteristics has been fabricated by introducing calcium copper titanate [CaCu3Ti4O12] (CCTO) dielectric material onto macromolecular chains of styrene–isoprene–styrene (SIS) triblock copolymer via a solution‐based polymer processing technique. CCTO powders have been synthesized using sol–gel technique. The resulting composite is ultra‐stretchable with strain at break of ~3200% and has high dielectric permittivity of ~10. High dielectric property is attributed to the well‐dispersed dielectric CCTO fillers within the SIS matrix, which provide sites for interfacial polarization and space charge accumulation. The influence of CCTO on dielectric properties has also been validated using the modified Cole–Cole model.
Rohit Shrikhande, Dhiraj Kumar Rana, Aniruddha Molla, Gih‐Keong Lau, and Shib Shankar Banerjee
Wiley
AbstractCarbon dots (CDs) are an interesting nanomaterial due to their tunable photoluminescence and other functional properties. Herein, by introducing amine‐functionalized CDs nanoparticles onto macromolecular chains of maleic anhydride grafted styrene‐ethylene‐butylene‐styrene (SEBS‐g‐MA) via a possible ring‐opening reaction of anhydride with amine, a mechanically robust and ultrastretchable thermoplastic elastomeric materials with fluorescence and dielectric functionality was developed. The amine‐functionalized CDs nanoparticles were synthesized from pyrene precursor by hydrothermal treatment. The transmission electron micrograph, Raman, Fourier transform infrared, and x‐ray photoelectron spectra confirmed the formation of highly crystalline graphitized structure of the CDs nanoparticles. Fluorescence and UV–Vis spectroscopy were used to evaluate the optical properties of the developed materials. The developed CDs/SEBS‐g‐MA nanocomposites exhibited strong intense green fluorescence compared with the pure SEBS‐g‐MA film. The thermal stability of the developed nanocomposites was improved by an increase of the Tmax by about 18°C. In addition, the developed composite showed high stretchability (strain at break ~1000%), good mechanical strength, and dielectric properties (room temperature dielectric constant ~5.2). The enhanced dielectric property of the developed composites may be due to the space charge accumulation and induced interfacial polarization at the filler–matrix interface.
P. S. Lekshmipriya, Saubhagyalaxmi Behera, Sabyasachi Parida, Abhisek Choudhary, Dhiraj Kumar Rana, and Prasant Kumar Dash
Springer Science and Business Media LLC
Dhiraj Kumar Rana, Pratip Sankar Banerjee, and Shib Shankar Banerjee
Springer Science and Business Media LLC
Pratip Sankar Banerjee, Dhiraj Kumar Rana, and Shib Shankar Banerjee
Elsevier BV
Santanu Dey, Subhamay Pramanik, Pradipta Chakraborty, Dhiraj Kumar Rana, and Soumen Basu
Springer Science and Business Media LLC
Santanu Dey, Pradipta Chakraborty, Dhiraj Kumar Rana, Subhamay Pramanik, and Soumen Basu
Springer Science and Business Media LLC
AbstractWe have synthesized carbon-supported silver (Ag/C) nanobars by a simple surfactant-free hydrothermal method using glucose as the reducing reagent as well as the source of carbon in Ag/C nanobars. Physicochemical characterization of the materials was performed by X-ray Diffraction (XRD), field emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The XRD pattern confirmed the presence of a pure metallic silver phase. No carbon phase was detected, which indicates that the carbon exists mainly in the amorphous form. The electrocatalytic activity of Ag/C in different electrolyte solutions such as 0.5 M NaOH, 0.5 M NaOH + 1 M ethanol (EtOH), 0.5 M NaOH + 1 M ethylene glycol (EG), and 0.5 M NaOH + 0.01 M NaBH4 (sodium borohydride) was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) study. Alcohol tolerance of the catalysts was also established in the presence of ethanol and ethylene glycol. The forward-to-backward current ratio from cyclic voltammetry (CV) study of Ag/C-20 (20 h) in 0.5 M NaOH + 1 M ethanol solution at 100 mV s−1 scan rate is 4.13 times higher compared to that of Ag/C-5 (5 h). Hence, Ag/C-20 is a better candidate for the tolerance of ethanol. In the presence of ethylene glycol (1 M) in 0.5 M NaOH solution, it is obtained that the forward-to-backward current ratio at the same scan rate for Ag/C-20 is lower than that in the presence of ethanol. The durability of the catalyst was studied by chronoamperometry measurement. We studied the electrochemical kinetics of Ag/C catalysts for borohydride oxidation in an alkaline medium. The basic electrochemical results for borohydride oxidation show that Ag/C has very well strength and activity for direct borohydride oxidation in an alkaline medium. The reaction of borohydride oxidation with the contemporaneous BH4−. hydrolysis was noticed at the oxidized silver surface. Among all the synthesized Ag/C catalysts, Ag/C-20 exhibited the best electrocatalytic performance for borohydride oxidation in an alkaline medium. The activation energy and the number of exchange electrons at Ag/C-20 electrode surface for borohydride electro-oxidation were estimated as 57.2 kJ mol−1 and 2.27, respectively.
Pradipta Chakraborty, Dhiraj Kumar Rana, and Soumen Basu
Springer Science and Business Media LLC
Dhiraj Kumar Rana and Soumen Basu
Elsevier
Pradipta Chakraborty, Dhiraj Kumar Rana, Shovan Kumar Kundu, and Soumen Basu
AIP Publishing
Dhiraj Kumar Rana, Shovan Kumar Kundu, and Soumen Basu
AIP Publishing
Polyvinyl alcohol-Cobalt ferrite (CoFe2O4) (PVA-CFO) flexible nanocomposite films with different concentration of CFO nanoparticles (i.e. 4 and 10 wt%) is successfully synthesized by wet-chemical and drop casting process. The asymmetric nature of the imaginary part of the electric modulus spectra with frequency represent the presence of dielectric relaxation behavior in the charge transport mechanism and follow the non-Debye type behavior. The presence of relaxation peaks also observed in frequency dependent impedance spectroscopy plot. The contribution of grain and the interfacial effect on the conduction mechanism is confirmed from the Nyquist plot. The detailed dielectric relaxation phenomena of charge transport conduction mechanism study here.
Dhiraj Kumar Rana, Vivek Mehta, Shovan Kumar Kundu, and Soumen Basu
Elsevier BV
Shovan Kumar Kundu, Dhiraj Kumar Rana, and Soumen Basu
World Scientific Pub Co Pte Lt
The formation and characterization of multiferroic Gadolinium Ferrite (GdFeO3) nanoparticles has been demonstrated in detail. The structural, magnetic, magnetodielectric, ferroelectric, optical and electrical properties are studied at different temperature ranges. Dielectric properties, DC and AC transport properties and dielectric relaxation behavior are analyzed in electrical characterization. XRD pattern confirms the phase formation where crystallite size, lattice strain, etc. are carried out by Rietveld refinement and Williamson–Hall plot. Average particle size is 64 nm, which is calculated from TEM image. Mixed ferroic order of ferromagnetism and antiferromagnetism along with exchange bias are detected in the nanoparticles. Ferroelectric nature of the sample is confirmed by the P-E hysteresis loops. Positive magnetodielectric coupling is observed in GdFeO3 nanoparticles, which is a signature of multifunctionality nature. Charge transport mechanism of DC and AC applied electric field is successfully analyzed with Mott’s variable range hopping (VRH) and correlated barrier hopping (CBH) theoretical models, respectively. Non-Debye type relaxation behavior is observed with activation energy of 0.37 eV. Optical band gap is calculated from the Tauc plot (2.98 eV) which confirms the semiconducting nature of the sample. Existence of ferromagnetic/antiferromagnetic (FM/AFM) and ferroelectric along with magnetodielctric coupling ensures the multiferroic property of GdFeO3 nanoparticles, which may enhance potentiality in spintronic device applications.
Shovan Kumar Kundu, Dhiraj Kumar Rana, Laxmikanta Karmakar, Debajyoti Das, and Soumen Basu
Springer Science and Business Media LLC
Dhiraj Kumar Rana, Shovan Kumar Kundu, Ram Janay Choudhary, and Soumen Basu
IOP Publishing
Polyvinylidene fluoride (PVDF) with bismuth ferrite (BiFeO3) (BFO) flexible nanocomposite films by varying the concentration of BFO nanoparticles are successfully synthesized by in situ sol-gel process. X-ray diffraction (XRD) pattern confirmed the phase purity of BFO nanoparticles and different crystalline phases of PVDF in PVDF-BFO nanocomposites. The average particle size of BFO nanoparticles is estimated as 34 nm from the fitting of the log-normal distribution function with particle distribution pattern obtained from the transmission electron microscopy (TEM) image analysis. The frequency dependence of ac conductivity confirmed the correlated barrier hopping (CBH) conduction mechanism follows by charge carriers in nanocomposites. The higher value of dielectric permittivity is observed in nanocomposite due to the increase of dipole-dipole interaction at the interface of PVDF and BFO by increasing the BFO concentration. The room temperature M-H and P-E hysteresis loop confirmed the nanocomposites exhibit both magnetic and ferroelectric ordering at the room temperature. The energy storage density of the nanocomposites is increasing with the concentration of BFO nanoparticles. Variation of room temperature magnetodielectric coupling confirmed the multiferroic nature exist in PVDF-BFO nanocomposites, which can be more useful in flexible electronics, energy storage or spintronics devices in multifunctional area.
Shovan Kumar Kundu, Dhiraj Kumar Rana, Amit Banerjee, Debajyoti Das, and Soumen Basu
IOP Publishing
In the present work, we have successfully prepared pure and Manganese (Mn) doped single phase nanocrystalline LaFeO3 by using an auto combustion route. X-ray diffraction (XRD) study ensures the purity of phase whereas the transmission electron microscope (TEM) measurement confirms the nanocrystalline nature. The details of the DC and AC conduction mechanism are studied to illustrate the dielectric behavior and charge transfer mechanism. The DC resistivity increases with the doping concentration which has been illustrated by Mott’s variable range hopping (VRH) model. The AC conductivity mechanism as a function of frequency (20Hz ≤ f ≤ 1MHz) and temperature (303K ≤ T ≤ 573K) is explained by correlated barrier hopping (CBH) model. The dielectric constant and activation energy (AC) increase with Mn concentration whereas dielectric loss decreases. So, the leakage behavior decreases within the samples. The XPS spectra confirm that there is a rise of Fe2+ and Mn4+ ions in the samples with the doping concentration which may be responsible for the enhancement in magnetization. Mixed ferromagnetic (ferromagnetic and antiferromagnetic) order exists within the samples. As a result exchange bias arises. We have achieved the highest value of the coercive field (2.5 kOe) in Mn doped LaFeO3 system. The room temperature ferroelectric and magnetodielectric measurements indicate that the polarization and magnetodielectric coefficient increases significantly by virtue of Mn doping. Therefore, an enhancement of multiferroic and magnetodielectric properties has been achieved for chemically prepared nanocrystalline lanthanum ferrite (LaFeO3) system by virtue of Mn doping. All the observations indicate that these materials to be potential candidates in the emerging field of spintronics.
Dhiraj Kumar Rana, Suresh Kumar Singh, Shovan Kumar Kundu, Subir Roy, S. Angappane, and Soumen Basu
Royal Society of Chemistry (RSC)
The higher values of magneto-dielectric coupling is observed in flexible multiferroic polyvinylidene fluoride (PVDF) nanocomposites doped with nickel ferrite (NFO) nanoparticles.
Dhiraj Kumar Rana, Suresh Kumar Singh, Shovan Kumar Kundu, Ram Janay Choudhary, and Soumen Basu
Springer Science and Business Media LLC
Dhiraj Kumar Rana, Shovan Kumar Kundu, and Soumen Basu
Author(s)
The pure phase Bismuth ferrite (BFO) nanomaterial calcined at 500°C for 2hr. is synthesized by sol-gel method. From the TEM micrograph analysis the average particle size of BFO is calculated as 37nm. The polyvinyl alcohol (PVA) and PVA-BFO (2wt%) composites films are synthesized by drop casting method. The thermal stability of the composites films is increased with adding BFO 2wt% in PVA matrix and which is observed by TGA curve analysis. The variation of real part of dielectric constant and the ac electrical conductivity with frequency range 20Hz to 1MHz at different temperature range from 30°C to 130°C is measured. The electrical transport properties shows the correlated barrier hopping (CBH) model and it is well fitted with the experimental data which is measured from the ac conductivity plot.
T. Badapanda, V. Senthil, D. K. Rana, S. Panigrahi, and S. Anwar
Springer Science and Business Media LLC