Sandeep Chhoker

Jaypee Institute of Information Technology | JIIT · Department of Physics and Material Science

Chalcogenides glasses Ge17Sb8Se75-xErx with composition x = 0, 0.4, 0.8, 1.0 have been synthesized by conventional melt quenching technique and its dielectric and ac conductivity studies have been carried out in the temperature and frequency range 300–334 K and 5 kHz–20 kHz, respectively. Dielectric constant dependence on temperature and frequency...

In recent study, we investigated the effect of erbium doping in Ge18Sb8Se75 chalcogenide systems to improve their electrical and photoluminescence properties. The chalcogenide glasses (ChG) were synthesized using the traditional melt-quenching technique, and the thin film was deposited using the thermal evaporation technique. Photoluminescence stud...

The influence of erbium in selenium-based chalcogenides (ChG) glass is a potential material for various applications due to its narrow bandgap and good efficiency in photocatalytic activity. Ge17Sb8Se75-xErx where x=0, 0.2. ChG were synthesized by the cost-effective melt-quench method. The photocatalytic activity of Ge17Sb8Se75-xErx(x=0, 0.2%) was...

For the first time, simple and robust melt quench synthesis based pure and doped quaternary Ge17Sb8Se75-xErx(Er; x = 0, 0.6, 1) chalcogenides have been demonstrated under green light (560 nm) illumination photo-catalytic dye degradation. Inspired by the excellent optoelectronic and thermal properties of studied composition, further, rare earth elem...

Barium and manganese (Ba and Mn) co-doped nanostructures of tin oxide (SnO2) are synthesized in situ using a thermal chemical vapour deposition method. The structural property correlation is established using X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, ultraviolet–visible light (...

Here, we report the systematic studies on photoanodes of phase pure polycrystalline microrods of Barium Stannate (BaSnO3) microrods for application in porphyrin dye-sensitized solar cell (DSSC). We were able to establish the effect of vacuum annealing on BaSnO3 thin films on its electrical, optical and adsorption properties using XPS, UV–Vis, photo...

In this study we report the successful synthesis of doped and co-doped SnO2 nanowire using facile Chemical Vapor deposition (CVD) technique. In this studies, the role of Pr as a codopant in Ba doped SnO2 nanowires has been investigated for optical, morphological and RT transport studies. Pr codoping significantly tunes the morphology, band gap and...

We report band structural calculations on full Heusler alloy Co2TiSi by using Korringa–Kohn–Rostoker method. Optimized lattice parameter is estimated using Birch–Murnaghan isothermal equation of state. Half-metallic nature is confirmed by density of states at the Fermi level and this alloy is found to exhibit 100% spin polarized character in the vi...

CoGdxFe2-xO4 nanoparticles with x = 0.0, 0.03, 0.05, 0.07, 0.10 and 0.15 were prepared by co-precipitation route. The effect of Gd³⁺ replacement over Fe³⁺ on optical properties of CoFe2O4 nanoparticles has been analyzed. X-ray diffraction analysis confirmed single phase formation with spinel structure and lattice parameter reduced with increasing G...

Ca and Ca–Li substitution dependent modification in structural, electron density, vibrational, magnetic and optical properties of BiFeO3 nanoparticles synthesized by tartaric acid based sol–gel route are reported. X-ray diffraction and transmission electron microscopy techniques revealed the phase purity and nanocrystalline nature of BiFeO3, Bi0·95...

Polycrystalline zinc stannate (Zn2SnO4) nanowires have been studied for its synthesis optimization using novel carbothermal catalytic method, wherein binary oxide precursors were used under inert atmosphere at variable CVD synthesis parameters. X-ray diffraction, FESEM, EDS, HRTEM, Raman and CL measurements are used to understand the typical behavi...

Single step growth of carbon nanoflakes over p-silicon (100) substrates in MPECVD system using acetylene, hydrogen and argon as reactant gases has been carried out. FESEM studies of the deposited carbon films revealed that the morphology is greatly influenced with deposition time. Transmission electron microscope (TEM) and Raman spectra analysis of...

Transparent semiconductors have outpaced other contemporary material in the field of semiconductor industry. Ternary oxides with complex structures (pervoskites and spinels) have shown multifunctional properties e.g. ferromagnetism, piezoelectricity, superconductivity etc. To explore the field, micro rods of barium stannate (BaSnO3) were synthesize...

Bi1-xCaxFe1-xNixO3 nanoparticles with x = 0.0, 0.05, 0.10 and 0.15 were effectively synthesized using a profitable route, tartaric acid based sol-gel one. In BiFeO3 at Bi and Fe-sites, the co-substitution of alkali earth metal Ca²⁺ ions and transition metal Ni²⁺ ions leads to structural distortion, reduction in average grain size and enhanced magne...

We have investigated the magnetic and electrical properties of Mn doped zinc stannate (Zn2SnO4; ZTO) nanorods synthesized via vapour transport method in a vacuum operated thermal CVD setup. Saturation magnetization up to 21.55 emu/cm³ has been observed for Mn doped ZTO samples. Room temperature resistivity, mobility and carrier concentration has be...

Bi1−xCaxFeO3; (x = 0–0.20) nanoparticles were synthesized by tartaric acid based sol–gel route. X-ray diffraction and electron microscopy studies reveal the phase purity and nanocrystalline nature (45–90 nm) of Bi1−xCaxFeO3 samples. The Ca ion substitution driven structural transition from rhombohedral (space group R3c) to orthorhombic (Pnma) symme...

The manifestation of dimensionalities and SiO2 shell induced modifications in structural, vibrational, dielectric and magnetic properties of microcrystalline, nanocrystalline BiFeO3 and core-shell structured BiFeO3@SiO2 nanoparticles are reported. Transmission electron microscopy image confirmed the core-shell structure of BiFeO3@SiO2 nanoparticles...

Bi1−xCaxFe1−xCoxO3 nanoparticles with x=0.0, 0.05, 0.10 and 0.15 were successfully synthesized by cost effective tartaric acid based sol–gel route. The alkali earth metal Ca2+ ions and transition metal Co3+ ions codoping at A and B-sites of BiFeO3 results in structural distortion and phase transformation. Rietveld refinement of XRD patterns suggest...

Polycrystalline BiFeO3 (BFO) and Bi0.90Gd0.10Fe1−xZrxO3 (x = 0.0–0.10; BGFZx) ceramics were synthesized by solid-state reaction method. Rietveld analysis of X-ray diffraction patterns showed that BFO and BGFZx = 0.0 samples are stabilized in rhombohedral structure (space group R3c), whereas a small fraction of orthorhombic phase (space group Pn21a)...

Eu substituted BiFeO3 (Bi1−xEuxFeO3; x=0–0.15) polycrystalline ceramics were synthesized by a solid state reaction method. Rietveld refinement of X-ray diffraction patterns reveals that samples crystallize in R3c structure for x≤0.10 and (R3c+Pn21a) phases coexist for x≥0.12–0.15. The magnetic measurements show weak ferromagnetic nature of Eu subst...

Polycrystalline Bi1−xDyxFeO3 (x=0.03, 0.05, 0.07, 0.10, and 0.12) ceramics were synthesized by solid state reaction method. Rietveld refinement reveals that all the samples crystallize in the rhombohedral structure with non-centrosymmetric R3c space group. Substitution induced suppression of the spiral spin structure and Dy3+-Fe3+ interaction enhan...

Polycrystalline BiFeO3 (BFO), Bi0.90Gd0.10FeO3 (BGF), Bi0.90Gd0.10Fe1−xTixO3 (x = 0.03–0.10; BGFTx) ceramics were prepared via solid state reaction method. X-ray diffraction studies reveal R3c symmetry for BFO and BGF samples and coexistence of R3c + Pn2 1 a symmetries for BGFTx samples. The change in line width of Raman modes indicates the structu...

Zr substituted BiFeO3 (BiFe1-xZrxO3 with x = 0.03, 0.07, 0.10 and 0.15) nanoparticles were synthesized by sol-gel method. Powder X-ray diffraction studies showed rhombohedral crystal structure for x = 0.03-0.10 samples. The substitution induced structural transformation from rhombohedral to triclinic phase has been observed for x = 0.15. Raman anal...

Polycrystalline Bi 1 À x Gd x FeO 3 (x ¼ 0.00–0.15) ceramics were prepared by solid-state reaction method. The samples preserve rhombohedral symmetry for x r 0.10 and coexistence of rhombohedral R3c and orthorhombic Pn2 1 a symmetries for x 4 0.10. A significant change in the phonon frequencies of A 1 modes and line widths in Raman spectra also con...

Rare earth Dy substituted BiFeO3 (Bi1-xDyxFeO3) nanoparticles with x=0.03, 0.05 and 0.10 were prepared by a sol-gel method. Rietveld analysis of the X-ray diffraction Patterns and Raman spectroscopy confirmed substitution induced phase transformation from rhombohedral to orthorhombic phase for x=0.10. In Raman spectra, the broad band ranging from 9...

a b s t r a c t Structural, magnetic and optical properties of Bi 0.85 Ho 0.15 Fe 1 À x Co x O 3 (x ¼0.0–0.15) nanoparticles have been studied. X-ray diffraction patterns and Raman spectra demonstrate orthorhombic structure for all samples. Spontaneous magnetization of Ho–Co co-substituted BiFeO 3 nanoparticles increased up to 3.71 emu/g for x ¼ 0....

Single-phase (Bi1−xPrx)(Fe1−xTix)O3 ceramics (x=0.03, 0.06, and 0.10 as BPFT-3, BPFT-6 and BPFT-10, respectively) were synthesized by conventional solid state reaction method. The effect of varying Pr and Ti codoping concentration on the structural, magnetic, dielectric and optical properties of the BPFT ceramics have been investigated. X-ray diffr...

Bulk BiFeO3, BiFeO3 nanoparticles and core-shell structured BiFeO3@SiO2 nanoparticles were synthesized by solid state reaction method, sol-gel and Stöber process (SiO2 shell) respectively. Transmission electron microscopy image confirmed the core-shell structure of BiFeO3@SiO2 nanoparticles with BiFeO3 core ̃50-90 nm and SiO2 shell ̃16 nm. X-ray di...

In this work, we have investigated the interplay between structure, magnetic and dielectric properties of (Bi1-xPrx)(Fe1-xTix)O-3 ceramics (x = 0.03, 0.06 and 0.10) synthesised via solid state reaction method. X-ray diffraction and Raman studies exhibited the structural transition from rhombohedral to orthorhombic phase for higher codoping concentr...

(Bi1−xPrx)(Fe1−xZrx)O3 ceramics with x = 0.03, 0.06 and 0.10 were prepared via solid state reaction route. X-ray diffraction and Raman spectra of the ceramics were recorded for calculating its lattice parameters and structural analysis. Magnetic studies indicated a significant enhancement in magnetization of (Bi1−xPrx)(Fe1−xZrx)O3 ceramics with max...

Nd doped ZnO (Zn1-xNdxO, x = 0.0, 0.03, 0.06 and 0.10) nanoparticles were prepared by sol–gel method. Phase identification and effect of Nd ions substitution in ZnO lattice were confirmed by Rietveld analysis of XRD patterns. UV–Visible absorption spectra of pure and Nd doped ZnO nanoparticles showed the variation of the band gap in the range of 3....

Bi1−xBaxFeO3 (x=0.05, 0.10 and 0.15) nanoparticles were synthesized by the sol–gel method. X-ray diffraction and Raman spectroscopy results showed the presence of distorted rhombohedral structure of Bi1−xBaxFeO3 nanoparticles. Rietveld refinement and Williamson–Hall plot of the x-ray diffraction patterns showed the increase in lattice parameters, u...

Ba and Mn doped BiFeO3 nanoparticles were synthesized by sol-gel method. X-ray diffraction and Raman spectroscopy results showed the presence of distorted rhombohedral structure for Bi0.85Ba0.15FeO3 nanoparticles and the substitution induced phase transition (rhombohedral to orthorhombic) phase for Bi0.85Mn0.15FeO3 nanoparticles. FESEM images of bo...

Abstract Bi1−xDyxFeO3 (x=0.03, 0.05, and 0.10) nanoparticles were synthesized using sol–gel method. X-ray diffraction results show a compositional driven phase transition from a rhombohedral phase for x=0.03 and 0.05 samples to orthorhombic phase for x=0.10 sample. Raman spectroscopy also suggested substitution induced phase transition in Bi1−xDyxF...

The effect of phase transition in catalyst nanoparticles due to increasing growth temperatures and its effect over the morphology and field emission of carbon nanotubes (CNT) films is reported here. Thin Fe film coated Si substrates are used to obtain Fe nanoparticles under hydrogen and argon plasma treatment. For this, three different microwave po...

Single-phase (Bi1-xPrx)(Fe1-xZrx)O3 ceramics with x¼0.03, 0.06, 0.10 (named BPFZ-3, BPFZ-6, and BPFZ-10, respectively) were synthesized by solid state reaction method. X-ray diffraction suggested the pure phase formation with distorted rhombohedral structure in all samples. Raman spectroscopy also confirmed the rhombohedrally distorted perovskite s...

BiFeO3 nanoparticles were prepared via a soft chemical method using citric acid and tartaric acid routes followed by calcination at low temperature. Structural characterization showed remarkably different conditions for pure phase formation from both routes. The tartaric acid route was effective in obtaining pure phase BiFeO3 nanoparticles while ci...

Mn doped BiFeO3 (5, 10 and 15 mol%) nanoparticles were synthesized using sol–gel technique. The influence of Mn doping on structural, dielectric, magnetic, magnetoelectric and optical properties of BiFeO3 was studied. Rietveld refinement of XRD patterns showed rhombohedral to orthorhombic phase transition for 15 mol% Mn doped BiFeO3 sample. Magneti...

Current research on the carbon-based nanotechnology needs progressive methods to control the shape, location and size of the nanostructures. Here, we report significant progress by synthesising the density controlled carbon nanostructures (CNSs) using acetylene and hydrogen in microwave plasma enhanced chemical vapour deposition system. Thin films...

The effect of substrate pretreatments such as ultrasonication or scratching by diamond powder on the microstructure and field emission characteristics of diamond grown over silicon and macroporous (anodized) silicon substrates was investigated. These films were grown in a hot filament chemical vapor deposition (CVD) system. Scanning electron micros...

Single step growth of self-assembled graphitic nanoflakes (GNF) over carbon nanotubes (CNT) on iron coated silicon(100) substrates is reported. These nanostructures were grown by varying the deposition time in a microwave plasma enhanced chemical vapor deposition reactor using acetylene, hydrogen and argon as reactant gases. Scanning electron micro...

Carbon nanotubes (CNTs), carbon nanoflakes (CNFs), carbon nanoparticles (CNPs) and other related structures (known as carbon nanostructures (CNSs)) have emerged as a promising class of materials as field electron emitters. They have a low threshold field and a high emission current density which make them attractive for technological applications....