Other affiliations: Indian National Association
Bio: Subhadra Chaudhuri is an academic researcher from Indian Association for the Cultivation of Science. The author has contributed to research in topics: Band gap & Photoluminescence. The author has an hindex of 45, co-authored 271 publications receiving 7212 citations. Previous affiliations of Subhadra Chaudhuri include Indian National Association.
Papers published on a yearly basis
TL;DR: In this paper, an intermixing of ethylenediamine (EN) either with ethanol (EtOH) or water in different volume ratios (either 15:85, 50:50 or 85:15 in particular) was used to generate the structural forms of α-Fe2O3.
Abstract: Nanospindle and nanorhombohedron and nanocube structured α-Fe2O3 was synthesized by the solvothermal method. An intermixing of ethylenediamine (EN) either with ethanol (EtOH) or water in different volume ratios (either 15:85, 50:50 or 85:15 in particular) was used to generate the structural forms of α-Fe2O3. The study showed that, during synthesis, EN functioned as a ligand and facilitated the growth of nanostructured samples. The probable growth mechanism is discussed in this paper. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) investigations revealed that the nanostructures were formed through oriented attachment of primary nanocrystals. Fourier transform infrared spectroscopy (FTIR) results showed the presence of Fe–O or Fe–O–Fe vibrational bands whereas UV–vis–NIR optical absorbance spectra showed two prominent absorption bands around 540–560 and 670–680 nm. The room temperature magnetization measurement revealed that the remanence and coercivity depend on the morphological attributes of the nanocrystals. The magnetic hysteresis measurement also revealed that α-Fe2O3 nanostructures displayed weak ferromagnetic behaviour at room temperature.
TL;DR: The morphological change of the ZnS nanostructures and their growth sequence were studied through scanning electron microscopy and room-temperature photoluminescence measurements showed intense blue emission from both the nanowires and the nanoribbons.
Abstract: Rapid synthesis of wurtzite ZnS nanowires and nanoribbons has been achieved by a simple thermal evaporation of ZnS powder onto Si substrate in the presence of Au catalyst. A vapor−liquid−solid process is proposed for the formation of the ZnS nanostructures. The flow rate of the inert carrier Ar gas along with the temperature play an important role in defining the morphology of the ZnS nanostructures. The morphological change of the ZnS nanostructures and their growth sequence were studied through scanning electron microscopy. Room-temperature photoluminescence measurements showed intense blue emission at ∼398 nm from both the nanowires and the nanoribbons.
TL;DR: The electrical response of the ZnO nanonail arrays to different gases (CO, NO2, and H2S) indicated that there could be possible application as gas sensors for this material.
Abstract: One-dimensional ZnO nanostructure arrays such as nanowires, nanonails, and nanotrees, have been synthesized by oxygen assisted thermal evaporation of metallic zinc on a quartz substrate over a large area. Morphological evolution of ZnO nanostructures at different time scales and different positions of the substrates have been studied by electron microscopy. A self-catalyzed vapor-liquid-solid (VLS) process is believed to be responsible for the nucleation and subsequently a vapor-solid process is operative for further longitudinal growth. The photoluminescence spectrum showed a weak UV and a broad green emission peak at 3.25 and 2.49 eV, respectively. The latter was attributed to the presence of zinc interstitial defects. Electrical resistivity as a function of temperature showed activated mechanisms to be present. The electrical response of the ZnO nanonail arrays to different gases (CO, NO 2 , and H 2 S) indicated that there could be possible application as gas sensors for this material.
TL;DR: Manganese-incorporated ZnS (MnxZn1-xS) nanorods were synthesized by a simple solvothermal process and intense orange luminescence at approximately 585 nm was observed for the nanorod.
Abstract: Manganese-incorporated ZnS (MnxZn1-xS) nanorods were synthesized by a simple solvothermal process. Synthesized nanorods were single crystalline. Manganese incorporation in the ZnS lattice induces a phase transformation from hexagonal wurtzite to cubic zinc blende structure. The diameter of the nanorods increased with the increase of Mn concentration. Intense orange luminescence at ∼585 nm was observed for the nanorods. Six-line hyperfine splitting was observed in the EPR spectra for lower Mn concentrations, whereas broad Lorentzian-shaped EPR spectra were obtained for higher Mn concentrations because of the Mn−Mn cluster formation at higher Mn concentrations.
TL;DR: In this article, phase pure rutile SnO2 nanoparticles and nanorods were prepared by solvothermal technique by using x-ray diffraction and transmission electron microscopy.
Abstract: Phase pure rutile SnO2 nanoparticles and nanorods were prepared by solvothermal technique. The diameters of the nanoparticles were in the range of 5–10nm while the length and width of the nanorods were within 100–200nm and ∼50nm, respectively. The crystal structure, morphology, and sizes of the SnO2 nanocrystals were determined by x-ray diffraction and transmission electron microscopy. Optical properties of the products were explored by Fourier transform infrared spectroscopy, optical absorption, photoluminescence, and Raman studies. Size dependent blueshift of the optical band gap of the nanocrystals was observed due to quantum confinement. The photoluminescence spectra showed broad UV emission. The influence of the particle size and the morphology of the SnO2 nanocrystals on the vibration band in the Raman scattering was studied.
TL;DR: The present review mainly focuses on NMOs' preparation, their physicochemical properties, adsorption characteristics and mechanism, as well as their application in heavy metal removal.
Abstract: Nanosized metal oxides (NMOs), including nanosized ferric oxides, manganese oxides, aluminum oxides, titanium oxides, magnesium oxides and cerium oxides, provide high surface area and specific affinity for heavy metal adsorption from aqueous systems. To date, it has become a hot topic to develop new technologies to synthesize NMOs, to evaluate their removal of heavy metals under varying experimental conditions, to reveal the underlying mechanism responsible for metal removal based on modern analytical techniques (XAS, ATR-FT-IR, NMR, etc.) or mathematical models, and to develop metal oxide-based materials of better applicability for practical use (such as granular oxides or composite materials). The present review mainly focuses on NMOs’ preparation, their physicochemical properties, adsorption characteristics and mechanism, as well as their application in heavy metal removal. In addition, porous host supported NMOs are particularly concerned because of their great advantages for practical application as compared to the original NMOs. Also, some magnetic NMOs were included due to their unique separation performance.
TL;DR: In this article, the authors present stretchable and printable semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed, or otherwise deformed.
Abstract: The present invention provides stretchable, and optionally printable, semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed or otherwise deformed. Stretchable semiconductors and electronic circuits of the present invention preferred for some applications are flexible, in addition to being stretchable, and thus are capable of significant elongation, flexing, bending or other deformation along one or more axes. Further, stretchable semiconductors and electronic circuits of the present invention may be adapted to a wide range of device configurations to provide fully flexible electronic and optoelectronic devices.
TL;DR: In this article, a review of recent developments in the use of ZnO nanostructures for dye-sensitized solar cell (DSC) applications is presented.
Abstract: This Review focuses on recent developments in the use of ZnO nanostructures for dye-sensitized solar cell (DSC) applications. It is shown that carefully designed and fabricated nanostructured ZnO films are advantageous for use as a DSC photoelectrode as they offer larger surface areas than bulk film material, direct electron pathways, or effective light-scattering centers, and, when combined with TiO2, produce a core–shell structure that reduces the combination rate. The limitations of ZnO-based DSCs are also discussed and several possible methods are proposed so as to expand the knowledge of ZnO to TiO2, motivating further improvement in the power-conversion efficiency of DSCs.
TL;DR: The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed in this article.
Abstract: Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.