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Papers by Manoj K. Rajbhar

Research paper thumbnail of Augmented electrochemical properties of manganese oxide nanorods on low energy nitrogen ion irradiation

Journal of Alloys and Compounds

Research paper thumbnail of Detection of Energetic Ions Based on Tapered Optical Fiber

Research paper thumbnail of Tapered Optical Fiber-based Detection of Charged Particle Irradiation in Space Exploration and Nuclear Reactors

arXiv (Cornell University), Oct 19, 2022

In this work, we demonstrate the use of tapered optical fibers (TOF) to detect charged particle (... more In this work, we demonstrate the use of tapered optical fibers (TOF) to detect charged particle (ions), irradiated at various energies, fluences and species. The single mode tapered optical fiber has been used in various sensing applications in recent times. Here, tapered optical fibers have been exposed to two different ion species namely Ar + and N + at different energies and different fluences, respectively. The optical spectrum analyser (OSA) detects the changes in the free spectral range (FSR), period, and transmission power loss from the ion beam irradiated TOFs. The change in the refractive index of the cladding material due to the implanted ions influences the transmission spectra of the TOFs and we could able to detect ions of energy as low as 80 keV. COMSOL simulation results are employed to explain the observed changes in spectra. The ion beams induced surface modification and defect formation as well as the implantation in TOF have been predicted using Monte Carlo based 3D TRI3DYN ion-solid interaction simulation and corroborated with other experimental studies such as scanning electron microscopy and Raman scattering spectroscopy. Such tapered optical fiber-based detection technique will help to develop portable device to detect charged particles in space exploration and in nuclear reactors.

Research paper thumbnail of CoreShell Nanostructures of Tungsten Oxide and Hydrogen Titanate for H2 Gas Adsorption

Research paper thumbnail of Broad Beam-Induced Fragmentation and Joining of Tungsten Oxide Nanorods: Implications for Nanodevice Fabrication and the Development of Fusion Reactors

In this work, for the first time, fragmentation and joining of tungsten oxide (WO 3) nanorods ind... more In this work, for the first time, fragmentation and joining of tungsten oxide (WO 3) nanorods induced by broad ion-beam are reported. While at low energy (5 keV) and moderate ion fluence nanorods fragment into smaller pieces along the length; at higher ion energies (50-100 keV), a contrary process occurs, which leads to the joining of the nanorods. A state-of-the-art ion-solid interaction simulation, namely TRI3DYN, has been invoked to explore the possible mechanisms, which reveal subtle contributions of surface defects, ion beam mixing, and sputtering. High-resolution electron microscopy, photoluminescence study, and X-ray photoelectron spectroscopy support the observed results and proposed mechanisms. Such modifications have interesting effects on the electrical conductivity of the nanorod assembly. The change of sample color upon ion irradiation from initial white to yellow, light blue, deep blue, light green, and cyan shows an excellent and reversible chromatic response of tungsten oxide nanorods to irradiation. Such property can be exploited to fabricate radiation sensors. The fragmentation and joining at different energy scales have essential implications in nanodevice fabrication through the bottom-up approach as well as for the development of fusion reactors.

Research paper thumbnail of Low energy ion beam-induced joining of TiO2 nanoparticles

Journal of Alloys and Compounds

Research paper thumbnail of Formation of core-shell nanostructure through wrapping of cuprous oxide nanowires by hydrogen titanate nanotubes

Radiation Physics and Chemistry

Research paper thumbnail of Ion Beam Induced Formation of One-Dimensional Nanostructures from Tio2 Nanoparticles

Research paper thumbnail of Ion beam joining of similar and dissimilar materials

Joining Processes for Dissimilar and Advanced Materials, 2022

Research paper thumbnail of Superior electrical conduction of a water repelling 3D interconnected nano-network

Journal of Materials Chemistry C, 2018

3D ceramic nanowelded porous network.

Research paper thumbnail of Nanoscale modification of one-dimensional single-crystalline cuprous oxide

Nanotechnology, 2019

In this work we report for the first time a method to modify the surface of Cu2O nanowires in a c... more In this work we report for the first time a method to modify the surface of Cu2O nanowires in a controllable way and physically weld them into a network form, which contributes to higher electrical conductivity as well as a strong water-repelling nature. We have used state-of-the-art theoretical calculations to support our experimental observations. We demonstrate how varying the irradiation fluence can modulate the surface and decorate the nanowire with a uniform distribution of Cu8O nanocrystals due to preferential sputtering. While several well studied joining techniques are available for carbon and metal-based nanowires, the same information for ceramic nanowires is scarce at present. The current study sheds light into this and a state-of-the-art 3D simulation technique predicts most of the modifications including surface modulation, oxygen depletion and welding. The welded network shows higher electrical conductivity than the unwelded assembly. With Cu2O being of p-type the current ion beam joining technique shows a novel path for fabricating p-i-n junctions or solar cell devices through bottom-up approach. Furthermore, we have explored the response of this network to moisture. Our calculation based on density functional theory predicts the hydrophilic nature of individual copper oxide nanowires both before and after irradiation. However, the network shows a strong water-repelling nature, which has been explained quantitatively using the Cassie-Baxter model.

Research paper thumbnail of Joining of two different ceramic nanomaterials for bottom-up fabrication of heterojunction devices

Applied Surface Science, 2019

Fabrication of device though bottom-up approach and using nanowires as building blocks has receiv... more Fabrication of device though bottom-up approach and using nanowires as building blocks has received significant attention as one can build flexible electronics which can handle stress better than thin film based device. However successful joining of the nanowires for fabrication of such device remains a challenge till date. While several well researched joining techniques are available for metal based nanowires, the same for ceramic nanowires is scarce at present. In this work we explore ion beam induced formation of heterojunction between two metal oxide nanowires, namely hydrogen titanate (H 2 Ti 3 O 7) and cuprous oxide (Cu 2 O). The electron microscopy studies reveal detailed structural modifications at the joining sections. The ion beam modifications are explained using state-of-the-art TRI3DYN simulations, which details about migration of atoms, defects, sputtering, redeposition and atomic mixing between the two nanowires and emphasize that such junction formation is caused mainly due to atomic collisional effects.

Research paper thumbnail of Moisture repelling perovskite nanowires for higher stability in energy applications

Applied Surface Science, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Augmented electrochemical properties of manganese oxide nanorods on low energy nitrogen ion irradiation

Journal of Alloys and Compounds

Research paper thumbnail of Detection of Energetic Ions Based on Tapered Optical Fiber

Research paper thumbnail of Tapered Optical Fiber-based Detection of Charged Particle Irradiation in Space Exploration and Nuclear Reactors

arXiv (Cornell University), Oct 19, 2022

In this work, we demonstrate the use of tapered optical fibers (TOF) to detect charged particle (... more In this work, we demonstrate the use of tapered optical fibers (TOF) to detect charged particle (ions), irradiated at various energies, fluences and species. The single mode tapered optical fiber has been used in various sensing applications in recent times. Here, tapered optical fibers have been exposed to two different ion species namely Ar + and N + at different energies and different fluences, respectively. The optical spectrum analyser (OSA) detects the changes in the free spectral range (FSR), period, and transmission power loss from the ion beam irradiated TOFs. The change in the refractive index of the cladding material due to the implanted ions influences the transmission spectra of the TOFs and we could able to detect ions of energy as low as 80 keV. COMSOL simulation results are employed to explain the observed changes in spectra. The ion beams induced surface modification and defect formation as well as the implantation in TOF have been predicted using Monte Carlo based 3D TRI3DYN ion-solid interaction simulation and corroborated with other experimental studies such as scanning electron microscopy and Raman scattering spectroscopy. Such tapered optical fiber-based detection technique will help to develop portable device to detect charged particles in space exploration and in nuclear reactors.

Research paper thumbnail of CoreShell Nanostructures of Tungsten Oxide and Hydrogen Titanate for H2 Gas Adsorption

Research paper thumbnail of Broad Beam-Induced Fragmentation and Joining of Tungsten Oxide Nanorods: Implications for Nanodevice Fabrication and the Development of Fusion Reactors

In this work, for the first time, fragmentation and joining of tungsten oxide (WO 3) nanorods ind... more In this work, for the first time, fragmentation and joining of tungsten oxide (WO 3) nanorods induced by broad ion-beam are reported. While at low energy (5 keV) and moderate ion fluence nanorods fragment into smaller pieces along the length; at higher ion energies (50-100 keV), a contrary process occurs, which leads to the joining of the nanorods. A state-of-the-art ion-solid interaction simulation, namely TRI3DYN, has been invoked to explore the possible mechanisms, which reveal subtle contributions of surface defects, ion beam mixing, and sputtering. High-resolution electron microscopy, photoluminescence study, and X-ray photoelectron spectroscopy support the observed results and proposed mechanisms. Such modifications have interesting effects on the electrical conductivity of the nanorod assembly. The change of sample color upon ion irradiation from initial white to yellow, light blue, deep blue, light green, and cyan shows an excellent and reversible chromatic response of tungsten oxide nanorods to irradiation. Such property can be exploited to fabricate radiation sensors. The fragmentation and joining at different energy scales have essential implications in nanodevice fabrication through the bottom-up approach as well as for the development of fusion reactors.

Research paper thumbnail of Low energy ion beam-induced joining of TiO2 nanoparticles

Journal of Alloys and Compounds

Research paper thumbnail of Formation of core-shell nanostructure through wrapping of cuprous oxide nanowires by hydrogen titanate nanotubes

Radiation Physics and Chemistry

Research paper thumbnail of Ion Beam Induced Formation of One-Dimensional Nanostructures from Tio2 Nanoparticles

Research paper thumbnail of Ion beam joining of similar and dissimilar materials

Joining Processes for Dissimilar and Advanced Materials, 2022

Research paper thumbnail of Superior electrical conduction of a water repelling 3D interconnected nano-network

Journal of Materials Chemistry C, 2018

3D ceramic nanowelded porous network.

Research paper thumbnail of Nanoscale modification of one-dimensional single-crystalline cuprous oxide

Nanotechnology, 2019

In this work we report for the first time a method to modify the surface of Cu2O nanowires in a c... more In this work we report for the first time a method to modify the surface of Cu2O nanowires in a controllable way and physically weld them into a network form, which contributes to higher electrical conductivity as well as a strong water-repelling nature. We have used state-of-the-art theoretical calculations to support our experimental observations. We demonstrate how varying the irradiation fluence can modulate the surface and decorate the nanowire with a uniform distribution of Cu8O nanocrystals due to preferential sputtering. While several well studied joining techniques are available for carbon and metal-based nanowires, the same information for ceramic nanowires is scarce at present. The current study sheds light into this and a state-of-the-art 3D simulation technique predicts most of the modifications including surface modulation, oxygen depletion and welding. The welded network shows higher electrical conductivity than the unwelded assembly. With Cu2O being of p-type the current ion beam joining technique shows a novel path for fabricating p-i-n junctions or solar cell devices through bottom-up approach. Furthermore, we have explored the response of this network to moisture. Our calculation based on density functional theory predicts the hydrophilic nature of individual copper oxide nanowires both before and after irradiation. However, the network shows a strong water-repelling nature, which has been explained quantitatively using the Cassie-Baxter model.

Research paper thumbnail of Joining of two different ceramic nanomaterials for bottom-up fabrication of heterojunction devices

Applied Surface Science, 2019

Fabrication of device though bottom-up approach and using nanowires as building blocks has receiv... more Fabrication of device though bottom-up approach and using nanowires as building blocks has received significant attention as one can build flexible electronics which can handle stress better than thin film based device. However successful joining of the nanowires for fabrication of such device remains a challenge till date. While several well researched joining techniques are available for metal based nanowires, the same for ceramic nanowires is scarce at present. In this work we explore ion beam induced formation of heterojunction between two metal oxide nanowires, namely hydrogen titanate (H 2 Ti 3 O 7) and cuprous oxide (Cu 2 O). The electron microscopy studies reveal detailed structural modifications at the joining sections. The ion beam modifications are explained using state-of-the-art TRI3DYN simulations, which details about migration of atoms, defects, sputtering, redeposition and atomic mixing between the two nanowires and emphasize that such junction formation is caused mainly due to atomic collisional effects.

Research paper thumbnail of Moisture repelling perovskite nanowires for higher stability in energy applications

Applied Surface Science, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.