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Smita Chaturvedi - One of the best experts on this subject based on the ideXlab platform.
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tunable band gap and coercivity of Bismuth Ferrite polyaniline core shell nanoparticles the role of shell thickness
RSC Advances, 2015Co-Authors: Smita Chaturvedi, Raja Das, Pankaj Poddar, S K KulkarniAbstract:We report a tunable band gap of Bismuth Ferrite–polyaniline core–shell nanoparticles from 2.24 to 1.98 eV and the variation of coercivity from 118 to 100 Oe, by varying the thickness of the polyaniline shell. Bismuth Ferrite nanoparticles were synthesized via a chemical route and coating of polyaniline was achieved by a double surfactant layer technique. Coating of polyaniline introduced oxygen vacancies, local distortions and microstrains in the Bismuth Ferrite lattice which resulted in a change in the Fe–O–Fe bond angle of the Bismuth Ferrite lattice. This is confirmed with structural analysis tools i.e. X-ray Diffraction, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. Moreover, the absorption of light around 600 nm is increased and photoluminescence emission around 430 nm is decreased, as the thickness of shell is increased, which also indicates the changes in optical properties due to variation in shell thickness. Thus tunability of the band gap and coercivity is achieved as a function of shell thickness in Bismuth Ferrite–polyaniline core–shell nanoparticles.
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Tunable band gap and coercivity of Bismuth Ferrite–polyaniline core–shell nanoparticles: the role of shell thickness
RSC Advances, 2015Co-Authors: Smita Chaturvedi, Raja Das, Pankaj Poddar, Sulabha K. KulkarniAbstract:We report a tunable band gap of Bismuth Ferrite–polyaniline core–shell nanoparticles from 2.24 to 1.98 eV and the variation of coercivity from 118 to 100 Oe, by varying the thickness of the polyaniline shell. Bismuth Ferrite nanoparticles were synthesized via a chemical route and coating of polyaniline was achieved by a double surfactant layer technique. Coating of polyaniline introduced oxygen vacancies, local distortions and microstrains in the Bismuth Ferrite lattice which resulted in a change in the Fe–O–Fe bond angle of the Bismuth Ferrite lattice. This is confirmed with structural analysis tools i.e. X-ray Diffraction, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. Moreover, the absorption of light around 600 nm is increased and photoluminescence emission around 430 nm is decreased, as the thickness of shell is increased, which also indicates the changes in optical properties due to variation in shell thickness. Thus tunability of the band gap and coercivity is achieved as a function of shell thickness in Bismuth Ferrite–polyaniline core–shell nanoparticles.
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Probing Bismuth Ferrite nanoparticles by hard x-ray photoemission: Anomalous occurrence of metallic Bismuth
Applied Physics Letters, 2014Co-Authors: Smita Chaturvedi, Mandar M. Shirolkar, Ranguwar Rajendra, Nirmalya Ballav, Indranil Sarkar, U-ser Jeng, Yi-qi Yeh, Sulabha K. KulkarniAbstract:We have investigated Bismuth Ferrite nanoparticles (∼75 nm and ∼155 nm) synthesized by a chemical method, using soft X-ray (1253.6 eV) and hard X-ray (3500, 5500, and 7500 eV) photoelectron spectroscopy. This provided an evidence for the variation of chemical state of Bismuth in crystalline, phase pure nanoparticles. X-ray photoelectron spectroscopy analysis using Mg Kα (1253.6 eV) source showed that iron and Bismuth were present in both Fe3+ and Bi3+ valence states as expected for Bismuth Ferrite. However, hard X-ray photoelectron spectroscopy analysis of the Bismuth Ferrite nanoparticles using variable photon energies unexpectedly showed the presence of Bi0 valence state below the surface region, indicating that Bismuth Ferrite nanoparticles are chemically inhomogeneous in the radial direction. Consistently, small-angle X-ray scattering reveals a core-shell structure for these radial inhomogeneous nanoparticles.
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Coercivity and exchange bias of Bismuth Ferrite nanoparticles isolated by polymer coating
Journal of Applied Physics, 2014Co-Authors: Smita Chaturvedi, Mandar M. Shirolkar, Ranguwar Rajendra, Surjeet Singh, Nirmalya Ballav, Sulabha K. KulkarniAbstract:Bismuth Ferrite nanoparticles have been extensively investigated over the last few years due to their potential candidacy for application in future memory devices. However, all the work reported so far on Bismuth Ferrite nanoparticles is on agglomerated nanoparticles. Agglomerated particles can magnetically interact with each other. To utilize them for device application, it is useful to know the properties of the individual particles. Here, de-agglomeration of ∼75 nm Bismuth Ferrite nanoparticles is achieved by polyaniline coating on the surface. The structural and magnetic properties of agglomerated and de-agglomerated nanoparticles are compared. It is observed that there is a change in the lattice parameters and Fe-O-Fe and O-Bi-O bond angles due to polyaniline shell. The coercivity of the Bismuth Ferrite/polyaniline core shell particles is reduced as compared to pure and agglomerated Bismuth Ferrite particles. The observed changes in the magnetic properties of coated particles are attributed to the shell induced isolation of individual Bismuth Ferrite nanoparticles as well as structural changes due to polyaniline coating.
Himadri Sekhar Maiti - One of the best experts on this subject based on the ideXlab platform.
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Nanosized Bismuth Ferrite powder prepared through sonochemical and microemulsion techniques
Materials Letters, 2007Co-Authors: Nandini Das, Amarnath Sen, Ranabrata Majumdar, Himadri Sekhar MaitiAbstract:Abstract Two processing routes, namely sonochemical and microemulsion have been exploited to prepare Bismuth Ferrite powders. Phase pure nanosized BiFeO 3 powders are prepared by sonochemical and microemulsion techniques in the temperature range of 400 °C and at 500 °C which is much lower than that of the conventional preparation methods. The XRD obtained from both cases was likely to be pure Bismuth Ferrite. Though the microemulsion based powders showed slightly better properties with respect to particle size, surface area, and final density, sonochemically prepared powders may be more acceptable considering the ease of preparation and cost effectiveness.
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low temperature synthesis of nanosized Bismuth Ferrite by soft chemical route
Journal of the American Ceramic Society, 2005Co-Authors: Sushmita Ghosh, Subrata Dasgupta, Amarnath Sen, Himadri Sekhar MaitiAbstract:The present research describes a simple low-temperature synthesis route of preparing Bismuth Ferrite nanopowders through soft chemical route using nitrates of Bismuth and Iron. Tartaric acid is used as a template material and nitric acid as an oxidizing agent. The synthesized powders are characterized by X-ray diffractometry, thermogravimetry and differential thermal analysis, infrared spectroscopy, and scanning electron microscopy. The particle size of the powder lies between 3 and 16 nm. In the process, phase pure Bismuth Ferrite can be obtained at a temperature as low as 400°C, in contrast to 550°C for coprecipitation route. On the other hand, we find that, like solid state reaction route, Pechini's autocombustion method of synthesis generates a lot of impurity phases along with Bismuth Ferrite.
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Low temperature synthesis of Bismuth Ferrite nanoparticles by a ferrioxalate precursor method
Materials Research Bulletin, 2005Co-Authors: Sushmita Ghosh, Subrata Dasgupta, Amarnath Sen, Himadri Sekhar MaitiAbstract:Abstract The synthesis of Bismuth Ferrite by solid-state reaction of Bi 2 O 3 and Fe 2 O 3 results in the formation of multiphase products. Even coprecipitation followed by calcination leads to the formation of impurity phases. Here, we report the synthesis of magnetoelectric Bismuth Ferrite by a ferrioxalate precursor method. In this process, Bismuth Ferrite, synthesized through solutions of some specific salts led to the formation of phase pure (perovskite) nanocrystalline powder (11–22 nm as evident from X-ray diffraction analysis) at a temperature of 600 °C. The synthesized powders were characterized by X-ray diffractometry, thermogravimetry and differential thermal analysis, Fourier transformation infrared spectroscopy and scanning electron microscopy. The synthesis route is simple, energy saving and cost-effective. Such nanosized Bismuth Ferrite powder may have a potential application in making lead free piezoelectric materials for actuators as well as magnetoelectric sensors.
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Low‐Temperature Synthesis of Nanosized Bismuth Ferrite by Soft Chemical Route
Journal of the American Ceramic Society, 2005Co-Authors: Sushmita Ghosh, Subrata Dasgupta, Amarnath Sen, Himadri Sekhar MaitiAbstract:The present research describes a simple low-temperature synthesis route of preparing Bismuth Ferrite nanopowders through soft chemical route using nitrates of Bismuth and Iron. Tartaric acid is used as a template material and nitric acid as an oxidizing agent. The synthesized powders are characterized by X-ray diffractometry, thermogravimetry and differential thermal analysis, infrared spectroscopy, and scanning electron microscopy. The particle size of the powder lies between 3 and 16 nm. In the process, phase pure Bismuth Ferrite can be obtained at a temperature as low as 400°C, in contrast to 550°C for coprecipitation route. On the other hand, we find that, like solid state reaction route, Pechini's autocombustion method of synthesis generates a lot of impurity phases along with Bismuth Ferrite.
Sulabha K. Kulkarni - One of the best experts on this subject based on the ideXlab platform.
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Tunable band gap and coercivity of Bismuth Ferrite–polyaniline core–shell nanoparticles: the role of shell thickness
RSC Advances, 2015Co-Authors: Smita Chaturvedi, Raja Das, Pankaj Poddar, Sulabha K. KulkarniAbstract:We report a tunable band gap of Bismuth Ferrite–polyaniline core–shell nanoparticles from 2.24 to 1.98 eV and the variation of coercivity from 118 to 100 Oe, by varying the thickness of the polyaniline shell. Bismuth Ferrite nanoparticles were synthesized via a chemical route and coating of polyaniline was achieved by a double surfactant layer technique. Coating of polyaniline introduced oxygen vacancies, local distortions and microstrains in the Bismuth Ferrite lattice which resulted in a change in the Fe–O–Fe bond angle of the Bismuth Ferrite lattice. This is confirmed with structural analysis tools i.e. X-ray Diffraction, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. Moreover, the absorption of light around 600 nm is increased and photoluminescence emission around 430 nm is decreased, as the thickness of shell is increased, which also indicates the changes in optical properties due to variation in shell thickness. Thus tunability of the band gap and coercivity is achieved as a function of shell thickness in Bismuth Ferrite–polyaniline core–shell nanoparticles.
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Probing Bismuth Ferrite nanoparticles by hard x-ray photoemission: Anomalous occurrence of metallic Bismuth
Applied Physics Letters, 2014Co-Authors: Smita Chaturvedi, Mandar M. Shirolkar, Ranguwar Rajendra, Nirmalya Ballav, Indranil Sarkar, U-ser Jeng, Yi-qi Yeh, Sulabha K. KulkarniAbstract:We have investigated Bismuth Ferrite nanoparticles (∼75 nm and ∼155 nm) synthesized by a chemical method, using soft X-ray (1253.6 eV) and hard X-ray (3500, 5500, and 7500 eV) photoelectron spectroscopy. This provided an evidence for the variation of chemical state of Bismuth in crystalline, phase pure nanoparticles. X-ray photoelectron spectroscopy analysis using Mg Kα (1253.6 eV) source showed that iron and Bismuth were present in both Fe3+ and Bi3+ valence states as expected for Bismuth Ferrite. However, hard X-ray photoelectron spectroscopy analysis of the Bismuth Ferrite nanoparticles using variable photon energies unexpectedly showed the presence of Bi0 valence state below the surface region, indicating that Bismuth Ferrite nanoparticles are chemically inhomogeneous in the radial direction. Consistently, small-angle X-ray scattering reveals a core-shell structure for these radial inhomogeneous nanoparticles.
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Coercivity and exchange bias of Bismuth Ferrite nanoparticles isolated by polymer coating
Journal of Applied Physics, 2014Co-Authors: Smita Chaturvedi, Mandar M. Shirolkar, Ranguwar Rajendra, Surjeet Singh, Nirmalya Ballav, Sulabha K. KulkarniAbstract:Bismuth Ferrite nanoparticles have been extensively investigated over the last few years due to their potential candidacy for application in future memory devices. However, all the work reported so far on Bismuth Ferrite nanoparticles is on agglomerated nanoparticles. Agglomerated particles can magnetically interact with each other. To utilize them for device application, it is useful to know the properties of the individual particles. Here, de-agglomeration of ∼75 nm Bismuth Ferrite nanoparticles is achieved by polyaniline coating on the surface. The structural and magnetic properties of agglomerated and de-agglomerated nanoparticles are compared. It is observed that there is a change in the lattice parameters and Fe-O-Fe and O-Bi-O bond angles due to polyaniline shell. The coercivity of the Bismuth Ferrite/polyaniline core shell particles is reduced as compared to pure and agglomerated Bismuth Ferrite particles. The observed changes in the magnetic properties of coated particles are attributed to the shell induced isolation of individual Bismuth Ferrite nanoparticles as well as structural changes due to polyaniline coating.
Raja Das - One of the best experts on this subject based on the ideXlab platform.
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tunable band gap and coercivity of Bismuth Ferrite polyaniline core shell nanoparticles the role of shell thickness
RSC Advances, 2015Co-Authors: Smita Chaturvedi, Raja Das, Pankaj Poddar, S K KulkarniAbstract:We report a tunable band gap of Bismuth Ferrite–polyaniline core–shell nanoparticles from 2.24 to 1.98 eV and the variation of coercivity from 118 to 100 Oe, by varying the thickness of the polyaniline shell. Bismuth Ferrite nanoparticles were synthesized via a chemical route and coating of polyaniline was achieved by a double surfactant layer technique. Coating of polyaniline introduced oxygen vacancies, local distortions and microstrains in the Bismuth Ferrite lattice which resulted in a change in the Fe–O–Fe bond angle of the Bismuth Ferrite lattice. This is confirmed with structural analysis tools i.e. X-ray Diffraction, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. Moreover, the absorption of light around 600 nm is increased and photoluminescence emission around 430 nm is decreased, as the thickness of shell is increased, which also indicates the changes in optical properties due to variation in shell thickness. Thus tunability of the band gap and coercivity is achieved as a function of shell thickness in Bismuth Ferrite–polyaniline core–shell nanoparticles.
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Tunable band gap and coercivity of Bismuth Ferrite–polyaniline core–shell nanoparticles: the role of shell thickness
RSC Advances, 2015Co-Authors: Smita Chaturvedi, Raja Das, Pankaj Poddar, Sulabha K. KulkarniAbstract:We report a tunable band gap of Bismuth Ferrite–polyaniline core–shell nanoparticles from 2.24 to 1.98 eV and the variation of coercivity from 118 to 100 Oe, by varying the thickness of the polyaniline shell. Bismuth Ferrite nanoparticles were synthesized via a chemical route and coating of polyaniline was achieved by a double surfactant layer technique. Coating of polyaniline introduced oxygen vacancies, local distortions and microstrains in the Bismuth Ferrite lattice which resulted in a change in the Fe–O–Fe bond angle of the Bismuth Ferrite lattice. This is confirmed with structural analysis tools i.e. X-ray Diffraction, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. Moreover, the absorption of light around 600 nm is increased and photoluminescence emission around 430 nm is decreased, as the thickness of shell is increased, which also indicates the changes in optical properties due to variation in shell thickness. Thus tunability of the band gap and coercivity is achieved as a function of shell thickness in Bismuth Ferrite–polyaniline core–shell nanoparticles.
Pankaj Poddar - One of the best experts on this subject based on the ideXlab platform.
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tunable band gap and coercivity of Bismuth Ferrite polyaniline core shell nanoparticles the role of shell thickness
RSC Advances, 2015Co-Authors: Smita Chaturvedi, Raja Das, Pankaj Poddar, S K KulkarniAbstract:We report a tunable band gap of Bismuth Ferrite–polyaniline core–shell nanoparticles from 2.24 to 1.98 eV and the variation of coercivity from 118 to 100 Oe, by varying the thickness of the polyaniline shell. Bismuth Ferrite nanoparticles were synthesized via a chemical route and coating of polyaniline was achieved by a double surfactant layer technique. Coating of polyaniline introduced oxygen vacancies, local distortions and microstrains in the Bismuth Ferrite lattice which resulted in a change in the Fe–O–Fe bond angle of the Bismuth Ferrite lattice. This is confirmed with structural analysis tools i.e. X-ray Diffraction, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. Moreover, the absorption of light around 600 nm is increased and photoluminescence emission around 430 nm is decreased, as the thickness of shell is increased, which also indicates the changes in optical properties due to variation in shell thickness. Thus tunability of the band gap and coercivity is achieved as a function of shell thickness in Bismuth Ferrite–polyaniline core–shell nanoparticles.
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Tunable band gap and coercivity of Bismuth Ferrite–polyaniline core–shell nanoparticles: the role of shell thickness
RSC Advances, 2015Co-Authors: Smita Chaturvedi, Raja Das, Pankaj Poddar, Sulabha K. KulkarniAbstract:We report a tunable band gap of Bismuth Ferrite–polyaniline core–shell nanoparticles from 2.24 to 1.98 eV and the variation of coercivity from 118 to 100 Oe, by varying the thickness of the polyaniline shell. Bismuth Ferrite nanoparticles were synthesized via a chemical route and coating of polyaniline was achieved by a double surfactant layer technique. Coating of polyaniline introduced oxygen vacancies, local distortions and microstrains in the Bismuth Ferrite lattice which resulted in a change in the Fe–O–Fe bond angle of the Bismuth Ferrite lattice. This is confirmed with structural analysis tools i.e. X-ray Diffraction, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. Moreover, the absorption of light around 600 nm is increased and photoluminescence emission around 430 nm is decreased, as the thickness of shell is increased, which also indicates the changes in optical properties due to variation in shell thickness. Thus tunability of the band gap and coercivity is achieved as a function of shell thickness in Bismuth Ferrite–polyaniline core–shell nanoparticles.