Department Of Physics
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Item Observation of magnetic vortex configuration in non-stoichiometric Fe3O4 nanospheres(Royal Society of Chemistry, 2023-08-31T00:00:00) Niraula, Gopal; Toneto, Denilson; Goya, Gerardo F.; Zoppellaro, Giorgio; Coaquira, Jose A. H.; Muraca, Diego; Denardin, Juliano C.; Almeida, Trevor P.; Knobel, Marcelo; Ayesh, Ahmad I.; Sharma, Surender K.Theoretical and micromagnetic simulation studies of magnetic nanospheres with vortex configurations suggest that such nanostructured materials have technological advantages over conventional nanosystems for applications based on high-power-rate absorption and subsequent emission. However, full experimental evidence of magnetic vortex configurations in spheres of submicrometer size is still lacking. Here, we report the microwave irradiation fabrication of Fe3O4 nanospheres and establish their magnetic vortex configuration based on experimental results, theoretical analysis, and micromagnetic simulations. Detailed magnetic and electrical measurements, together with M�ssbauer spectroscopy data, provide evidence of a loss of stoichiometry in vortex nanospheres owing to the presence of a surface oxide layer, defects, and a higher concentration of cation vacancies. The results indicate that the magnetic vortex spin configuration can be established in bulk spherical magnetite materials. This study provides crucial information that can aid the synthesis of magnetic nanospheres with magnetically tailored properties; consequently, they may be promising candidates for future technological applications based on three-dimensional magnetic vortex structures. � 2023 RSC.Item Enhanced photocatalytic activity of BiOBr/ZnWO4 heterojunction: A combined experimental and DFT-based theoretical approach(Elsevier B.V., 2023-03-28T00:00:00) Andrade, Alana O.C.; Lacerda, Lu�s Henrique da Silveira; Lage J�nior, M.M.; Sharma, Surender K.; Maia da Costa, M.E.H.; Alves, Odivaldo C.; Santos, Evelyn C.S.; dos Santos, C.C.; de Menezes, A.S.; San-Miguel, Miguel Angel; Filho, Francisco Moura; Longo, Elson; Almeida, Marcio A.P.We report a successful fabrication of BiOBr/ZnWO4 heterojunction with enhanced photocatalytic performance for degrading Rhodamine B dye validated by joint experimental and theoretical approaches. The structural and microstructural analysis indicate that the heterostructures consist of a mixed tetragonal/monoclinic phase with enhanced surface area, which is crucial for photocatalysis. The results indicate increased photocatalytic activity for heterojunctions since BiOBr/ZnWO4 heterostructure showed a better degradation rate for Rhodamine B dye as compared to BiOBr due to higher surface area, pore size, and better photogenerated electron-hole pair separation efficiency. Additional analyses using isopropanol, benzoquinone, and sodium azide scavengers analysis were performed, showing that superoxide radicals (O2?) as the main responsible for the photocatalytic degradation of investigated materials. The theoretical analysis offers a complete overview of the composition and electronic structure of the interface. � 2023 Elsevier B.V.Item Bi-phasic BiPO4 prepared through template-assisted hydrothermal method with enhanced electrochemical response for hybrid supercapacitor applications(Springer Science and Business Media B.V., 2023-03-27T00:00:00) Monteles, Iara A.; Penha, Bruno V.; Fonseca, Weliton S.; Silva, Let�cia M. B.; Santos, Evelyn C. S.; de Souza, Luiz K. C.; Santos, C.C.; de Menezes, A.S.; Sharma, Surender K.; Javed, Yasir; Khawar, Muhammad R.; Tanaka, Auro A.; Almeida, Marcio A. P.Abstract: We report the structural evolution of BiPO4 prepared in aqueous under different synthesis conditions viz., templates and temperatures to explore their electrochemical performance for supercapacitor applications. The templates [(hexadecyltrimethylammonium bromide (CTAB)), sodium dodecyl sulfate (SDS)] were added in bismuth precursor solution at 60��C, alternatively ethylene glycol (EG), a less toxic additive was incorporated at 90��C. BiPO4 exhibits a monoclinic phase, whereas a hexagonal structure was observed with the addition of the templates SDS and CTAB. Interestingly, both monoclinic and hexagonal phases were obtained by the addition of EG. The presence of mixed phase was thoroughly validated through Raman spectra, where vibrational modes for both monoclinic and hexagonal phases of BiPO4-EG were witnessed. The effect of template was clearly seen through electron microscopy with a rod-like morphology with (no template) and unfaceted (template). The electrochemical behavior of the synthesized materials was investigated, and it was found that the mixed structure of BiPO4-EG exhibited the highest specific capacity (167.15 C�g?1) at a scan rate of 5�mV�s?1, good capacitance retention at high current densities of up to 10 A�g?1 and the lowest electrochemical series resistance (ESR) of 57 ?. Graphical abstract: [Figure not available: see fulltext.]. � 2023, The Author(s), under exclusive licence to Springer Nature B.V.Item BiOBr/ZnWO4 heterostructures: An important key player for enhanced photocatalytic degradation of rhodamine B dye and antibiotic ciprofloxacin(Elsevier Ltd, 2022-11-07T00:00:00) Santana, Rafael W.R.; Lima, A.E.B.; Souza, Luiz K.C. de; Santos, Evelyn C.S.; Santos, C.C.; Menezes, A.S. de; Sharma, Surender K.; Cavalcante, L.S.; Maia da Costa, Marcelo E.H.; Sales, T.O.; Jacinto, Carlos; Luz, G.E.; Almeida, M.A.P.We report a facile synthesis of p-BiOBr/n-ZnWO4 heterostructures by hydrothermal/precipitation method as an important key player to enhance the photocatalytic degradation of Rhodamine B (RhB) dye and ciprofloxacin antibiotic. The structural and microstructural features confirm that p-BiOBr/n-ZnWO4 heterostructures display a mixed tetragonal/monoclinic phase with the presence of several n-ZnWO4 nanocrystals on the surface of petals of flower-like p-BiOBr microcrystals. X-ray photoluminescence (XPS) analysis of BiOBr exhibits the existence of Bi, O, and Br, whereas BiOBr/ZnWO4-5%, in addition to Bi, O, and Br, consist of signature of Zn and W. UV�Visible spectra of p-BiOBr/n-ZnWO4-5% showed better absorption than p-BiOBr and n-ZnWO4, which displayed an enhanced collection of photons in the heterojunction. An intense photoluminescence emission at room temperature was observed for p-BiOBr microcrystals as compared to p-BiOBr/n-ZnWO4. We observed the best photocatalytic activity for p-BiOBr/n-ZnWO4-2.5% in the degradation of RhB dye at 99.4% in 25 min and CIP antibiotic at 58.2% in 170 min, which is assigned due to high surface area SBET (13 m2/g), pore size, providing active catalytic sites for bonding chemical and surface interaction and bonding chemical between the bromide/oxides. Finally, we have investigated the use of scavengers for isopropanol, benzoquinone, and sodium azide, which proves that the hydroxyl (�OH) and superoxide (O2?) radicals as the foremost reactive oxygen spicies (ROS) in photocatalytic degradation of RhB dye and antibiotic CIP. � 2022 Elsevier LtdItem State of Art of Spinel Ferrites Enabled Humidity Sensors(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Mathpal, Mohan Chandra; Niraula, Gopal; Chand, Mahesh; Kumar, Promod; Singh, Manish Kumar; Sharma, Surender K.; Soler, Maria A. G.; Swart, H.C.Controlling the moisture level in air and gases is an important aspect in defense, weather station, industry, laboratory and healthcare systems. The accurate measurement and sensing of the humidity/moisture level in the surrounding environment can help to maintain the temperature level for ideal living conditions; from a safety point of view, it can help to prevent the virus/disease transmission; importantly, it can protect expensive equipment, electronic devices and optical devices against damage which are sensitive to high humidity in the atmosphere. The controlled monitoring, regulation and management of humidity necessarily require humidity sensors with high sensitivity, high stability and low response time. Currently, there are various types of humidity sensors available in the market, but there are always limitations on the practical applications as the main problems are associated with their eco-friendly nature, cost, sensitivity, response time (rapid action) and lifetime. Aiming to address these issues, the spinel ferrite nanostructures arise as promising nanomaterials due to their moderate semiconducting features with high resistance, porous nature and high surface activities enabling easy fabrication of the humidity sensors. This chapter provides an overview of the role of spinel ferrite nanostructures for their applications in humidity sensors. � 2021, Springer Nature Switzerland AG.Item Ferrites as an Alternative Source of Renewable Energy for Hydroelectric Cell(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Mathpal, Mohan Chandra; Niraula, Gopal; Kumar, Promod; Chand, Mahesh; Singh, Manish Kumar; Sharma, Surender K.; Soler, Maria A. G.; Swart, H.C.There are many conventional ways of producing energy at large scales such as fossil fuels, hydroelectric power station, wind energy, solar cell plants, marine energy, etc., but most of these require bulky plantation, huge manpower, wide land occupation and are non-portable and expensive to handle too. In the twenty-first century, there is still a huge gap between worldwide energy supply and its demand. The advances in the technology sector have also increased the consumption of energy, but the sources of generating the renewable energy remain limited. In order to account for these problems in recent years, several methods have been adopted and a significant research in this direction has been made by the invention of the hydroelectric cell by Dr. R. K. Kotnala�s group in 2016. Instead of using the magnetic character in the ferrite nanostructures, these nanomaterials were first time effectively exploited for direct energy harvesting application by using their capability to dissociate the absorbed water molecules on its porous surface. This allows the production of ions, which is then followed by the charge transfer of hydronium, hydroxyl and hydrogen ions between the electrodes of the ferrite nanostructures and results in the generation of an electric current across the circuit. The concept of the hydroelectric cell is new, and these cells are easily portable, inexpensive, biodegradable and eco-friendly in nature. This chapter provides an insight on the concept of spinel ferrite nanostructures for the application in the hydroelectric cell. � 2021, Springer Nature Switzerland AG.Item Magnetic Ferrites-Based Hybrids Structures for the Heavy Metal Removal(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Abbas, Muhammad Khawar; Yasin, Effat; Sajid, Muhammad Munir; Shad, Naveed Akhtar; Akhtar, Kanwal; Manhas, Anita; Sharma, Surender K.; Javed, YasirAdsorption is a major process for heavy metal removal and the research trend is focused toward the applications of new technologies in order to intensify the already existing processes. Intrinsic properties of magnetic materials (arrangement and surface-to-volume ratio) of adsorbate and adsorbent are critical for satisfactory results. Magnetic field strength plays an important role as it indicates the alignment of spins with the magnetic field to provide adsorbate mobility and generate heterogeneity at adsorbent surface. Applications of magnetic field for intensification of adsorption process provide environment friendly, safe and economic alternative. This chapter describes different types of magnetic ferrites-based hybrids for heavy metal removal. Surface modification of magnetic nanohybrids through different surface modification strategies and general adsorption mechanisms for different types of pollutants are discussed comprehensively. Major thrust of this chapter is to provide information about different features of magnetic ferrites for their potential application as adsorbent for heavy metal removal. � 2021, Springer Nature Switzerland AG.Item Potential of Iron Oxide Nanoparticles as Drug Delivery Vehicle(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Hassan, Muhammad Aamir; Khan, Aqib Zafar; Sajid, Muhammad Munir; Javed, Yasir; Ullah, Asmat; Shad, Naveed Akhtar; Sharma, Surender K.; Shafique, Muhammad; Sarwar, MuhammadNanotechnology has introduced new techniques and therapeutic approaches for the treatment of different cancer types. Current cancer-curing drugs have many limitations such as use of high concentrations, effects on other cells, and non-confinement at cancer sites, which reduce the efficacy of drugs and also induce toxic effects in other normal cells. Nanomaterials have provided new ways to increase the efficacy of already used cancer drugs by providing drug delivery systems. Anticancer drugs can be encapsulated/attached with the nanomaterials and delivered at specific sites and cells under certain microenvironment conditions. Among metallic oxide nanoparticles, iron-based particles have shown great potential in drug delivery and at the same time for cancer treatment by producing localized heat. Therefore, researchers have focused on iron oxide nanoparticles as drug delivery vehicles. This chapter highlights the synthesizing methods of iron oxide nanoparticles such as co-precipitation, thermal decomposition, microemulsion, sol�gel, and additional chemical methods including hydrothermal, sonochemical decomposition, and electrochemical for their wide range of biomedical applications. It also provides a brief overview of recent developments in iron oxide nanoparticles, some limitations in the explored research areas. and suggests future directions to overcome these limitations. � 2021, Springer Nature Switzerland AG.Item Superparamagnetic Iron Oxide-Based Nanomaterials for Magnetic Resonance Imaging(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Niraula, Gopal; Mathpal, Mohan Chandra; Medrano, Jason J. A.; Singh, Manish Kumar; Coaquira, Jose A. H.; Verma, Ramesh; Sharma, Surender K.Magnetic resonance imaging (MRI) is the technique for the visualization of targeted macromolecules or cells in biological system. Nowadays, superparamagnetic iron oxide nanoparticles (SPIONs) have been attracted and remarkably emerging as a negative contrast agent (T2-weighted) offering sufficient detection sensitivity as compared to positive contrast agent (T1-weighted). In the present chapter, we first introduce the necessary background of superparamagnetic iron oxide-based nanoparticles and MRI taking into an account to discuss both T1�T2-weighted imaging. The liquid-based synthesis methods of SPIONs and their applicability in MRI have been thoroughly revised. Finally, several nanohybrids such as magnetic-silica, magneto-luminescent, magneto-plasmonic along with ferrite-based SPIONs are thoroughly presented in light of MRI application. � 2021, Springer Nature Switzerland AG.Item Low Loss Soft Ferrites Nanoparticles for Applications Up to S-band(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Sharma, Sucheta; Verma, Ramesh; Singh, Mahavir; Sharma, Surender K.This chapter aims at providing a better understanding of soft ferrites and their role in ultra-high-frequency applications. In wireless communication industry trends of miniaturized, highly efficient and wide-band antenna become the new research areas of the antenna technology. Antenna miniaturization cannot be achieved by simply changing the structural design, and it is important to improve the material characteristics of antenna substrates. Furthermore, to improve the antenna efficiency, almost matched permittivity and permeability values and low magnetic as well as dielectric loss tangents are required especially at ultra-high frequency (UHF), L-band, and S-band frequency range. For efficiency improvement and miniaturization of antennas, magneto-dielectric materials have significant advantages with matching permittivity and permeability values along with sufficiently low magnetic and dielectric loss tangents. Ferrites with very high resistance have been reported as the best host materials to produce low loss magneto-dielectric materials for high-frequency antenna applications as they present moderate permeability and permittivity values. In this chapter, the emphasis is given on the soft ferrites Mn�Zn, Ni�Zn spinel ferrite, and Co2Z type barium hexaferrite. The chapter also explains the effect of substitution of different dopant ions on the properties of soft ferrites. � 2021, Springer Nature Switzerland AG.