Browsing by Author "Paramananda Jena"

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Influence of Lanthanum Doping on Structural and Electrical/Electrochemical Properties of Double Perovskite Sr2CoMoO6 as Anode Materials for Intermediate-Temperature Solid Oxide Fuel Cells
(American Chemical Society, 2019) Pravin Kumar; Paramananda Jena; P.K. Patro; R.K. Lenka; A.S.K. Sinha; Prabhakar Singh; Rajendra Kumar Singh
Lanthanum (La3+)-doped double perovskites Sr2CoMoO6 (Sr2-xLaxCoMoO6, 0.00 ≤ x ≤ 0.03) were synthesized via the citrate-nitrate autocombustion route. The Reitveld refinement analysis of X-ray diffraction reveals the tetragonal symmetry as the main phase with space group I4/m and also confirms the presence of some peaks corresponding to extra phase SrMoO4. The SEM micrograph images reflect that grains are in irregular shape and sizes for all samples. Average grain size gradually decreases with the increase of the SrMoO4 phase. The X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of mixed valence states of Mo5+/Mo6+, Co2+/Co3+, and O-lattice/O-chemisorbed/O-physisorbed species. Coefficient of thermal expansion (CTE) analysis shows that the particular composition Sr1.97La0.03CoMoO6 has the lowest CTE value among the compositions studied. The electrical conductivity of Sr2CoMoO6 is enhanced effectively by doping La at Sr sites. The measured area-specific resistance (ASR) for the composition Sr1.97La0.03CoMoO6 (SLCM03) is found to be appreciably low, â0.053 Ohm cm-2 at 800 °C. The obtained highest electrical conductivity with the lowest activation energy and low ASR value for the composition Sr1.97La0.03CoMoO6 encompasses it as a promising candidate for anode material in the intermediate-temperature solid oxide fuel cell (IT-SOFC) application. © 2019 American Chemical Society.
R3c to P1 phase transition in Nd3+/Gd3+ co-doped BiFeO3 nanoparticles: Enhanced magnetic and photocatalytic properties
(Elsevier Ltd, 2025) Sandeep Kumar Chauhan; Amit A. Kumar; Narendra Kumar Verma; Paramananda Jena; Bani Mahanti; Sandeep Kumar Singh Patel
We successfully synthesized pure and Nd3+/Gd3+ co-doped BiFeO3 nanoparticles (NPs) via the sol–gel route. X-ray diffraction (XRD) and Raman spectroscopy studies indicates that co-doping at the Bi3+ sites triggered a structural phase transition from rhombohedral (R3c) to triclinic (P1). Also resulted in a decrease in particle size from 41 nm to 33 nm. XPS analysis confirmed successful Nd3+/Gd3+ co-doping in BiFeO3 NPs and reveals the presence of Fe2+ ions. The optical band gap of doped NPs decreased significantly from 2.10 to 1.94 eV. Magnetization measurements revealed a significant enhancement in magnetization values under an applied field of 50 kOe, reaching 1.70 emu/g, a 300 % increase compared to pure BiFeO3 due to the suppression of the spiral spin structure, suggests potential application for spintronics. Nd3+/Gd3+ co-doped BiFeO3 NPs showed remarkable photocatalytic activity, degrading 99 % of methylene blue dye under sunlight irradiation in just 90 min as compared to BiFeO3 NPs. © 2025 Elsevier B.V.
Room-temperature dilute magnetic semiconductor behavior in nonmagnetic Ti4+-doped CeO2 nanoflowers for efficient spintronics and photocatalytic applications
(Springer, 2025) Sandeep Kumar Chauhan; Amit A. Kumar; Paramananda Jena; Simant Kumar Srivastav; Sandeep Kumar Singh Patel
This study investigates the synthesis and characterization of Ti-doped CeO2 nanoflowers (Ce1-xTixO2, x = 0, 0.01, 0.03, and 0.05) prepared via a hydrothermal method. Characterization techniques, including XRD, TEM, XPS, and Raman spectroscopy, confirmed the successful incorporation of Ti into the CeO2 lattice, leading to the formation of pure CeO2 nanoflowers with cubic structure and an increase in oxygen vacancies. The optical band gap of the doped nanoflowers decreased from 3.27 to 3.07 eV. Room temperature ferromagnetism was observed in Ce1-xTixO2 nanoflowers (x = 0.01, 0.03, and 0.05). Notably, the x = 0.05 composition exhibited a remarkable 376% increase in ferromagnetism, reaching 55 × 10−3 emug−1 at 15 kOe. This ferromagnetism is likely attributed to the oxygen vacancies created by doping, which trap charges and lead to the formation of F-centers. These F-centers then interact with impurity atoms, enhancing the magnetic properties. Increased Ti-doping resulted in a noticeable quenching of photoluminescence intensity, indicating improved charge carrier separation. This enhanced separation contributed to the photocatalytic activity of the synthesized samples, which was assessed by methylene blue degradation under UV light. The sample with x = 0.05 exhibited the highest photocatalytic activity. These findings suggest that Ti-doped CeO2 based diluted magnetic semiconductors hold promise for applications in spin-based electronics, optoelectronics and photocatalysis. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.