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Author: search.filters.author.Prasad Dasari, H.P.

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    Solubility Limits of Ceria-Zirconia-Lanthana Solid-Solutions
    (Elsevier Ltd, 2017) Abbas, Z.; Surendran, M.; Anjana, P.A.; Jidev, P.K.; Harshini, H.; Sudhakar Naidu, N.; Anandhan, S.; Bhat, K.U.; Bhaskar Babu, G.U.; Prasad Dasari, H.P.
    We demonstrate, the solubility limits of Ceria-Zirconia-Lanthana (CZLa) solid-solutions with the increase in heat-treatment temperature from 600°C to 1300°C. CZLa nano-crystalline samples were successfully synthesized by EDTA-Citrate complex method and were characterized by Raman Spectroscopy (RS) and Transmission Electron Microscopy (TEM) analysis. With an increase in temperature, it is noticed that the solubility limit is decreased in CZLa system. At 600°C, a very good solubility is observed in CZLa system and is confirmed from RS analysis. At higher heat-treatment temperatures (1000 and 1300°C), with an increase in La content, Zr precipitated in the CZLa system and is confirmed from RS analysis. The reason for such kind of behavior in this CZLa system is clearly explained in this work. © 2017 Elsevier Ltd.
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    Shrinkage Behavior, Thermal expansion Behavior, and Electrical Conductivity Study of Samarium Doped Ceria Electrolytes
    (IOP Publishing Ltd, 2021) Lakhanlal, u.; Prasad Dasari, H.P.; Saidutta, M.B.
    In the present study, sintering behavior and electrical conductivity of Sm doped Ceria (SDC) and multi-doped (Sm/Pr/Li) Ceria electrolytes synthesized by microwave-assisted co-precipitation method is studied. SDC green pellet displayed a unimodal shrinkage behavior with a linear shrinkage of 15.67% along with a slight dedensification above 1350?. An increase in electrical conductivity with an increase in sintering temperature from 1200 to 1300 ? was observed. Further increasing the sintering temperature (1400 and 1500 ?) electrical conductivity decreased, which could be due to dedensification (as observed in sintering behavior). At 600 ?, the electrical conductivity of SDC1200 is around 1.34 × 10- 2 S cm-1. The sintering temperature is drastically decreased to 850 ? from 1200 ? with the addition of Li, and the electrical conductivity is increased with the addition of Pr to SDC electrolytes. At 600 ?, the electrical conductivity of 3Li-SPDC850 sintered at 850 ? is 1.44 × 10-2 S cm-1. The thermal expansion coefficient (TEC) of the electrolytes studied were in the range of 12.7 × 10-6 to 17.6 × 10-6 K-1. © 2021 Electrochemical Society Inc.. All rights reserved.
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    Synthesis of Praseodymium-Doped Ceria-Based Electrolyte Material by Hydrothermal Method
    (Springer Science and Business Media Deutschland GmbH, 2022) Rao, R.; Kamath, K.; Priyanka, R.; Shajahan, I.; Prasad Dasari, H.P.
    Praseodymium-doped ceria (PDC)-based electrolyte powder was synthesised by the hydrothermal method. The as-synthesised powder was studied by various powder characterisations such as X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM) analysis to find out the crystallinity, phase, nature and structural morphology. The shrinkage behaviour (linear shrinkage and shrinkage rate) of PDC powder at high temperatures was performed by dilatometer studies. The crystallographic parameters including the crystallite size, lattice strain and lattice parameter were calculated from XRD analysis. Raman spectroscopy analysis revealed the characteristic peak at 460 cm−1 which corresponds to the F2g peak of the cubic phase of ceria and the peak at 550 cm−1 is attributed to intrinsic oxygen vacancies that confirmed the formation of ceria praseodymium solid solution. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Potential of pyrochlore structure materials in solid oxide fuel cell applications
    (Elsevier Ltd, 2021) Anjana, A.P.; Prasad Dasari, H.P.
    Pyrochlore structure material (A2B2O7) has gained interest in diverse applications like catalysis, nuclear waste encapsulation, sensors, and various electronic devices due to the unique crystal structure, electrical property, and thermal stability. This review deals with the ionic/electronic conductivity of numerous pyrochlore structure materials (titanates, zirconates, hafnates, stannates, niobates, ruthenates, and tantalite based pyrochlore) as electrolyte and electrode materials for solid oxide fuel cells (SOFCs). The impact of cation radius ratio (rA/rB) on the lattice constant and oxygen ‘x’ parameter of different pyrochlore structure materials obtained by various synthesis methods are reported. Higher ionic conductivity is essential for better ion transport in an electrolyte, and mixed ionic and electronic conductivity in electrode is essential for attaining higher efficiency in a typical SOFC. GdxTi2O7-δ, Gd2-xCaxTi2O7-δ, Nd2-yGdyZr2O7, Y2Zr2O7, Y2Zr2-xMnxO7-δ, SmDy1-xMgxZr2O7-x/2, Gd2-xCaxTi2O7-δ pyrochlore are reported as electrolytes for fuel cell applications. Some pyrochlore material (La2-xCaxZr2O7, Sm2-xMxTi2O7 (M = Mg, Co, and Ni) pyrochlore) shows protonic conductivity at lower temperatures and ionic conductivity at higher temperature condition. Also, the mixed ionic-electronic conductivity behavior is reported in electrode materials for SOFC such as R2MnTiO7 (R = Er and Y), R2MnRuO7 (R = Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y), R2Ru2O7 (R = Bi, Pb and Y), Y2-xPrxRu2O7, Ni-(Gd0.9Ca0.1)2Ti2O7-δ, (Gd0.9Ca0.1)2Ti2O7-δ, Gd2(Ti0.8Ru0.2)2O7-δ, (Sm0.9Ca0.1)2Ti2O7-δ and (Y0.9Ca0.1)2Ti2O7-δ pyrochlore. The detailed study of the electronic behavior of these pyrochlore system confirms the necessity of defect structure with high oxygen mobility, lower activation energy, ionic radii ratio criterion should satisfy, and possess notable ion-ion interaction. Ionic conductivity in pyrochlore is increased by enhancing the oxygen migration through 48f-48f site with the formation of oxygen vacancy. Vacancy formation can be achieved by adding a suitable dopant that creates oxygen vacancy by charge compensation mechanism or as anion Frenkel defects. Similarly, the electrical conductivity is improved while adding suitable dopant (Ce, Pr, Ru, etc.) due to disordered structure and anti-Frenkel defect formation which leads to oxygen vacancy formation and thus improves conductivity. © 2020 Elsevier Ltd and Techna Group S.r.l.
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    Ceria-based electrospun nanofibers and their widespread applications: A review
    (Academic Press, 2025) Prasad Dasari, H.P.; Patil, S.S.; Kamath, R.S.; Kisiela-Czajka, A.M.
    Electrospinning is a highly efficient technique for producing nanofibers, and it is noted for its cost-effectiveness, versatility, and user-friendly nature. The article evaluates the production of Ceria-based nanofibers primarily utilizing electrospinning technology and electrospinning parameters and explores their various potential applications. Ceria infused with lanthanoids and transition metals demonstrates significant potential as catalysts, optical sensors, and supercapacitors in various energy-related industrial applications. Their role as catalysts in water-gas and reverse water-gas shift reactions greatly enhances the water-splitting reaction in the Deacon process. Composite ceria nanofibers for wound therapy were developed by integrating polyurethane, cellulose acetate, and zein for biological applications. Soot-induced blockages in automobile filters pose challenges for the regeneration process of diesel particle filters, and the effectiveness of ceria-based nanofibers in soot and CO oxidation has been explored. Ce-based nanofibers produced via the electrospinning technique, with different operating parameters, exhibit notable variations in their morphology. Research indicates that, compared to traditional ceria, Ce-based nanofibers demonstrate greater surface area and porosity, a higher density of oxygen vacancies, and improved oxygen transfer efficiency, all essential for numerous redox and catalytic processes. The nanofibrous structure enhances electrical conductivity by expanding the surface area accessible for interaction with active components. The nanofibrous composite structure exhibits enhanced thermal and mechanical durability, making it appealing for numerous applications. © 2025 Elsevier Ltd
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    From non-renewable waste to activated carbon: A smart move towards sustainable development and environmental protection in a circular economy
    (Elsevier Ltd, 2025) Patil, S.S.; Kisiela-Czajka, A.M.; Prasad Dasari, H.P.
    Waste generation is unavoidable as the population grows and globalisation/modernisation occurs. Ineffective garbage management and treatment raise major environmental concerns. This study provides a comprehensive and unique compilation of available knowledge on the potential use of various non-renewable waste materials to produce activated carbon (AC). One document brings together and evaluates the potential for converting hazardous and non-hazardous waste – from industrial and municipal to recyclable and medical waste – into a valuable resource with wide-ranging applications. The appropriately selected conversion method is key to converting waste into a valuable activated carbon product. It must consider both the applicable legal regulations and the key technological parameters that determine the quality and suitability of the final product for a specific application. The numerous carbonisation and activation methods employed to convert waste to AC include hydrothermal, ionothermal, pyrolysis and microwave-assisted methods. AC's elemental composition and functional groups are analysed using elemental analysis, XPS and FTIR. Crystal structure and phase identification are performed via XRD, SEM and TEM. Surface area and porosity are determined using the BET and BJH methods, along with the iodine index. Following the thermal conversion of various waste materials into AC, it is widely used in multiple disciplines, including energy and the environment. AC is used as an adsorbent to effectively remove harmful elements from water, including pharmaceutical contamination, dyes and heavy metals. AC has excellent electrochemical characteristics and is highly efficient in CO2 capture. AC also extracts valuable products such as hydrocarbons, methane and uranium. © 2025 The Author(s)
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    Record-low sintering-temperature (600 °c) of solid-oxide fuel cell electrolyte
    (Elsevier Ltd, 2016) Prasad Dasari, H.P.; Ahn, K.; Park, S.-Y.; Hong, J.; Kim, H.; Yoon, K.J.; Son, J.-W.; Kim, B.-K.; Lee, H.-W.; Lee, J.-H.
    One of the major problems arising with Solid-Oxide Fuel Cell (SOFC) electrolyte is conventional sintering which requires a very high temperature (>1300 °C) to fully densify the electrolyte material. In the present study, the sintering temperature of SOFC electrolyte is drastically decreased down to 600 °C. Combinational effects of particle size reduction, liquid-phase sintering mechanism and microwave sintering resulted in achieving full density in such a record-low sintering temperature. Gadolinium doped Ceria (GDC) nano-particles are synthesized by co-precipitation method, Lithium (Li), as an additional dopant, is used as liquid-phase sintering aid. Microwave sintering of this electrolyte material resulted in decreasing the sintering temperature to 600 °C. Micrographs obtained from Scanning/Transmission Electron Microscopy (SEM/TEM) clearly pointed a drastic growth in grain-size of Li-GDC sample (?150 nm) than compared to GDC sample (<30 nm) showing the significance of Li addition. The sintered Li-GDC samples displayed an ionic conductivity of ?1.00 × 10-2 S cm-1 at 600 °C in air and from the conductivity plots the activation energy is found to be 0.53 eV. © 2016 Elsevier B.V. All rights reserved.
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    Synthesis of GDC electrolyte material for IT-SOFCs using glucose & fructose and its characterization
    (Elsevier B.V., 2017) Medisetti, S.; Ahn, J.; Patil, S.; Goel, A.; Bangaru, Y.; Sabhahit, G.V.; Babu, G.U.B.; Lee, J.-H.; Prasad Dasari, H.P.
    Nano-powder of gadolinium-doped-ceria (GDC, Ce0.9Gd0.1O2) has been synthesized using a novel sol–gel method with glucose and fructose as organic additives. The main objective of the present study is to find the suitability of this synthesis method in synthesizing ceria-based SOFC electrolyte materials and evaluate its performance. The average crystallite/particle size obtained from XRD, TEM, BET surface area was found to be 4–12 nm. The phase was found to be cubic fluorite from XRD and further the structure and the nature of oxygen vacancies was confirmed using Raman spectroscopy. Dilatometer studies illustrated two shrinkage maxima (450 °C and 1450 °C). The ionic conductivity measurements were done using DC four-probe method on the GDC electrolyte sintered at 1500 °C. The sintered sample showed an ionic conductivity of 1.13E?02 Scm?1 at a temperature of 700 °C in the air, and the activation energy is 1.02 eV. The present study reveals that this synthesis method can be adaptable for synthesizing SOFC electrolyte materials. © 2017 Elsevier B.V.
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    Soot Oxidation Activity of Redox and Non-Redox Metal Oxides Synthesised by EDTA–Citrate Method
    (Springer New York LLC barbara.b.bertram@gsk.com, 2017) Anjana, A.P.; Prasad Dasari, H.P.; Lee, J.-H.; Harshini, H.; Babu, G.U.B.
    Abstract: In the present study, redox (CeO2, SnO2, Pr6O11 and Mn3O4) and non-redox (Gd2O3, La2O3 ZrO2 and HfO2) metal oxides were successfully synthesised using the EDTA–citrate complexing method and tested for soot oxidation activity. The characterization of the metal oxides is carried out using FTIR, XRD, BET surface area, pore volume analyser, SEM and TEM. The redox nature and metal–oxygen bond information of the metal oxides are obtained from XPS analysis. In redox metal oxides, three critical parameters [lattice oxygen binding energy, reduction temperature and ?r (ionic size difference of the corresponding metal oxide oxidation states)] govern the soot oxidation activity. Among the redox metal oxide samples, Mn3O4 and Pr6O11 samples showed lower binding energy for oxygen (O?—529.4, 528.9 eV respectively), lower reduction temperature (T?—317 and 512 °C respectively) and have smaller ?r value (9 pm and 17 pm respectively). Thus, displayed a better soot oxidation activity (T50 = 484 and 482 °C respectively) than compared to other redox metal oxides. Among the non-redox metal oxides, HfO2 sample displayed higher BET surface area (21.06 m2/g), lattice strain (0.0157), smaller ionic radius (58.2 pm) and higher relative surface oxygen ratio (58%) and thus resulted in a significantly better soot oxidation activity (T50 = 483 °C) than compared to other non-redox metal oxides. Graphical Abstract: [Figure not available: see fulltext.]. © 2017, Springer Science+Business Media, LLC.
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    Ceria-samarium binary metal oxides: A comparative approach towards structural properties and soot oxidation activity
    (Elsevier B.V., 2018) Anjana, A.P.; Geethu, J.; P, M.R.; Prasad Dasari, H.P.; Lee, J.-H.; Harshini, H.; Bhaskar Babu, G.U.
    Binary metal oxides of CeO2-Sm2O3 (CSx, x varies from 10 to 90 mol%) along with pure CeO2 and Sm2O3 were synthesised successfully by the EDTA-Citrate method. From XRD, Raman spectroscopy and UV–vis DRS results, the whole composition of metal oxides exist in three phases: (fluorite phase (F) (CS10-CS30), bi-phase (fluorite (F) + cubic (C)) (CS30-CS90) and cubic phase (C) (Sm2O3)). For CSx samples, the calculated band gap energy values obtained from the UV–vis DRS results were in between 3.0–5.1 eV and fluorite phase samples (CS10–CS30) displayed lower band gap energy values (3.04–3.07 eV) than compared to the samples in other phases. Similarly, from XPS analysis, fluorite phase samples (CS10–CS30) showed higher surface oxygen vacancy concentration than compared to samples in other phases. Catalytic activity for soot oxidation is carried out on CSx samples, and the T50 temperature is in between 480–540 °C. Fluorite phase samples (CS10 CS30) showed higher surface area, lower degree of agglomeration, lower band gap energy, higher oxygen vacancy concentration and better catalytic activity for soot oxidation. Among all the CSx samples, CS10 sample displayed highest surface area (38 m2/g), lowest degree of agglomeration (0.36), lowest band gap energy (3.04 eV), highest oxygen vacancy concentration (64%) and highest soot oxidation activity (T50 = 480 °C). The order of the soot oxidation activity of CSx samples followed the same trend of band gap energy values. © 2018 Elsevier B.V.