Faculty Publications
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Item 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.Item Promotional effect of nickel addition on soot oxidation activity of Ce0.9Pr0.1O2 oxide catalysts(Springer, 2020) Rajvanshi, K.; Patil, S.S.; Lakhanlal, u.; Prasad Dasari, H.P.; Saidutta, M.B.; Harshini, H.The present study investigates the promotional effect of Ni addition on soot oxidation activity of Ce0.9Pr0.1O2 oxide catalysts. A series of xNi-PDC (x= 0, 3, 5, 7, 10, 15, and 20 mol%) catalysts were synthesized by solution combustion synthesis method and characterized by XRD, Raman spectroscopy and TEM analysis. XRD and SAED patterns of the catalysts show cubic fluorite structure of ceria with an average crystallite size of 6–8 nm, and only 20Ni-PDC display NiO as a secondary phase. Raman spectra of xNi-PDC catalysts display an increase in oxygen vacancies. With a minimum addition of 10 mol% Ni to PDC, i.e., the 10Ni-PDC catalyst showed optimum soot oxidation activity (T50 = 360 °C) than compared to PDC and other Ni-PDC catalysts. Lattice strain and oxygen vacancies played a key descriptor role in showing better soot oxidation activity of the 10Ni-PDC catalyst. From the soot oxidation kinetic studies, the activation energy obtained by Ozawa plots for the 10Ni-PDC catalyst is 137 kJ/mol. © 2020, Institute of Chemistry, Slovak Academy of Sciences.Item Dilatometer studies on LAMOX based electrolyte materials for solid oxide fuel cells(Elsevier Ltd, 2021) Das, A.; Lakhanlal, u.; Shajahan, I.; Prasad Dasari, H.P.; Saidutta, M.B.; Harshini, H.The present study deals with the citrate complexion synthesis of LAMOX-based Solid Oxide Fuel Cell (SOFC) electrolyte materials (La1.8Dy0.2Mo2-xWxO9 (x = 0, 0.1, 0.2, 0.5, and 1), La1.8Dy0.2Mo2-xGaxO9 (x = 0.1 and 0.2), and La1.8Dy0.2Mo2-xVxO9 (x = 0.025, 0.05, 0.1, and 0.2)) and their characterization to understand the sintering behaviour and phase stability. From the dilatometer studies, the linear shrinkage and shrinkage rate of the LDMW (x = 0, and 0.1) showed better shrinkage than LM and LDM. Gallium addition (LDMG) and Vanadium addition (LDMV) showed a negative impact on shrinkage behaviour. In the temperature range of 500–580 °C, the abrupt change in shrinkage rate showed the transition of phase from ? to ? for the LM. The modification of LM to LDM, LDMW, and LDMV suppressed the formation of the ? phase. During thermal expansion behaviour study in the temperature range of 100–500 °C and 550–800 °C, the LM sintered pellet showed the coefficient of thermal expansion (CTE) values of 13.3 ? 10?6/°C and 21.6 ? 10?6/°C respectively. The LDM and LDMW sintered pellets showed the CTE values in the range of 14–15 ? 10?6/°C and 16–19 ? 10?6/°C, respectively. The relative density of the sintered pellets (1100 °C/5 h in air) (LM, LDM, LDMW, and LDMG (x = 0.1)) is found to be >90%. It provides the suitability of these materials for further investigation as electrolytes of SOFCs/SOECs. © 2020 Elsevier B.V.Item Electrical conductivity studies on LAMOX based electrolyte materials for solid oxide fuel cells(Elsevier Ltd, 2022) Srijith; Lakhanlal, u.; Das, A.; Prasad Dasari, H.P.; Saidutta, M.B.In this study, the electrical conductivity of the LAMOX based electrolytes (La1.8Dy0.2Mo2-xWxO9 (x = 0, 0.1, 0.2, 0.5, and 1), and La1.8Dy0.2Mo2-xGaxO9 (x = 0.1)) synthesized by the citrate complexion method has been studied using DC four-probe method. The electrical conductivity of the electrolytes is measured in the temperature range of 800–400 °C in the air (∼100 ml min−1). The effect of W and Ga substitution at the Mo site on the electrical conductivity is evaluated. The long-term electrical conductivity stability test (time on stream) (5 h) is conducted at 650, 580, and 520 °C to study the effect of possible phase transition on electrical conductivity. A high-temperature XRD study is also conducted in the temperature range of 500–650 °C (during heating and cooling) on selected electrolyte materials (La1.8Dy0.2Mo2-xWxO9 (x = 0 and 0.1) and La1.8Dy0.2Mo2-xGaxO9 (x = 0.1)) to study the α↔β phase transition. The electrical conductivity of these electrolytes in the air at 800 °C is in the range of 5.3 × 10−2 – 14 × 10−2 S cm−1. The activation energy (EA) of these electrolytes is in the range of 1.11–1.62 eV. The VTF parameters σo, B, and To are in the range of 67.46–395.88 S cm−1 K0.5, 0.122–0.254 eV, and 247–347 °C, respectively. The La1.8Dy0.2Mo2-xWxO9 (x = 0.1) shows highest electrical conductivity (14 × 10−2 S cm−1, EA = 1.54 eV) among all electrolytes in air at 800 °C and for this material the VTF parameters σo, B, and To are 170.32 S cm−1 K0.5, 0.153 eV, and 302 °C, respectively. © 2022 Elsevier Ltd and Techna Group S.r.l.Item Current-Voltage (i-V) characteristics of electrolyte-supported (NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF) solid oxide electrolysis cell during CO2/H2O co-electrolysis(Elsevier B.V., 2024) Shirasangi, R.; Lakhanlal, u.; Prasad Dasari, H.P.; Saidutta, M.B.Solid oxide electrolysis cells (SOECs) stabilize CO2 emissions by converting CO2/H2O into synfuel. Current-Voltage (i-V) characteristics of an electrolyte-supported button cell (NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF) were measured as a function of temperature, water vapor concentration, and CO2 gas concentrations. The cell microstructure was characterized by the Field Emission Scanning Electron Microscope (FE-SEM). FE-SEM micrographs depict that the electrolyte layer is relatively dense, and porous fuel and air electrode layers are well adhered to the electrolyte. The i-V curves were obtained at a scan rate of 0.02 Vs?1 from 0.3 to 1.5 V. Electrolysis current density increases as the temperature increases. SOEC performance increases, but SOFC performance decreases with increased water vapor concentration. Electrolysis current densities decrease as the CO2 concentration increases. The i-V characteristics show only ohmic polarization under fuel-lean and fuel-rich conditions. At optimal conditions, current density values at 800 °C/1.5 V are -174, -187, and -195 mA cm?2 for 5 %H2O, 30 %CO2, and 30 %CO2/5 %H2O co-electrolysis. At 800 °C, open-circuit voltage (OCV) values for H2O, CO2, and co-electrolysis are 0.906, 0.891, and 0.885 V, respectively. The electrolysis area-specific resistances (ASRs) give information on the reduction of CO2 or H2O, forming CO or H2, respectively. At optimal conditions, ASR values are 3.43, 3.29, and 3.18 ? cm2 for H2O, CO2, and co-electrolysis, respectively. Co-electrolysis has a lower ASR value than pure H2O and CO2 electrolysis, indicating that H2O and CO2 are involved in the electrochemical processes. © 2024 The Author(s)