Improved Conductivity of Spark Plasma Sintered Ho-Substituted BaZrO3 Electrolyte Ceramics for IT-SOFCs

Saini, Deepash Shekhar; Ghosh, Avijit; Tripathy, Snehasis; Sharma, Shubham; Kumar, Aparabal; Bhattacharya, Debasis

doi:10.1021/acsaem.8b00655

Cited by 14 publications

(4 citation statements)

References 41 publications

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“…But, according to theoretical studies, the Ho-substituted BaZrO 3 may support to progress the conductivity and explore the new substituent for BaZrO 3 regarding proton-conducting electrolyte since the ionic radius of Ho 3+ (90.1 pm) is very similar to that of Y 3+ (90 pm) 34 . However, the study about Ho-substituted BaZrO 3 has been little consideration in the scientific world so far [34][35][36] . In this work, we adopted Ho as a single substituent for BaZrO 3 ceramics to explore the influence of Ho 3+ on the electrical properties of BaZrO 3 ceramics for operative SOFC applications.…”

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confidence: 99%

A Promising Proton Conducting Electrolyte BaZr1-xHoxO3-δ (0.05 ≤ x ≤ 0.20) Ceramics for Intermediate Temperature Solid Oxide Fuel Cells

Saini

Ghosh

Tripathy

et al. 2020

Sci Rep

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In this study, the Ho-substituted BaZrO 3 electrolyte ceramics (BaZr 1-x Ho x o 3-δ , 0.05 ≤ x ≤ 0.20) were synthesized through a low-cost flash pyrolysis process followed by conventional sintering. The effects of Ho-substitution in BaZrO 3 studied in terms of the structural phase relationship, microstructure and electrical conductivity to substantiate augmented total electrical conductivity for intermediate temperature solid oxide fuel cells (IT-SOFCs). The Rietveld refined X-ray diffraction (XRD) patterns revealed that pure phase with Pm m 3 space group symmetry of cubic crystal system as originated in all samples sintered at 1600 °C for 8 h. The Raman spectroscopic investigations also approved that Ho incorporation in BaZro 3 ceramics. Field Emission Scanning Microscopic (FESEM) study informed a mixture of fine and coarse grains in the fracture surface of Ho-substituted BaZrO 3 sintered samples. The relative density and average grain size of samples were observed to decrease as per the addition of Hosubstitution in BaZro 3 ceramics. The electrical conductivity study was accomplished by Electrical Impedance Spectroscopy (EIS) under 3% humidified O 2 atmosphere from 300 to 800 °C. Furthermore, the total electrical conductivity of BaZr 0.8 Ho 0.2 o 3-δ ceramic was found to be 5.8 × 10 −3 S-cm −1 at 600 °C under 3% humidified atmosphere, which may be a promising electrolyte for IT-SOFCs. Recently, the proton conductive oxide ceramics have fascinated worldwide attention due to widespread applications in intermediate temperature solid oxide fuel cells (IT-SOFCs), hydrogen separation and electrolysis of steam, etc. In this context, the rare-earth cerates and zirconates with the perovskite-type A(II)B(IV)O 3 crystallographic structure are the two foremost families of proton-conducting oxides for electrochemical applications 1-4. Generally, in these categories of oxide materials, oxygen vacancies are increased by replacement of tetravalent cation B(IV) by trivalent cation M(III) as given in the Eq. (1) using Kröger-Vink notation.

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confidence: 99%

A Promising Proton Conducting Electrolyte BaZr1-xHoxO3-δ (0.05 ≤ x ≤ 0.20) Ceramics for Intermediate Temperature Solid Oxide Fuel Cells

Saini

Ghosh

Tripathy

et al. 2020

Sci Rep

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“…In general, a net εr value arises in dipolar, electronic, ionic, and interfacial polarization of the charge carriers. At low frequencies, primarily electric dipolar and interfacial polarizations are responsible for a frequency-dependent εr behavior [12,16]. Eventually, in the plots in Figure 6, a recurring εr value is decreasing rapidly on raising frequency up to 10 1 Hz in a microscopic region-1 in a prominently interfacial polarization.…”

Section: Dielectric Propertiesmentioning

confidence: 92%

“…Eventually, in the plots in Figure 6, a recurring εr value is decreasing rapidly on raising frequency up to 10 1 Hz in a microscopic region-1 in a prominently interfacial polarization. In the next regime-2, it retards decreasing smoothly up to 1 kHz in an account of a electric dipolar relaxation, which explains that at low frequencies the dipoles coherently follow the frequency of applied electric field but at higher frequencies, they lag behind in response to the external field in effect becomes insignificant at these frequencies [16,17]. At further higher frequencies, an intrinsic electronic polarization is responsible for a steady εr value independent of frequency.…”

Section: Dielectric Propertiesmentioning

confidence: 96%

Dielectric Properties of Cr3+ Doped Al2O3 of a Hierarchical Nanostructure Synthesized Using a Highly Porous Precursor of Tubular AlO(OH)⋅αH2O Fibers

Jangu

Sharma

Sudhansu³

et al. 2021

MSF

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Herein, we have developed a Cr3+ doped Al2O3 of a hierarchical nanostructure by a simple two-step synthesis. A pure AlO(OH)⋅αH2O, as synthesized in forms of small tubular fibers by hydrolysis of Al-metal sheets, is easily doped with selective Cr3+ dosages up to 2.0 mol% using an aqueous CrO3. As-synthesized samples exhibit XRD of a single phase Cr3+: Al2O3 of a rhombohedral crystal structure. Average pore-volume is decreased as 98.1, 89.8, and 61.5 cm3-g-1 in the 0.5, 1.0 and 2.0 % Cr% doped samples, with average pore radius of 1.70, 2.17 and 1.90 nm, respectively, as measure from BET specific surface area. Local Al-O vibrations exhibit IR bands of 400 to 1200 cm-1 intrinsic of oxygen polygons. At room temperature, a duly tailored dielectric permittivity of 480 is obtained in a 2.0 mol% Cr3+:Al2O3 and that is enhanced progressively on heating it over 25 to 300 °C, showing a value 6700 at 300 °C in phonon induced dynamics of charge carriers, useful for solid-state electronics.

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“…Furthermore, our research group previously investigated Ho-doped BaZrO3 system and found 91.1% relative density for BaZr0.8Ho0.2O3-δ sintered at 1600 ℃ for 8 h with 1.11×10 -3 S-cm -1 total conductivity at 650 ℃ in 3% humidified atmosphere [25]. Similarly, Saini et al reported 99.1% relative density for spark plasma sintered BaZr0.8Ho0.2O3-δ with 9.64×10 -2 S-cm -1 total conductivity at 700 ℃ in 3% humidified atmosphere [26]. Thus, it is concluded that doping of Y 3+ and Ho 3+ in BaZrO3 helps to enhance the electrical conductivity of BaZrO3 while doping of Nd 3+ in BaZrO3 helps to improve the sinterability of BaZrO3.…”

Section: Introductionmentioning

confidence: 92%

Electron Density Distribution using Maximum Entropy Method and Conductivity Studies of Highly Dense BaZr0.85Ho0.10Y0.025Nd0.025O3-δ Electrolyte Ceramic for Intermediate Temperature Solid Oxide Fuel Cells

Singh,

Kumar,

Singh

et al. 2024

Preprint

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In this research work, highly dense BaZr0.85Ho0.10Y0.025Nd0.025O3-δ electrolyte ceramic was synthesized through a cost-effective flash pyrolysis route followed by conventional sintering for intermediate-temperature solid oxide fuel cells. The calcined powder and sintered pellet were characterized through various techniques like HRXRD, HRTEM, FESEM, EDS, and Raman spectroscopy. The XRD pattern of calcined and sintered pellet shows the pure cubic phase with space group symmetry through the Rietveld refinement. The study of the electron density distribution of calcined powder and sintered pellet calculated by the maximum entropy method reveals the presence of oxygen vacancies at the octahedral site in the sintered sample. The microstructure of the fracture surface of the sintered sample indicates highly dense with a relative density of 97.4% through FESEM. The Raman analysis confirms the distortion along the c-axis and oxygen vacancies in the octahedral site of BaZr0.85Ho0.10Y0.025Nd0.025O3-δ. Impedance spectroscopy measurements was conduct in the temperature range of 50 to 700 ℃ and frequency range of 1 Hz to 1 MHz. The Nyquist plots in the temperature range of 350 to 700 ℃ provide information of three types of relaxations corresponding to grain and grain boundary, and electrode effect. The temperature-dependent exponent (n) associated with grain and grain boundary decreases with the increase in temperature, indicating that large polaron hopping is involved in the electrical conduction mechanism.

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Improved Conductivity of Spark Plasma Sintered Ho-Substituted BaZrO₃ Electrolyte Ceramics for IT-SOFCs

Cited by 14 publications

References 41 publications

A Promising Proton Conducting Electrolyte BaZr1-xHoxO3-δ (0.05 ≤ x ≤ 0.20) Ceramics for Intermediate Temperature Solid Oxide Fuel Cells

A Promising Proton Conducting Electrolyte BaZr1-xHoxO3-δ (0.05 ≤ x ≤ 0.20) Ceramics for Intermediate Temperature Solid Oxide Fuel Cells

Dielectric Properties of Cr<sup>3+</sup> Doped Al<sub>2</sub>O<sub>3</sub> of a Hierarchical Nanostructure Synthesized Using a Highly Porous Precursor of Tubular AlO(OH)⋅αH<sub>2</sub>O Fibers

Electron Density Distribution using Maximum Entropy Method and Conductivity Studies of Highly Dense BaZr0.85Ho0.10Y0.025Nd0.025O3-δ Electrolyte Ceramic for Intermediate Temperature Solid Oxide Fuel Cells

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