Evaluation of solid solution formation between ThO2 and δ-Bi2O3 by molecular precursor route

Pokhriyal, Meenakshi; Kumari, Promila; Uma, S.; Nagarajan, Rajamani

doi:10.1016/j.materresbull.2018.07.001

Cited by 9 publications

(6 citation statements)

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“…17−20 Our recent success in establishing the limit of dissolution of bismuth in fluorite-structured thoria kindled our curiosity to address some of the issues related to the stabilization of pyrochlore-like Bi 2 Zr 2 O 7 by employing a chelate-based wet-chemical bottom-up synthesis and to further investigate their oxygen ion conductivity and catalytic property. 21,22 2. EXPERIMENTAL SECTION 2.1.…”

Section: Introductionmentioning

confidence: 99%

“…Both Bi 2 Hf 2 O 7 and Bi 2 Zr 2 O 7 phases have been found to be metastable. Bi 2 Zr 2 O 7 having defect fluorite structure has been synthesized by co-precipitation, hydrothermal, and solution combustion methods with a singular objective of using them as photocatalysts. − Our recent success in establishing the limit of dissolution of bismuth in fluorite-structured thoria kindled our curiosity to address some of the issues related to the stabilization of pyrochlore-like Bi 2 Zr 2 O 7 by employing a chelate-based wet-chemical bottom-up synthesis and to further investigate their oxygen ion conductivity and catalytic property. , …”

Section: Introductionmentioning

confidence: 99%

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Metastable Bi₂Zr₂O₇ with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties

2018

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Equimolar concentrations of Zr4+ and Bi3+ were chelated with ethylenediaminetetraacetic acid ligand with the purpose of using it as a precursor to generate pyrochlore-like Bi2Zr2O7. When the X-ray amorphous precursor was calcined at 750 °C for 3 h in air, pyrochlore-like product with superstructure reflections was identified by powder X-ray diffraction (PXRD) along with one minor reflection due to β-Bi2O3. This phase was found to be metastable from additional experiments conducted by varying calcination conditions. Structural refinement of PXRD pattern by Le Bail method in Fd3̅m space group yielded cubic lattice constant of 10.8421(27) Å. Flower-petal-like morphology of the sample was evident in its field-emission scanning electron microscopy image and energy-dispersive X-ray analysis performed at various locations of the specimen confirmed nearly equal concentration of zirconium and bismuth. Six bands at 260, 320, 448, 531, 597, and 828 cm–1 were observed for this sample in its Raman spectrum and supported our claim of pyrochlore-like structure. Indexation of bright spots present in selected area electron diffraction pattern and observed distances of lattice fringes in high-resolution transmission electron microscopy image were in conformity with the results from PXRD measurements. Absorbance maxima at 312, 372, and 423 nm with a broad tailing stretching up to visible region was noticed in the UV–visible spectrum of this sample. Direct band gap of 2 eV was estimated for this sample from Tauc plot. The oxygen ion conductivity of the sample in the temperature range of 333–773 K was examined, and the highest conductivity at 773 K was 3.071 × 10–6 S/cm. From activation energy estimation and dielectric loss analysis, thermally activated process related to the mobility of oxygen ion vacancy was found responsible for the observed ionic conductivity. A similar conclusion was reached after careful analysis of dielectric spectroscopy data of this sample. High surface area (125.04 m2/g) and mesoporosity (pore diameter of 3.81 nm) were possessed by this sample, which paved way for studying its catalytic role in the reduction of nitroaromatics and carcinogenic Cr6+. Cyclability experiments showed the retainment of catalytic activity up to five cycles by the sample without undergoing any structural change.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Metastable Bi₂Zr₂O₇ with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties

2018

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“…49−52 Stabilization of δ-Bi 2 O 3 to room temperature can be achieved by doping, 53 in mind that incorporation of dopants into the crystal lattice of bismuth(III) influences the physical properties and, for example, reduces the oxygen ion conductivity by several orders of magnitude. 10,54−56 In the last decades, numerous reports have dealt with the stabilization of δ-Bi 2 O 3 using a variety of main-group elements and transition metals (B, 14 P, 57 Ti, 58,59 V, 31−34 Fe, 60 Y, 61,62 Nb, 62,63 Te, 64 Ta, 65 Ce, 66−68 Eu, 69 Tb, 70 Dy, 71,72 Er, 73−75 Tm, 76 Yb, 77,78 Lu, 79 and Th 80 ) and double-doping (Hf/Zr, 81 Te/V, 82 Y/Yb, 83 Er/Nb, 84 Er/Gd, 85 Ho/Gd, 86 Ho/Dy, 87 Dy/W, 88 Sm/Ce, 89 Sm/Yb, 90 La/Mo, 91 Pr/Mo, 92 Dy/Tm, 93 Gd/Lu, 94,95 Yb/Dy, 96,97 Eu, or Tb/Th 98 ).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, a plethora of synthetic approaches for δ-Bi 2 O 3 in the form of powders, − ,,,,− films, ,− nanosheets, and nanowires was developed. However, stabilization of pure δ-Bi 2 O 3 at room temperature is still a challenge; therefore, the application of the metastable modification is restricted to a low number of examples. − Stabilization of δ-Bi 2 O 3 to room temperature can be achieved by doping, but it must be kept in mind that incorporation of dopants into the crystal lattice of bismuth(III) influences the physical properties and, for example, reduces the oxygen ion conductivity by several orders of magnitude. ,− In the last decades, numerous reports have dealt with the stabilization of δ-Bi 2 O 3 using a variety of main-group elements and transition metals (B, P, Ti, , V, − Fe, Y, , Nb, , Te, Ta, Ce, − Eu, Tb, Dy, , Er, − Tm, Yb, , Lu, and Th) and double-doping (Hf/Zr, Te/V, Y/Yb, Er/Nb, Er/Gd, Ho/Gd, Ho/Dy, Dy/W, Sm/Ce, Sm/Yb, La/Mo, Pr/Mo, Dy/Tm, Gd/Lu, , Yb/Dy, , Eu, or Tb/Th…”

Section: Introductionmentioning

confidence: 99%

Polymorphism and Visible-Light-Driven Photocatalysis of Doped Bi₂O₃:M (M = S, Se, and Re)

et al. 2022

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δ-Bi 2 O 3 :M (M = S, Se, and Re) with an oxygendefective f luorite-type structure is obtained by a coprecipitation m e t h o d s t a r t i n g f r o m t h e b i s m u t h o x i d o c l u s t e r [Bi 38 O 45 (OMc) 24 (dmso) 9 ]•2dmso•7H 2 O (A) in the presence of additives such as Na 2 SO 4 , Na 2 SeO 4 , NH 4 ReO 4 , Na 2 SeO 3 •5H 2 O, and Na 2 SO 3 . The coprecipitation of the starting materials with aqueous NaOH results in the formation of alkaline reaction mixtures, and the cubic bismuth(III)-based oxides Bi 14 O 20 (SO 4 ) ( 1 c ) , B i 1 4 O 2 0 ( S e O 4 ) (2 c ) , B i 1 4 O 2 0 ( R e O 4 . 5 ) (3 c ) , Bi 12.25 O 16.625 (SeO 3 ) 1.75 (4c), and Bi 10.51 O 14.765 (SO 3 ) 0.49 (SO 4 ) 0.51 (5c) are obtained after microwave-assisted heating; formation of compound 5c is the result of partial oxidation of sulfur. The compounds 1c, 2c, 4c, and 5c absorb UV light only, whereas compound 3c absorbs in the visible-light region of the solar spectrum. Thermal treatment of the as-prepared metastable bismuth(III) oxide chalcogenates 1c and 2c at T = 600 °C provides a monotropic phase transition into their tetragonal polymorphs Bi 14 O 20 (SO 4 ) (1t) and Bi 14 O 20 (SeO 4 ) (2t), while compound 3c is transformed into the tetragonal modification of Bi 14 O 20 (ReO 4.5 ) (3t) after calcination at T = 700 °C. Compounds of the systems Bi 2 O 3 −SO x (x = 2 and 3) and Bi 2 O 3 −Re 2 O 7 are thermally stable up to T = 800 °C, whereas compounds of the system Bi 2 O 3 −SeO 3 completely lose SeO 3 . Thermal treatment of 4c and 5c in air results in the oxidation of the tetravalent to hexavalent sulfur and selenium, respectively, upon heating to T = 400−500 °C. The as-prepared cubic bismuth(III)-based oxides 1c−5c were studied with regard to the photocatalytic decomposition of rhodamine B under visible-light irradiation with compound 3c showing the highest turnover and efficiency.

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“…Due to the low melting point of sintering aid, electrolyte particles were surrounded by liquid phase of sintering aid. The surface atom of the electrolyte can diffuse greatly in liquid phase; thus, the grain growth rate increases in this environment [128,129]. Moreover, the pore filling process by liquid-phase sintering aid can promote the densification, resulting in the electrolyte pellet with a larger grain size and a higher relative density [130].…”

Section: Fig 57mentioning

confidence: 99%

Development and characterization of solid oxide electrolysis cells based on zirconia and ceria based electrolyte for hydrogen production from steam

Temluxame

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Steam electrolysis for hydrogen production is investigated in solid oxide electrolysis cell (SOEC). Sc3+, Ce4+, and Gd3+ are doped in zirconia (SCGZ) and compared with yttria stabilized zirconia (YSZ) and gadolinium doped ceria (GDC) electrolyte. Electrolyte-supported cells are fabricated. The SCGZ and YSZ electrolytes are dense with >95% relative density while GDC is less densified. The activation energy of conduction of the SCGZ electrolyte is the lowest at 65.58 kJ mol-1 although phase transformation is detected after electrolyte fabrication process. Cathode-supported cell having SCGZ electrolyte (Ni-SCGZ/SCGZ/BSCF) shows the highest electrochemical performance. Durability test of the cells in electrolysis mode is carried out over 60 h (0.3 A cm-2, 800 ?C, H2O to H2 ratio of 70:30). Significant performance degradation of Ni-GDC/YSZ/GDC/BSCF cell is observed (0.0057 V h-1) whereas the performance of Ni-YSZ/YSZ/BSCF and Ni-SCGZ/SCGZ/BSCF are rather stable under the same operating conditions. The BSCF remains attaching to the SCGZ electrolyte and additional phase transformation is not observed after prolong operation. However, stabilization of high conducting cubic phase by adding 1-2 mol% of Bi2O3 in SCGZ is also investigated. Bi2O3 is found to act as both phase stabilizer and sintering aid. In addition, the ionic conductivity of the electrolyte is also improved with adding Bi2O3.

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Evaluation of solid solution formation between ThO2 and δ-Bi2O3 by molecular precursor route

Cited by 9 publications

References 40 publications

Metastable Bi₂Zr₂O₇ with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties

Metastable Bi₂Zr₂O₇ with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties

Polymorphism and Visible-Light-Driven Photocatalysis of Doped Bi₂O₃:M (M = S, Se, and Re)

Development and characterization of solid oxide electrolysis cells based on zirconia and ceria based electrolyte for hydrogen production from steam

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Evaluation of solid solution formation between ThO2 and δ-Bi2O3 by molecular precursor route

Cited by 9 publications

References 40 publications

Metastable Bi2Zr2O7 with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties

Metastable Bi2Zr2O7 with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties

Polymorphism and Visible-Light-Driven Photocatalysis of Doped Bi2O3:M (M = S, Se, and Re)

Development and characterization of solid oxide electrolysis cells based on zirconia and ceria based electrolyte for hydrogen production from steam

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Metastable Bi₂Zr₂O₇ with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties

Metastable Bi₂Zr₂O₇ with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties

Polymorphism and Visible-Light-Driven Photocatalysis of Doped Bi₂O₃:M (M = S, Se, and Re)