Oxide ionic conductivity and microstructures of Pr and Sm co-doped CeO2-based systems

AbstractThe compositions Ce0.80Sm0.2-xPrxO2-δ (x=0-0.12) were prepared through the citrate-nitrate method. The synthesized Pr3+ and Sm3+ co-doped ceria powders with different compositions were calcined at 600°C for 3 h. Phase structure of the calcined powders was characterized by X-Ray diffraction (XRD) analysis.All the calcined samples were found to be ceria based solid solutions of fluorite type structures. The morphology examinations were carried out by scanning electron microscopy (SEM) analysis. Relative density of more than 91% of the theoretical can be achieved by sintering the Ce0.80Sm0.2-xPrxO2-δ pellets at 1400°C for 6 h. The two-probe a.c. impedance spectroscopy was used to study the ionic conductivity of the doped ceria samples. The Ce0.80Sm0.80Pr0.12O1.90 composition showed the highest total ionic conductivity value which is 2.39 × 10−2 S/cm at 600°C.

Download Full-text

High Pressure X-ray Diffraction as a Tool for Designing Doped Ceria Thin Films Electrolytes

Coatings ◽

10.3390/coatings11060724 ◽

2021 ◽

Vol 11 (6) ◽

pp. 724

Author(s):

Sara Massardo ◽

Alessandro Cingolani ◽

Cristina Artini

Keyword(s):

Thin Films ◽

High Pressure ◽

Rare Earth ◽

Ionic Conductivity ◽

Bulk Material ◽

Threshold Temperature ◽

Doped Ceria ◽

X Ray Diffraction ◽

X Ray ◽

Rare Earth Doped

Rare earth-doped ceria thin films are currently thoroughly studied to be used in miniaturized solid oxide cells, memristive devices and gas sensors. The employment in such different application fields derives from the most remarkable property of this material, namely ionic conductivity, occurring through the mobility of oxygen ions above a certain threshold temperature. This feature is in turn limited by the association of defects, which hinders the movement of ions through the lattice. In addition to these issues, ionic conductivity in thin films is dominated by the presence of the film/substrate interface, where a strain can arise as a consequence of lattice mismatch. A tensile strain, in particular, when not released through the occurrence of dislocations, enhances ionic conduction through the reduction of activation energy. Within this complex framework, high pressure X-ray diffraction investigations performed on the bulk material are of great help in estimating the bulk modulus of the material, and hence its compressibility, namely its tolerance toward the application of a compressive/tensile stress. In this review, an overview is given about the correlation between structure and transport properties in rare earth-doped ceria films, and the role of high pressure X-ray diffraction studies in the selection of the most proper compositions for the design of thin films.

Download Full-text

Ionic conductivity in nanocrystalline Gd doped ceria

MRS Proceedings ◽

10.1557/proc-1122-o06-02 ◽

2008 ◽

Vol 1122 ◽

Cited By ~ 1

Author(s):

Gianguido Baldinozzi ◽

David Simeone ◽

Dominique Gosset ◽

Mickael Dollé ◽

Georgette Petot-Ervas

Keyword(s):

Grain Size ◽

Ionic Conductivity ◽

Sol Gel ◽

Doped Ceria ◽

Narrow Size Distribution ◽

Conductivity Measurements ◽

X Ray Diffraction ◽

X Ray ◽

Grain Sizes ◽

The Impact

AbstractWe have synthesized Gd-doped ceria polycrystalline samples (5, 10, 15 %mol), having relative densities exceeding 95% and grain sizes between 30 and 160 nm after axial hot pressing (750 °C, 250 MPa). The samples were prepared by sintering nanopowders obtained by sol-gel chemistry methods having a very narrow size distribution centered at about 16 nm. SEM and X-ray diffraction were performed to characterize the sample microstructures and to assess their structures. We report ionic conductivity measurements using impedance spectroscopy. It is important to investigate the properties of these systems with sub-micrometric grains and as a function of their composition. Therefore, samples having micrometric and nanometric grain sizes (and different Gd content) were studied. Evidence of Gd segregation near the grain boundaries is given and the impact on the ionic conductivity, as a function of the grain size and Gd composition, is discussed and compared to microcrystalline samples.

Download Full-text

Calcination Temperature Influence on Ionic Conductivity of Solid Electrolytes

Materials Science Forum ◽

10.4028/www.scientific.net/msf.798-799.419 ◽

2014 ◽

Vol 798-799 ◽

pp. 419-425

Author(s):

Jesús Mauricio González Martínez ◽

Licurgo Borges Winck ◽

Cosme Roberto Moreira da Silva

Keyword(s):

Infrared Spectroscopy ◽

Ionic Conductivity ◽

Calcination Temperature ◽

Electrical Characterization ◽

Uniaxial Pressure ◽

X Ray Diffraction ◽

Precursor Method ◽

X Ray ◽

Microstructure Evaluation ◽

Fluorite Type

The gadolinia doped ceria was developed in Ce0,8Gd0,2O1,9 composition, with the objective to study the influence of calcination temperature on the ionic conductivity of sintered samples (pellets) used as solid electrolyte for the fuel cells applications. The powder was synthesized by the polymeric precursor method (Pechini) from cerium and gadolinium nitrates hexahydrates, obtaining a polymeric resin characterized by infrared spectroscopy. The heat treatments at 600 and 800°C resulted on oxides formation which have been characterized by infrared spectroscopy and X-ray diffraction for each sample. In each case, the fluorite type structure was identified. The pellets were formed by uniaxial pressure and sintered at 1500°C with relative densities of 93.1 and 89.4% for the samples calcined at 600 and 800°C, respectively. The microstructure evaluation was performed by scanning electron microscopy, and the electrical characterization was carried out by impedance spectroscopy, reaching a conductivity of 1.49x10-4 S/cm at 400°C in this work.

Download Full-text

Defect evolution in Eu3+, Nb5+ doped and co-doped CeO2: X-ray diffraction, positron annihilation lifetime and photoluminescence studies

Inorganic Chemistry Frontiers ◽

10.1039/c9qi00668k ◽

2019 ◽

Vol 6 (8) ◽

pp. 2167-2177 ◽

Cited By ~ 2

Author(s):

K. Sudarshan ◽

V. Tiwari ◽

P. Utpalla ◽

S. K. Gupta

Keyword(s):

Positron Annihilation ◽

Rietveld Refinement ◽

Luminescence Spectroscopy ◽

X Ray Diffraction ◽

Light Emitting ◽

X Ray ◽

Positron Annihilation Lifetime ◽

Doped Ceo2 ◽

Photoluminescence Studies ◽

Co Doped

Defects and their influence on light emitting properties were explored in CeO2:Eu,Nb using Rietveld refinement, positron annihilation and luminescence spectroscopy.

Download Full-text

Influence of mg doping on structural, optical and photocatalytic performances of ceria nanopowders

Processing and Application of Ceramics ◽

10.2298/pac1704304m ◽

2017 ◽

Vol 11 (4) ◽

pp. 304-310

Author(s):

Branko Matovic ◽

Jelena Lukovic ◽

Bojan Stojadinovic ◽

Sonja Askrabic ◽

Aleksandra Zarubica ◽

...

Keyword(s):

Solid Solutions ◽

Oxygen Vacancies ◽

Uv Light ◽

Doped Ceria ◽

X Ray Diffraction ◽

X Ray ◽

Ceria Solid Solutions ◽

Fluorite Type ◽

Photocatalytic Performances ◽

Mg Doped

Nanosized Mg-doped ceria powders were obtained by self-propagating room temperature reaction without using surfactants or templates. X-ray diffraction analysis and field emission scanning microscopy results showed that the doped samples are solid solutions with fluorite-type structure and spherical morphology. Raman spectra revealed an increase in the amount of oxygen vacancies with the increase of Mg concentration. This increasing results in a narrowing of the bandgap of CeO2. The photocatalytic performances of the Mg-doped ceria solid solutions were evaluated by decomposing an organic dye, crystal violet under UV irradiation. The Mg-doped ceria solid solutions exhibit significantly better photocatalytic activity than the pure CeO2 and commercial TiO2. The higher first rate constant of the Mg-doped samples demonstrated that they are much more efficient than TiO2 and CeO2 under UV light. Mg2+ dopant ions and oxygen vacancies play a significant role in the enhancement of photocatalytic performances of the Mg-doped ceria.

Download Full-text

Oxide ionic conductivity and microstructures of Pr and Sm co-doped CeO2-based systems

energyo ◽

10.1515/energyo.0131.00005 ◽

2019 ◽

Author(s):

Aliye Arabacı

Keyword(s):

Ionic Conductivity ◽

Doped Ceo2 ◽

Oxide Ionic Conductivity ◽

Co Doped

Download Full-text

Synthesis of Gadolinium Doped Ceria Ceramic Powder by Polymeric Precursor Method (Pechini)

Materials Science Forum ◽

10.4028/www.scientific.net/msf.798-799.182 ◽

2014 ◽

Vol 798-799 ◽

pp. 182-188 ◽

Cited By ~ 5

Author(s):

Jesús Mauricio González Martínez ◽

Rodrigo Arabey Muñoz Meneses ◽

Cosme Roberto Moreira da Silva

Keyword(s):

Ceramic Powder ◽

Doped Ceria ◽

Polymeric Precursor ◽

X Ray Diffraction ◽

Precursor Method ◽

Calcination Process ◽

X Ray ◽

Before And After ◽

Fluorite Type ◽

Gadolinium Doped Ceria

The synthesis by polymeric precursors method (Pechini) was used to acquire gadolinium doped ceria forming Ce0,8Gd0,2O1,9 system, reaching high stoichiometric control features and nanosized particles to form dense solid electrolyte of high ionic conductivity. The synthesis was performed with cerium and gadolinium nitrates hexahydrates, citric acid and ethylene glycol. After the pre-calcination at 250°C/18h a resin was obtained like an expanded foam (puff). According to the iterature, this fact indicates that there is a reduction of agglomerates amount in a ceramic powder. A thermogravimetry-differential thermal analysis evaluated the thermal behavior of the resin. Infrared spectroscopy determined the organic matter and nitrates presence, before and after the calcination process. The X-ray diffraction identified the fluorite-type structure and was determined the crystallite size by the Scherrer equation in 22 and 46 nm for the powder calcined respectively at 600 and 800°C. The scanning electron microscopy evaluated the agglomeration degree and the morphology of the powders.

Download Full-text

Influence of Thickness on Oxide Ionic Conductivity in Sm3+ and Nd3+ Co-Doped CeO2 Electrolyte

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.434-435.710 ◽

2010 ◽

Vol 434-435 ◽

pp. 710-713 ◽

Cited By ~ 1

Author(s):

Wei Liu ◽

Bin Li ◽

Wei Pan

Keyword(s):

Electrical Conductivity ◽

Ionic Conductivity ◽

Solid Electrolytes ◽

Combustion Process ◽

Ac Impedance Spectroscopy ◽

Boundary Conductivity ◽

Conductivity Enhancement ◽

Doped Ceo2 ◽

Oxide Ionic Conductivity ◽

Co Doped

Sm3+ and Nd3+ co-doped CeO2 solid electrolytes with various thicknesses were prepared by citric-nitrate combustion process. The electrical conductivity as a function of electrolyte thickness was determined by ac impedance spectroscopy. The results showed that the ionic conductivity increases with the decrease of the electrolyte thickness approximately and it was estimated that the conductivity enhancement was due to the increased grain boundary conductivity.

Download Full-text

X-ray diffraction and UV-visible spectroscopy study of Fe-Cu co-doped CeO2

10.1063/5.0001562 ◽

2020 ◽

Author(s):

Preeti ◽

Anupam Vyas ◽

P. A. Alvi ◽

Mayuri Sharma ◽

Kavita Kumari ◽

...

Keyword(s):

Spectroscopy Study ◽

X Ray Diffraction ◽

Visible Spectroscopy ◽

X Ray ◽

Uv Visible ◽

Doped Ceo2 ◽

Co Doped

Download Full-text

Defect-Mediated Conductivity Enhancements in Na3-xPn1-xWxS4 (Pn = P, Sb) using Aliovalent Substitutions

10.26434/chemrxiv.9943961.v2 ◽

2019 ◽

Author(s):

Till Fuchs ◽

Sean Culver ◽

Paul Till ◽

Wolfgang Zeier

Keyword(s):

Ionic Conductivity ◽

Vacancy Concentration ◽

Sodium Ion ◽

High Ionic Conductivity ◽

Ionic Conductors ◽

X Ray Diffraction ◽

X Ray ◽

Solid State Batteries ◽

Ion Conducting ◽

Very High

The sodium-ion conducting family of Na3PnS4, with Pn = P, Sb, have gained interest for the use in solid-state batteries due to their high ionic conductivity. However, significant improvements to the conductivity have been hampered by the lack of aliovalent dopants that can introduce vacancies into the structure. Inspired by the need for vacancy introduction into Na3PnS4, the solid solutions with WS42- introduction are explored. The influence of the substitution with WS42- for PS43- and SbS43-, respectively, is monitored using a combination of X-ray diffraction, Raman and impedance spectroscopy. With increasing vacancy concentration improvements resulting in a very high ionic conductivity of 13 ± 3 mS·cm-1 for Na2.9P0.9W0.1S4 and 41 ± 8 mS·cm-1 for Na2.9Sb0.9W0.1S4 can be observed. This work acts as a stepping-stone towards further engineering of ionic conductors using vacancy-injection via aliovalent substituents.

Download Full-text