Influence of sintering methods on microstructure and ionic conductivity of La1.95Sr0.05Zr2O6.975 synthesized by co-precipitation

Huo, Da; Gosset, Dominique; Siméone, David; Baldinozzi, Gianguido; Khodja, H.; Villeroy, Benjamin; Surblé, Suzy

doi:10.1016/j.ssi.2015.05.028

Cited by 13 publications

(7 citation statements)

References 30 publications

(27 reference statements)

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“…1c). The characteristic size t of diffracting domains derived via analyses of the broadening of even reflexions using Hall Williamson (HW) plots 12 agrees with the observation of grain sizes performed via Transmission Electron Microscopy (HW curves are plotted in Figure 4 in the supporting information). Surprisingly, the broadening of the odd reflexions is more important as the grain size decreases (Fig.…”

Section: Introductionsupporting

confidence: 77%

“…Moreover, the grain sizes tg extracted from these HW plots are in good agreement with TEM observations thus adding to the validity of our analysis. No variation of unit cell parameters was observed and the maximum value of the strain fields extracted from the slopes of the HW plots 12 of all reflexions are similar. This indicates that the defect fluorite/pyrochlore transition is not driven by the elastic fields in agreement with non ferroic phase transitions 20 .…”

Section: Methodsmentioning

confidence: 81%

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Intricate disorder in defect fluorite/pyrochlore: a concord of chemistry and crystallography

Siméone

Thorogood

Huo

et al. 2017

Sci Rep

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Intuitively scientists accept that order can emerge from disorder and a significant amount of effort has been devoted over many years to demonstrate this. In metallic alloys and oxides, disorder at the atomic scale is the result of occupation at equivalent atomic positions by different atoms which leads to the material exhibiting a fully random or modulated scattering pattern. This arrangement has a substantial influence on the material’s properties, for example ionic conductivity. However it is generally accepted that oxides, such as defect fluorite as used for nuclear waste immobilization matrices and fuel cells, are the result of disorder at the atomic scale. To investigate how order at the atomic scale induces disorder at a larger scale length, we have applied different techniques to study the atomic composition of a homogeneous La 2 Zr 2 O 7 pyrochlore, a textbook example of such a structure. Here we demonstrate that a pyrochlore, which is considered to be defect fluorite, is the result of intricate disorder due to a random distribution of fully ordered nano-domains. Our investigation provides new insight into the order disorder transformations in complex materials with regards to domain formation, resulting in a concord of chemistry with crystallography illustrating that order can induce disorder.

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Section: Introductionsupporting

confidence: 77%

Section: Methodsmentioning

confidence: 81%

Intricate disorder in defect fluorite/pyrochlore: a concord of chemistry and crystallography

Siméone

Thorogood

Huo

et al. 2017

Sci Rep

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“…SPS is based on heating the compact through pulsed electric current under uniaxial pressing conditions, with high heating rates and short processing times measured in minutes. In particular, the potential of SPS has been experimentally demonstrated for synthesizing pyrochlore structure ceramic [26], scheelite [27][28][29], feldspar-like [30], sodium zirconium phosphate (NZP) [31], and glass-ceramic composites for immobilizing 90 Sr [32][33][34][35][36]. Additionally, our work has initially demonstrated high promise for applying SPS to produce a mineral-like SrTiO 3 perovskite matrix for 90 Sr immobilization, as well as to fabricate a prototype of IRS based on this approach [37].…”

Section: Introductionmentioning

confidence: 95%

Perovskite/Pyrochlore Composite Mineral-like Ceramic Fabrication for 90Sr/90Y Immobilization Using SPS-RS Technique

Papynov,

Shichalin,

Belov

et al. 2023

Coatings

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A novel solid-phase synthetic approach was developed to produce a mineral-like composite ceramic based on strontium titanate (SrTiO3) and yttrium titanate (Y2Ti2O7) matrices for immobilizing radionuclides such as 90Sr and its daughter product 90Y, as well as lanthanides and actinides, via reactive spark plasma sintering technology (SPS-RS). Using XRD, SEM, and EDS analyses, the sintering kinetics of the initial mixed oxide reactants of composition YxSr1–1.5xTiO3 (x = 0.2, 0.4, 0.6 and 1) and structure-phase changes in the ceramics under SPS-RS conditions were investigated as a function of Y3+ content. In addition, a detailed study of phase transformation kinetics over time as a function of the heating temperature of the initial components (SrCO3, TiO2, and Y2O3) was conducted via in situ synchrotron XRD heating experiments. The composite ceramic achieved relatively high physicomechanical properties, including relative density between 4.92–4.64 g/cm3, Vickers microhardness of 500–800 HV, and compressive strength ranging from 95.5–272.4 MPa. An evaluation of hydrolytic stability and leaching rates of Sr2+ and Y3+ from the matrices was performed, demonstrating rates did not exceed 10−5–10−6 g·cm−2·day−1 in compliance with GOST R 50926-96 and ANSI/ANS 16.1 standards. The leaching mechanism of these components was studied, including the calculation of solution penetration depth in the ceramic bulk and ion diffusion coefficients in the solution. These findings show great promise for radioactive waste conditioning technologies and the manufacturing of radioisotope products.

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“…Those dopants that cause the least deformation of the crystal lattice of the base material have the lowest dissolution energy and give the highest conductivity of materials, therefore the replacement of lanthanides with Ca in Ln 2 Zr 2 O 7 pyrochlores is usually most advantageous [21,23,35]. Against the background of the fairly well-studied mechanism of acceptor doping in both ordered La 2 Zr 2 O 7 [23,[36][37][38][39][40][41][42][43] and noticeably disordered Gd 2 Zr 2 O 7 [7-9, 44-46, 48], moderately disordered Sm 2 Zr 2 O 7 has been less studied, although it should combine the advantages of the previous two. Liu et al [49][50][51] even made attempts to take advantage of equimolar GdSm 1−x M x Zr 2 O 7−δ (M = Ca, Mg) compositions.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium of intrinsic and impurity point defects in Ca-doped Sm2Zr2O7

Vorotnikov,

Belyakov,

Ivanov

et al. 2024

Nanosystems: Phys. Chem. Math.

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In this work, a doping strategy was used to achieve a good conductivity in samarium zirconate which crystallizes in the pyrochlore. The production of nanopowders made it possible to form high-density ceramics with an optimal microstructure.It is shown that intrinsic and impurity defects coexist in Sm 2−x Ca x Zr 2 O 7−δ , impairing ion transport at high doping levels. Despite this, Sm 1.95 Ca 0.05 Zr 2 O 7−δ maintains low activation energy of the parent and has good ionic conductivity (10 −3 S•cm −1 at 600 • C) which is one of the largest among oxide pyrochlores. It has been shown to have a good chemical stability. The material has a thermal expansion coefficient (TEC) of 12 ppm K −1 which is higher than YSZ and provides better compatibility with electrode materials. The above makes it possible to successfully use it as a highly stable oxygen electrolyte or an intermediate thin layer at the electrolyte-electrode interface in electrochemical devices.

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Influence of sintering methods on microstructure and ionic conductivity of La1.95Sr0.05Zr2O6.975 synthesized by co-precipitation

Cited by 13 publications

References 30 publications

Intricate disorder in defect fluorite/pyrochlore: a concord of chemistry and crystallography

Intricate disorder in defect fluorite/pyrochlore: a concord of chemistry and crystallography

Perovskite/Pyrochlore Composite Mineral-like Ceramic Fabrication for 90Sr/90Y Immobilization Using SPS-RS Technique

Equilibrium of intrinsic and impurity point defects in Ca-doped Sm2Zr2O7

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