Conductivity enhancement in fluorite-structured Ba1−xLaxF2+x solid solutions

Wapenaar, Kees; Koesveld, J.L. Van; Schoonman, J.

doi:10.1016/0167-2738(81)90172-7

Cited by 72 publications

(47 citation statements)

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“…This value is in satisfactory agreement with the value 2.0 eV reported by Fielder [9] and the value 2.08 eV reported by Chadwick et al [10]. [3][4][5][6] In the intermediate region the ionic conductivity increases, and the activation enthalpy decreases with increasing dopant concentration (see figs. 3 and 4).…”

Section: "Pure"laf 3 (Samples 1 and 2)supporting

confidence: 82%

“…rare-earth (III) fluorides, exhibit relatively high fluoride ion conductivities. Especially fluorite-type solid solutions based on alkaline-earth fluorides have been studied extensively [5,6]. In previous studies performed in our laboratory, the ionic conductivity of fluorite-type solid solutions of alkaline-earth fluorides doped with LaF 3 or UF 4 has been investigated.…”

Section: Introductionmentioning

confidence: 99%

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Ionic conductivity in tysonite-type solid solutions La1−xBaxF3−x

et al. 1984

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The ionic conductivity of single crystals of tysonite-type solid solutions Lal_xBaxFa_x(O • x • 0.095) has been studied parallel and perpendicular to the crystallographic c axis in the temperature range 293-1300 K. Three regions can be discerned in the compositional dependence of the ionic conductivity: (i) the "pure" crystal, in which at room temperature no exchange occurs between different types of anion sites in the tysonite structure; (ii) an intermediate region (0 < x < 7 X 10 -2) which reveals changes in both the conductivity activation enthalpy and the magnitude of the conductivity; (iii) a concentrated solid-solution region (x > 7 X 10-2), where fluoride ions interchange easily among the different anion sublattices. Diffusion coefficients calculated from ionic conductivity results, are in good agreement with those calculated from 19F NMR measurements. Using the present data, along with 19F NMR data, dielectric relaxation data and structural considerations, mechanisms governing the ionic conductivity are proposed.

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Section: "Pure"laf 3 (Samples 1 and 2)supporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Ionic conductivity in tysonite-type solid solutions La1−xBaxF3−x

et al. 1984

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“…The growth and characterization of the Ba l_x-LaxF2+ x solid solution crystals have been described before [15]. Unoriented disks, 1 X 10 -3 to 2 X 10 -3 m thick, and "8 X 10 -3 m in diameter, were cut from the ingots.…”

Section: Methodsmentioning

confidence: 99%

“…We considered LaF 3 concentrations up to the solubility limit in BaF2, which is about 50 mole% (m/o) [15]. The papers discuss the results of our investigations regarding defect chemical models adequately accounting for the increasing disorder in the solid solutions.…”

Section: Ked Icapenaar Et Al/low-ternperature Ionic Conductivitymentioning

confidence: 99%

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Low-temperature ionic conductivity and dielectric relaxation phenomena in fluorite-type solid solutions

Wapenaar

Koekkoek

1982

Solid State Ionics

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Low-temperature ionic conductivity and dielectric relaxation phenomena in Ba 1 _xLaxF2+x crystals (1.19 X 10 -3 < x < 0.492) have been studied by ionic thermal current (ITC) and ac dielectric loss (DL) techniques. The conductivity results agree with those of an earlier ~tudy of the same crystals at higher temperatures. At low LaF 3 concentrations, i.e. 1.19 X 10 -3 ~ x ~ 2.37 X 10 -2 , the dielectric spectra show three relaxation peaks, two of which are ascribed to simple associates of interstitial F-ions (Fi) nearest-neighbour (nm) and next-nearest-neighbour (nnn) to substitutional La 3÷ ions (LaBa). They are denoted as type I and II dipoles, respectively. We attribute the third peak to angled ("L-shaped") (LaBa2~'i}' complexes. Relaxation parat~etors for the relaxations are presented. We have calculated effective dipole moments for type I . eli eli .and II dipole8 PI and/Zli , taking rote account the displacements and polarizabilities of the defects. Several combinations of host lattice cations and dQpant ions have been co~idered for the fluorites M l -xRExF2+x, i.e. M = Ca, S~Ba, and RE = La, Eu, Lu. For nearly all combinations the ratio ~[f/~ff is found to have a value of 2.4 ± 0.1. With the tt eII values thus obtained, the dipole concentrations of type I and II dipoles can be calculated. Their dependence on solute content is discussed. In the calculations, Debye-Hiickel-Lidiard interactions between defects and the charge clouds surrounding them have been taken into account. At high concentrations, i.e. 0.133 < x < 0.492, broad structureless absorption losses dominate the dielectric relaxation spectra. These losses are analysed by the fractional polarization (FP) technique, and by a special analysis of the DL data. The feasibility of these techniques is discussed. The analysis reveals that two localized relaxation processes occur in concentrated solid solutions. One is characterized by reorientation activation enthalpies (AH R) which are ghe same as the corresponding conductivity activation enthalpies (AH), and is ascr~ed to F-interstitial motion in crystal areas around defect clusters. The second process is characterized by AH R values which are much lower than AH. We propose that this process is related to F-interstitial reorientation within clusters. The results presented indicate that no typical polarizable cluster is preferred in concentrated Ba I _xLaxF2+x solid solutions.

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Electropositive Metal Doping into Lanthanum Hydride for H⁻ Conducting Solid Electrolyte Use at Room Temperature

Izumi,

Takeiri,

Okamoto

et al. 2023

Advanced Energy Materials

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Hydride ion conductors have made remarkable progress in recent years; in particular, the fluorite‐type LaH3‐δ series exhibits high conductivity around room temperature. However, its intrinsic character of hydrogen non‐stoichiometry still makes its application as a solid electrolyte challenging, for which high electronic insulation is essential. Here, Sr‐substituted LaH3‐δ with slight O2− incorporation, represented as La1‐xSrxH3‐x‐2yOy (0.1 ≤ x ≤ 0.6, y ≤ 0.171), is synthesized, which exhibits H− conductivity of 10−4 – 10−5 S cm−1 at room temperature. The galvanostatic discharge reaction using an all‐solid‐state cell composed of Ti|La1‐xSrxH3‐x‐2yOy|LaH3‐δ shows that the Ti electrode is completely hydrogenated to TiH2 for x ≥ 0.2, whereas a short circuit occurs for x = 0.1. These experimental observations, together with calculation studies on the density of states and the defect formation energy, provide clear evidence that electropositive cation, such as Sr, doping critically suppresses the electron conduction in LaH3‐δ. Achieving a superior H− conducting solid electrolyte is a novel milestone in the development of electrochemical devices that utilize its strong reducing ability (E°(H−/H2) = −2.25 V vs SHE), such as batteries with high energy density and electrolysis/fuel cells with high efficiency.

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Conductivity enhancement in fluorite-structured Ba1−xLaxF2+x solid solutions

Cited by 72 publications

References 10 publications

Ionic conductivity in tysonite-type solid solutions La1−xBaxF3−x

Ionic conductivity in tysonite-type solid solutions La1−xBaxF3−x

Low-temperature ionic conductivity and dielectric relaxation phenomena in fluorite-type solid solutions

Electropositive Metal Doping into Lanthanum Hydride for H⁻ Conducting Solid Electrolyte Use at Room Temperature

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Conductivity enhancement in fluorite-structured Ba1−xLaxF2+x solid solutions

Cited by 72 publications

References 10 publications

Ionic conductivity in tysonite-type solid solutions La1−xBaxF3−x

Ionic conductivity in tysonite-type solid solutions La1−xBaxF3−x

Low-temperature ionic conductivity and dielectric relaxation phenomena in fluorite-type solid solutions

Electropositive Metal Doping into Lanthanum Hydride for H− Conducting Solid Electrolyte Use at Room Temperature

Contact Info

Product

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Electropositive Metal Doping into Lanthanum Hydride for H⁻ Conducting Solid Electrolyte Use at Room Temperature