Alkaline‐Earth‐Fluoride—LaF<sub>3</sub> Systems with Implications for Electroslag Melting

Nafziger, R. H.; Riazance, N.

doi:10.1111/j.1151-2916.1972.tb11235.x

Cited by 32 publications

(22 citation statements)

References 8 publications

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“…17,18 Moreover, the solubility limit of BaF 2 in LaF 3 needs to be ascertained. 19,20 Roos et al have largely investigated the fluorine mobility on La 1−x Ba x F 3−x single-crystals: electrical, 21 electronic 22 and ionic 23 conductivities, bulk and interfacial polarization, 24 dielectric relaxation 25 and small-signal ac response. 26 They proposed the first equivalent circuits to model the impedance spectra 24 and they demonstrated that the electronic conductivity can be neglected.…”

Section: Introductionmentioning

confidence: 99%

“…28,29 Recently, Fichtner et al observed a conduction maximum at x = 0.1 for mechanosynthesized powders 6 and thin films 34 and that the absence of sintering is detrimental to the conductivity. 35 The last aspect of La 1−x Ba x F 3−x characterization concerns 19 F NMR experiments, which are particularly useful to probe accurately the environment and mobilities of fluoride ions. In the tysonite structure (P3 ˉc1), three crystallographic fluorine sites have different occupancies (F1 (12g), F2 (4d) and F3 (2a)).…”

Section: Introductionmentioning

confidence: 99%

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Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La_1−xBa_xF_3−x (x < 0.15)

et al. 2015

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Pure tysonite La1-xBaxF3-x solid solutions for x < 0.15 were prepared by solid state synthesis in a platinum tube under an azote atmosphere with subsequent quenching for 0.07 ≤x < 0.15. The solid solutions were studied by X-ray, electron and neutron diffractions and by (19)F NMR and impedance spectroscopy. The evolution of the cell parameters obeying Vegard's rule was determined for 0 < x≤ 0.15 and atomic position parameters were accurately refined for x = 0.03, 0.07 and 0.10. The chemical pressure induced by large Ba(2+) cations leads to an increase of the unit cell parameters. Fluorine environment and mobilities are discussed on the basis of the results of neutron diffraction and (19)F solid state NMR. The F1 subnetwork is lacunar; fluorine exchange occurs according to the order: F1-F1 and F1-F2,3. 2D EXSY NMR spectra of La0.97Ba0.03F2.97 reveal, for the first time, a chemical exchange between F2 and F3 sites that requires two successive jumps. The ionic conductivity was evaluated from sintered pellets and different shaping methods were compared. The only structural features which could explain the conductivity maximum are a crossover together with a smaller dispersion of F1-F1,2,3 distances at x = 0.05-0.07.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La_1−xBa_xF_3−x (x < 0.15)

et al. 2015

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“…Phase equilibria in the SrF 2 ‐LaF 3 system have been studied repeatedly, 1‐6 see Figure 1. In this eutectic type system (eutectic coordinates are 70 mol% LaF 3 , 1450°C), wide areas of solid solutions are formed based on the components: Sr 1− x La x F 2+ x with the fluorite‐type structure (cubic system, Space Symmetry Group (SSG) Fm

F m \overset{3}{true} m

) and La 1− y Sr y F 3− y with the structure of LaF 3 ‐tysonite (trigonal system, SSG P

\bar{3}

c 1).…”

Section: Introductionmentioning

confidence: 99%

Low‐temperature phase formation in the SrF₂–LaF₃ system

et al. 2021

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Phase formation in the SrF2–LaF3 system was studied at temperatures ranging from 300°C to 450°C using nitrate flux. The solubility of LaF3 in SrF2 decreases with decreasing temperature. The equilibrium width of the solid solution region Sr1−xLaxF2+x at 400°C, it is 44.6 ± 0.4 mol% LaF3 (x = 0.446), at 350°C — 38.3 ± 0.7 mol% LaF3 (x = 0.383), and decreases almost to zero at 300°C.

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“…This result is in line with eqs. (13) and (14), because the free F I concentration increases exponentially with temperature, and so contributes to a further decrease of AH A.…”

Section: Lonic Conductivitymentioning

confidence: 99%

“…(14) and (23). The parameter A/-/~I 2 is calculated from data obtained on sample 1, under the assumption that x c equals the difference between the nominal impurity concentration and the dipole concentration in this sample.…”

Section: Dipole Concentrationsmentioning

confidence: 99%

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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Alkaline‐Earth‐Fluoride—LaF₃ Systems with Implications for Electroslag Melting

Cited by 32 publications

References 8 publications

Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La_1−xBa_xF_3−x (x < 0.15)

Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La_1−xBa_xF_3−x (x < 0.15)

Low‐temperature phase formation in the SrF₂–LaF₃ system

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

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Alkaline‐Earth‐Fluoride—LaF3 Systems with Implications for Electroslag Melting

Cited by 32 publications

References 8 publications

Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La1−xBaxF3−x (x < 0.15)

Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La1−xBaxF3−x (x < 0.15)

Low‐temperature phase formation in the SrF2–LaF3 system

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

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Alkaline‐Earth‐Fluoride—LaF₃ Systems with Implications for Electroslag Melting

Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La_1−xBa_xF_3−x (x < 0.15)

Fluoride solid electrolytes: investigation of the tysonite-type solid solutions La_1−xBa_xF_3−x (x < 0.15)

Low‐temperature phase formation in the SrF₂–LaF₃ system