Anion diffusivity in highly conductive nanocrystalline BaF2:CaF2 composites prepared by high-energy ball milling

Ruprecht, Benjamin; Wilkening, Martin; Steuernagel, Stefan; Heitjans, Paul

doi:10.1039/b811453f

Cited by 78 publications

(165 citation statements)

References 24 publications

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“…High-energy ball milling also increases the density of defects in the interior of the nanograins [9,24]. Starting with binary fluorides, such as nanocrystalline BaF 2 , whose F anion conductivity exceeds that of BaF 2 monocrystals by some orders of magnitude [11], iso-and aliovalent substitution of the metal cations drastically improves ion transport [10,25]. As activation energy shows a minimum, the same holds for Ba 1−x Ca x F 2 [10].…”

Section: Introductionmentioning

confidence: 99%

“…Considering nanocrystalline ionic conductors [1][2][3][4], a range of studies report on enhanced anion and cation dynamics [5,6]. Structural disorder and defects [7][8][9], lattice mismatch [10][11][12] as well as size effects [13][14][15][16][17], which results in extended space charge regions, are used to explain the properties of nanocrystalline compounds. Especially for nano-engineered systems, which were prepared by bottom-up procedures, such as gas condensation or epitaxial methods [18,19], space charge regions lead to non-trivial effects that may enhance ion transport.…”

Section: Introductionmentioning

confidence: 99%

“…Although the original cubic crystal structure remains untouched for the mixed systems, strain and defects resulting from mixing sensitively affects F anion dynamics [10,11,26]. Metastable Ba 1−x Ca x F 2 , however, cannot be prepared via solid state synthesis; instead, it is only accessible by high-energy ball milling that forces the cations ions, substantially differing in size, to form a solid solution at atomic scale [11]. Provided the cubic crystal system is retained, aliovalent substitution, e.g., with LaF 3 or YF 3 , increases the number density of mobile F anions.…”

Section: Introductionmentioning

confidence: 99%

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Fluorine Translational Anion Dynamics in Nanocrystalline Ceramics: SrF2-YF3 Solid Solutions

Breuer¹,

Stanje²,

Pregartner³

et al. 2018

Preprint

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Nanostructured materials have already become an integral part of our daily life. In many applications ion mobility decisively affects the performance of, e.g., batteries and sensors. Nanocrystalline ceramics often exhibit enhanced transport properties due to their heterogeneous structure showing crystalline (defect-rich) grains and disordered interfacial regions. In particular, anion conductivity in nonstructural binary fluorides easily exceeds that of their coarse-grained counterparts. To further increase ion dynamics aliovalent substitution is a practical method to influence the number of (i) defect sites and (ii) the charge carrier density. Here, we used high energy-ball milling to incorporate Y 3+ ions into the cubic structure of SrF 2 . As compared to pure nanocrystalline SrF 2 the ionic conductivity of Sr 1−x Y x F 2+x with x = 0.3 increased by 4 orders of magnitude reaching 0.8 × 10 −5 S cm −1 at 450 K. We discuss the effect of YF 3 incorporation on conductivities isotherms determined by both activation energies and Arrhenius pre-factors. The enhancement seen is explained by size mismatch of the cations involved, which are forced to form a cubic crystal structure with extra F anions if x is kept smaller than 0.5.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fluorine Translational Anion Dynamics in Nanocrystalline Ceramics: SrF2-YF3 Solid Solutions

Breuer¹,

Stanje²,

Pregartner³

et al. 2018

Preprint

Self Cite

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show abstract

“…As seen for other systems, see Ref. [12] for a brief review on fluorides, we expect lattice strain and distortions [13][14][15], caused by the difference in ionic radii, to promote ionic transport.…”

Section: Introductionmentioning

confidence: 67%

F anion dynamics in cation-mixed nanocrystalline LaF3: SrF2

2018

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Ion dynamics in nanocrystalline materials can be quite different compared to that in materials with lm-sized crystallites. In particular, the substitution of isoor aliovalent ions opens pathways to systematically control ion transport properties. Here we studied the incorporation of SrF 2 into the tysonite structure of LaF 3 and its effect on F À transport. High-energy ball milling directly transforms the binary fluorides in a structurally disordered, phase pure nanocrystalline ceramic. Compared to Sr-free LaF 3 , ionic conductivity could be increased by several orders of magnitude. We attribute this enhancement to the generation of lattice strain and the formation of F defect sites. In agreement with this increase, the activation energy E a of long-range ionic transport in the solid solution La 1Àx Sr x F 3Àx significantly decreases from 0.75 eV (x ¼ 0) to 0.49 eV (x ¼ 0:1).

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“…Considering nanocrystalline ionic conductors [2][3][4][5], a range of studies report on enhanced anion and cation dynamics [6,7]. Structural disorder and defects [8][9][10], lattice mismatch [11][12][13] as well as size effects [14][15][16][17][18][19], which results in extended space charge regions, are used to explain the properties of nanocrystalline compounds. Especially for nano-engineered systems, which were prepared by bottom-up procedures, such as gas condensation or epitaxial methods [20,21], space charge regions lead to non-trivial effects that may enhance ion transport.…”

Section: Introductionmentioning

confidence: 99%

Fluorine Translational Anion Dynamics in Nanocrystalline Ceramics: SrF2-YF3 Solid Solutions

et al. 2018

Self Cite

View full text Add to dashboard Cite

Nanostructured materials have already become an integral part of our daily life. In many applications, ion mobility decisively affects the performance of, e.g., batteries and sensors. Nanocrystalline ceramics often exhibit enhanced transport properties due to their heterogeneous structure showing crystalline (defect-rich) grains and disordered interfacial regions. In particular, anion conductivity in nonstructural binary fluorides easily exceeds that of their coarse-grained counterparts. To further increase ion dynamics, aliovalent substitution is a practical method to influence the number of (i) defect sites and (ii) the charge carrier density. Here, we used high energy-ball milling to incorporate Y 3+ ions into the cubic structure of SrF 2 . As compared to pure nanocrystalline SrF 2 the ionic conductivity of Sr 1−x Y x F 2+x with x = 0.3 increased by 4 orders of magnitude reaching 0.8 × 10 −5 S cm −1 at 450 K. We discuss the effect of YF 3 incorporation on conductivities isotherms determined by both activation energies and Arrhenius pre-factors. The enhancement seen is explained by size mismatch of the cations involved, which are forced to form a cubic crystal structure with extra F anions if x is kept smaller than 0.5.

show abstract

Anion diffusivity in highly conductive nanocrystalline BaF2:CaF2 composites prepared by high-energy ball milling

Cited by 78 publications

References 24 publications

Fluorine Translational Anion Dynamics in Nanocrystalline Ceramics: SrF2-YF3 Solid Solutions

Fluorine Translational Anion Dynamics in Nanocrystalline Ceramics: SrF2-YF3 Solid Solutions

F anion dynamics in cation-mixed nanocrystalline LaF3: SrF2

Fluorine Translational Anion Dynamics in Nanocrystalline Ceramics: SrF2-YF3 Solid Solutions

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