Conductivity of aliovalent substitution solid solutions Pb1-R SnF4+ (R = Y, La, Ce, Nd, Sm, Gd) with β-PbSnF4 structure

The case for fluoride-ion batteries

“…The ionic conductivity of both Tysonite and Fluorite structures can be increased significantly (by one to three orders of magnitude) through aliovalent cation substitution. 25,30,35,36 The most commonly employed technique involves the introduction of divalent cations at the typically trivalent sites in the Tysonite lattice (e.g. La 1-x Ba x F 3-x ); this increases the ionic conductivity by introducing an additional fluoride anion vacancy.…”

Fluoride ion conductivity of solid solutions KxPb0.86-xSn1.14F4-x

“…The electrical conductivity was calculated from the equation σ=l/s•R, where l is the thickness of disk-shaped sample, s is contact area, R is ohmic resistance, which was determined from the results of impedance spectroscopy by the procedure described in 19,20 .…”

“…Unlike the compounds with purely interstitial conduction mechanism, the activation energy for K x Pb 0.86-x Sn 1.14 F 4-x solid solutions at T > 450 K increases with potassium fluoride content. 20 This may be due to the fact that the motion of fluoride ions between vacant positions requires a higher expenditure of energy than that in interstitial spaces.…”

“…The solid solutions containing 10.0-15.0 mol.% LnF 3 have a maximum conductivity. 20,21 The substitution of a part of the lead ions by potassium ions contributes to increase in electrical conductivity relative to β-PbSnF 4 . The samples of the composition K 0.10 Pb 0.90 SnF 3.90 has the highest conductivity and the lowest conductivity activation energy in the high-temperature region (σ 573 = 0.13 S cm -1 ).…”

“…The samples of the composition K 0.10 Pb 0.90 SnF 3.90 has the highest conductivity and the lowest conductivity activation energy in the high-temperature region (σ 573 = 0.13 S cm -1 ). 22 Despite the large body of accumulated experimental data on the effect of aliovalent substituents, including potassium ions, on the conduction properties of PbSnF 4 -based complex fluorides, [15][16][17][18][19][20][21][22] the effect of the different degree of substitution of a part of the Pb 2+ or Sn 2+ ions by potassium ions on the properties of the fluoride ion conducting phases in the KF-PbF 2 -SnF 2 system has not been unambiguously established. The effect of aliovalent substitution on the conductivity of complex lead and tin fluorides with nonstoichiometric ratio is studied scantily.…”