Mixed fluoride ion conductors prepared by a mechanical milling technique: effect of grain size and strain on the ionic conductivity

Abstract

Mixed metal fluoride ion conductors which have been prepared by a mechanical milling process have been found to have higher value of conductivity than single fluorides. Specific results for the synthesis of mixed metal fluorides of composition xPbF2·(1-x)SnF2 and NH4F-2SnF2 are presented. The variation of conductivity with composition (x), milling time and temperature has been studied. The grain size and the strain factor were calculated from the linewidth of different x-ray diffraction lines and their correlation with the conductivity value and the milling time has been studied.

Temperature dependence of19F NMR and ion transport parameters of fluoride ion conductors SnF2—PbF2and 2SnF2—NH4F prepared by mechanical milling

“…The room temperature conductivity of mixed metal fluorides SnF 2 :PbF 2 and 2SnF 2 :NH 4 F prepared by mechanical milling has been found to depend upon the milling time and maximum conductivity of 1.34 × 10 -3 Scm -1 for SnF 2 -PbF 2 and 1.9 × 10 -4 Scm -1 for 2SnF 2 -NH 4 F samples at 25 °C has been reported for samples milled for 8 h [19,20]. These samples with maximum conductivity have been used in the present study.…”

“…Mixed metal fluorides composed of SnF 2 -PbF 2 in 1:1 molar ratio and SnF 2 -NH 4 F in a 2:1 molar ratio were prepared by mechanical milling described in detail earlier [19,20]. Samples with maximal value of room temperature conductivity (corresponding to milling time of 8 h) were used in the present study.…”

“…The SnF 2 -PbF 2 and 2SnF 2 -NH 4 F samples studied in the present case have been prepared by ball milling. The variation of conductivity of ball milled samples has earlier been found to depend upon the milling time and has been explained to be closely related to the average grain size and strain developed during milling [19,20].…”

“…In the present study, mixed metal fluorides composed of SnF 2 -PbF 2 and 2SnF 2 -NH 4 F have been studied by 19 F NMR technique. The samples studied have been synthesized by using mechanical milling and samples of maximal values of conductivity have been used.…”

Nanocrystalline CaF2 particles obtained by high-energy ball milling

“…The products were investigated exclusively by X-ray diffraction (XRD) [13]. Further studies were published on milling of PbF 2 and NH 4 F with SnF 2 to examine the influence of grain sizes on the ion conductivity [14][15][16]. More recently, mechanochemical reactions of alkali acid bifluorides (MHF 2 ) with alkali halides (MX) were studied by XRD and IR spectroscopy [17].…”