Local and Overall Ionic Conductivity in Nanocrystalline CaF2

Abstract

Ionic conductivity data on nanocrystalline CaF2 is evaluated. The d.c. conductivity is distinctly larger than in coarse-grained materials. The impedance plot exhibits two regimes: a high- and a low-frequency semicircle, the diameters of which increase with increasing grain size. The high-frequency semicircle reflects both bulk transport plus transport along the boundaries while the low-frequency semicircle describes the blocking effect of the grain boundaries. Absolute values and activation energy of the conductivity suggest dominating transport along space charge layers. The increase of the low frequency semicircle is due to increased current constriction because of the appearance of large pores.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Mar 10, 1999
Accession Number
ADP011207

Entities

People

  • J. Maier
  • P. Heitjans
  • R. Ramlau
  • S. Rodewald
  • W. Puin

Organizations

  • Leibniz University Hannover

Tags

Communities of Interest

  • Advanced Electronics
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Electron Microscopes
  • Electron Microscopy
  • Equivalent Circuits
  • Frequency
  • Grain Boundaries
  • Grain Growth
  • Grain Size
  • Heat Of Activation
  • Impedance
  • Magnetic Resonance
  • Materials
  • Measurement
  • Nanocomposites
  • Nuclear Magnetic Resonance
  • Polycrystals
  • Space Charge
  • Subatomic Particles

Fields of Study

  • Materials science

Readers

  • Electromagnetic Wave Scattering and Antenna Radiation Engineering
  • Nanocomposite Materials Science
  • Powder metallurgy of Titanium alloys.

Technology Areas

  • Space
  • Space - Hall-Effect Thruster