DC Ionic Conductivity of Potassium Azide

The electrical conductance of both single crystal and pressed pellets of potassium azide has been measured. The ionic conductance parameters of KN 3 were calculated from samples containing known amounts of Ba 2+ ion impurity. The conventional theory of association was found to be adequate to describe association between Ba 2+ and cation vacancies. A value of 0.2 eV was determined for — ζ, where ζ is the free energy of association of complexes. The following point defect parameters were determined: h , the enthalpy change for the formation of a defect pair = 1.25 eV, Δ h , the enthalpy for migration of a cation vacancy = 0.76 eV, s , the entropy change on the formation of a defect pair = 0.119 × 10 −3 eV deg −1 . Equations describing X 0 , the number of thermally produced defects in a pure crystal, and μ, the mobility of the cation vacancy, both as a function of temperature have been derived.