The electronic conductivity, σe, and the Hall coefficient, RH, of β‐Ag2 + δS are experimentally determined at temperatures T between 190°C and 320°C and at values of δ covering the entire stability range. The change of composition is achieved by in situ coulometric titration. At δ > 5 · 10−4, where β‐Ag2 + δS shows a metallic behaviour, the data are consistent with a parabolic conduction band and an electronic relaxation time which is proportional to T−3/2, but does not depend on the electronic energy. The same concept, plus number densities of defect electrons taken from the titration curves, is also used for an interpretation of σe and RH at smaller δ, where the metal‐semiconductor transition is observed.
The electronic conductivity, σe, and the Hall coefficient, RH, of the high‐temperature phase of silver selenide, β‐Ag2+δSe, are experimentally determined at temperatures T between 170° and 300° and at values of σ covering the entire stability range. The change of composition is achieved and monitored by in situ coulometric titration. The electronic transport data yield the following results. The conduction band is harmonic, whereas the valence band is anharmonic. Mobility and relaxation time of conduction‐band electrons vary with temperature as T−1 and with the electronic energy as ϵ−1/2. This is the behaviour normally assumed to be valid, if the relaxation is due to the scattering of electrons by acoustic phonons.
In a previous paper (I) we presented the composition dependent electronic conductivity and Hall coefficient of β‐Ag2+δS at different temperatures. The mobility of conduction‐band electrons was found to vary with temperature as T−3/2. In this paper we point out that, due to a temperature dependent effective electron mass, the relaxation time of conduction‐band electrons varies as T−1 and not as T−3/2.
Im Bereich des metallischen Verhaltens (parabolisches Leitungsband bei ö 5‐ l0") ist die elektronische Relaxationszeit nicht von der Elektronenenergie abhängig (T"m‐Temp‐Abhängigkeit).
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