Electrical Properties of Ag_2Te

概要

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The electronic conductivity, σ_e, Hall constant, R, and thermoelectric power, θ, in α Ag_2Te are measured as the Ag/Te ratio is varied by the use of the galvanic cell Ag|AgI|Ag_2Te|Pt, where the e.m.f. of the cell, E, represents the position of the Fermi level relative to Ag-saturated Ag_2Te. According as Ag is removed across the cell, starting from the Ag-saturated composition, σ_e decreases at first, and then increases. θ changes its sign at the minimum of σ_e, although R is always n-type, duing to the large mobility ratio (〜100). The energy gap is, therefore, as narrow as several κT. When Ag is removed further, σ_e decreases again, keeping E constant. This is a mixed state of Ag_2Te and a new phase mentioned below. After a minimum of σ_e is attained, σ_e and E increase again, suggesting a new phase, Ag_<〜1.03>Te. The energy gap of this phase is fairly larger than that in Ag_2Te phase and the mobilities of electron and hole are far smaller than those in Ag_2Te. When Ag is removed still further, σ_e and E become to be independent of the composition, indicating the precipitation of Te or Te rich compound. Those experimental data are compared with the Lorentz-Sommerfeld theory, proving a good accordance between them. On the other hand, ionic conductivity is estimated from the ionic polarization effect.
社団法人日本物理学会の論文
1958-04-05