Structural based interpretation for the electrical conduction in AgAs 2S 3 glasses

Abstract

The electrical conduction in three glasses of the system Ag x(As 0.4S 0.6) 100−x with x=6, 15 and 25, has been studied. Below T g, the dc conductivity increases with increasing absolute temperature in accordance with the thermal activation formula: σ = C exp(−E σ/2kT). The addition of silver (6–25 at.%) to As 2S 3 leads to a big decrease in E σ (1.29 to 0.38 eV), relative small increase in σr.t. (20°C) (1.4×10 −12 to 5.6×10 −9 ohm −1 cm −1), and very pronouced decrease in the pre-exponent C. The small variation in the value of C of As 2S 3 and Ag 6(As 0.4S 0.6) 94, (4 and 0.2 ohm −1 cm −1), confirms the non-variation of the orpiment structure due to the addition of up to 6 at.% Ag. The decrease in E σ for the 6 at.% Ag glass is discussed in terms of Mott's charged dangling bonds. The X-ray radial distribution function tetrahedral base structure for higher Ag percentage glasses is confirmed by the value of E σ and the very low value of C (less than 10 −4 ohm −1 cm −1).