Structural, Thermal, Electrical, and Negative Resistance Properties of (Se60Te40)xTl(100−x) Chalcogenide Glasses

Bulk (Se60Te40)xTl(100−x) glass (x = 80, 75, 70, and 60 mol.%) is prepared by the melt quenching technique. The density of the samples is found to increase with increasing the Tl content in the glass. Only the sample (Se60Te40)80Tl20 is confirmed to be amorphous according to XRD results, while some nanocrystals are grown and increase with increasing the Tl content in the glass. Average bond energy is calculated and found to decrease with increasing the Tl content. Thermal characteristics and responses of the glass are investigated by DSC and TGA measurements. The electrical measurements are carried out in the temperature range 100–300 K. The direct current (dc) conductivity is discussed in the light of the variable range hopping (VRH) model with activation energies decreasing with the increase of the Tl content in the glass. The alternating current (ac) conductivity is discussed and fitted for the sample (Se60Te40)80Tl20 on the bases of the Correlated Barrier Hopping (CBH) model with N ≈ 2 × 1019 cm−3 eV−1and the τo ≈ 10−13 s. Different types of switching modes with threshold voltage are obtained in the range 5–17 V. Fth is found to decrease with increasing the average bond energy, and increase with increasing the sample thickness indicating that the mechanism of switching is of electrothermal origin.