Structural, Thermal, Electrical, and Negative Resistance Properties of (Se_(60)Te_(40))xTl_((100-x)) Chalcogenide Glasses

摘要

Bulk (Se_(60)Te_(40))_xTl_((100-x)) glass (x=80, 75, 70, and 60 mol.%) is prepared byrnthe melt quenching technique. The density of the samples is found tornincrease with increasing the Tl content in the glass. Only the samplern(Se_(60)Te_(40))_(80)Tl_(20) is confirmed to be amorphous according to XRD results,rnwhile some nanocrystals are grown and increase with increasing the Tlrncontent in the glass. Average bond energy is calculated and found torndecrease with increasing the Tl content. Thermal characteristics andrnresponses of the glass are investigated by DSC and TGA measurements. Thernelectrical measurements are carried out in the temperature range 100–300 K.rnThe direct current (dc) conductivity is discussed in the light of the variablernrange hopping (VRH) model with activation energies decreasing with thernincrease of the Tl content in the glass. The alternating current (ac)rnconductivity is discussed and fitted for the sample (Se60Te40)80Tl20 on thernbases of the Correlated Barrier Hopping (CBH) model with N≈2×10~(19)rncm~(-3) eV~(-1)and the τo ≈10~(-13) s. Different types of switching modes withrnthreshold voltage are obtained in the range 5–17 V. F_(th) is found to decreasernwith increasing the average bond energy, and increase with increasing thernsample thickness indicating that the mechanism of switching is ofrnelectrothermal origin.