High pressure studies on the electrical resistivity of As–Te–bond Si glasses and the effect of network topological thresholds

The variation of resistivity in an amorphous As30Te70−x Si x system of glasses with high pressure has been studied for pressures up to 8 GPa. It is found that the electrical resistivity and the conduction activation energy decrease continuously with increase in pressure, and samples become metallic in the pressure range 1.0–2.0 GPa. Temperature variation studies carried out at a pressure of 0.92 GPa show that the activation energies lie in the range 0.16–0.18 eV. Studies on the composition/average co-ordination number ⟨ r⟩ dependence of normalized electrical resistivity at different pressures indicate that rigidity percolation is extended, the onset of the intermediate phase is around ⟨ r⟩=2.44, and completion at ⟨ r⟩=2.56, respectively, while the chemical threshold is at ⟨ r⟩=2.67. These results compare favorably with those obtained from electrical switching and differential scanning calorimetric studies

Extended rigidity percolation and chemical thresholds in Ge-Te-Pb glasses as revealed by MDSC

Thermal analysis of Ge20Te80−xPbx (2≤x≤8) glasses has been undertaken using modulated differential scanning calorimetry (MDSC). The compositional dependence of thermal parameters is investigated. The crystallization temperatures (Tc) estimated from the total heat flow show detectable changes at compositions x=4, 6.5 and 7.5. Further, the heat capacity change at the glass transition temperature, measured from the reversible heat flow curve (ΔCpR), is found to exhibit a maximum and an inflexion at compositions x=4 and 6.5 and minimum at x=7.5, respectively. Also, the relaxation enthalpy, estimated from the area under the non-reversing heat flow curve (ΔHNR), exhibits similar features at the said compositions. From the observed MDSC results, it has been proposed that the compositions x=4 and x=6.5 denote to the onset and completion of rigidity percolation and x=7.5 corresponds to the chemical threshold of the system

A modulated differential scanning calorimetric study of As-Te-In glasses

Bulk As-Te-In glasses have been prepared by conventional melt-quenching technique. Modulated differential scanning calorimetric studies have been undertaken to investigate the glass transition and crystallization behavior and also to understand the composition dependence of various thermal parameters. These studies indicate the occurrence of rigidity percolation and chemical thresholds at average coordinations ãrã = 2.65 and 2.70 respectively. © 2003 Elsevier B.V. All rights reserved

High-pressure resistivity behavior of As-Te-In glasses - The effect of network topological thresholds

Electrical resistivity measurements have been carried out on As–Te–In glasses up to a pressure of 8 GPa using an Opposed Anvil Cell. It is found that the electrical resistivity and conductivity activation energy decrease continuously with pressure and the samples become metallic at pressures in the range 1.5–2.5 GPa. The variation with composition of the normalized electrical resistivity at different pressures suggests the possibility of rigidity percolation and chemical thresholds occurring around the average coordination of 〈r〉=2.65 and 2.7 respectively. It is also observed that As–Te–In samples remain amorphous when they undergo metallization at high pressures, which is analogous to the threshold switching exhibited by these sample

SIFT-PCA: An efficient and accurate face representation and recognition model

Proceedings of the 4th Indian International Conference on Artificial Intelligence, IICAI 20091969-198

Threshold electrical switching in bulk As-Te-In glasses: Composition dependence and topological effects

The current-voltage (I-V) characteristics and electrical switching behaviours of As40Te60-xInx (5 ≤ x ≤ 16.5), As35Te65-xInx (10 ≤ x ≤ 19) and As30Te70-xInx (12.5 ≤ x ≤ 21.5) have been studied over wide ranges of indium concentrations x and average coordination numbers . All the glasses studied show a threshold switching behaviour. Further, the composition dependence of the switching field is found to exhibit a distinct change in slope at = 2.65 and a local minimum at around = 2.69. These results indicate the possibility that rigidity percolation occurs at around = 2.65 and chemical threshold around = 2.69

Threshold electrical switching in As45Te55-xInx and As50Te50-xInx glasses

The electrical switching behaviour of As45Te55-x Inx (5 ≤ x ≤ 15) and As50Te50-xInx (2.5 ≤ x ≤ 11.5) has been studied over a wide range of compositions. These glasses are found to exhibit threshold switching. The composition dependence of switching voltage (Vt) has been found to exhibit a change in slope and a local minimum at compositions x = 10 and 12.5 for As45Te55-xInx and x = 7.5 and 10.8 for As50Te55-xInx, respectively. The slope change in Vt verses x and the local minimum have been identified using two network topological effects, namely the rigidity percolation threshold and the chemical threshold

Nonlinear I-​V characteristics and threshold switching in As-​Te-​In glasses

Nonlinear I-​V behavior and elec. switching exhibited by chalcogenide glassy semiconductors, find applications in variety of areas including information storage and power control. Semiconducting chalcogenide As40Te60-​xInx glasses were prepd. by melt quenching technique. The current-​voltage and elec. switching behavior of these glasses were studied using a custom-​built PC based system. The results obtained clearly indicate that all the glasses studied exhibit current controlled neg. resistance behavior, which leads to the low resistance state. The switching to the low resistance estate is reversible and the samples revert back to the high resistance state on reducing the current. Threshold switching over such a wide range of compns. was obsd. only in very few systems so far. The most interesting outcome of the present studies is the variation of the switching voltage with compn. There is an increase in the switching voltage Vt with the increase in In concn. in the compn. range 7.5 ≤ x ≤ 12.5. Further, the compn. dependence of switching field is found to exhibit a distinct change in slope at x is 12.5 and Vt continues to increase with x until x = 13.5. Around x = 13.5, the trend is reversed and Vt starts decreasing with x. A min. in Vt is seen around the compn. x = 14.3, which corresponds to the chem. threshold of the As-​Te-​In system. Beyond x = 14.3, switching voltage increases with compn. again. The present result are consistent with earlier observations, which indicate the compn. dependence of switching voltages of chalcogenide glasses are influenced by chem. ordering and rigidity percolation