Thermal diffusivity of IV-V-VI glassess - An evidence for the existence of a mechanical threshold

The thermal diffusivity of two sets of $Ge_xSb_ySe_{l00-x-y}, Ge_xAs_yTe_{100-x-y}$ and $Si_xAs_yTe_{l00-x-y}$ glasses have been measured using the photoacoustic technique. The thermal diffusivity data of the three glass systems show maxima at the compositions corresponding to the average coordination number $\langle r \rangle$ = 2.60. These results have been interpreted in the light of the existence of a mechanical threshold and the formation and development of a layered structure in these network glasses

Differential Scanning Calorimetry Of Si-As-Te Glasses

Differential scanning calorimetry (DSC) can be used for obtaining various non-isothermal properties of glassy materials. The thermal properties of the Si-As-Te glass system are discussed in relation to the interesting information obtained on the local ordering in these glasses

Chemical ordering in SixAsyTe100–x–ySi_xAs_yTe_{100–x–y} glasses

Tellurium-based glasses find application as electrical switching devices [1]. The formation of a crystalline filament between the electrodes has been observed in memory-type switching glasses after being switched to the conducting state from the high-resist-ance state [2]. This has led to the suggestion that the crystallization of these glasses could possibly be the mechanism behind the irreversible switching action observed in these materials. An understanding of the crystallization kinetics of these glasses is important in this respect. The thermal crystallization behaviour of Si-As-Te has not been well investigated. In this letter differential scanning calorimetry studies on $Si_{l0}As_xTe_{90_ x}$ $(10\leq x \leq50)$ and $Si_{15}AS_x-Te_{85-x}$ $(5\leq x \leq45)$ glasses are reported

Observation of a threshold behavior in the optical band gap and thermal diffusivity of Ge-Sb-Se glasses

The optical band gap $(E_0)$ and thermal diffusivity (α) of bulk $Ge_xSb_5Se_{95-x}$ and $Ge_xSb_{10}Se_{90-x}$ glasses have been measured using the photoacoustic technique. The behavior of $E_0$ and α as the mean coordination number $\langle r \rangle$ is varied shows a maximum at $\langle r \rangle=2.6$. The anomalous behavior at $\langle r \rangle=2.6$ is explained on the basis of changes in the network topology due to the formation and development of layered structure in these glasses

Threshold behaviour in the nonisothermal properties of Ge-Sb-Se glasses

Differential scanning calorimetry studies have been performed on GexSb5Se95-x (12.5≤x≤35) and GexSb10Se90-x (10≤x≤32.5) glasses. The observed dependence of the glass transition temperature on the mean coordination number <r> up to <r>=2.60 and the maxima in the glass transition temperature and the activation energy of crystallisation at <r>=2.65 have been interpreted in terms of the mechanical and chemical thresholds occuring near these compositions

Anomalous behaviour in the composition dependence of the photoacoustic properties of Si---As---Te glasses

The optical bandgap and thermal diffusivity of Si10AsxTe90−x (10 ≤ x ≤ 50) and Si15AsxTe85−x (5 ≤ x ≤ 40) glasses have been measured using the photoacoustic technique. The anomalous behaviour observed in these properties at the mean coordination number left angle bracketrright-pointing angle bracket = 2.60 is interpreted by reference to the formation and development of a layered structure in these glasses

High-pressure studies on the critical composition in Ge—As—Te glasses

High-pressure resistivity measurements have been performed on G37.5AsxTe92.5-x (x = 20, 40, 45, 50 and 55) and Ge10AsxTe90-x (x = 15, 20, 35, 40, 45 and 50) glasses. The glasses show reversible metallization behaviour under pressure. The pressure derivative of the logarithm of the resistivity of the glasses is a minimum at glass compositions corresponding to the average coordination number [r] = 2.60. This behaviour is interpreted on the basis of the existence of a critical composition in glasses with a layered structure

High pressure studies on Si-As-Te glasses-evidence for rigidity percolation

The resistivity of the glasses decreased with an increase in applied pressure. The glasses showed resistance value of <1 $\Omega$ at pressures above 4 GPa. The glasses regained their high resistance when the pressure was released. This showed that the transition to the high conduction state under pressure is reversible. To check the reversibility, the glass sample was subjected to a pressure run and the pressure was released

Photoacoustic investigations on the critical composition in Ge-As-Te glasses

The optical band-gap $(E_0)$ and thermal diffusivity $(\alpha)$ of bulk $Ge_{7.5}As_xTe_{92.5-x} (x=20, 40, 45, 50, 55)$ and $Ge_{10}As_xTe_{90-x} (x=15, 20, 35, 40, 45, 50)$ glasses have been determined by the photoacoustic spectroscopy technique. The behaviour of $E_0$ and α have been explained on the basis of the network topology, in terms of the mean coordination number $<\gamma>$. The $E_0$ and $\alpha$ values of both the sets of glasses show subtle features at$<\gamma>=2.6$ indicating the occurrence of a threshold at this value of $<\gamma>