Glassy Se80Te20 Research Articles

Metal-Induced Effects of Cu, Zn, Pb Additives on Glass Transition/Crystallization Phenomena in Glassy Se80Te20 Alloy

Metal-Induced Effects of Cu, Zn, Pb Additives on Glass Transition/Crystallization Phenomena in Glassy Se₈₀Te₂₀ Alloy

Study of dielectric relaxation and thermally activated a.c. conduction in glassy Se70Te30 and Se70Te28M2 (M = Ag, Zn and Cd) alloys

A detailed study of conduction mechanism of glassy Se70Te30 and Se70Te28M2 (M = Ag, Zn and Cd) alloys has been carried out in terms of dielectric properties and a.c. conductivity. Temperature and frequency dependent dielectric constant, dielectric loss and σac for the same system were measured in the frequency spectrum, 1 kHz to 1 MHz and temperature range, 303–338 K. The a.c. conductivity (σac) is found to be proportional to ωs (s < 1). The temperature dependence of both a.c. conductivity and frequency exponent (s) is reasonably well interpreted by the correlated barrier hopping (CBH) model. We showed that the bi-polaron hopping is dominant over the potential barrier and estimated the density of defect states (DOS) at 10 kHz. We found a good agreement between bi-polaron conductivity and experimental results.

Investigation of silver as chemical modifier for tailoring of some physico-chemical properties in inorganic glassy Se80Te20 alloy

In the present work, an attempt has been made to correlate the structural modifications in glassy Se80Te20 alloy after incorporation of Ag as chemical modifiers in terms of some significant physico-chemical parameters. For this, we have determined some significant physic-chemical parameters i.e., coordination number, constraints, density, molar volume, cohesive energy, heat of atomization etc in glassy Se80-xTe20Agx (0 ≤ x ≤ 15) alloys. Our results indicate that there is a significant change in the structural environment of the parent glassy system due to rigidity percolation.

Effect of Tin Incorporation on Thermo-Mechanical Properties of Glassy Se80Te20 Alloy

We report an analysis on the hardness behavior of glassy Se80–xTe20Snx alloy. The crucial thermo-mechanical parameters (micro-hardness, volume and formation energy of micro-voids and the modulus of elasticity) are examined. The results indicate that the thermo-mechanical parameters are changed significantly after incorporation of Sn in glassy Se80Te20 alloy.

Thermal analysis for study of influence of Cd, In, and Sb on glass transition kinetics in glassy Se80Te20 alloy using DSC technique

In this paper, we have incorporated Cd, In, and Sb in glassy Se80Te20 alloy to see the metal-induced effect of these additives on its glass network and kinetic properties. Specifically, we report results of systematic calorimetric measurements to study the glass transition kinetics. The glass transition behavior of glassy Se80Te20 and glassy Se80Te10M10 (M = Cd, In, Sb) alloys has been analyzed by differential scanning calorimetric technique at various heating rates. The activation energy (E g) of glass transition was determined using different kinetic models. Analysis of experimental data reveals that E g varies with the additive elements. The value of various kinetic parameters such as thermal stability, Hruby number, and fragility index has been calculated in non-isothermal mode.

Calorimetric Study of Crystallization Kinetics in Glassy Se80Te20 and Se80Te10M10 (M = Cd, In, Sb) Alloys

Calorimetric Study of Crystallization Kinetics in Glassy Se₈₀Te₂₀ and Se₈₀Te₁₀M₁₀ (M = Cd, In, Sb) Alloys

Composition dependence of specific heat in Se80 − x Te20Sn x chalcogenide glasses

Differential Scanning Calorimetry (DSC) is performed at different heating rates under non-isothermal conditions to study the specific heat studies of glassy Se80 − x Te20Sn x (0 ≤ x ≤ 10) alloys. An extremely large increase in the specific heat values has been observed at the glass transition temperature. It has also been found that the values of C p below glass transition temperature (C pg ) and after glass transition (C pe ) are highly composition dependent. This indicates that the Sn additive used in the present study influences the structure of the glassy Se80Te20 alloy. The results show that C p values reveal local extrema in Se-Te-Sn glassy system at x = 4 and x = 8. The composition dependence of both parameters (C pe and C pg ) has been explained in terms of the glassy structure of Se-Te-Sn system.

Metal-induced effects on the glass transition kinetics of glassy Se70Te30 alloy

The calorimetric measurements have been made in glassy Se70Te30 and Se70Te28M2 (M = Ag, Cd, and Zn) alloys using non-isothermal differential scanning calorimetry technique to see the effects of Ag, Cd, and Zn additives on the glass transition kinetics of binary Se70Te30. From the heating rate dependence of glass transition temperature, T g, different kinetic parameters of glass transition have been evaluated. The composition dependence of glass transition temperature T g and the related activation energy (Et ) is also discussed.

Effect of In additive on the photosensitivity of glassy Se80Te20 alloy

Photo-electrical measurements are done on thin films of Se80−x Te20In x (0 ≤ x ≤ 20) to see the effect of In on the photoconductive properties of binary Se80Te20 alloy. The photosensitivity (σph/σd) and activation energy of photoconduction (ΔE ph) are determined for this purpose. It has been found that σph/σd and ΔE ph are decreased with increasing concentration of the third element. The results are explained in terms of the increase in density of the defect states with the increase in concentration of the additive in thin films of Se80−x Te20In x .

Pre-exponential factor for the crystallization of glassy Se80Te20 and Se75Te20M5 alloys: applicability of Meyer–Neldel rule

The Meyer–Neldel rule or MN rule (also known as compensation effect) is an empirical law known since 1937. This rule is observed in wide range of phenomena in physics, chemistry, biology and electronics. Many activated phenomena, including solid state diffusion in crystals and polymers, dielectric relaxation, conduction and thermally stimulated processes in polymers, and electronic conduction in amorphous semiconductors obey the MN rule. In the present article, we report the MN rule in the non-isothermal crystallization in glassy Se80Te20 and Se75Te20M5 (M = Ag, Cd, In, Sb) alloys. We have observed MN rule between pre-exponential factor K o and activation energy of crystallization E c in the present case for thermally activated non-isothermal crystallization.

Observation of compensation effect for isothermal crystallization in glassy Se80−x Ge20Inx and Se78−x Ge22Bix alloys

Many activated phenomena, including solid state diffusion in crystals and polymers, dielectric relaxation, conduction and thermally stimulated processes in polymers, and electronic conduction in amorphous semiconductors obey the compensation law or Meyer-Neldel rule. In the present paper, we discuss the results of investigation into the compensation effect observed under isothermal crystallization in glassy Se70Te30−xSbx alloys. It is found that the relation between the pre-exponential factor Ko and activation energy of crystallization Ec follows the Meyer-Neldel rule for the alloys studied.

A study of thermal crystallization in glassy Se80Te20 and Se80In20 using DSC technique

Abstract Different methods have been used by various workers to determine the activation energy of thermal crystallization (Ec) in chalcogenide glasses using non-isothermal DSC data. In the present work, the crystallization kinetics of two important binary alloys Se80Te20 and Se80In20 is studied using non-isothermal DSC data. DSC scans of these alloys have been taken at five different heating rates. The values of activation energy of crystallization (Ec) have been determined by four different methods, i.e., Kissinger's method, Matusita-Sakka method, Augis-Bennett's method and Ozawa's method, have been used to calculate Ec. The results obtained have been compared with each other to see the effect of using different methods in the determination of Ec.

Electrical conductivity and crystallization kinetics of Se 70Te 30 films

Glassy Se70Te30 thin films were thermally evaporated onto chemically cleaned glass substrates. Crystallization kinetics were determined under isothermal conditions. DC conductivity of the investigated film was used as a parameter to calculate the crystallized fraction χ(t). The values obtained for the activation energy of crystallization and the Avrami index were 239.8±0.5 kJ/mol and 2.21±0.1, respectively. The non-integer value of the Avrami index indicates that two crystallization mechanisms, one- and two-dimensional growth, are responsible for the crystallization process.

Effect of Ag addition on glass transition and crystallization in Se80Te20 glass

The present paper reports on the differential scanning calorimetric (DSC) behaviour of glassy Se80Te20 containing Ag up to 10 at%. DSC runs were taken at different heating rates. Well-defined endothermic and exothermic peaks were obtained at glass transition and crystallization temperatures. The glass transition temperature (Tg) and crystallization temperature (Tc) increase with the increase in heating rate. Tg and Tc both decrease with increase in Ag concentration. The activation energies for glass transition and crystallization also decrease with Ag incorporation in the Se80Te20 binary alloy. Copyright © 2000 John Wiley & Sons, Ltd.

Effect of Ag addition on glass transition and crystallization in Se80Te20 glass

The present paper reports on the differential scanning calorimetric (DSC) behaviour of glassy Se80Te20 containing Ag up to 10 at%. DSC runs were taken at different heating rates. Well-defined endothermic and exothermic peaks were obtained at glass transition and crystallization temperatures. The glass transition temperature (Tg) and crystallization temperature (Tc) increase with the increase in heating rate. Tg and Tc both decrease with increase in Ag concentration. The activation energies for glass transition and crystallization also decrease with Ag incorporation in the Se80Te20 binary alloy. Copyright © 2000 John Wiley & Sons, Ltd.

Dielectric properties of glassy Se80Te20 and Se 80Te10M10 (M = Cd, In and Sb)

The temperature and frequency dependence of dielectric constant and loss is measured in glassy Se 80 Te 20 and Se 80 Te 10 M 10 (M=Cd, In and Sb) in the temperature range 100 K to 330 K and the frequency range 120 Hz to 10 kHz. The dielectric constant and loss are independent of temperature and frequency at low temperatures (T La dependance en temperature et en frequence de la constante et des pertes dielectriques dans les verres Se 80 Te 20 et Se 80 Te 10 M 10 (M=Cd, In et Sb) est mesuree dans la gamme de temperatures de 100 a 330 K et dans la gamme de frequence de 120 Hz a 10 kHz. La constante et les pertes dielectriques sont independantes de la temperature et de la frequence a basse temperature (T<200 K). Cependant, a haute temperature, une forte dispersion dielectrique apparait. Les resultats sont interpretes a l'aide d'un modele dipolaire qui considere le saut des porteurs de charge a travers la barriere de potentiel entre niveaux de defauts charges