Kinetics of Amorphous-Crystalline Transformation of Some Se-Te-In Chalcogenide Glasses Using Gao and Wang Model

The present study reports the assessment of activation energy for crystallization and crystallization reaction order (Avrami exponent n) for the amorphous-crystallization transformation process of Se85 − xTe15Inx (x 2, 6 and 10) amorphous alloys using differential scanning calorimetry (DSC) technique under non-isothermal conditions at four different heating rates (5, 10, 15 and 20 °C/min) through Gao and Wang model. The introduction of In to the Se-Te system is found to bring a change in crystallization mechanisms and dimensions of growth. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3101

Structural analysis and theoretical investigations in Pb additive Se-Te-Ge chalcogenide nano-composites

In the present study, the impact of lead addition on the structural and physical properties of newly prepared quaternary (Se80Te20)94-xGe6Pbx (x= 0, 2, 4, 6, 8 and 10) chalcogenide nano-composites has been studied in detail. Nano particle size of each Pb addtive chalcogenide alloy has been deduced using the highest intensity peak of the X-ray diffractograms and it has also been confirmed by field emission scanning electron microscope (FESEM). The detailed study of physical parameters namely average co-ordination number (Z) and number of constraints, lone pair electrons, glass transition temperature, heat of atomization, cohesive energy and energy gap has been made. It is observed that Z and constraints have been found to increase with the addition in Pb content. However, all the other investigated parameters viz lone pair electrons, glass transition temperature, heat of atomization, cohesive energy and energy gap show a reverse variation. Glass transition temperature has been estimated theoretically using Tichy-Ticha approach and found to be in consonance with the experimental results. The cohesive energy has been calculated using chemical bond approach (CBA) model. Due to lower band gap of Pb, the overall bandgap of the composition has been found to decrease with Pb at.wt.%

Non-isothermal crystallization kinetics of chalcogenide Se79Te20Pb1 glass using differential scanning calorimetry technique

In the present paper, the overall amorphous-crystallization transformation kinetics of chalcogenide Se79Te20Pb1 alloy has been reported using differential scanning calorimetry technique under non-isothermal conditions at three different heating rates (5, 10 and 15 °C/min). Amorphous nature of the investigated alloy is verified using X-ray diffraction. The glass transition region has been investigated using three empirical approaches and consonance of these methods has been discussed. The apparent activation energy for glass transition and crystallization region has been deduced using different methods. The Avrami exponent of the investigated alloy indicates one dimension growth of the investigated glass. The deduced values of Hruby’s parameter and fragility index indicate that amorphous alloy has been formed from good glass forming liquids

Iso-conversional study of crystallization activation energy of amorphous-crystallization transformation for Se79Te20Pb1 glass using non-isothermal differential scanning calorimetry technique

135-140The ternary Se79Te20Pb1 chalcogenide glass is prepared using melt quenching technique. Differential scanning calorimetry technique (DSC) is used to investigate the kinetics of crystallization of amorphous-crystallization (a-c) phase transformation under non-isothermal conditions at three different heating rates; 5, 10 and 15° C min-1. The variation of crystallized activation energy (Ec) with crystallized fraction (ϰ) and hence, with temperature (T) is investigated using five iso-conversional methods namely KAS, OFW, Friedman, Tang and Chen and Starink. It is found that Ec is not constant but vary with ϰ as well as T. Thus, the iso-conversional analysis of investigated glass indicates that the assumption of constant Ec is not appropriate

Dielectric Properties and AC Conductivity Measurements of Amorphous Ge15Se85 Glass

In the present study, investigations of dielectric parameters viz dielectric constant (), dielectric loss () and AC conductivity measurements have been made for bulk chalcogenide Ge15Se85 glass in the frequency range 10 to 500 kHz within the temperature range from 300 to 390 K. The variation of dielectric constant and dielectric loss with frequency at room temperature is reported and discussed in the investigated glassy binary alloy. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3101

Iso-conversional study of crystallization activation energy of amorphous-crystallization transformation for Se79Te20Pb1 glass using non-isothermal differential scanning calorimetry technique

The ternary Se79Te20Pb1 chalcogenide glass is prepared using melt quenching technique. Differential scanning calorimetry technique (DSC) is used to investigate the kinetics of crystallization of amorphous-crystallization (a-c) phase transformation under non-isothermal conditions at three different heating rates; 5, 10 and 15° C min-1. The variation of crystallized activation energy (Ec) with crystallized fraction (ϰ) and hence, with temperature (T) is investigated using five iso-conversional methods namely KAS, OFW, Friedman, Tang and Chen and Starink. It is found that Ec is not constant but vary with ϰ as well as T. Thus, the iso-conversional analysis of investigated glass indicates that the assumption of constant Ec is not appropriat

Calorimetry to Understand Structural Relaxation in Chalcogenide Glasses

Thermal behavior of chalcogen additive materials synthesized via melt quench method can be studied by reheating the bulk samples in differential scanning calorimetry (DSC) or differential thermal analyzer (DTA) experiment. It involves kinetics of structural transformations as three basic characteristic phenomena correspond to glass transition, crystallization and melting are involved. Thermal stability and glass forming ability are important factors from technological point of view in various applications. Thermal stability of glasses can be ascertained based on calorimetric measurements. In the glass transition region (first region in reheating experiment), structural relaxation takes place. The temperature in glass transition region, its heating rate dependence and empirical approaches for estimation of apparent activation energy are useful to determine utility of these materials in various applications

Non-isothermal crystallization kinetics of chalcogenide Se₇₉Te₂₀Pb₁ glass using differential scanning calorimetry technique

498-505In the present paper, the overall amorphous-crystallization transformation kinetics of chalcogenide Se79Te20Pb1 alloy has been reported using differential scanning calorimetry technique under non-isothermal conditions at three different heating rates (5, 10 and 15 °C/min). Amorphous nature of the investigated alloy is verified using X-ray diffraction. The glass transition region has been investigated using three empirical approaches and consonance of these methods has been discussed. The apparent activation energy for glass transition and crystallization region has been deduced using different methods. The Avrami exponent of the investigated alloy indicates one dimension growth of the investigated glass. The deduced values of Hruby’s parameter and fragility index indicate that amorphous alloy has been formed from good glass forming liquids

Structural analysis and theoretical investigations in Pb additive Se-Te-Ge chalcogenide nano-composites

128-135In the present study, the impact of lead addition on the structural and physical properties of newly prepared quaternary (Se80Te20)94-xGe6Pbx (x= 0, 2, 4, 6, 8 and 10) chalcogenide nano-composites has been studied in detail. Nano particle size of each Pb addtive chalcogenide alloy has been deduced using the highest intensity peak of the X-ray diffractograms and it has also been confirmed by field emission scanning electron microscope (FESEM). The detailed study of physical parameters namely average co-ordination number (Z) and number of constraints, lone pair electrons, glass transition temperature, heat of atomization, cohesive energy and energy gap has been made. It is observed that Z and constraints have been found to increase with the addition in Pb content. However, all the other investigated parameters viz lone pair electrons, glass transition temperature, heat of atomization, cohesive energy and energy gap show a reverse variation. Glass transition temperature has been estimated theoretically using Tichy-Ticha approach and found to be in consonance with the experimental results. The cohesive energy has been calculated using chemical bond approach (CBA) model. Due to lower band gap of Pb, the overall bandgap of the composition has been found to decrease with Pb at.wt.%