Crystallization kinetics of Se–Zn–Sb nano composites chalcogenide alloys

Abstract

Crystallization kinetics could be define the working limits of the material, thereby, this work is described the kinetics of Se₉₆Zn₂Sb₂ (SZS) chalcogenide alloy and its composites with 0.05% multi walled carbon nano tubes (MWCNT) and 0.05% graphene (GF). The crystallization kinetic parameters have been obtained using the Differential Scanning Calorimetric (DSC) measurement traces at 5, 10, 15 and 20 °C/min heating rates, by employing the different approximations at the glass transition, onset crystallization and peak crystallization temperatures. Subsequently, Hruby Hr glass forming ability parameter, thermal stability and nucleation and growth order parameter (n) and dimensional parameter (m) of the materials have also been discussed. Outcomes demonstrate these materials have a variation in kinetic parameters with the incorporation MWCNT and GF in SZS regime. It has been noticed MWCNT composite glass transition activation energy (E_g), onset crystallization temperature (E_c), peak crystallization (E_p) higher than GF composite while lowest for the parent alloy, however, a variation in Hr and thermal stability have been obtained for the composites. The overall two-one dimensional nucleation and growth mechanism have been evaluated for these materials.

Introduction

Composite of the material can deliver more than individual physical property of a parent element or alloy. Chalcogenide as well as other composites materials, like, rare earth, polymer, oxide [1], [2], [3], [4], [5], [6], [7], [8], [9], [10] etc. have been intensively studied more than five decades. Composite elements can influence the electrical, thermal optical properties of the materials [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], which can be useful in various technical applications, specifically rear earth-chalcogenide composites have been attended much attention for optical fibers, optical non linearity [1], [2], [3], [4], [5], [6], [7] and polymer composites for optoelectronics memory applications [1], [2], [3], [4], [5], [6], [7], cause, this kind composites offers a large range of structural modifications. Therefore, chalcogenide composite field is a rapidly growing scientific area and their flexible fullerene [11], [12] like structural property favorable to make other composites, such as chalcogenide-multi walled carbon nano tubes (MWCNT) and chalcogenide–graphene (GF) composites materials.

The larger number of excitonic levels in carbon MWCNT can (on the order of a few hundred meV), emphasize the greater importance in the low-dimensional nanosystems, cause the impurities can form states within the bandgaps of semiconducting materials, therefore the generating electronic transitions from the valence band to impurity levels, as a consequence, the phononic transitions and mean free path can be affects in a semiconductor. Modification in low energy π-bond electrons state may play an important role in the electronic structures of MWCNT, cause the π-bonds produce the plasmon resonance [13]. The π-plasmon is a collective excitation of the π bond electrons depend on surface plasmons. Therefore, the phononic transitions occur between π and π^∗ energy bands at the same cutting line for the initial and final state [14]. However bilayer GF also follows the similar thermal behavior, but due to honeycomb structure and its energy wave vector limit not as sharp as carbon nano tubes. The quadratic thermal expansion and greater suppressed ability allow to a large change in chairility, thereby, zigzag and armchair bonds spread actively and 2D structure transform into 1D, creates large numbers of localized states within the composite density of state. Thus the phonon characteristic of the rings and chains could be derived; therefore, thermal property reflect a combined behavior with contributions from both the ring and chain components under at most weak effect owing to the inter-structural forces [15], in which induced heat energy accountable to allowed phonon creation.

Crystallization kinetics of the described materials can be provide the detail information about their temperature dependent structural changes and stability, which is useful to define their working performances [16], [17]. Crystallization kinetics study of the material can be performed from the Differential Scanning Calorimetry under the non-isothermal mode. In the non-isothermal mode the sample is heated at a fixed rate and change in physical parameters recorded as a function of temperature and kinetic parameters interpreted at T_g, T_c and T_p by employing the different existing approximations [18], those obey the most reliable JMA model [19], [20], [21] rule, to explain the crystallization kinetics of chalcogenide glassy composites, polymers, metallic and oxide glasses. Crystallization kinetic properties, glass forming abilities and thermal stabilities of the under test materials at the critical transitions temperatures can be interpreted by employing the Ozawa, Augis and Bennett, Takhor, Hruby, Hu et al. and Saad and pauling approximations [22], [23], [24], [25], [26], [27], [28].

Therefore, goal of this work to present a detail study on crystallization kinetics such as T_g, T_c, T_p at the DSC heating rates 5, 10, 15 and 20 °C/min, glass transition activation energy (E_g), onset crystallization temperature (E_c), peak crystallization (E_p), Hr Hruby glass forming ability parameter, thermal stability and nucleation and growth order parameters (n) and dimensional parameter (m) for Se₉₆Zn₂Sb₂ (SZS) and Se₉₆Zn₂Sb₂ + 0.05% multi walled carbon nano tubes (SZS-MWCNT) & Se₉₆Zn₂Sb₂ + 0.05% bilayer Graphene (SZS-GF) composites.