Eur. Phys. J. B 71, 21-25 (2009)
https://doi.org/10.1140/epjb/e2009-00268-2

Evidence of an intermediate phase in ternary Ge₇Se_93-xSb_x glasses

¹ Department of Physics, Kuvempu University, Shankaraghatta, 577 451, India
² Department of Instrumentation, Indian Institute of Science, Bangalore, 560 012, India

Corresponding author: ^a sasokan@isu.iisc.ernet.in

Received: 12 August 2008
Revised: 21 March 2009
Published online: 24 July 2009

Abstract

The compositional dependence of thermal properties, such as glass transition temperature (T_g), non-reversing enthalpy change (ΔH_NR) and the specific heat capacity change (ΔC_p) of melt quenched Ge₇Se_93-xSb_x (21 ≤ x ≤ 31) glasses, has been studied using alternating differential scanning calorimetry (ADSC) which is analogous to modulated differential scanning calorimetry (MDSC). The glass transition temperature, T_g, which is a measure of global connectivity of the glass, has been found to increase with the addition of Sb. In addition, a change in slope has been observed in the composition dependence of T_g at an average coordination 〈r〉 = 2.40. The experimentally observed compositional variation of glass transition temperature, has been compared with the theoretical predictions from the stochastic agglomeration theory (SAT) and has been found to be consistent. Further, a narrow thermally reversing window is seen in the compositional variation of the relaxation enthalpy (ΔH_NR), which is centered around 〈r〉 = 2.40. The change in specific heat capacity (ΔC_p) at T_g is also found to exhibit a distinct minima at 〈r〉 = 2.40, suggesting that the structural rearrangements for the liquid in the glass transition region are minimized around 〈r〉 = 2.4.