Evidence of an intermediate phase in ternary Ge7Se93-xSbx glasses
Department of Physics, Kuvempu University, Shankaraghatta, 577 451, India
2 Department of Instrumentation, Indian Institute of Science, Bangalore, 560 012, India
Corresponding author: a email@example.com
Revised: 21 March 2009
Published online: 24 July 2009
The compositional dependence of thermal properties, such as glass transition temperature (Tg), non-reversing enthalpy change (ΔHNR) and the specific heat capacity change (ΔCp) of melt quenched Ge7Se93-xSbx (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, Tg, 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 Tg 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 (ΔHNR), which is centered around 〈r〉 = 2.40. The change in specific heat capacity (ΔCp) at Tg 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.
PACS: 61.43.Fs – Glasses / 65.60.+a – Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2009