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Extended rigidity percolation and chemical thresholds in Ge–Te–Pb glasses as revealed by MDSC

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  • Instrumentation And Applied Physics (Formally Isu)
  • Chemistry


Thermal analysis of $Ge_{20}Te_{80-x}Pb_x$ $(2 \leq x \leq 8)$ glasses has been undertaken using modulated differential scanning calorimetry (MDSC). The compositional dependence of thermal parameters is investigated. The crystallization temperatures $(T_c)$ estimated from the total heat flow show detectable changes at compositions x = 4,6.5 and 7.5. Further, the heat capacity change at the glass transition temperature, measured from the reversible heat flow curve $(\triangle {C}^R _p ),$ is found to exhibit a maximum and an inflexion at compositions x = 4 and 6.5 and minimum at x = 7:5, respectively. Also, the relaxation enthalpy, estimated from the area under the non-reversing heat flow curve $({\triangle}H^{NR}),$ exhibits similar features at the said compositions. From the observed MDSC results, it has been proposed that the compositions x = 4 and x = 6.5 denote to the onset and completion of rigidity percolation and x = 7:5 corresponds to the chemical threshold of the system.

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