2018/12/22 by B. Tanujit, Tanujit, Biswas, S. Asokan +1 · 1 citation
Materials Science · #Glass properties and applications #Phase-change materials and chalcogenides #Material Dynamics and Properties
paper · pdf · doi:10.48550/arxiv.1901.00742
In this work, we observe the rigidity percolation phenomena in a fast ion\nconducting, conditional glass forming system (AgI)75-x-(Ag2O)25-(MoO3)x. To\nfind out where, why and how the rigidity percolation phenomenon occurs within\nthe range of 20 < x < 37.5, calorimetry and photoelectron spectroscopy\nexperiments are performed. The temperature dependence of heat capacity\n(normalized) at glass transition temperature (Tg), exhibits fluctuations for\nsamples with higher AgI concentration. This specific quality attributes to\nfragile glass. The wide range of composition accommodates both the fragile and\nstrong glasses, and therefore a fragility threshold. The heat capacity\n(absolute) values, at Tg when plotted over the whole range of compositions,\nexhibits an abrupt sign shift, from negative to positive, revealing the\nfragility threshold. The appearance of negative heat capacity has been\ncorroborated with the thermodynamic behavior of nanoclusters. This technique\nhas been identified as a novel method to recognize the existence of\nnanoclusters in this type of glasses. The photoelectron spectroscopy study\nshows the formation of essential covalent structural units, [- Mo - O - Ag - O\n-] and complex molybdenum oxides in the positive heat capacity region. Finally,\nthe non-reversing enthalpy profile has been studied over the whole composition\nrange. The global, square well minima sandwiched between floppy and stress\nrigid region has been identified to be the intermediate phase, within the range\n32.25 < x < 35.\n