Low-temperature specific heat in caesium borate glasses

摘要: Low-temperature specific heat measurements (1.5-25K) performed on caesium borate glasses at different concentrations have pointed out the presence of an excess heat, Cp, over Debye contribution. In a plot C p /T 3 vs. T, it appears as bump, temperature location which is almost unchanged whereas its intensity increases with concentration. A comparison in sodium has revealed highly dissimilar low-energy dynamics, despite same structural units building up matrix. The behaviours observed been related to peculiar changes that inclusion alkaline cations cause mesoscopic length scale where effects medium-range order (MRO) are usually observed. It believed particularly open structure assures very low frequency for local oscillations Cs + ions that, consequently, rule vibrational dynamics region boson peak by their localized character.