Frequency dependence of heat capacity of the Pd40Ni10Cu30P20 amorphous alloy by temperature-modulated calorimetry

The newly developed temperature-modulated differential scanning calorimetry (DSC) has been used to investigate the frequency dependence of heat capaci ty in the glass transition region for the Pd40Ni10Cu30P20 alloy upon heatin g and cooling. In contrast to conventional DSC results, the present work sh owed a dissipative behavior of the heat-flow response of the deeply superco oled Pd40Ni10Cu30P20 liquid in the glass transition region, qualitatively s imilar to the results obtained by specific heat spectroscopy on glycerol. A strong dependence of the temperature modulation period on the temperature of the peak imaginary part of complex heat capacity, T-max, was found indic ating a slowdown of the supercooled liquid dynamics as temperature decrease d. This frequency dependence of T-max can be well described by either the A rrhenius law or the Vogel-Fulcher-Tamman (VFT) equation. Furthermore, the V FT fit to the experimental data showed that the VFT temperature To was coin cident with the thermodynamically determined Kauzmann temperature TK. The a verage characteristic time of enthalpy relaxation was determined to be appr oximately 50 s at 579 K and the apparent activation energy of glass transit ion was estimated to be 577 +/- 22 kJ/mol.