Specific heat of sodium tellurite glasses has been measured at 80-673 K to evaluate bonding characteristics and structural relaxation in the glass transition region from the values of specific heat at low and high temperatures, respectively. The temperature variation of specific heat at 80 K to room temperature has been analysed in terms of a three band model which describes the vibrational density of state for glass in terms of three characteristic temperatures, θ1, θ2 and θE; these parameters correspond to the interatomic vibration in the glass network, intermolecular type interaction in glass network and vibration of network modifying cation, respectively. The values of θ1 of sodium tellurite glasses are 820-840 K which are smaller than those of silicate, borate, germanate and phosphate glasses. This fact reflects the weak bond strength of Te- O. The specific heat data at room temperature to 673 K have been used for the analysis of glass transition. The activation enthalpy relevant to the cooling rate dependence of glass transition temperature obtained on the basis of the Tool-Narayanaswamy model lies in 690-1100 kJlmol range depending on glass composition.
|Number of pages||5|
|Journal||Physics and Chemistry of Glasses|
|Publication status||Published - Apr 1 1997|
ASJC Scopus subject areas
- Ceramics and Composites
- Physical and Theoretical Chemistry