Tellurite And Fluorotellurite Glasses For Active And Passive

4. Thermal properties and glass stability; MDO 91
temperature increase, simply because there is no increase in temperature. Only after
completion of the transformation does the sample catch up with the reference which
corresponds to the exponential decay portion of the endotherm. This part of the peak
needs to be included in the integral so sample and reference both show the same
contribution to enthalpy change due to the temperature increase [3].
4.1.3. Modelling transformation kinetics
Form of DTA transformation peaks
Transformation kinetics can be modelled using data from the DTA. If it is assumed that
the heat released per unit time is proportional to the rate of reaction, then the partial area
swept under the peak divided by the entire peak area is equal to the fraction transformed
[3]. For example, the crystallisation peak shown in fig. (4.4), was integrated and the
resulting curve shows the fraction of the glass which has crystallised at any particular
temperature. This integration was performed using Microcal Origin software. The
background was first removed by manually generating a suitable equation, so only the
area under the peak was integrated. Fig. (4.7) shows the crystallisation peak with
background removed and integration results.