Tellurite And Fluorotellurite Glasses For Active And Passive

4. Thermal properties and glass stability; MDO 94
indicate the degree of fit between the generated peaks and the data (the closer χ 2 is to 0
and R 2 to 1, the better the Gaussian fit correlates with the data). Fig. (4.8) illustrates this.
o C
Data: Data1_B
Model: Gauss
DTA data
Gaussian fit
Peak 1
Peak 2
Chi^2 = 0.00538
R^2 = 0.99658
y0 0 ±0
xc1 410.32613 ±3.17816
w1 21.6052 ±1.8686
A1 49.06648 ±16.99576
xc2 420.84542 ±0.4698
w2 16.16155 ±0.85662
A2 49.33312 ±16.89197
360 380 400 420 440
Temperature / o C
Fig. (4.8): DTA trace of glass MOF005 (70TeO2-10Na2O-20ZnF2 (mol. %)) showing the
crystallisation peak with background removed and Gaussian deconvolution performed
(where xcn is the position of peak n, wn the half width of peak n, and An the area of peak
n, with 100% confidence limits displayed).
Modelling equations
Nucleation and growth processes, such as glass devitrification, generally follow the
Johnson-Mehl-Avrami (JMA) equation [3]:
m
F = 1−
exp( −k
t )
(4.1)
t
c