Tellurite And Fluorotellurite Glasses For Active And Passive

7. Surface properties; MDO 322
∫ ∞ 2
2
−u
erfc( z) ≡ 1−
erf( z)
= e d u
z π
(7.15)
Using equation (7.14), the diffusion profiles of the glasses studied were modelled using
Mathcad software. For each glass, N0 values from EDX were used (or generated if not
known). Times (t) of the experiments were known and constant, and D was iterated to
give N values equal to EDX values at the maximum depth into the glass recorded for each
glass. For the 300 µm side of glass T08, N0 = 0.0242 (2.41 at. %), t = 43200 seconds (i.e.
12 hours), and D = 25.21×10 -6 m 2 .s. -1 (using constraint: silver fraction = 4.244×10 -3 (0.42
at. %) at x = 2 µm). Fig. (7.39) shows the EDX data, and the modelling for glass T08
(80TeO2-9ZnO-10Na2O-1Er2O3 mol. %), with 300 µm silver layer evaporated on one
side, followed by heat treatment at 285°C for 12 hours.
Fraction silver
0.030
0.025
0.020
0.015
0.010
0.005
0.000
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00
Depth / microns
Model
EDX
Fig. (7.39): Silver concentration profile (EDX data and model) for glass T08 (80TeO2-
9ZnO-10Na2O-1Er2O3 mol. %), with 300 µm silver layer evaporated on one side,
followed by heat treatment at 285°C for 12 hours (error bars +1 at. %).