Tellurite And Fluorotellurite Glasses For Active And Passive

7. Surface properties; MDO 259
opposite sides (see section 6.1.1.1), and treated with silver ion-exchange, as described in
table (7.2).
Table (7.2): Ion-exchange methods used on tellurite glasses.
Sample
ID
T08
ST08
Composition /
mol. %
80TeO2-9ZnO-
10Na2O-1Er2O3
79TeO2-5ZnO-
10Na2O-5PbO-
1Yb2O3
T /
°C
t /
hr.
285 12
270 5
Treatment
Evaporated silver layer on both flat sides (100
and 300 µm), followed by heat treatment
under an inert atmosphere (argon).
Dipped one flat side into a molten salt
solution of 2AgNO3-49NaNO3-49KNO3
(mol. %).
These glasses were then annealed to reduce stresses introduced by the ion-exchange
process, and mounted in epoxy resin and cross-sectioned for EDX analysis in the electron
microscope.
7.1.3.2. Environmental scanning electron microscopy (ESEM)
The concentration profile of the silver ions in the glass was mapped using electron
dispersive X-ray (EDX) analysis in an environmental scanning electron microscope
(ESEM), using a FEI XL30 FEG-ESEM. This instrument was used in auxiliary mode,
with the chamber filled with nitrogen (BOC). This mode enabled the sample to be imaged
and analysed without coating the sample. In standard SEM operating under a vacuum,
insulating samples must be sputtered with a conductive coating such as carbon or gold.
Aperture size, accelerating voltage and scales are displayed on all electron micrographs.