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Tellurite And Fluorotellurite Glasses For Active And Passive

Tellurite And Fluorotellurite Glasses For Active And Passive

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8. Fibre drawing; MDO 334<br />

Table (8.2): Parameters relating to unstructured tellurite and fluorotellurite preform<br />

manufacture: preform ID, composition, melting time and temperature, crucible and<br />

mould (CB = cylindrical brass, CA = cylindrical aluminium) used, and comments on<br />

preform / fibre quality relating to melting / casting process, all made from 30 g batches,<br />

of 1 cm diameter.<br />

Preform ID<br />

MOD010_i<br />

Composition<br />

/ mol. %<br />

75TeO2-10Na2O-<br />

10ZnO-5PbO<br />

MOF004_iv 60TeO2-10Na2O-<br />

30ZnF2<br />

MOF005_ii<br />

70TeO2-10Na2O-<br />

20ZnF2<br />

MOF005_iii ″<br />

MOF005_iv ″<br />

MOF005_v ″<br />

MOF005_vi ″<br />

MOF005_vi<br />

i<br />

MOF005_vi<br />

ii<br />

MOF005_ix<br />

2<br />

″<br />

″<br />

T /<br />

°C<br />

t /<br />

hr.<br />

Crucible Mould Comments<br />

800 2.0 Pt CB<br />

800<br />

670<br />

800<br />

670<br />

800<br />

670<br />

800<br />

670<br />

800<br />

670<br />

800 1<br />

670<br />

800 1<br />

670<br />

800 1<br />

670<br />

1.5<br />

1.5<br />

1.0<br />

1.0<br />

1.0<br />

1.0<br />

1.5<br />

1.5<br />

2.0<br />

2.0<br />

2.5<br />

2.5<br />

5.0<br />

5.0<br />

6.0<br />

6.0<br />

″ ″<br />

″ ″<br />

″ ″<br />

″ ″<br />

Au ″<br />

″ ″<br />

″ ″<br />

″ ″<br />

″ 800 1 12.0 ″ CA<br />

MOF005_x 2 ″ 800 1 12.0 ″ ″<br />

Contained small bubbles,<br />

and after drawing, fibre<br />

poor surface<br />

Surface frosted, poor<br />

fibre when drawn with<br />

N2 atmosphere<br />

Good glass,<br />

homogeneous, and no<br />

bubbles, however fibre<br />

drawing not steady or<br />

dimentionally consistent,<br />

producing weak fibre<br />

Good glass, resulting in<br />

strong pristine fibre<br />

Some striations, but<br />

produced good fibre and<br />

drew steadily<br />

Good glass, resulting in<br />

strong pristine fibre<br />

Discoloured surface<br />

It can be seen that the use of Au crucibles resulted in good quality fibre, however the<br />

melting atmosphere was also altered for preforms MOF005_iv to MOF005_x (see table<br />

(8.3) in the next section for further details), and also had a significant effect on the<br />

control of fibre drawing. Using an aluminium mould in a nitrogen rich glovebox<br />

atmosphere caused preform surface discolouration, most likely due to the reduction of the<br />

1 Used fluorinated ZnF2<br />

2 Melted in glovebox with 2:1 ratio dry N2:O2

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