Tellurite And Fluorotellurite Glasses For Active And Passive
Tellurite And Fluorotellurite Glasses For Active And Passive Tellurite And Fluorotellurite Glasses For Active And Passive
3. Glass batching and melting; MDO 77 Table (3.6): Melting details for fluoride containing tellurite glasses melted in this study. Stage 1 5 Stage 2 6 Stage 3 7 MOF ID Temp. Time / / °C hr. Temp. Time / °C / hr. Temp. Time / / °C hr. Weight / g Mould 8 Wt. % Volatil -isation Crystallisation 001i 700 1.00 - - 250 1.00 10 SA - N 001ii 750 1.00 - - 230 1.00 10 SA - N 001iii 750 1.00 600 0.75 225 1.00 10 SA 5.84 N 001iv 750 1.00 650 0.75 230 1.00 10 SA 6.19 N 001v 800 9 1.00 670 1.00 230 1.00 10 SA - N 001vi 800 1.00 670 1.00 230 1.00 30 CB - N 002 750 1.00 - - 250 1.00 10 SA - N 003 750 1.00 650 0.75 225 1.00 10 SA 1.77 N 004i 750 1.00 650 0.75 232 1.00 10 SA 10.06 N 004ii 800 1.00 670 1.00 230 1.00 30 CB 2.99 N 004iii 800 1.50 670 1.50 230 1.00 30 CB 3.05 N 004iv 800 1.50 670 1.50 230 1.00 30 CB 2.96 N 005i 750 1.00 650 0.75 234 1.00 10 SA 4.34 N 005ii 800 1.00 670 1.00 230 1.00 30 CB 2.03 N 005iii 800 1.00 670 1.00 230 1.00 30 CB 2.02 N 005iv 800 1.50 670 1.50 230 1.00 30 CB 2.44 N 005v 800 2.00 670 2.00 230 1.00 30 CB 2.83 N 005vi 800 9 2.50 670 2.50 230 1.00 30 CB 1.90 N 005vii 800 9 5.00 670 5.00 230 1.00 30 CB 5.53 N 005viii 800 9 6.00 670 6.00 230 1.00 30 CB 6.27 N 005ix 10 800 9 12 - - 230 1.00 30 CA - N 005x 10 800 9 12 - - 230 1.00 30 CA - N 006 750 1.00 650 0.75 230 1.00 10 SA 3.53 N 007 750 1.00 650 0.75 230 1.00 10 SA 2.32 N 11 008 800 1.00 650 0.75 240 1.00 10 SA 0.68 N 10 009 800 1.00 670 1.00 235 1.00 10 SA 4.50 N 010 800 1.00 670 1.00 235 1.00 10 SA 4.03 N 011 800 1.00 670 1.00 240 1.00 10 SA 0.33 N 012 800 1.00 670 1.00 240 1.00 10 SA 1.78 N 013 800 1.00 670 1.00 240 1.00 10 SA 0.33 N 014 850 1.00 700 1.00 250 1.00 10 SA 14.97 N 015 800 9 2.00 670 2.00 230 1.00 10 LB - Y 016 800 9 2.50 670 2.50 230 1.00 15 LB - Y 017i 800 9 2.50 670 2.50 230 1.00 15 LB - Y 017ii 800 9 2.50 670 2.50 230 1.00 10 SA 7.61 N 018i 800 9 1.50 670 1.50 230 1.00 6 SA - N 018ii 800 9 2.50 670 2.50 230 1.00 10 SA 7.90 N 5 Stage 1 was the first stage of melting 6 Stage 2 was the second stage of melting 7 Stage 3 was the annealing stage 8 LB = large brass, SA = small aluminium, CB = cylindrical brass 9 Used fluorinated ZnF2 10 Melted in glovebox, with 2:1 ration of dry N2:O2 11 Partial
3. Glass batching and melting; MDO 78 3.4. Fluorination of ZnF2 To ensure batch materials were as dry as possible, the ZnF2 was fluorinated before melting, as the as-received chemicals were not phase pure (see chapter 5). The OH - group can readily substitute with the F - ion in a number of compounds due to similar ionic radii (140 and ≈ 131 pm respectively [2]). The fluorination reaction was based on TGA (thermogravimetric analysis) results obtained by Sanghera et al. [3, 4]. This type of pre-melt drying has been employed for halide glasses for a number of years [5]. Equation (3.5) and (3.6) summarise the reactions which are believed to take place during fluorination. Saito et al. [6] are the only group, to the current authors knowledge, to describe the reaction between similar compounds to those used in this study (Zn(OH)F and NH4F) in any detail (a patent by Watanabe et al. [7] does briefly mention the fluorination reaction). From this work, and the work of Sanghera et al. [3, 4] which describes the drying of compounds used to synthesise ZBLAN glasses with (NH4)HF2, the following chemical reactions are proposed. (NH4)HF2 + Zn(OH)F ZnF2 + NH3↑ + HF↑ + H2O↑ (3.5) (NH4)HF2 + Zn(OH)2 ZnF2 + NH3↑ + H2O↑ (3.6) From XRD patterns obtained (see chapter 5), it was assumed that the as-received ZnF2 was of average composition Zn(OH)F (i.e. batch composed of ZnF2, Zn(OH)F and Zn(OH)2). Therefore for each gram of fluoride, 0.56 g of (NH4)HF2 was needed for complete fluorination to ZnF2, although the amount of (NH4)HF2 was likely to have been excessive (see section 5). Therefore, for each fluorination, 8.4 g of (NH4)HF2
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3. Glass batching and melting; MDO 77<br />
Table (3.6): Melting details for fluoride containing tellurite glasses melted in this<br />
study.<br />
Stage 1 5 Stage 2 6 Stage 3 7<br />
MOF<br />
ID<br />
Temp. Time /<br />
/ °C hr.<br />
Temp. Time<br />
/ °C / hr.<br />
Temp. Time /<br />
/ °C hr.<br />
Weight<br />
/ g<br />
Mould 8<br />
Wt. %<br />
Volatil<br />
-isation<br />
Crystallisation<br />
001i 700 1.00 - - 250 1.00 10 SA - N<br />
001ii 750 1.00 - - 230 1.00 10 SA - N<br />
001iii 750 1.00 600 0.75 225 1.00 10 SA 5.84 N<br />
001iv 750 1.00 650 0.75 230 1.00 10 SA 6.19 N<br />
001v 800 9 1.00 670 1.00 230 1.00 10 SA - N<br />
001vi 800 1.00 670 1.00 230 1.00 30 CB - N<br />
002 750 1.00 - - 250 1.00 10 SA - N<br />
003 750 1.00 650 0.75 225 1.00 10 SA 1.77 N<br />
004i 750 1.00 650 0.75 232 1.00 10 SA 10.06 N<br />
004ii 800 1.00 670 1.00 230 1.00 30 CB 2.99 N<br />
004iii 800 1.50 670 1.50 230 1.00 30 CB 3.05 N<br />
004iv 800 1.50 670 1.50 230 1.00 30 CB 2.96 N<br />
005i 750 1.00 650 0.75 234 1.00 10 SA 4.34 N<br />
005ii 800 1.00 670 1.00 230 1.00 30 CB 2.03 N<br />
005iii 800 1.00 670 1.00 230 1.00 30 CB 2.02 N<br />
005iv 800 1.50 670 1.50 230 1.00 30 CB 2.44 N<br />
005v 800 2.00 670 2.00 230 1.00 30 CB 2.83 N<br />
005vi 800 9 2.50 670 2.50 230 1.00 30 CB 1.90 N<br />
005vii 800 9 5.00 670 5.00 230 1.00 30 CB 5.53 N<br />
005viii 800 9 6.00 670 6.00 230 1.00 30 CB 6.27 N<br />
005ix 10 800 9 12 - - 230 1.00 30 CA - N<br />
005x 10 800 9 12 - - 230 1.00 30 CA - N<br />
006 750 1.00 650 0.75 230 1.00 10 SA 3.53 N<br />
007 750 1.00 650 0.75 230 1.00 10 SA 2.32 N 11<br />
008 800 1.00 650 0.75 240 1.00 10 SA 0.68 N 10<br />
009 800 1.00 670 1.00 235 1.00 10 SA 4.50 N<br />
010 800 1.00 670 1.00 235 1.00 10 SA 4.03 N<br />
011 800 1.00 670 1.00 240 1.00 10 SA 0.33 N<br />
012 800 1.00 670 1.00 240 1.00 10 SA 1.78 N<br />
013 800 1.00 670 1.00 240 1.00 10 SA 0.33 N<br />
014 850 1.00 700 1.00 250 1.00 10 SA 14.97 N<br />
015 800 9 2.00 670 2.00 230 1.00 10 LB - Y<br />
016 800 9 2.50 670 2.50 230 1.00 15 LB - Y<br />
017i 800 9 2.50 670 2.50 230 1.00 15 LB - Y<br />
017ii 800 9 2.50 670 2.50 230 1.00 10 SA 7.61 N<br />
018i 800 9 1.50 670 1.50 230 1.00 6 SA - N<br />
018ii 800 9 2.50 670 2.50 230 1.00 10 SA 7.90 N<br />
5 Stage 1 was the first stage of melting<br />
6 Stage 2 was the second stage of melting<br />
7 Stage 3 was the annealing stage<br />
8 LB = large brass, SA = small aluminium, CB = cylindrical brass<br />
9 Used fluorinated ZnF2<br />
10 Melted in glovebox, with 2:1 ration of dry N2:O2<br />
11 Partial
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