Tellurite And Fluorotellurite Glasses For Active And Passive

7. Surface properties; MDO 307
over four times less than the as-received powder, and will be further reduced by self
drying during melting. Table (7.8) summarises these proportions [7].
Table (7.8): Proportion of Zn(OH)F and ZnF2 in untreated and fluorinated ZnF2 powder,
calculated from O1s XPS peaks [7].
Species
Untreated / at. %
Zn(OH)F ZnF2
Fluorinated / at. %
Zn(OH)F ZnF2
Zn 13.22 20.11 3.12 30.22
OH 13.22 - 3.12 -
F 13.22 40.22 3.12 60.43
Total / mol. % 39.66 60.33 9.36 90.65
The proportion of Zn(OH)F in the untreated ZnF2 was less than the 50 mol. % value
assumed in the fluorination batch calculations (see section 3.4), therefore excess
(NH4)HF2 was used. Fig. (7.38) shows the mol. % of ZnF2 and Zn(OH)F before and after
fluorination graphically. After fluorination, the Zn2p3/2 peak position was identical to the
value for ZnF2 from the NIST XPS database (1022.8 eV). The F1s peak also shifted
towards the value for ZnF2 (684.8 eV). This is to be expected as the powder contained
over 90 mol. % ZnF2 after fluorination, compared to around 60 mol. % before. A double
fluorination of ZnF2 may reduce the oxygen content further, and should be investigated.
.