Structure and properties of hafnium iron borophosphate glass-ceramics

• Published in: Journal of non-crystalline solids Vol. 411; pp. 19 - 25
• Main Authors: Karabulut, M., Aydın, C., Ertap, H., Yüksek, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2015
• Subjects: Crystallization; Dissolution; Durability; Glass; Hafnium; Hafnium iron borophosphate glasses; Hafnium oxide; Iron; Mossbauer spectroscopy; Mössbauer; Radioactive waste; Spectra; Vitrification; Radioactive waste; IR; Mössbauer; Hafnium iron borophosphate glasses; Vitrification
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2014.12.014

Effects of hafnium addition on the structure and properties of iron borophosphate glasses with nominal composition of xHfO2–yB2O3–[40–(x+y)]Fe2O3–60P2O5 (x=0–8, mol%) and xHfO2–yB2O3–[40–(x+y)][40Fe2O3–60P2O5] (x=2–6, mol%) have been investigated by XRD, DTA, IR, SEM and Mössbauer spectroscopy. There were some surface crystallizations on some of the samples containing high amounts of Hf and B. XRD spectra revealed that HfP2O7 crystallized in the glass matrix when HfO2 content was above 2mol% even when there was no surface crystallization and samples looked glassy. SEM-EDAX image-analyses supported the formation of the HfP2O7 phase. Dissolution rates of Hf-containing iron borophosphate glasses were in the 10−9–10−10g/cm2min range which shows that the existence of the crystalline HfP2O7 phase in the glass matrix has not degraded the aqueous chemical durability of these glasses. The band observed at ~984cm−1 in the IR spectra of Hf containing samples was attributed to the Hf–O–P bonds in HfP2O7. Iron existed in two valence states, i.e. Fe2+ and Fe3+ and Mössbauer hyperfine parameters indicated that both ions have octahedral coordinations in the samples studied. •Possible use of iron phosphate/borophosphate glasses for the vitrification of Pu bearing nuclear wastes.•Structure and thermal properties were studied by XRD, FT-IR, DTA, SEM-EDAX and Mössbauer spectroscopy.•Compositions containing more than 2mol% HfO2 had HfP2O7 crystalline phase in glass matrix.•All of the samples had superior chemical durability irrespective of the presence of HfP2O7 crystalline phase.•Structural changes upon Hf addition have been identified by IR and Mössbauer spectroscopies.