Properties of (0.5−x)Zn–xFe2O3–0.5P2O5 glasses

Jermoumi, T; Hafid, M.; Niegisch, Nico; Mennig, Martin; Sabir, A.; Toreis, N

doi:10.1016/s0025-5408(01)00797-8

Cited by 49 publications

(45 citation statements)

References 11 publications

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“…This behavior is broadly consistent with that observed by other researchers for similar phosphate glasses [29], [30] and [33]. The increase in Tg is probably due to the decrease in average value of Q with increasing modifier oxide content, discussed in Section 4.3.1.…”

Section: Thermal Propertiessupporting

confidence: 91%

“…The increase in α50-300 with increasing modifier content would appear to dispute this structural assertion, as thermal expansion is also strongly influenced by the strength of network bonding, its connectivity and the interactions between cations and non-bridging oxygens. However, others [33] have also observed similar trends in modified iron phosphate glasses. It is noted that, for our glasses, distinct differences occur between the effects of monovalent and divalent modifiers.…”

Section: Thermal Propertiessupporting

confidence: 51%

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Effects of modifier additions on the thermal properties, chemical durability, oxidation state and structure of iron phosphate glasses

Bingham

Hand

Hannant

et al. 2009

Journal of Non-Crystalline Solids

168

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Modified iron phosphate glasses have been prepared with nominal molar compositions [(1−x)·(0.6P2O5-0.4Fe2O3)]·xRySO4, where x = 0-0.5 in increments of 0.1 and R = Li, Na, K, Mg, Ca, Ba, or Pb and y = 1 or 2. In most cases the vast majority or all of the sulfate volatalizes and quarternary P2O5-Fe2O3-FeO-RyOz glasses or partially crystalline materials are formed. Here we have characterized the structure, thermal properties, chemical durability and redox state of these materials. Raman spectroscopy indicates that increasing modifier oxide additions result in depolymerization of the phosphate network such that the average value of i, the number of bridging oxygens per -(PO4)-tetrahedron, and expressed as Q i , decreases. Differences have been observed between the structural effects of different modifier types but these are secondary to the amount of modifier added. Alkali additions have little effect on density; slightly increasing Tg and Td; increasing α and Tliq; and promoting bulk crystallization at temperatures of 600-700 °C.Additions of divalent cations increase density, α, Tg, Td, Tliq and promote bulk crystallization at temperatures of 700-800 °C. Overall the addition of divalent cations has a less deleterious effect on glass stability than alkali additions.57 FeMössbauer spectroscopy confirms that iron is present as Fe 2+ and Fe 3+ ions which primarily occupy distorted octahedral sites. This is consistent with accepted structural models for iron phosphate glasses. The iron redox ratio, Fe 2+/ΣFe, has a value of 0.13-0.29 for the glasses studied. The base glass exhibits a very low aqueous leach rate when measured by Product Consistency Test B, a standard durability test for nuclear waste glasses. The addition of high quantities of alkali oxide (30-40 mol% R2O) to the base glass increases leach rates, but only to levels comparable with those measured for a commercial soda-lime-silica glass and for a surrogate nuclear waste-loaded borosilicate glass. Divalent cation additions decrease aqueous leach rates and large additions (30-50 mol% RO) provide exceptionally low leach rates that are 2-3 orders of magnitude lower than have been measured for the surrogate waste-loaded borosilicate glass. The P2O5-Fe2O3-FeO-BaO glasses reported here show particular promise as they are ultra-durable, thermally stable, lowmelting glasses with a large glass-forming compositional range.

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Section: Thermal Propertiessupporting

confidence: 91%

Section: Thermal Propertiessupporting

confidence: 51%

Effects of modifier additions on the thermal properties, chemical durability, oxidation state and structure of iron phosphate glasses

Bingham

Hand

Hannant

et al. 2009

Journal of Non-Crystalline Solids

168

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“…The poor chemical durability of phosphate glasses can be significantly enhanced by the addition of the Fe2O3. [4−6] As a result, the iron phosphate glasses are of the great interest for several technological and biological applications, [7,8] The structure of the phosphate glass is based on corner-sharing PO4 tetrahedra which form chains, rings or isolated PO4 groups. With the addition of Fe2O3 to a phosphate glass, the P−O−P bonds are replaced by more chemically durable P−O−Fe 2+ and/or P−O−Fe 3+ bonds.…”

Section: Introductionmentioning

confidence: 99%

Iron Phosphate Glass-ceramics

Moguš‐Milanković¹,

Šantić²,

Pavić³

et al. 2015

Croat. Chem. Acta

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Abstract:The crystallization of 40Fe2O3-60P2O5, 10ZnO-30Fe2O3-60P2O5 and (43.3−x)PbO-(13.7+x)Fe2O3-43P2O5, (0 < x < 30), glasses and glassceramic have been investigated. The structural evolution of glasses during heat treatment at various temperatures and the tendency for crystallization for series of glasses with modified composition are characterized by a dendrite-like phase separation in the early stage of crystallization. Such a behavior leads to the formation of randomly dispersed agglomerates which contain the anhedrally shaped crystallites embedded in glass matrix. Therefore, regardless of the type of crystallization, controlled or spontaneous, the formation of crystalline phases in these phosphate glasses and glass-ceramics is attributed to the disordered interfaces between crystalline grains and glassy matrix.

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“…G 4 -G 5 ). The Asymmetric stretching vibrations of t as P-O-P,of bridging oxygen atoms in phosphate chains [27][28][29][30][31][32][33][34] 781-735 Symmetric stretching vibrations of t s P-O-P, of bridging oxygen atoms in phosphate chains [27][28][29][30][31][32][33][34] and also due to pyrophosphate groups (P 2 O 7 ) 4- [36] 512 Fundamental frequency of PO 4 3-species of phosphate glasses or as harmonics of P-O bending vibration [37] 564 and 485 Two FeO 6 octahedral bands [40].…”

Section: Resultsmentioning

confidence: 99%

“…The fundamental and strong band at 1,275 cm -1 is attributed to the asymmetric stretching mode of the two non-bridging oxygen atoms bonded to phosphorus atoms, the O-P-O or t as (PO 2 ) units, in the phosphate Q 2 -tetrahedra [28][29][30][31][32]. The band at 1,091 cm -1 is attributed to the symmetric stretching vibration of t s (PO 2 ) -terminal group [28,[30][31][32][33][34]. The band around 903 cm -1 is due to the asymmetric stretching vibrations, t as P-O-P, of bridging oxygen atoms in phosphate chains, which confirms the chain structure of metaphosphate glass [28][29][30][31][32][33][34][35].…”

Section: Ft-ir Spectroscopymentioning

confidence: 99%

Electrical and physicochemical properties of some Ag2O-containing lithia iron silica phosphate glasses

Ibrahim

Darwish

Gomaa

2011

J Mater Sci: Mater Electron

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The present paper reports the influence of Ag 2 O addition at the expense of Li 2 O on the local structure of xAg 2 OÁ(30 -x)Li 2 OÁ10Fe 2 O 3 Á10SiO 2 Á50P 2 O 5 glass matrix (with x = 0, 0.5, 1, 1.5 and 2 mol %). The phosphate structural units of the network former are assessed from Fourier transform infrared (FT-IR) spectroscopy. The addition of Ag 2 O to the glass network matrix B1 mol % leads to the occurrence of a depolymerization process of the phosphate structure and consequently, to the appearance of a distortion of the PO 4 tetrahedra. When the content of Ag 2 O is increased from 1.5 up to 2 mol %, a remarkable polymerization process has been observed. The density, molar volume, microhardness and chemical durability have been investigated in order to study the effect of Ag 2 O/Li 2 O replacements on the physicochemical properties the studied glasses. The AC electrical properties are affected to a great extent with composition. These results are related to the internal structure of the glass samples. The conductivity, dielectric constant and dielectric loss of the studied glasses were studied using the frequency response in the interval 100 Hz-100 kHz and the effect of compositional changes on the measured properties was investigated. Measurements showed that the electrical responses of glass samples were different and complex for interpretation. The increase of Ag 2 O addition at the expense of Li 2 O contents (from 0 to 1 mol %) led to increase the conductivity, dielectric constant and dielectric losses of samples. The addition of more Ag 2 O at the expense of Li 2 O (from 1.5 to 2 mol %), resulting into decreasing the conductivity, the dielectric constant and dielectric losses of the studied glasses. The experimental data of the glass samples were argued to the internal structure of the glasses and the nature and role-played by weakening or increasing the rigidity of the structure of the sample. It could be concluded, therefore, that the AC electrical properties of the samples were influenced by the distribution of its constituents, connectivity, and number of free charges.

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Properties of (0.5−x)Zn–xFe2O3–0.5P2O5 glasses

Cited by 49 publications

References 11 publications

Effects of modifier additions on the thermal properties, chemical durability, oxidation state and structure of iron phosphate glasses

Effects of modifier additions on the thermal properties, chemical durability, oxidation state and structure of iron phosphate glasses

Iron Phosphate Glass-ceramics

Electrical and physicochemical properties of some Ag2O-containing lithia iron silica phosphate glasses

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