Investigations of molybdenum redox phenomenon in Li2O–MoO3–P2O5 phosphate glasses

Bih, L.; Abbas, L.; Nadiri, A.; Khemakhem, H.; Elouadi, Brahim

doi:10.1016/j.molstruc.2007.02.005

Cited by 43 publications

(26 citation statements)

References 33 publications

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“…6(b)). In some cases, changing glass basicity does not adequately explain the redox behavior in glasses of iron [66] and [67] and certain other multivalent species [68], [69], [70], [71] and [72]. Others have also noted that redox behavior may involve other factors than glass basicity [63] and [65].…”

Section: Fe Mössbauer Spectroscopymentioning

confidence: 99%

“…Some authors have, like Schreiber et al [67], attempted to explain this behavior by a change in transition metal ion coordination as a function of glass composition [70] and [71]. Bih et al [72] studied the effects of Li2O/P2O5 ratio and MoO3 content on the Mo 5+ /ΣMo redox ratio in Li2O-MoO3-P2O5 glasses. They observed that, when (MoO3)2 content was constant at 5 mol%, the ratio Mo 5+ /ΣMo decreased with increasing Li2O content.…”

Section: Fe Mössbauer Spectroscopymentioning

confidence: 99%

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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

169

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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: Fe Mössbauer Spectroscopymentioning

confidence: 99%

Section: Fe Mössbauer Spectroscopymentioning

confidence: 99%

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

169

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“…Most of the studies available on MoO3 containing glasses are on the understanding of their structure by spectroscopic investigations [19−21] and ionic conductivity studies [22]. Molybdenum trioxide (MO3) forms glasses [23][24][25][26][27][28][29][30] fairly easily in which Mo is known to exist in Mo 5+ (4d 1 ) and Mo 6+ (4d 0 ) states [27,[29][30][31]. These glasses are known to contain [MoO6/2] or [OMoO5/2] -groups [32] in the glass network.…”

Section: Absorption Patternsmentioning

confidence: 99%

Infrared spectroscopy of undoped and Cu-doped (80-x)Sb2O3-20Li2O-xMoO3 glasses

Petkova¹,

Boubaker²,

Vasilev³

et al. 2016

AIP Conference Proceedings

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“…The conductivity of such glasses as a function of alkali content frequently exhibits a minimum similar to the mixed alkali ions effect [ 10]. Recently, the mixed ionic-electronic conductors glasses have an attracted interest due to their potential applications in electrochemical cells and electro-optical devices [11].…”

Section: Introductionmentioning

confidence: 99%

Dielectric properties and scaling behavior of lithium tungsten phosphate glasses

Shaaban

2012

J Electroceram

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In the present study a series of ternary (30 Li 2 O, (70-x) P 2 O 5 , xWO3) glasses were prepared and their dielectric properties and ac conductivity were investigated. The measurements have been taken in the frequency range from 100 Hz to 100 kHz and over the temperature range from 296 K to 578 K. The temperature dependence of ac conductivity can be adequately explained by considering the contributions from mixed ionic and electronic mechanisms. In the studied glasses it is found that the ac conductivity increases with increasing frequency. By investigating the relation between temperature and the frequency exponent "s" of the power law σ ac 0Aω s , it is found that the Correlated Barrier Hopping model (CBH) is appropriate for describing the conduction mechanism in the samples. In an attempt to investigate the universality of ac conductivity in these glasses, it is found that the data obtained follow Rolling scaling model. When considering the dielectric properties, it is found that the M″vs. M′ plots give master ColeCole curves at all temperatures. These results can be considered as an indication of the presence of space charge or accumulation of charges in some regions inside the samples. The relation between M″/ M max″ and f/f p represent a master plot at different temperatures. These scaling suggest the existence of a distribution of potential wells, in which the carriers are trapped.

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Investigations of molybdenum redox phenomenon in Li2O–MoO3–P2O5 phosphate glasses

Cited by 43 publications

References 33 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

Infrared spectroscopy of undoped and Cu-doped (80-x)Sb2O3-20Li2O-xMoO3 glasses

Dielectric properties and scaling behavior of lithium tungsten phosphate glasses

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