The modifier/former role of MoO3 in some calcium-phosphate glasses

Toloman, Dana; Lucacel, R. Ciceo; Măgdaş, Dana Alina; Regos, Adriana N.; Biriş, Alexandru R.; Leoștean, Cristian; Ardelean, I.

doi:10.1016/j.jallcom.2012.12.112

Cited by 40 publications

(13 citation statements)

References 26 publications

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“…[24] It clearly indicates the number of isolated Mo 5 + ions is much more than that of defective MoO 3-x . [25] We also have noticed that the peak of g = 2.003 is a typical characteristics of oxygen vacancies, originating from free electrons of OVs for defective MoO 3 . However, the disappear- ance of peak of g = 2.003 in 2D A-MoO 3-x suggests that electrons prefer to be specifically trapped by Mo 5 + atoms, [26] and achieve the localization of free electrons.…”

Section: Anderson Localization In 2d Amorphous Moo 3-x Monolayers Formentioning

confidence: 77%

“…Apparently, the EPR spectrum exhibits a hyperfine structure with two very sharp peaks of parallel (g ∥ =1.895) and perpendicular (g ⊥ =1.934) bands, which is substantially different from defective MoO 3 nanosheets with two low peaks (g=2.003 and 1.926) . It clearly indicates the number of isolated Mo 5+ ions is much more than that of defective MoO 3‐ x . We also have noticed that the peak of g=2.003 is a typical characteristics of oxygen vacancies, originating from free electrons of OVs for defective MoO 3 .…”

Section: Figurementioning

confidence: 99%

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Anderson Localization in 2D Amorphous MoO_3‐x Monolayers for Electrochemical Ammonia Synthesis

Liu

et al. 2019

ChemCatChem

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Two‐dimensional amorphous semiconductor (2DAS) monolayers can be regarded as a new phase of 2D monolayers materials and will serve as a promising field for the various electronic and optoelectronic applications. Here, together with the first‐principles calculations within density functional theory, we experimentally demonstrate that the 2DAS MoO3‐x monolayers can enhance the electrochemical nitrogen reduction reaction (NRR). To be specific, the NH3 yield and faradaic efficiency (FE) reach 35.83 ug h−1 mg−1cat at −0.40 V and 12.01 % at −0.20 V vs. reversible hydrogen electrode (RHE), respectively, and which can be dramatically improved than that of reported defective MoO3 nanosheets. Further theoretical calculations reveal that the high electrochemical performance in NH3 yield is contributed to the strong Anderson localization and electron confinement dimensionally. And such Anderson tail states can resonate effectively with the states of intermediate HNNH, playing the critical role in the rate limiting step of NRR. Integrated experimental findings and theoretical understanding, a new concept of Anderson confinement catalysis is put forward, and could be extended to other 2DAS for potential catalytic reactions.

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Section: Anderson Localization In 2d Amorphous Moo 3-x Monolayers Formentioning

confidence: 77%

Section: Figurementioning

confidence: 99%

Anderson Localization in 2D Amorphous MoO_3‐x Monolayers for Electrochemical Ammonia Synthesis

Liu

et al. 2019

ChemCatChem

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“…15). This broadening is attributed to Mo 5 + clustering, where dipole-dipole interactions and exchange of coupled Mo 5 + ions leads to a superposition of the unresolved hyperfine structure [58,59]. The formation of crystallites is therefore presumed to influence the proximity of defects through enforced rigidity of the crystal network by the surrounding amorphous network.…”

Section: Kb Patel Et Al Journal Of Non-crystalline Solids 473 (201mentioning

confidence: 99%

Impacts of composition and beta irradiation on phase separation in multiphase amorphous calcium borosilicates

Patel

Boizot

Facq

et al. 2017

Journal of Non-Crystalline Solids

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A B S T R A C TBorosilicate glasses for nuclear waste applications are limited in waste loading by the precipitation of watersoluble molybdates. In order to increase storage efficiency, new compositions are sought out that trap molybdenum in a water-durable CaMoO 4 crystalline phase. Factors affecting CaMoO 4 combination and glass-inglass phase separation in calcium borosilicate systems as a function of changing [MoO 3 ] and [B 2 O 3 ] are examined in this study in order to understand how competition for charge balancers affects phase separation. It further examines the influence of radiation damage on structural modifications using 0.77 to 1.34 GGy of 2.5 MeV electron radiation that replicates inelastic collisions predicted to occur over long-term storage. The resulting microstructure of separated phases and the defect structure were analyzed using electron microscopy, XRD, Raman and EPR spectroscopy prior to and post irradiation. Synthesized calcium borosilicates are observed to form an unusual heterogeneous microstructure composed of three embedded amorphous phases with a solubility limit~2.5 mol% MoO 3. Increasing [B 2 O 3 ] increased the areas of immiscibility and order of (MoO 4 ) 2 − anions, while increasing [MoO 3 ] increased both the phase separation and crystallization temperature resulting in phases closer to metastable equilibrium, and initiated clustered crystallization for [MoO 3 ] > 2.5 mol%. β-irradiation was found to have favorable properties in amorphous systems by creating structural disorder and defect assisted ion migration that thus prevented crystallization. It also increased reticulation in the borosilicate network through 6-membered boroxyl ring and Si ring cleavage to form smaller rings and isolated units. This occurred alongside an increased reduction of Mo 6 + with dose that can be correlated to molybdenum solubility.In compositions with existing CaMoO 4 crystallites, radiation caused a scattering effect, though the crystal content remained unchanged. Therefore β-irradiation can preferentially prevent crystallization in calcium borosilicates for [MoO 3 ] < 2.5 mol%, but has a smaller impact on systems with existing CaMoO 4 crystallites.

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“…For small amounts of ammonium molybdate, a network where the potassium and aluminum atoms are modifiers will be favored. Then, when the amounts of ammonium molybdate increase in the mixture, the aluminum and molybdenum atoms play the role of network formers as can be observed in various types of glass [45,46]. In the case of the 25 M2 geopolymer, the Mk2 metakaolin releases siliceous and aluminous species very rapidly.…”

Section: Mechanisms Versus the Reactivities Of The Metakaolinsmentioning

confidence: 95%

“…Moreover, the large bands between 600 and 1200 cm −1 are still observed. [45,46], the molybdenum atoms could play the role of either network modifiers or network formers in various types of silicate glass. In effect, these authors have demonstrated that in phosphate glass at low concentrations the molybdenum oxide plays the role of a network modifier, and at high concentrations, it acts as a network former.…”

Section: Impact Of the Addition Of A Fixed Percentage Of Ammonium Molmentioning

confidence: 99%

Effect of the addition of ammonium molybdate on metakaolin-based geopolymer formation: Shrinkage and crystallization

et al. 2015

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The modifier/former role of MoO3 in some calcium-phosphate glasses

Cited by 40 publications

References 26 publications

Anderson Localization in 2D Amorphous MoO_3‐x Monolayers for Electrochemical Ammonia Synthesis

Anderson Localization in 2D Amorphous MoO_3‐x Monolayers for Electrochemical Ammonia Synthesis

Impacts of composition and beta irradiation on phase separation in multiphase amorphous calcium borosilicates

Effect of the addition of ammonium molybdate on metakaolin-based geopolymer formation: Shrinkage and crystallization

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The modifier/former role of MoO3 in some calcium-phosphate glasses

Cited by 40 publications

References 26 publications

Anderson Localization in 2D Amorphous MoO3‐x Monolayers for Electrochemical Ammonia Synthesis

Anderson Localization in 2D Amorphous MoO3‐x Monolayers for Electrochemical Ammonia Synthesis

Impacts of composition and beta irradiation on phase separation in multiphase amorphous calcium borosilicates

Effect of the addition of ammonium molybdate on metakaolin-based geopolymer formation: Shrinkage and crystallization

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Anderson Localization in 2D Amorphous MoO_3‐x Monolayers for Electrochemical Ammonia Synthesis

Anderson Localization in 2D Amorphous MoO_3‐x Monolayers for Electrochemical Ammonia Synthesis