Insertion of MoO₃in Borophosphate Glasses Investigated by Magnetic Resonance Spectroscopies

Abstract

Insertion of MoO 3 oxide in the mixed borophosphate glass network has been analyzed for the first time by advanced magnetic resonance spectroscopies. For the first time, the xMoO 3 -(100x)(50PbO-10B 2 O 3 -40P 2 O 5 ) composition line has been investigated by 1D ( 11 B, 31 P, 95 Mo) and 2D-correlation NMR ( 11 B DQ-SQ, 11 B( 31 P) D-HMQC) at high magnetic field (18.8 T). The set of data allowed for analyzing both local and medium range orders and identifying the modifications in the BOB and/or BOP mixing induced by the MoO 3 insertion. In a second step, continuous wave EPR has been used to detect the presence of Mo 5+ ions, resulting from partial reduction of Mo 6+ during the melting stage, and the chemical environment around the Mo 5+ species has been documented for the first time by pulsed EPR technique (HYSCORE). Altogether, the data contribute to a better understanding of the glass network modifications induced by the MoO 3 insertion, including the nonlinear evolution of the glass transition temperature that has been explained by a modification of the glass network nature.

Atomic Modulation Triggering Improved Performance of MoO3 Nanobelts for Fiber‐Shaped Supercapacitors

“…To further confirm the existence of more oxygen vacancies (Mo 5+ ) in S‐MoO 3− x , we conducted the electron paramagnetic resonance (EPR) spectra (Figure d). As shown in Figure d, the S‐MoO 3− x sample exhibits a substantially stronger EPR signal at g = 1.92 than the pristine MoO 3 sample, indicating more species with a single electron exist in the S‐MoO 3− x sample . Given that Mo 5+ is a d 1 species and Mo 4+ is a d 2 species, the EPR spectra in Figure d convincingly demonstrate the higher contents of Mo 5+ occurred in S‐MoO 3− x NBs than pristine MoO 3 , which is in good agreement with XPS results.…”

Recent progress in solid‐state nuclear magnetic resonance of half‐integer spin low‐γ quadrupolar nuclei applied to inorganic materials

“…Broad signals are observed centred approximately −100 ppm, suggesting the molybdenum is present in tetrahedral coordination throughout, although the linewidth increases for samples with >30 mol% MoO 3 . [238] Sodium and calcium borosilicate glasses are good models for nuclear waste encapsulation media. Molybdenum is a fission product in spent-fuel reprocessing, which is weakly soluble in such glasses.…”

Swift heavy ion-irradiated multi-phase calcium borosilicates: implications to molybdenum incorporation, microstructure, and network topology

“…NBO conversion during synthesis. Furthermore, the insertion of MoO 3 in the borosilicate network was observed to further increase formation of BO 3 units as 11 B MAS NMR results indicate, and thus decrease Si-O-B connectivity and promote the mobility of Ca ions [32,70]. This is in contrast to soda lime borosilicate glasses, which were observed to have little effect on the [BO 4 -]/[BO 3 ] ratio with the inclusion of MoO 3 [26].…”

“…4 and 12 O 3 ] to[ 4.7 would cause growth of three-membered SiO 4 rings, and therefore Si-rich domains. This relationship implies a beneficial outcome of radiation damage, in which an initial structural defect created by Mo linkages [70] can limit those created by high-energy ionization, thereby increasing the radiation tolerance of these calcium borosilicate glasses to additional phase separation. Furthermore, the collective results from Raman and EDS analysis indicate that while many structural changes are observed representative of lingering phase separation between boron and silica-rich regions following irradiation, these modifications saturate around 4 9 10 13 to 8 9 10 13 ions/cm 2 .…”