Vibrational Studies of Calcium Magnesium Ultraphosphate Glasses

Abstract

Phosphate glasses in a system of magnesium calcium phosphate for host matrix luminescent materials wereinvestigated. The glass samples in a series of xMgO–(40- x)CaO–60P2O5 in molar ratio (0x40 mol%) were preparedusing melt-quenching technique. The effect of Mg and Ca content on the structure and glass stability againstcrystallization in the system of MgO–CaO–P2O5 ultraphosphate has been investigated using XRD, Infrared and Ramanspectroscopy. The compositions containing up to 40 mol% of CaO and /or MgO formed glasses and no crystallinephases were detected by XRD. The results of IR and Raman spectroscopy suggest that the phosphate network of theseglasses is composed of middle (Q2) and branching (Q3) phosphate tetrahedral and other calcium/magnesium anions.All the symmetric and asymmetric stretching vibrations of POP and PO2 observed in the spectra are characteristic ofQ3 and Q2 groups. The glass network, especially the Q2 units can be modified by the presence of Ca and Mg ions. Thismodification is primarily associated with the phosphate and the Q2 and Q3 phosphate units randomly distributed in thenetwork. Spectroscopic results shows that the modification of the phosphate network is higher for the Ca containingglasses with respect to the Mg ones, at the same alkali earth content, due to the well defined Ca properties as amodifying cation. Formation of P–O–H bond expresses the hygroscopic nature of the phosphate glasses. This studyshows that the vibrational spectroscopy (Infrared and Raman) are provide useful, complementary information aboutthe network structures of ultraphosphate glasses.

Design, processing, and characterization of an optical core‐bioactive clad phosphate fiber for biomedical applications

“…The only peak that could not be assigned to any calcium crystal is located at 762 cm −1 . This peak can be related to the asymmetric stretching vibration of the P-O-P bonds in ultraphosphate glasses, in agreement with 48 . Such surface depletion in alkaline and alkaline-earth cations in phosphate glasses immersed in aqueous solutions was reported in a previous study.…”

“…46 The immersion in SBF for 28 days leads to a slight decrease in the intensity of the bands at 300-400 cm −1 and at 700 cm −1 and also to an increase in intensity of the bands in the 800-1100 cm −1 region. This peak can be related to the asymmetric stretching vibration of the P-O-P bonds in ultraphosphate glasses, in agreement with 48 . The spectrum shows sharp peaks which can be related to the formation of the reactive layer, in accordance with the EDS/SEM analysis.…”

Vibrational Studies of Zinc Antimony Borophosphate Glasses Doped Rare Earth

“…Band at 1600 cm -1 is attributed to the deformation modes of O-H (δ H-O-H) and usually indicates the water incorporation before glass devitrification unexpectedly decrease with addition of rare earth ions into the glass system even all doped and undoped sample were prepared under the same processing condition such as sample thickness and melting temperature during glass preparation. In particular, sample under investigation does not have H 2 O as unit in the glass network but the presence of these bands causing due to reabsorption of water from atmospheric moisture by pellet sample because the infrared spectra were not recorded in situ [6]. In comparison, glass doped Er 3+ sample shows the most enormously changes towards the OH group.…”

Ftir and Raman Spectroscopic Study of a Complex Perovskite: Ca0.91-XCe0.09Rb0.04Csx[(Zr0.50Ti0.45)Al0.05]O3, X=0.2 to 0.4, Dedicated for Radioactive Waste Confinement

“…The Ca-O bonds' vibration in CaTiO3 cuboids is evidenced at 563 and 558 cm -1 for Cs contents of 0.2 and 0.3 at.%. It is nonexistent for 0.4 at.% Cs (the lowest Ca content), indicating the Ca-O vibration energy attenuation [61]. The TiO3 2groups' asymmetric Ti-O stretching appears at 425, 425 and 420 cm -1 , for Cs contents of 0.2, 0.3, and 0.4 at%, respectively [63].…”

“…The δ(Ti-O-Ti) bending active mode, which is characteristic of alkaline titanates, appears at 460, 457 and 463 cm -1 , for Cs contents of 0.2, 0.3 and 0.4 at.% respectively [61].This band can shift from 460 cm -1 to lower values when Ca content increases in CaTiO3 lattice, demonstrating the steric effect of Ca on TiO6 octahedrons vibrations [15]. The stretching mode around 521, 524 and 526 cm -1 , for Cs contents of 0.2, 0.3 and 0.4 at.%, respectively, is due either to Ti-O or Zr-O vibrations [62].…”