Structural Studies on Ag<sub>2</sub>O-P<sub>2</sub>O<sub>5</sub> Glasses

Abstract

Silver phosphate glasses of general formula xAg 2 O•(100 − x)P 2 O 5 have been investigated over compositional range from x = 40 to 62.5 mol%. The local structure around phosphorus atom has been studied via 31 P nuclear magnetic resonance. leads to formation of phosphate groups with specific resonance peaks which are mainly related to pyro and orthophosphate species. The rate of change of the chemical shift of the 31 P NMR depends on the bond type, which in turn reflects the extent of double bonding between phosphorus and oxygen atoms. Increasing concentration of Q 0 with increasing Ag 2 O content leads to decreasing quantities of bridging and double bonds. As a consequence, specific symmetric resonance peak of higher intensity and chemical shift (Q 0 ) is a feature of silver rich glasses (orthophosphate). The latter species is therefore proposed to compose of separated membered rings, which cause deshielding of phosphate units. XRD and EDP studies have shown that, amorphous phosphate network is the dominant structure of glasses containing ≤ 55 mol% Ag 2 O. Some ordered and well crystallized phases are formed at higher Ag 2 O concentration. Increasing non-bridging oxygen atoms is shown to have the main effect on crystallization behavior. Orthophosphate composition is the most crystalline one among the other compositions (ultra, meta-and pyrophosphate). Presence of orthophosphate species which typically contains highest concentration from isolated Q 0 units is the main reason for building up crystalline Ag 3 PO 4 phosphate phase.

Structure and related physical properties of Li2O-Sb2O3-B2O3 glasses

“…The ionic conductivity in glasses has been studied for over a hundred years and there are many indicators that glassy electrolytes are promising for the use in solid state batteries and other devices [1][2][3]. Efforts are still being directed towards discovering new glassy systems, and optimizing the levels of ionic conductivity in these materials.…”

Structural Characterization of Novel Cerium Phosphate Glass Ionomer Cements (GICs) Doped with GaCl (Phthalocyanine)

“…There is an increasing interest in metal phosphates composites due to their relevance in biology and materials science [1] [2]. It is known that addition of modifier oxide to P 2 O 5 leads to disruption of P-O-P bridges [3] [4]. At first, PO 4 branching units in Q 3 configuration (Q is phosphors cation, n is the number of bridging bonds) can form metaphosphate composition.…”

“…The corresponding changes are widely presented by results of 31 P magic angle spinning nuclear magnetic resonance (MAS NMR) and vibrational spectroscopy. Many of such results are reviewed in references [3] [4].…”