Alkali phosphate glasses

Studies performed on alkali phosphate glasses with low content of transition metals, showed that the TM ions (vanadium, chromium, titanium, iron and others) are predominantly found in octahedral coordination, which can be related to a more modifier character of TM ions, as previously reported [68, 76, 77]. Bianconi et al. [78] observed that at low V2O5 concentration (ca. 5mol%) vanadium exists only as six folded V +. This is the more common coordination for ions and it is... 

J. Swenson, A. Matic, A. Brodin, Structure of mixed alkali phosphate glasses by neutron diffraction and Raman spectroscopy. Phys. Rev. B 58(17), 331-337 (1998)... 

Fig. 4.4 (a) Comparison on a logarithmic scale of the conductivity ratio and the thermodynamic activity ratio of alkali oxide in several silica based glasses. Activity ratios are deduced from potentiometric measurements, (b) On the same scale, conductivity vs activity of AgX (X = Cl, Br, I) in phosphate glasses. Activity values are deduced from calorimetric measurements. 

Figure 7.25. A. chemical shifts for a series of sodium phosphate glass compositions compared with those of known tetrahedral phosphate units. From Brow et al. (1990). B. P chemical shifts for a series of sodium lithium phosphate glasses as a function of the mixed alkali ratio.

Transition metal (TM) ions can be readily incorporated particularly into phosphate glasses. Since TM ions give rise to characteristic spectra in the region of near IR to near UV, their characterization is relatively easy. An example is the study of a series of glasses having chemical compositions of NASICONs. NASICON is an acronym for sodium superionic conductors of the general formula A B2(P04)3, where B is generally a TM ion or elements like Zr, Ge, Sn, etc. (or their combination) and A is an alkali metal, whose number n in the formula is dependent on the... 

In Fig. 2-45, the degrees of polymerization of (PO ) units are shown as the number of linked tetrahedra. Therefore, different structural units result. These units are produced by adding network-modifier ions to the phosphate glasses. First, however, it must be ensured that the addition of alkali or alkaline-earth... 

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