Fluorophosphate glasses

Other uses of Snp2 are in the synthesis of fluorophosphate glasses having low melting temperatures (13—15), in formation of transparent film (16), and in the preparation of optically active alcohols (17). 

Special care must be taken when applying the Judd-Ofelt theory to Eu3+ ions. At room temperature, absorption occurs not only from the 7F0 ground state, but also from the thermalized 7Fj level located a 300 cm-1 above. Thus, the respective population of both levels must be considered to properly apply the theory [37,38], Very good agreement between experiment (4 ms) and calculation (4.2 ms) was obtained for the 5D0 lifetime of Eu3+ in a fluorophosphate glass [38],... 

It is well-known that concentration quenching of the 5D4 luminescence is not observed in usual glasses whose rare-earth concentration is limited to a few atomic percent. In some sodium fluorophosphate glasses, whose terbium concentration is as high as 35 atm%, 5D4 luminescence quenching is found to occur at concentration of 20 atm% (3.3 1021 ions cm-3) and greater [145]. 

A two-step up-conversion process involving 982-nm photons is capable of exciting the 5D4 level of Tb3+ ions in (Yb, Tb) co-doped fluorophosphate glasses. This is due to a cooperative effect between two Yb3+ ions which transfer their energy to one Tb3+ ion. The process leads to the characteristic 5D4 7F5 green emission. 

The application of P NMR to structural studies of alkali and alkaline earth phosphate and aluminophosphate glasses, fluorophosphate glasses and phosphorus oxynitride glasses has been reviewed by Kirkpatrick and Brow (1995). 

Duhamel-Henry N, Adam JL, Jacquier B, Linare C. Photoluminescence of new fluorophosphate glasses containing a high concentration of terbium (III) ions. Opt Mater 1996 5 197-207. 

Many other systems have subsequently been found to display anion conductivity. The electrical conductivity of lead fluoroborate and fluorogermanate glasses is similar to that of the lead fluorosilicate glasses. Calcium fluoroaluminate glasses also conduct by fluorine migration. Fluorophosphate glasses have also proven to be good anionic conductors. All of these systems are free of alkali ions. 

Urman, K., Madbouly, S., and Otaigbe, J.U. (2007) Unusual accelerated molecular relaxations of a tin fluorophosphate glass/polyamide 6 hybrid studied by broadband dielectric spectroscopy. Polymer, 48, 1659-1666. 

Some zinc phosphate glasses have low transition temperatures and excellent water resistance [19], Fluorophosphate glasses based on AlfPOjlj and LiF possess special optical properties in addition to having good water resistance. Glasses of this kind, based on combinations of other cation metaphosphates and fluorides, have been patented [20]. 

Within a few years these very first results were followed by laser effects in other R ions such as Pr +, Ho +, Er +, Tm +, Yb +, Dy +. In particular Er laser emission at 1.5 pm was obtained in silica glass (Snitzer and Woodcock 1965), and studied in phosphate, beryllium fluoride, fluorophosphate glasses (Auzel 1966a, 1968). All these pioneer results have already been reviewed in several books (for instance, Di Bartolo 1968, Roess 1969, Weber 1979 in volume 4 of this Handbook Kaminskii 1981, Reisfeld and Jorgensen 1977). 

Energy transfer from Ce(III) to Tb(III) and Tm(III) was also found to take place in fluorophosphate glasses (Kermaoui et al., 1984) and attributed to a diffusion-limited process. 

Chowdari BVR, Mok KF, Xie JM, Gopalakrishnan R (1995) Electrical and structural studies of lithium fluorophosphates glasses. Solid State Ionics 86 189-198... 

Sreedhar B, Sairam M, Chattopadhyay DK, Kojima K (2005) Preparation and characterization of lithium fluorophosphates glasses doped with M0O3. Mater Chem Phys 92 492-498... 

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