Fluoride borate glasses

The idea of increasing the maximum temperature at which a hole can be burnt or can survive after an excursion is very important when one considers the application of PHB to ultra-high density optical storage. Room temperature hole burning has been realized so far only in the case of Sm2+ in alkaline halide crystals and in fluoride or borate glasses.28 It has been reported that an organic system, the dihydrophenazine/fluorene crystal, can be subjected to an excursion to room temperature, with hole recovery when brought back to 4 K. 

Sm + ions were for the first time introduced in glasses by Hirao et al. (1993) and Kurita and Kushida (1994). They used fluoride and borate glasses for the matrices of the Sm + ions. Samarium ions are generally incorporated as the trivalent state in glasses. Fluoride and borate compositions were melted in a glassy carbon crucible under a H2 gas atmosphere, where some Sm + ions are reduced to the Sm + during melting. 

Ammonolysis, 401 Ampoules, glass. 205 n-Amylamine, 413, 417 n-Amyl acetate, 383 -Amyl alcohol, 247, 249 n-Amylbenzene, 511, 517 n-Amyl borate, 305 n-Amyl bromide, 279 tao-Amyl bromide, 279 n-Amyl chloride, 273 tao-Amyl chloride, 273 tert.-Amyl chloride, 275 n-Amyl cyanide, 407, 408 Amylene, 239 n-Amyl fluoride, 272, 289 n-Amyl iodide, 288 n-Amyl nitrite, 302, 306... 

The study of absorption spectra has demonstrated the unusual invariance of octahedral chromophores, Cr(III)X6, in glasses and minerals (4, 77). Empirical evidence from glass-making 124) has been extended, and one can study e.g. the equilibria between blue Co(II)04 and pink Co(II)06 or between purple Ni(II)04 and yellow-green Ni(II)06 in borate and silicate glasses 65). Similar observations can be made on molten chlorides 27) and sulfates 64). Relations between the crystal structure and absorption spectra of mixed oxides 61y 87, 90, 103, 104y 105) and fluorides 91) have been carefully evaluated. In this connection, Clark 11) discussed the invariance of the chromophores, M(II)Cl6 and M(III)Cl6, in solid halides and halide complexes. 

The textbooks describe the industrially important types of glass as large network modifier cations Na(I), K(I), Ca(II), Pb(II),.. . , accommodated (with rather long M-O internuclear distances) within the cavities of the network former, the ramified polyanion formed by borate, silicate, phosphate,.. . , or by a mixture of such oxo-complexes of small atoms of nonmetallic elements. However, the real situation may be even more complicated, as exemplified by the fluoride glasses in section 6.1. The absorption spectra (Weyl, 1959 Landry et al., 1967) of... 

Fig. 3. Dependence of multiphonon relaxation on the number of phonons in the glass former needed to bridge the energy gap between the luminescent /-level and the closest lower-lying level. The curves refer to glasses of the following types (1) phosphate (2) borate (3) silicate (4) tellurite (5) fluoroberyllate (6) germanate (7) zirconium fluoride (ZBLA) (8) aluminum lanthanide sulfide (ALS) and gallium lanthanide sulfide (GLS) (9) the crystalline hosts YjAljOj CYAG), and (10)...

Glasses are usually non-stoichiometric mixtures (excepting molten NaP03) of differing oxides forming borates, silicates, phosphates,. .. or, under more special circumstances, mixed fluorides The narrow absorption and luminescence... 

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