| Study of the influence of fluorine containing compounds on
the physical and chemical and optical properties of glasses of new fluorophosphate
systems.
Member of RAS Dr. G.T. Petrovsky, S.V. Liubimova, L.N. Urusovskaya Research and technology institute of the science of optical materials " Vavilov's State Optical Institute" The work has been supported by a grant and represented by Fluorine compounds Technology Fund (FTF). 1. Investigation strategy A phosphate system of Ba(PO3 ) 2-Al(PO3) 3 -Ln(PO3) 3 ( Ln = Ln,Y) has been chosen as a basis for following introduction of fluorides. To produce glasses of fluorophosphate crown glass type the following fluorides were introduced in the glass of the chosen system: BaF2, ZnF2, Ga F3, AlF3, In F3, Sc F3, Y F3, LaF3. The synthesis of the glasses was carried out in laboratory furnaces equipped with silit heaters. The glasses containing the fluorides were melt in platinum crucibles at a temperature of 1200-1250oC for 1.5 hours at vigorous stirring. Reagents of "extremely pure", "chemically pure" and "analytically pure" grade were used for the synthesis. Fluorides of gallium and indium were introduced via GaF3*3H2O and InF3*3H2O. All samples were subjected to fine annealing. The optical constants of the glasses were measured on a GS-5 tone meter and a refractometer IRF-23, the instrument error was plus-minus 1*10-5 and plus-minus 1*10-4 respectively. The density of the glasses was measured by a method of hydrostatic weighing in toluene to within plus-minus 0.001g/cm3. The crystallization ability of the glasses was determined by a method of forced crystallization in a gradient furnace. The IR spectra were recorded on a IKS-29 instrument (samples as tablets with KBr) within a range of 1400-400cm-1. The transmission spectra in UV and visible spectrum were recorded on a SPECORD-UV-VIS instrument. 2.Study of the glasses of Ba(PO3 ) 2-Al(PO3) 3 -La(PO3) 3 -Y(PO3) 3 -RFx system. To study the influence of fluorine - containing compounds into glasses - bases such as Ba(PO3 ) 2- 56, Al(PO3) 3 - 14, La(PO3) 3 - 20, Y(PO3) 3 - 10 the following fluorides were introduced: BaF2, ZnF2, GaF3, AlF3, InF3, ScF3, YF3, LaF3. We managed to introduce 30 mol.% of BaF2, ZnF2, GaF3, InF3, 20mol.% of ScF3, YF3, AlF3 and 10mol.% of LaF3. A further increase in the content of fluorides brings to crystallization at glass-making. The crystallization ability of the glasses synthesized is represented in Fig.1. Introduction of 10mol% of the mentioned fluorides results in insufficient improvement of crystallization stability. A further increase in the content of fluorides brings to a dramatic growth of crystallization tendency. The index of refraction and average dispersion of the investigated glasses are increasing with increasing the content of the fluorides.(Fig.3).Only the introduction of 10% of AlF3 does not change the index of refraction at a simultaneous increase in the average dispersion. The density of the glasses also is increasing at the introduction of the fluorides (Fig.4). The least increase in the density occurs when AlF3 and ScF3 are introduced. The greatest increase in the density takes place when BaF2 and InF3 are introduced. Such a change in the index of refraction and density may witness that a considerable amount of fluorine is evaporated during the synthesis. This conclusion was made on the basis of a comparison with the data of influence of fluorides on fluorophosphate bases. A chemical analysis of the glasses synthesized was carried out. Due to a high temperature of the synthesis (t= 1200o -1500oC) a considerable part of fluorine vaporized that was confirmed by the variation of the density and optical constants on the content of the fluorides. The results of the chemical analysis are given in Table 1. The greatest amount of fluorine is in the glasses with scandium fluoride, a little less amount of fluorine is contained in the glasses with fluorides of aluminum, yttrium, barium. Table 1. Results of chemical analysis of the glasses Ba(PO3 ) 2-Al(PO3) 3 -La(PO3) 3 -Y(PO3) 3 -RFx system.
The transmission in UV and visible spectrum was measured: The greatest deviation from a "normal straight line" is observed for
the glasses containing fluorides of scandium, yttrium, barium: A study of a possibility to introduce greater amount of fluorides into glasses has shown that the introduction in the glass-base of 55mol% of BaF2 resulted in formation of a glassy phase with crystal inclusions during glass-making. To reduce the crystallization rate, MgF2 was introduced into the glasses of Ba(PO3 ) 2-Al(PO3) 3 -La(PO3) 3 -Y(PO3) 3 -BaF2 system. During the glass –making on a cold plate it was managed to produce a glass. The replacement of BaF2 and Ba(PO3)2 with BaO allowed to obtain volume samples of glasses and to measure their optical characteristics. The compositions of the synthesized glasses and their optical characteristics are given
in Table 2. The crystallization ability of the synthesized glasses is
presented in Fig.6. The
experimental results have shown that the replacement of Ba(PO3 ) 2
with BaO results in a reduction in the index of refraction and average dispersion. A
negligible improvement of the crystallization stability was observed at the replacement of
BaF2 with SrF2 and/or BaO. The replacement of BaF2 with
BaO led to a growth of the index of refraction and average dispersion. To reduce the
crystallization ability, the content of MgF2 in the composition of glass was
increased up to 30 mol.% and 1mol.% of AlF3 was added (glass No157).That
resulted in a considerable improvement in resistance to crystallization (Fig.6).The optical
constants of the glasses were: ne= 1,5835, Table 2. Composition of the glasses and their optical constants.
The transmission in UV and visible spectrum was determined for all
synthesized glasses. Conclusions
Fig.1 Crystallization of glasses of Ba(PO3)2-Al(PO3)3-La(PO3)3-Y(PO3)3-RFx system. Fig.2 The index of refraction versus the content of fluorides Fig.3 The average dispersion versus the content of fluorides Fig.4 The density versus the content of fluorides Fig.6 Crystallization of the synthesized fluorophosphate glasses (aging time, hours) |
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was measured from 270 to
340 nm 
+6 - +8. 
=68,2,