JPS6311297B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an optical infrared transmitting glass containing fluoride as a main component. Glasses whose main components are zirconium fluoride or hafnium fluoride are attracting attention as materials for infrared optical components and infrared transmission paths, and this type of glass is said to be able to transmit infrared rays up to around 8 μm. However, due to large scattering, there is a problem for optical applications such as those mentioned above. For example, zirconium fluoride and/or hafnium fluoride is in the range of 50 to 70 mol%, and at least one of the following is selected from 10 to 35 mol% of barium fluoride, yttrium fluoride, fluorides of lanthanide elements, and thorium fluoride. A composition containing 1 to 8 mol% of fluoride or more, 0 to 30 mol% of sodium fluoride and/or cesium fluoride, and 1 to 10 mol% of aluminum fluoride can be a stable glass. All glasses cause strong scattering phenomena, making it difficult to put them to practical use as optical components and optical transmission line materials. In view of the above problems, the present invention aims to reduce scattering in this type of infrared transmitting glass by adding borofluoric acid ions (BF ₄ ^- ) to the glass. The configuration is as follows. That is, the infrared transmitting glass according to the present invention contains zirconium fluoride and/or hafnium fluoride.
~70 mol%, 10 to 35 mol% of barium fluoride, 1 to 8 mol% of at least one fluoride selected from yttrium fluoride, fluorides of lanthanide elements, and sodium fluoride, and fluoride. Sodium and/or
Or, in a fluoride glass consisting of 0 to 30 mol% of cesium fluoride and 1 to 10 mol% of aluminum fluoride, 0.1% of fluorine ions in the glass
It is characterized in that ~10 mol% is substituted with borofluoric acid ions. In the present invention, borofluoric acid ions (BF ₄ ^- ) are added to the fluoride glass to replace the fluorine ions in the glass. This can be carried out by using a raw material in which part of the raw material fluoride is replaced with borofluoride. For example, sodium borofluoride (NaBF ₄ ) may be used as part or all of the sodium-based raw materials, and other specific means include adding boron oxide and acidic ammonium fluoride to the raw materials in the vitrification reaction process. In addition, fluorine ions in the glass can be replaced with borofluoride ions at the same time as borofluoride is formed. The amount of borofluoric acid ions necessary to suppress the scattering phenomenon is 0.1 mol% or more based on the total fluorine ions in the glass, based on the lower limit of 0.1
If the amount is less than mol%, scattering phenomena cannot be sufficiently suppressed. It can be said that the amount of borofluoride ions is preferably about 5 mol %, but the amount may be increased arbitrarily as long as it does not adversely affect the physical properties of the glass. However, it is technically difficult to make a large amount of borofluoric acid ions exist in glass, and the upper limit of the amount of borofluoric acid ions is practically about 10 mol %. Next, examples will be described. Example 1 As glass raw materials, 0.59 mol of zirconium fluoride, 0.18 mol of barium fluoride, 0.05 mol of lanthanum fluoride, 0.07 mol of sodium fluoride, and aluminum fluoride.
These were placed in a platinum crucible at a ratio of 0.03 mol and 0.08 mol of sodium borofluoride, and heated and melted under an inert gas to produce an infrared transmitting glass. When the amount of borofluoric acid ions in this glass was measured, it was found that the amount of borofluoric acid ions was approximately
It was 2.6 mol%. For comparison, a glass containing no borofluoride ions was prepared using glass raw materials with a ratio of 0.59 mol of zirconium fluoride, 0.18 mol of barium fluoride, 0.05 mol of lanthanum fluoride, 0.15 mol of sodium fluoride, and 0.03 mol of aluminum fluoride. did. Diameter 8 from both glasses of Example 1 and Comparative Example above
When glass rods with a length of 20 mm and a helium-neon laser beam were incident on the glass rods in the longitudinal direction, and the amount of scattered light in a direction perpendicular to the direction of incidence was measured, it was found that Example 1. The scattered light intensity of the glass rod of the comparative example was reduced to 1/17 compared to the glass rod of the comparative example. Example 2 0.50 mol of zirconium oxide, hafnium oxide
0.09 mol, barium fluoride 0.18 mol, lanthanum fluoride
0.05 mole of sodium fluoride, 0.15 mole of aluminum fluoride, 0.005 mole of aluminum fluoride, and 0.005 mole of anhydrous boron oxide, together with twice the amount of acidic fluoride required for fluorination of the oxide in these raw materials. ammonium chloride was placed in a platinum crucible and heated to produce an infrared transmitting glass. When the amount of borofluoride ions in this glass was measured, the amount was about 0.3 mol% based on the total fluorine ions. For comparison, a glass containing no borofluoric acid ions was produced using the above raw materials without boron oxide anhydride. Glass rods similar to those described above were made from the glasses of Example 2 and Comparative Example, and the amount of scattered light was measured using the same measuring means as described above.
The scattered light intensity of the glass rod was reduced to 1/15 compared to the glass rod of the comparative example. Examples 3 to 9 In fluoride glasses having the compositions shown in the table below, part of the fluorine ions in these glasses (0.1 to 10 mol%
(within the range of ) with borofluoric acid ions, light scattering was able to be reduced in each example compared to the case where the prescribed substitution was not performed.

[Table] As explained above, the infrared transmitting glass according to the present invention not only has stable physical properties, but also
Light scattering is extremely low, and therefore it is suitable as an infrared optical component and a material for an infrared transmission line.

Claims (1)

[Claims] 1 Zirconium fluoride and/or hafnium fluoride 50-70 mol% and barium fluoride 10-35 mol%
and 1 to 8 mol% of at least one fluoride selected from yttrium fluoride, lanthanide element fluorides, and thorium fluoride, and 0 to 30 mol% of sodium fluoride and/or cesium fluoride. An infrared transmitting glass comprising 1 to 10 mol % of aluminum fluoride, in which 0.1 to 10 mol % of the fluorine ions are substituted with borofluoride ions.