DD211545A1 - METHOD FOR PRODUCING INFRARED LIQUID GLASS - Google Patents

Abstract

The invention relates to the production of infrared transmissive glass. Such glass is suitable for use in infrared and multispectral optics or as cuvette windows in applied infrared spectroscopy. The essence of the invention is that glass with similar optical and thermal properties as GeS is distilled down 2 glass to remove carbonaceous contaminants in the silica glass apparatus shown in FIG. The impurities are thereby frozen out in the form of COS and CS below 2 from the gas phase. In order to increase the glass-forming ability, 0.3 to 20 mol% of sulfur is added to the batch composition in addition to the composition GeS 2 below. The sulfur can be wholly or partially replaced by arsenic and / or phosphorus and / or antimony n. In this way, glass samples can be made in suitable for the production of lenses and prisms dimensions without interfering absorptions in the transmission range of 4 to 7 microns.

Description

Title of the invention

Process for the preparation of infrared transmissive glass

Field of application of the invention

The invention relates to the production of infrared-transparent optical glass which is suitable for use in infrared and multispectral optics or as cuvette windows in applied infrared spectroscopy.

Characteristic of the known technical solutions

Numerous infrared-transmissive glasses have already been described, whose wavelength range of transmittance exceeds that characteristic of optical oxide glasses of about 1.5, ura. They are characterized in the visible spectral range by impermissibility which is not sufficient for optical applications. Their thermal stability is the lower, the further the wavelength range of the transmission in the infrared is extended to larger values. A measure of the thermal stability is the transformation temperature Tg.

Examples are:

As-S, glass with a transmission range of 0.6 to 10, ura and a transformation temperature of 190 C / R.Frerichs, J. opt. Soc. America 43, 1153 (1953) /,

Glaziers in the ternary system Ge-As-Se with permeability between 1 and 15, and transformation temperatures

о up to a maximum of 401 C / P. Webber, I.A. Savage, CJ. Non-Cryst.

Solids 20, 271 (1976) / and glasses in the Ge-As-Se-Te quaternary system with transmittance between about 1.5 and 15, and transforation temperatures up to a maximum of 308 C / USA 4154 503 C 03 c / 13/00 /, Sisher is not detected by any technical solution to have a transmittance in the visible spectral range of up to 0.5 with simultaneous transmittance in the spectral range up to 10 μm, the thermal stability being due to the rather high transformation threshold of over 410 ° C. Such properties are exhibited by the glassy / Y. Kawamoto, S. Tsuchihashi, J. Amer. Cerara. Soc. 54, 526 (1971).

This glass is synthesized from germanium and sulfur by melt reaction in evacuated, fused silica glass vials. The GeSp melt must be cooled very rapidly because of its high tendency to crystallize. Therefore, the glass can only be obtained in quantities of a few grams. In addition, carbon contaminants at 4.90 and 6.60 cause spurious absorptions. The exploitation of the GeS ₂ glass for optical applications has failed to date.

Object of the invention

The aim of the invention is to produce, by influencing the crystallization behavior of GeSp melts while retaining the optical and thermal properties of vitreous GeS ^ compact glass specimens of sufficient dimensions that allow the production of optical components and cuvette windows.

By a suitable method, the carbon impurities are separated.

3 Presentation of the essence of the invention

The object of the invention is to produce infrared-transparent glasses of sufficient dimensions for practical applications on the basis of the systems GeS ₂ -S and GeS ₂ -As by suitable choice of the composition and with the combination of the additives without significant change in the properties of the GeS _{2 base} glass. the crystallization tendency of which is significantly reduced compared with glassy GeS ₂ and in whose permeability range between 4 and 7, to take place no absorption by impurities.

Erfindungsgeraäß the object is achieved in that the mixture to increase the glass forming ability 0.3 to 20 MoIJo sulfur are added and that the glasses for separating volatile volatiles in an evacuated silica glass apparatus at 900 C remelted, the melt is distilled and the volatile Distillation in the distillation at a different location are frozen than the constituents of the glass deposited.

The added sulfur can be partially or completely replaced by As and / or P and / or Sb. To produce the glass, the elements are reacted in the required molar ratio in evacuated, abgeschraolzen Kieselglasarapullen by gradually increasing the temperature, the melt homogenized for several hours at 9QQ ⁰ C and then cooled sufficiently fast. The crystallization tendency of the glasses is inversely proportional to the size TT

The transformation temperature of the glasses, the liquidus temperature T _{f of} the recrystallized Prooen and

the crystallization temperature T. of the melts on cooling with a defined cooling rate q are determined by differential thermal analysis. G depends on the cooling rate q.

It has been found that in these glass-forming systems values of G> 0.1 correspond to the crystallization tendency of the melts which is sufficiently low for the production of glass bodies of the required dimensions. This information refers to a cooling

speed q = 3.2 K "min"". Starting from pure GeS ₇ - * melts by G = 0.06

- 1 ¹ ^

are characterized for q = 3.2 K »min, is exceeded even at low additions of S and / or As and / or P and / or Sb G = 0.1. The permeability of these glasses is practically equivalent to that of the GeSp base glass and the thermal stability is only slightly reduced.

The advantage of this method over the previously known method is that the glass formation tendency of GeS ^ melts is greatly increased by the addition of said components, so that melt approaches of 50 g and above can be converted into stress-free glasses. After the distillation of the glasses, no external absorption by carbon impurities is detectable in their spectra.

embodiment

The invention will be explained in more detail in an Ausführungsbeispial.

FIG. 1 shows a silica glass appartur. The separation of the carbonaceous impurities is carried out by distillation of the glass in the evacuated and fused silica glass apparatus at 900 C.

In the course of the distillation of a distillation vessel 1 according to a distillation template 2, the volatile impurities CS ₂ and COS are frozen in a cold finger 3 at -19 ° C. After completion of the distillation is at a Abschmelzstelle 5 and a Abschmelzstelle б melted, the condensate completely overdriven in an ampoule 4 and also melted at a Abschmelzstelle 7. The heterogeneous, predominantly crystalline material in the ampoule 4 is converted by appropriate melting, homogenization and cooling in the glassy state.

In Taoelle 1 under the name Hr. 2 to no. 14 examples of erfindungsgeraäßen increase in glass-forming ability of GeS _o melts by the addition of S (As _n .S _n ..) or As reproduced. The glass forming ability is expressed by the empirical parameter G. In addition to the batch compositions and G, the transformation temperatures of the glasses are also listed. In No. 1, the corresponding data for pure GeS ₂ -GIaS are reproduced.

Table 1:

Name Glass composition in mol% GeS ₂ S ( ^As o, 4 ^S O,

100

99.5 0.5 97 3 94 5 39 11 32 13 99.3 - 0.7

93 - 7 87 - 13 99.7 -

97 -

94 92 39

Curve 1 in FIG. 2 shows the transmission spectrum of a 0.5 cm thick glass pane of composition 3 in the range from 4.5 to 14 before distillation. Although it has been used for glass synthesis semiconductor pure germanium, and sulfur with a designated quality of 99.9999] _'й, in addition to the system-typical absorptions, which limit the range of permeability for long-wave, relatively strong absorption bands at 4.90 and 5.50, in order to recognize which are caused by the antisymmetric valence oscillations of dissolved in the glass COS or CSp traces. Scattering losses on microcrystalline portions, whose formation is also due to impurities, reduce the permeability throughout the entire range.

No , 1 Mr , 2 No , 3 mr , 4 No , 5 mr , 6 No , 7 No , 8th No , 9 No .10 No .11 No .12 No .13 No .14

ace G q T / ° C - 0.06 495 - 0.09 481 - 0.12 47 p - 0.11 471 - 0.19 443 - 0.30 411 - 0.09 493 - 0.13 453 - 0.19 450 0.3 0.07 493 3 0.11 457 δ 0.23 453 8th 0.39 443 11 0.64 433

ι >">

After removal of the impurities by distillation according to the invention, the spectrum of a likewise 0.5-Eear glass pane of the glass, as shown by curve 2 in FIG. 1, no longer contains any foreign-absorbing bands in the region shown. The permeability is now 77 %. This is only 2 % less than the maximum value expected with a refractive index of 2.04 and an absorption of 0 % .

Claims (2)

invention claim 1. A process for the production of infrared-transparent optical glass having similar optical and thermal properties as GeS ₂ -GIaS characterized in that the mixture to increase the glass forming ability 0.3 to 20 mol % sulfur are added and that the glasses for the separation of volatile, carbon-containing impurities remelted in an evacuated silica glass apparatus at 900 C, the melt is distilled and the volatile contaminants are frozen in the distillation at a different location than the constituents of the glass deposit. 2. Infrared transparent glass according to item 1, characterized in that the added sulfur can be partially or completely replaced by arsenic and / or phosphorus and / or antimony. HieraüL pages Zeicnnungen