A method for preparing high rare earth doped large melting amount tellurite glass

Abstract

The present invention discloses a method for preparing a high rare earth doped large melting amount tellurite glass. The preparation method adopts a traditional high temperature melting process, and adds a multi-step stepped heating and sintering process between the two steps of physical or chemical reaction water removal and high temperature melting, that is, in the temperature range between the softening temperature and the melting temperature of the glass, a plurality of specific temperature values ​​are set, and different heat preservation times are set at each specific temperature value. As the amount of glass melting increases, the more specific temperature values ​​are set, the longer the sintering time. This invention solves the problem that as the melting amount of tellurite glass increases, the quality of the glass melt deteriorates in the subsequent high temperature melting stage due to no sintering or insufficient sintering temperature and time. It not only greatly improves the glass quality, but also increases the solubility of rare earth ions in the glass. It can prepare high rare earth doped large melting amount high quality tellurite glass, and provides possibilities for the processing and application of various large-sized tellurite glasses.

Description

Technical Field

[0001] The invention belongs to the field of optical glass materials, and in particular relates to a method for preparing high rare earth doped large melting amount tellurite glass. Background Art

[0002] The 2-5 micron mid-infrared band is an important low-loss atmospheric transmission window, and contains characteristic absorption lines of many organic and inorganic molecules such as methane and hydrogen chloride. It has extremely important application prospects in military and civilian fields such as chemical analysis, sensors, space communications, military confrontation, high-sensitivity gas detection, and polymer organic material processing. In recent years, the application of a variety of glass materials with lower phonon energy, including tellurite, fluoride and sulfide glasses, in the field of mid-infrared lasers has attracted much attention. Compared with fluoride and sulfide glasses, tellurite glass has lower production environment requirements, higher thermal stability, mechanical strength, laser damage threshold and rare earth ion solubility, and can provide good material support for the generation of high-power mid-infrared lasers.

[0003] Depending on the glass composition, the maximum phonon energy (MPE) of tellurite glasses can be around 650 cm -1 Up to 950cm -1 The corresponding maximum transmission window is between 5.2 microns and 6.5 microns. In order to obtain the highest transmission window, patent CN109574509B discloses that the tellurite glass composition cannot contain oxides such as tungsten oxide or niobium oxide that will increase the overall MPE of the glass. At present, the alkali-free tellurite glass system, especially the tellurium oxide (TeO2)-zinc oxide (ZnO)-lanthanum oxide (La2O3) glass system, has the lowest MPE among tellurite glasses, high anti-crystallization stability, and hydroxyl (OH - ) activity is low, and the glass transition temperature and anti-laser damage threshold are high, which has attracted increasing attention from researchers from all walks of life. In current patents and papers, most of them use a small amount (15g-20g) of raw materials, which are directly heated to the melting temperature for melting, clarification, pouring and annealing after appropriate physical (chemical) dehydration reactions, and then the properties of the obtained glass samples are measured to obtain research results.

[0004] This glass melting process with a small melting amount is not suitable for the preparation of tellurite glass with a large melting amount. When preparing tellurite glass with a mass of more than 35 grams, if the glass melting process with a small melting amount is replicated, the glass quality will deteriorate, such as the melt becoming black and the increase of particles in the glass body. Optical fiber preforms and other optical components with complex structures made of tellurite glass require large-sized and high-quality tellurite glass. On the other hand, the high-concentration and uniform doping of rare earth laser elements in high-quality tellurite glass is also one of the technical bottlenecks that need to be overcome in the preparation of low-loss and high-gain active tellurite glass optical fibers. For example, the TeO2-ZnO-La2O3 tellurite glass composition system disclosed in US Patent US3883357A has a doping limit concentration of the rare earth laser element Nd2O3 of only 1.5 mol%. Summary of the invention

[0005] In view of the phenomenon that when a large-melt tellurite glass is prepared using a small-melt tellurite glass preparation process, the glass is abnormally colored and the glass quality is deteriorated, such as an increase in particles in the glass body. The present invention provides a method for preparing high-rare-earth-doped large-melt tellurite glass. The method has a reasonable design, solves the shortcomings of the prior art, and has good effects.

[0006] In order to achieve the purpose of the invention, the following technical solutions are adopted:

[0007] A method for preparing high-rare-earth-doped large-melting-volume tellurite glass comprises the following steps: firstly, removing water from a raw material mixture for preparing the tellurite glass by physical or chemical reaction; then entering a multi-step stepped heating and sintering process, that is, setting a plurality of specific temperature values ​​within a temperature range between the softening temperature and the melting temperature of the glass, and setting a different heat preservation time at each specific temperature value, and sintering and heating the glass powder sintered body; then entering a high-temperature melting, clarifying, pouring and annealing process to complete the preparation of the tellurite glass.

[0008] Furthermore, as the amount of glass melted increases, the more specific temperature values ​​are set in the multi-step stepped heating sintering process, the longer the sintering time.

[0009] Furthermore, the amount of glass melted is generally greater than 35 grams.

[0010] Furthermore, when the powder sintered body gradually transforms into a mixture of countless brown wet colloidal clusters and melt, the heating sintering process is terminated and the high-temperature melting process begins.

[0011] Furthermore, the set multiple specific temperature values ​​constitute a gradually increasing step-by-step temperature increase.

[0012] Furthermore, specific temperature values ​​are set at 600°C and 650°C.

[0013] Furthermore, specific temperature values ​​are set to 600°C, 610°C, 620°C and 650°C.

[0014] Furthermore, the insulation time is between 15 minutes and 60 minutes.

[0015] The rare earth mentioned in the present invention is a rare earth doping element other than the rare earth contained in the main component of the glass.

[0016] Beneficial technical effects brought by the present invention:

[0017] The preparation method of the present invention not only improves the solubility of rare earth ions in tellurite glass, and obtains a rare earth ion uniform doping limit concentration significantly higher than that specified in other patents for the same glass system, but also greatly improves the quality of large-melt glass. The prepared glass body has no abnormal coloring, and no quality defects such as particles and stripes, thereby enabling the preparation of high-quality tellurite glass with high rare earth doping. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The transmission spectra of the glasses prepared in Comparative Examples 5 and 6 and Examples 3 and 5 of the present invention; DETAILED DESCRIPTION

[0019] The specific implementation of the present invention is further described below in conjunction with specific embodiments:

[0020] Comparative Example 1 (Preparation of 20 g of tellurite glass):

[0021] 1-1) The widely used and easy-to-fiberize TeO2-ZnO-La2O3 glass system was selected as the research system of the present invention. In order to eliminate the absorption segments related to hydroxyl groups, in addition to the physical (chemical) drying treatment at about 200°C, one or more additives such as fluoride and / or chloride, such as zinc fluoride and / or zinc chloride, and lanthanum fluoride were used in the glass raw materials to partially replace zinc oxide and lanthanum oxide, respectively. The raw materials were accurately weighed according to the calculated composition ratio, and the raw materials were evenly mixed and placed in a gold crucible for treatment;

[0022] 1-2) subjecting the raw material mixture obtained in step 1-1) to physical (chemical) drying at about 200° C. for 1 hour;

[0023] 1-3) Directly heat to 850℃ to melt, move into a closed environment and introduce high-purity nitrogen after the glass liquid is clarified, keep warm for a certain period of time, pour the glass liquid into a preheated cast iron mold, put it into an annealing furnace after it is fully solidified, cool to room temperature and take it out to obtain a normal transparent light brown glass block.

[0024] Comparative Example 2 (Preparation of 35 g of tellurite glass):

[0025] The glass composition and glass preparation process are exactly the same as those of Comparative Example 1, and an abnormal brown-black glass block is obtained.

[0026] Comparative Example 3 (Preparation of 35 g of tellurite glass):

[0027] The glass composition is exactly the same as that of Comparative Example 1, but the raw material mixture is kept at 600°C for 60 minutes before being directly heated to 850°C for melting after physical (chemical) drying. At this time, it is observed that a small part of the surface of the powder sintered body has turned light yellow. Steps 1-3) in Comparative Example 1 are repeated to obtain a brown-black glass block of the same color as that of Comparative Example 2.

[0028] Example 1 (Preparation of 35 g of tellurite glass):

[0029] The glass composition is exactly the same as that of Comparative Example 1, but before the raw material mixture is directly heated to 850° C. for melting after physical (chemical) drying, the following two-step step-type heating procedure is performed:

[0030] 4-1) Keep at 600°C for 20 minutes;

[0031] 4-2) Maintain heat at 650°C for 15 minutes.

[0032] At this time, it was observed that the powder sintered body gradually transformed into a mixture of countless brown wet colloidal clusters and melt. Steps 1-3) in Comparative Example 1 were repeated to obtain a transparent light brown glass block of the same color as Comparative Example 1.

[0033] Comparative Example 4 (Preparation of 150 g of tellurite glass):

[0034] The glass composition is the same as that of Comparative Example 1. The sintering process adopts the same two-step stepped heating program as that of Example 1. At this time, it is observed that the powder sintered body gradually transforms into a mixture of countless brown-black wet colloidal clusters and melt. At this time, continuing to extend the insulation time at 650°C or raising the temperature slightly and then insulation has no effect. Repeating steps 1-3) in Comparative Example 1, an abnormal brown-black glass block is obtained.

[0035] Example 2 (Preparation of 150 g of tellurite glass):

[0036] The glass composition is exactly the same as that of Comparative Example 1, but before the raw material mixture is directly heated to 850° C. for melting after physical (chemical) drying, the following three-step step-type heating procedure is performed:

[0037] 6-1) Keep at 600°C for 30 minutes;

[0038] 6-2) Keep at 615°C for 20 minutes;

[0039] 6-3) Maintain heat at 650°C for 15 minutes.

[0040] At this time, it was observed that the powder sintered body gradually transformed into a mixture of countless brown wet colloidal clusters and melt. Steps 1-3) in Comparative Example 1 were repeated to finally obtain a transparent light brown glass block of the same color as Comparative Example 1.

[0041] Comparative Example 5 (Preparation of 300 g of tellurite glass):

[0042] The glass composition is exactly the same as that of Comparative Example 1. The sintering process adopts the same two-step step-type temperature increase program as in Example 1. At this time, it is observed that the powder sintered body gradually transforms into a mixture of countless black wet colloidal clusters and melt. Steps 1-3) in Comparative Example 1 are repeated to obtain an abnormally dark black glass block. The glass transmission spectrum is shown in FIG. Figure 1 shown.

[0043] Comparative Example 6 (Preparation of 300 g of tellurite glass):

[0044] The glass composition is exactly the same as that of Comparative Example 1. The sintering process adopts the same three-step step-type temperature increase program as Example 2. At this time, it is observed that the powder sintered body gradually transforms into a mixture of countless brown-black wet colloidal clusters and melt. Steps 1-3) in Comparative Example 1 are repeated to obtain an abnormal brown-black glass block. The glass transmission spectrum is shown in FIG. Figure 1 shown.

[0045] Example 3 (Preparation of 300 g of tellurite glass):

[0046] The glass composition is exactly the same as that of Comparative Example 1, but the raw material mixture is subjected to the following 4-step step-type heating procedure before being directly heated to 850°C for melting after physical drying:

[0047] 9-1) Keep at 600°C for 60 minutes;

[0048] 9-2) Keep at 610°C for 45 minutes;

[0049] 9-3) Keep at 620°C for 30 minutes;

[0050] 9-4) Maintain heat at 650°C for 15 minutes.

[0051] At this time, it was observed that the powder sintered body gradually turned into a mixture of countless brown wet colloidal clusters and melt. Steps 1-3) in Comparative Example 1 were repeated to finally obtain a transparent light brown glass block of the same color as Comparative Example 1. The glass transmission spectrum is shown in Figure 1 shown.

[0052] Example 4 (Preparation of 150 g of tellurite glass):

[0053] The glass composition includes 72.8 mol% TeO2, 19.4 mol% ZnO, 4.9 mol% La2O3 and 3.0 mol% rare earth laser element Nd2O3. The glass preparation process is exactly the same as that of Example 2, and a uniform transparent high-quality glass block with the same color as that of Example 2 is obtained. The doping concentration of Nd2O3 in this embodiment is significantly higher than the limit concentration of rare earth laser element doping (1.5 mol%) of the glass system specified in the patent US3883357 in the background technology.

[0054] Example 5 (Preparation of 300 g of tellurite glass):

[0055] The glass composition includes 67.9 mol% TeO2, 24.3 mol% ZnO, 4.9 mol% La2O3 and 3.0 mol% rare earth laser element Tm2O3. The glass preparation process is exactly the same as that of Example 3, and a uniform transparent high-quality glass block with the same color as that of Example 3 is obtained. The glass transmission spectrum is as follows: Figure 1 The doping concentration of Tm2O3 in this embodiment is also significantly higher than the doping limit concentration (1.5 mol%) of the rare earth laser element in the glass system specified in the patent US3883357A in the background art.

[0056] The holding time and glass coloring at each gradient temperature in the above embodiments are shown in Table 1.

[0057] Table 1

[0058]

[0059]

[0060] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing high rare earth doped large melting amount tellurite glass, characterized in that: First, the raw material mixture for preparing tellurite glass is subjected to physical or chemical reaction to remove water, and then enters a multi-step stepped heating and sintering process, that is, multiple specific temperature values ​​are set in the temperature range between the softening temperature and the melting temperature of the glass, and different holding times are set at each specific temperature value to sinter and heat the glass powder sintered body; then it enters the subsequent high-temperature melting, clarification, pouring and annealing process to complete the preparation of tellurite glass; As the amount of glass melted increases, the more specific temperature values ​​are set in the multi-step stepped heating sintering process, the longer the sintering time; The melting amount of the glass is greater than 35 grams.

2. The method for preparing a high rare earth doped large melting amount tellurite glass according to claim 1, characterized in that: When the powder sintered body gradually transforms into a mixture of countless brown wet colloidal clusters and melt, the heating sintering process ends and enters the high-temperature melting process.

3. The method for preparing a high rare earth doped large melting amount tellurite glass according to claim 1, characterized in that: The set multiple specific temperature values ​​constitute a gradually increasing step-by-step temperature increase.

4. The method for preparing a high rare earth doped large melting amount tellurite glass according to claim 3, characterized in that: The specific temperature values ​​set are 600°C and 650°C.

5. The method for preparing a high rare earth doped large melting amount tellurite glass according to claim 4, characterized in that: The specific temperature values ​​set are 600°C, 610°C, 620°C and 650°C.

6. The method for preparing a high rare earth doped large melting amount tellurite glass according to claim 1, characterized in that: The insulation time is between 15 minutes and 60 minutes.

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