WO2021004078A1

WO2021004078A1 - Praseodymium-doped gadolinium scandate visible waveband laser crystal and preparation method therefor

Info

Publication number: WO2021004078A1
Application number: PCT/CN2020/078612
Authority: WO
Inventors: 李纳; 徐军; 徐晓东; 董建树; 刘坚; 胡冬华
Original assignee: 南京同溧晶体材料研究院有限公司
Priority date: 2019-07-11
Filing date: 2020-03-10
Publication date: 2021-01-14
Also published as: CN110408994A

Abstract

The present invention relates to a praseodymium-doped gadolinium scandate visible waveband laser crystal and a preparation method therefor. The formula of said crystal is Pr_xGd_1-xScO₃, in which the value x is in the range of 0.005-0.015, the space group thereof is Pbnm(62), and the unit cell parameter is formula (1). Pr₆O₁₁ with a purity of 5N, Gd₂O₃, and Sc₂O₃ are used as raw materials, are sufficiently ground, pressed into blocks, and sintered at a high temperature of 1350-1550 degrees centigrade. The praseodymium-doped gadolinium scandate crystal is grown by using a edge-defined film-fed growth technique, and the growth atmosphere is high purity argon. Compared with the prior art, the crystal material of the present invention can achieve high efficiency visible waveband red laser output, and can be applied to fields such as laser medical treatment, laser display and communication.

Description

Spectral-doped gadolinium scandate visible waveband laser crystal and preparation method thereof

Technical field

The invention relates to a visible waveband laser crystal and a preparation method thereof, in particular to a spectrum-doped gadolinium scandate laser crystal and a preparation method thereof, and belongs to the technical field of laser materials.

Background technique

With the development of the information age, people are paying more and more attention to special wavelength lasers. Visible light (380～780nm) laser not only has a wide range of applications in people’s daily life (such as laser headlights, laser reminders, medicine, projectors, and data storage), but also can be applied to many other fields (such as a new generation of display Technology, microscope, visible light communication, high-end material preparation and scientific research, etc.). In 2014, the Nobel Prize in Physics awarded the breakthrough of high-power blue LED, which reflects the importance of visible light laser in the future development.

Most of the research on direct emission of visible light laser at home and abroad has focused on several rare earths such as praseodymium (Pr), dysprosium (Dy), terbium (Tb), samarium (Sm), holmium (Ho), erbium (Er), europium (Eu), etc. ion. Among them, the trivalent Pr ³⁺ is a rare earth ion that is ^widely used. At 445nm, 468nm and 486nm, the absorption cross section reaches the order of 10-19cm ² . The absorption peak at 445nm is very consistent with the emission wavelength of the InGaN laser diode pump source, and the absorption peak at 468nm is very consistent with the emission wavelength of the 2ω-OPSLs pump source. Compared with other rare earth ions, Pr ³⁺ has a large number of radiation transitions, and its luminous range almost covers the red, orange, green, and blue light in the visible light band. Therefore, Pr3+-doped laser materials are currently the most potential visible waveband laser materials.

Among the crystal materials doped with Pr ^{3+ to} achieve laser output in the visible band, the fluoride LiYF ₄ has achieved laser output in the blue, green, orange, red and deep red wavelength bands. Using 2ω-OPSL to pump Pr:LYF, a green laser of about 4.2W was achieved at 523nm, with a slope efficiency of 45%. In addition, the same material is pumped by blue LD, the slope efficiency is 50% at 640nm, and the output power is as high as 4.8W, which is the highest output power of Pr ³⁺ doped laser crystals. However, the thermal performance of fluoride is poor, which largely limits the further improvement of its laser performance, while oxide crystals have better thermal conductivity and thermal expansion coefficient. Compared with higher power fluoride crystals, Pr ³⁺ oxides have been studied less. At present, the oxide laser crystals that realize laser output are mainly YAP, SRA and Sr0.7La0.3Mg0.3Al11.7O19 (ASL). It has been reported that for Pr ³⁺ ion-doped oxide crystals, lower phonon energy and smaller 5D energy level splitting are more conducive to its laser output.

GdScO ₃ crystal belongs to the perovskite structure, orthorhombic crystal system, with a maximum phonon energy of 452 cm ^-1 , which is more disordered than ortho aluminate in structure. The distance between Gd-Gd atoms is

Distance between Gd-O atoms

Compared with other oxide crystals that have been lasered, GdScO ₃ has smaller phonon energy and larger atomic distance, so the excited state absorption and non-radiation transition rate of its 3P0 energy level are relatively small, and higher power lasers can be obtained. The possibility of output is greater.

Summary of the invention

In order to solve the above-mentioned problem of poor laser performance of Pr ³⁺ oxide laser crystals, the present invention provides a spectrum doped gadolinium scandate visible waveband laser crystal with low matrix phonon energy and large atomic spacing. The chemical formula of the crystal is Pr _x Gd _1- _x ScO ₃ , where the range of x is 0.005-0.015, its space group is Pbnm(62), and the unit cell parameter is

At the same time, a method for preparing the above-mentioned laser crystal is proposed, which adopts guided mode growth, and the method mainly includes the following steps:

(1) The initial raw materials are 5N purity Pr ₆ O ₁₁ , Gd ₂ O ₃ and Sc ₂ O ₃ powders. When a specific concentration of Pr ions is selected to be doped to replace Gd ions, follow the chemical formula Pr _x Gd _1-x ScO ₃ Calculate the required mass of each raw material and weigh it accurately;

(2) Put the weighed powdered raw material into an agate mortar to fully grind the raw materials uniformly, then use a hydraulic press to press into a block material embryo, sinter it at high temperature, take it out and put it into a tungsten crucible, and load it into a guide mold furnace ；

(3) During the process of loading the guide mold furnace, set the seed crystal, the center of the tungsten crucible and the center of the coil to be on the same vertical line;

(4) After the furnace is installed, the mechanical pump is started to vacuum, filled with inert gas as a protective atmosphere, heated to 14-16KW within 1.8-2.8h and kept constant for 0.5-1.8h to ensure that the raw materials in the crucible are all melted, and the growth process Mainly include: seeding, shoulder setting and equal diameter. After the growth is completed, slowly lower to room temperature and take out the crystal.

As an improvement, in step (2), the time for grinding the raw materials is 40min-60min.

As an improvement, when the raw material is sintered at a high temperature in step (2), the heating rate is 80-150°C/h, and the temperature is kept at 1350-1550°C for 11-18h.

As an improvement, when the seed crystal, the center of the tungsten crucible and the center of the coil are on the same vertical line as described in step (3), a rotating pull rod is used to set the seed crystal swing not to exceed 1 mm.

As an improvement, the mechanical pump described in step (4) is started for vacuum, and the vacuum in the guide mold furnace is not more than 0.3 MPa.

As an improvement, the inert gas in step (4) is high-purity argon or high-purity nitrogen.

As an improvement, in step (4), the pulling speed of the seed rod is 7-9.5 mm/h when the shoulder is placed, and the pulling speed of the seed rod is 4.5-7.5 mm/h when the diameter is equal.

Beneficial effects: The present invention uses Pr ₆ O ₁₁ , Gd ₂ O ₃ and Sc ₂ O ₃ with a purity of 5N as raw materials, which are pressed into a block after sufficient grinding, and sintered at a high temperature at 1350-1550 degrees Celsius. The guided mode method is used to grow spectrum-doped gadolinium scandate crystals in a high-purity argon atmosphere. Compared with the prior art, the crystal material of the present invention can realize high-efficiency visible waveband red laser output, and can be applied to the fields of laser medical treatment, laser display, and communication.

Description of the drawings

Figure 1 is an X-ray powder diffraction pattern of a sample prepared in Example 1 of the present invention.

Figure 2 is a room temperature absorption coefficient spectrum of a sample prepared in Example 1 of the present invention.

Figure 3 is a room temperature fluorescence spectrum of a sample prepared in Example 1 of the present invention.

Fig. 4 is a fluorescence lifetime spectrum corresponding to the emission peak at 610 nm of the sample prepared in Example 1 of the present invention under excitation of 449 nm light.

Detailed ways

The drawings and specific embodiments of the present invention will be further described below.

Example 1:

Growing Pr _0.006 Gd _0.994 ScO ₃ by the guided mold method is specifically prepared by the following method: Use the guided mold method to grow Pr _0.006 Gd _0.994 ScO ₃ crystals, weigh the raw materials and grind them in an agate mortar, and choose a grinding time of 40 minutes to make the raw materials evenly mixed. , And then use a hydraulic press to press into a block material embryo. Perform high-temperature sintering at a heating rate of 80°C/h to 1400°C and a constant temperature for 15 hours, then put 200g of the high-temperature sintered bulk raw material in a tungsten crucible, and place it in a guide mold furnace for growth, in which pure GdScO is used ₃ Single crystal is grown as a seed crystal at a growth rate of 8mm/h. When the center of the seed crystal, the center of the tungsten crucible and the center of the coil are in the same vertical line, use a rotating pull rod to set the seed crystal swing not to exceed 1mm, preferably 0-0.5mm .

The vacuum in the guide mold furnace is evacuated to 4Pa, filled with high-purity nitrogen as a protective atmosphere, heated to 15KW in 2h, and kept at a constant temperature for 1h until the raw materials are completely melted, and the growth process mainly includes: seeding, placing Shoulder and equal diameter, the pulling speed of the seed rod is 7mm/h, and the pulling speed of the seed rod is 4.5mm/h when the diameter is equal. After the growth is completed, quickly pull the crystal out of the liquid surface, and take it out after slow cooling Crystal, a piece of Pr:GdScO ₃ crystal with good optical quality is obtained, and the experimental data obtained are shown in Figure 1-4. Its emission cross section at the emission peak of 661 nm is on the order of 10 ^-19 cm.

Example 2:

Growing Pr _0.012 Gd _0.988 ScO ₃ by the guided mode method is specifically prepared by the following method: use the guided mode method to grow Pr _0.012 Gd _0.988 ScO ₃ crystals, weigh the raw materials and grind them in an agate mortar, and choose a grinding time of 60 minutes to make the raw materials evenly mixed. , And then use a hydraulic press to press into a block material embryo. Perform high-temperature sintering at a heating rate of 150°C/h to 1550°C and a constant temperature for 18 hours, and then put 250g of the high-temperature sintered bulk raw material in a tungsten crucible, and place it in a guide mold furnace for growth, in which pure GdScO is used ₃ Single crystals are grown as seed crystals at a growth rate of 5-15mm/h. When the center of the seed crystal, the center of the tungsten crucible and the center of the coil are on the same vertical line, use a rotating pull rod to set the seed crystal swing not to exceed 1mm, preferably 0- 0.5mm.

The vacuum in the guide mold furnace is evacuated to 2.5-10Pa, filled with high-purity argon gas as a protective atmosphere, heated to 16KW in 1.8h, and then kept at a constant temperature for 1.8h until the raw material is completely melted, and the growth process mainly includes : Seeding, shoulder setting and equal diameter. The pulling speed of the seed rod is 8mm/h, and the pulling speed of the seed rod is 6mm/h when the diameter is equal. After the growth is completed, the crystal is quickly pulled to make it out of the liquid surface. The crystal was taken out after slowly cooling down, and a Pr:GdScO ₃ crystal with good optical quality was obtained, and its emission cross section at the emission peak of 661 nm was on the order of 10 ^-18 cm.

Example 3:

Growing Pr _0.005 Gd _0.995 ScO ₃ by the guided mold method is specifically prepared by the following method: Use the guided mold method to grow Pr _0.005 Gd _0.995 ScO ₃ crystals, weigh the raw materials and grind them in an agate mortar, and choose a grinding time of 50 minutes to make the raw materials evenly mixed. , And then use a hydraulic press to press into a block material embryo. Perform high-temperature sintering at a heating rate of 120℃/h from a heating rate of 120℃/h to 1350℃ and a constant temperature for 11h. Then put 280g of the high-temperature sintered bulk raw material in a tungsten crucible and place it in a guide mold furnace for growth, in which pure GdScO is used ₃ Single crystal is grown as a seed crystal at a growth rate of 7-9mm/h. When the center of the seed crystal, the center of the tungsten crucible and the center of the coil are in the same vertical line, use a rotating pull rod to set the seed crystal swing not to exceed 1mm, preferably 0- 0.5mm.

The vacuum in the guide mold furnace is evacuated to 0.5-8Pa, filled with high-purity nitrogen as a protective atmosphere, heated to 14KW in 2.8h, and kept at a constant temperature for 0.5h until the raw material is completely melted, and the growth process mainly includes: Seeding, shoulder setting and equal diameter, the pulling speed of the seed rod is 9.5mm/h, and the pulling speed of the seed rod is 7.5mm/h when the diameter is equal. After the growth is completed, the crystal is quickly pulled to make it out of the liquid surface , Take out the crystal after slowly cooling down, and obtain a Pr:GdScO ₃ crystal with good optical quality. Its emission cross section at the emission peak of 661nm is on the order of ^10-19 cm.

The above-mentioned embodiments only express several embodiments of the present invention, and the descriptions are more specific and detailed, but they should not be understood as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

A visible band laser crystal doped with gadolinium scandate, characterized in that the chemical formula of the crystal is Pr x Gd 1-x ScO 3 , wherein the value range of x is 0.005-0.015, and its space group is Pbnm(62), The unit cell parameters are
A method for preparing a spectrum-doped gadolinium scandate laser crystal in the visible band according to claim 1, characterized in that it is grown by a guided mode method, and the method mainly comprises the following steps:

(1) The initial raw materials are 5N purity Pr 6 O 11 , Gd 2 O 3 and Sc 2 O 3 powders. When a specific concentration of Pr ions is selected to be doped to replace Gd ions, follow the chemical formula Pr x Gd 1-x ScO 3 Calculate the required mass of each raw material and weigh it accurately;

(2) Put the weighed powdered raw material into an agate mortar to fully grind the raw materials uniformly, then use a hydraulic press to press into a block material embryo, sinter it at high temperature, take it out and put it into a tungsten crucible, and load it into a guide mold furnace ；

(3) During the process of loading the guide mold furnace, set the seed crystal, the center of the tungsten crucible and the center of the coil to be on the same vertical line;

(4) After the furnace is installed, the mechanical pump is started to vacuum, filled with inert gas as a protective atmosphere, heated to 14-16KW within 1.8-2.8h and kept constant for 0.5-1.8h to ensure that the raw materials in the crucible are all melted, and the growth process Mainly include: seeding, shoulder setting and equal diameter. After the growth is completed, slowly lower to room temperature and take out the crystal.
The method for preparing a spectrum-doped gadolinium scandate visible waveband laser crystal according to claim 2, characterized in that, in step (2), the grinding time of the raw material is 40min-60min.
The method for preparing a spectrum-doped gadolinium scandate visible waveband laser crystal according to claim 2, characterized in that, in step (2), when the raw material is sintered at a high temperature, the heating rate is 80-150°C/h, and the temperature is 1350-1550°C. Constant temperature 11-18h.
The method for preparing a spectrum-doped gadolinium scandate visible waveband laser crystal according to claim 2, characterized in that in step (3), when the seed crystal, the center of the tungsten crucible and the center of the coil are in the same vertical line, the rotation Lift the rod and set the seed crystal swing to no more than 1mm.
The method for preparing spectrum-doped gadolinium scandate visible waveband laser crystal according to claim 2, characterized in that, in step (4), the mechanical pump is started for vacuuming, and the vacuum in the guided mold furnace is not more than 0.3 MPa.
The method for preparing a spectrum-doped gadolinium scandate visible band laser crystal according to claim 2, wherein the inert gas in step (4) is high-purity argon or high-purity nitrogen.
The method for preparing a spectrum-doped gadolinium scandate visible waveband laser crystal according to claim 2, characterized in that the pulling speed of the seed rod during shoulder setting in step (4) is 7-9.5 mm/h, and the same diameter The pulling speed of the seed rod is 4.5-7.5mm/h.