CN-117230526-B - Method for growing large-size rare earth ion doped garnet series crystals by wide seed crystal guided mode method

CN117230526BCN 117230526 BCN117230526 BCN 117230526BCN-117230526-B

Abstract

The method for growing large-size garnet series crystals by using the wide seed crystal guided mode method does not carry out necking and shouldering processes, reduces the risk of crystal cracking, improves the crystallization rate, shortens the growth time, and can stably grow the large-size high-quality rare earth ion doped garnet series crystals with the size of more than six inches.

Inventors

PAN MINGYAN
ZHANG LU
QI HONGJI
TIAN RUIFENG

Assignees

中国科学院上海光学精密机械研究所

Dates

Publication Date: 20260512
Application Date: 20230316

Claims (4)

1. A method for growing large-size rare earth ion doped garnet series crystals by a wide seed crystal guided mode method comprises the following steps: a 3 B 5 O 12 , re=yb, nd, ce, a= Y, lu and Y/Lu solid solutions, b=al, ga and Al/Ga solid solutions, characterized by comprising the steps of: Step 1, selecting and processing raw materials, namely weighing the raw materials Re 2 O 3 、A 2 O 3 and B 2 O 3 according to the stoichiometric ratio of a molecular formula Re 3 B 5 O 12 , and obtaining a polycrystal block through the processes of mixing, pressing and firing; Step 2, crystal growth: Step 2.1, heating and melting the polycrystalline material block, and keeping overheat; step 2.2, descending the wide seed crystal to enable the wide seed crystal to be in contact with the die; The width W S and the thickness T S of the wide seed crystal and the width W D and the thickness T D of the die meet the condition W S = W D and ; After 2.3-30 minutes, carrying out equal-diameter growth on the pull crystal, wherein the pulling rate is 5-30mm/h; after the crystal growth of step 2.4 is finished, heating, lifting off, cooling to room temperature within 12-20 hours, and discharging; and 2.5, after high-temperature annealing, heating to 1000-1300 ℃ in an air atmosphere, keeping the temperature for 10-20 hours, and slowly cooling to room temperature.
2. The method for growing large-size rare earth ion doped garnet series crystals by the wide seed crystal guided mode method according to claim 1, wherein the mixing, pressing and firing processes in the step 1 are specifically as follows: Step 1.1 weighing the raw materials Re 2 O 3 、A 2 O 3 and B according to the stoichiometric ratio of the molecular formula Re to A 3 B 5 O 12 2 O 3 After 20-40 hours of mixing in a mixer, pressing in a cold isostatic press for 3-6 hours; Step 1.2, placing the pressed raw materials into an alumina crucible, placing the alumina crucible into an annealing furnace for calcination, wherein the temperature is 1000-1500 ℃ and the time is 10-15 hours, and obtaining the polycrystalline material block.
3. The method for growing large-sized rare earth ion doped garnet crystal according to claim 1, wherein the step 2 crystal growth process is performed in a flowing atmosphere, which is an inert gas.
4. The method for growing large-sized rare earth ion doped garnet series crystals by the wide seed crystal guided mode method according to claim 1, wherein the mold is a flaky molybdenum mold, in step 2, a molybdenum crucible filled with raw materials is placed in the center of a hearth, the molybdenum mold is placed in the center of the molybdenum crucible, and a molybdenum crucible cover is placed on the molybdenum crucible in the furnace charging process before the crystal growth.

Description

Method for growing large-size rare earth ion doped garnet series crystals by wide seed crystal guided mode method Technical Field The invention belongs to the technical field of crystal growth, and particularly relates to a method for growing large-size rare earth ion doped garnet series crystals by a wide seed crystal guided mode method. Background The growth principle of the guided mode method is that a mould with a capillary gap is placed in the middle of a crucible, the solution rises to the upper surface of the mould through capillary action to form a liquid film, and then seed crystal is pulled down for growth. By adjusting the shape and the size of the die, single crystals with specific shapes and sizes can be directly grown, and the method has the advantages of high growth speed, low growth cost and the like. In order to meet the strategic demands of the scintillation and laser fields on rare earth ion doped garnet crystals, large-size high-quality crystals with a size of more than six inches need to be developed, but the guided-mode method for growing large-size crystals has the risk of cracking. The guided-mode method is used for growing crystals, the width and thickness of the narrow seed crystal are far smaller than those of the top of the die, and necking and shouldering are needed in the crystal growing process to enter a stable constant-diameter growth stage. However, the shoulder crystallization area in the shouldering stage increases exponentially with time, and the rapid increase of the shoulder area of the crystal leads to faster heat dissipation, and the generated thermal strain exceeds a critical strain value to cause crystal cracking. The wide seed crystal is adopted for growth, the width of the wide seed crystal is equal to the width of the die, the thickness of the wide seed crystal is basically equal to the thickness of the die, the necking and shouldering steps do not exist in the crystal growing process, the problem of crystal cracking caused by overlarge thermal stress in the shouldering process is solved, and a temperature field suitable for large-size crystal growth is established jointly by the wide seed crystal and a thermal field structure. Patent document CN104962994a discloses a method for growing rare earth doped gallium-containing garnet series crystals with specific size by a guided mode method, which can rapidly grow the crystals with specific size, but clearly writes out that the length of the grown crystals is 4 inches, which is far smaller than that of the grown large-size crystals with the length of more than 6 inches. Meanwhile, patent document CN104962994A explicitly writes that the steps of seeding, neck collecting, shoulder placing and constant diameter are needed in the growth process, and the materials of the crucible and the die are iridium. Disclosure of Invention Aiming at the problems that the large-size single crystal grown by the guided-mode method is difficult to shoulder and is easy to crack in the prior art, the invention provides a process method for growing large-size garnet series crystals by the wide-seed crystal guided-mode method. The method does not carry out necking and shouldering processes, reduces the risk of crystal cracking, improves the crystallization rate, shortens the growth time, and can stably grow high-quality large-size rare earth ion doped garnet series crystals. The technical scheme of the invention is as follows: The invention provides a method for growing large-size rare earth ion doped garnet series crystals by a wide seed crystal guided mode method, wherein the molecular formula of the rare earth ion doped garnet series crystals is Re: a 3B5O12, re=yb, nd, ce, a= Y, lu and Y/Lu solid solutions, b=al, ga and Al/Ga solid solutions, characterized by comprising the steps of: Step 1, selecting and processing raw materials, namely weighing the raw materials Re 2O3、A2O3 and B 2O3 according to the stoichiometric ratio of a molecular formula Re 3B5O12, and obtaining a polycrystal block through the processes of mixing, pressing and firing; Step 2, crystal growth: Step 2.1, heating and melting the polycrystalline material block, and keeping overheat; step 2.2, descending the wide seed crystal to enable the wide seed crystal to be in contact with the die; The width W S and the thickness T S of the wide seed crystal and the width W D and the thickness T D of the die meet the condition W S=WD and 80 percent of T DTSTD; After 2.3-30 minutes, carrying out equal-diameter growth on the pull crystal, wherein the pulling rate is 5-30mm/h; after the crystal growth of step 2.4 is finished, heating, lifting off, cooling to room temperature within 12-20 hours, and discharging; and 2.5, after high-temperature annealing, heating to 1000-1300 ℃ in an air atmosphere, keeping the temperature for 10-20 hours, and slowly cooling to room temperature. The step 1 material mixing, pressing and firing processes comprise the following specific steps: step 1.