Aluminum-rare earth ion co-doped gallium oxide crystal and two preparation methods thereof

Abstract

The invention relates to an aluminum-rare earth ion co-doped gallium oxide crystal and two preparation methods thereof. The chemical formula of the aluminum-rare earth ion co-doped gallium oxide crystal is beta-(Ga1-x-yAlxREy) 2O3. The preparation method comprises the following steps: 1) mixing a gallium source, an aluminum source and a rare earth element source, and sequentially carrying out pre-sintering, isostatic pressing treatment and secondary sintering to obtain an aluminum-rare earth ion co-doped gallium oxide polycrystalline ceramic rod; and 2) loading the aluminum-rare earth ion co-doped gallium oxide polycrystalline ceramic charge bar into an optical floating zone method single crystal furnace, carrying out crystal growth under a protective atmosphere, and carrying out high-temperature annealing to obtain the aluminum-rare earth ion co-doped gallium oxide crystal. Compared with the prior art, according to the preparation method, Al < 3 + > and rare earth ions are co-doped into the gallium oxide crystal, the lattice distortion effect caused by the large radius of the doped rare earth ions can be effectively compensated, the effective doping concentration of the rare earth ions is improved, then the rare earth fluorescence effect is enhanced, and the problem that the rare earth ions cannot be effectively doped into the gallium oxide crystal is solved through co-doping of Al < 3 + >; and large-size crystals are grown.

Description

Technical Field

[0001] The invention belongs to the technical field of crystals, and relates to a gallium oxide crystal capable of improving the luminescence of rare earth ions and a preparation method thereof, and specifically relates to an aluminum-rare earth ion co-doped gallium oxide crystal and two preparation methods thereof. Background Art

[0002] With the birth of the world's first laser, laser technology has gone through decades of development and has been combined with multiple disciplines to form multiple technical fields, such as optoelectronic technology, laser medicine, nonlinear optics, laser controlled nuclear fusion, etc. The emergence of these cross-cutting technologies and new disciplines has greatly promoted the upgrading of traditional industries and the development of emerging industries.

[0003] Laser is a new type of energy light source with good monochromaticity, strong directionality, and high coherence. As the core of laser generation, activated ions have become the focus of research. Activated ions can be divided into transition metal ions and rare earth ions. Compared with transition metal ions that can be used in the field of ultrafast tunable lasers, rare earth ions have rich energy levels and can be directly pumped by commercial LDs, which greatly improves power and efficiency. For example, Pr 3+ , Tb 3+ 、Sm 3+ , Yb in the near-infrared band 3+ and Nd 3+ (1~1.5μm), Tm in mid- and far-infrared bands 3+ 、Ho 3+ , Er 3+ and Dy 3+ (2~5μm), etc.

[0004] Thermal effect is an inevitable problem in the laser generation process, and it is particularly important to select a gain medium with high thermal conductivity. The thermal conductivity of the

[010] direction in β-phase gallium oxide (β-Ga2O3) exceeds 28W / m·K, which is much higher than that of traditional high thermal conductivity sesquioxide matrix materials (Lu2O3~12.8W / m·K, Sc2O3~16.5W / m·K, Y2O3~13.6W / m·K, etc.), and can effectively dissipate the heat generated by the laser. In addition, the β-Ga2O3 crystal structure has rich metal cation coordination structures, including four-coordinate [Ga2O3] suitable for transition metal ion doping. Ⅰ O4] tetrahedron, and there are also six-coordinated [Ga ⅡThe [O6] octahedron. The high thermal conductivity and diverse coordination structure make the β-Ga2O3 crystal an excellent candidate for laser crystal dielectric materials. Currently, the β-Ga2O3 crystal is well-known as a substrate material for gallium nitride (GaN) and a semiconductor crystal, yet it has been scarcely explored in the field of solid-state lasers. Compared with rare-earth ions, the coordination radius of cations in the β-Ga2O3 crystal structure is relatively small ( CN = 4; CN = 6), which makes it difficult for rare-earth ions with larger ionic radii to form highly concentrated effective doping in the β-Ga2O3 crystal. The size of the grown laser crystal is very small (~1 mm 3 ), and it is difficult to have practical application value. Summary of the Invention

[0005] The purpose of the present invention is to provide an aluminum-rare-earth ion co-doped gallium oxide crystal and two preparation methods thereof, which are used to solve the problem that due to the relatively large ionic radius of rare-earth ions, it is difficult for them to form highly concentrated effective doping in the β-Ga2O3 crystal, difficult to grow large-size and high-quality crystals, and seriously affect their luminescence performance. The present invention is applicable to growing large-size and high-quality rare-earth-doped β-Ga2O3 laser crystals.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] In the first aspect of the present invention, an aluminum-rare-earth ion co-doped gallium oxide crystal is provided. The chemical formula of the crystal is β-(Ga 1-x-y Al x RE y )2O3, where 0.001 < x < 0.3, 0.001 < y < 0.1, and RE is at least one of Er, Ho, Tm, or Yb.

[0008] As a preferred technical solution, in the crystal chemical formula β-(Ga 1-x-y Al x RE y )2O3, 0.01 ≤ x ≤ 0.1, and y = 0.005.

[0009] In the second aspect of the present invention, a preparation method of an aluminum-rare-earth ion co-doped gallium oxide crystal - the optical floating zone method - is provided. The method includes the following steps:

[0010] 1) Mix a gallium source, an aluminum source, and a rare-earth element source, and successively undergo pre-sintering, isostatic pressing treatment, and secondary sintering to obtain an aluminum-rare-earth ion co-doped gallium oxide polycrystalline ceramic rod;

[0011] 2) Load the aluminum-rare-earth ion co-doped gallium oxide polycrystalline ceramic rod into an optical floating zone single crystal furnace for crystal growth under a protective atmosphere, and obtain an aluminum-rare-earth ion co-doped gallium oxide crystal after high-temperature annealing.

[0012] Furthermore, in step 1), the gallium source is gallium oxide, the aluminum source is aluminum oxide, and the rare earth element source is selected from at least one of erbium oxide (Er2O3), holmium oxide (Ho2O3), thulium oxide (Tm2O3) or ytterbium oxide (Yb2O3).

[0013] Furthermore, in step 1), the raw material obtained by mixing the gallium source, the aluminum source and the rare earth element source is placed in an oven and dried at 220° C. for 10 hours to remove the bound water adsorbed in the raw material.

[0014] Furthermore, in step 1), in the pre-sintering, the sintering temperature is 1000-1300°C, and the sintering time is 10-20 hours. Preferably, the sintering temperature is 1200°C, and the sintering time is 20 hours. 3+ and rare earth ions enter the β-Ga2O3 lattice.

[0015] Furthermore, in step 1), the isostatic pressing treatment is carried out at a pressure of 100-200 MPa and a holding time of 20-60 min. Preferably, the pressure is 150 MPa and the holding time is 40 min.

[0016] Furthermore, in step 1), in the secondary sintering, the sintering temperature is 1500-1700° C., and the sintering time is 20-30 hours. Preferably, the sintering temperature is 1500° C., and the sintering time is 20 hours.

[0017] Furthermore, in step 1), the pre-sintering is followed by grinding, isostatic pressing, and then secondary sintering.

[0018] Furthermore, in step 2), the protective atmosphere is a mixed flowing gas of oxygen (O2) and argon (Ar); O2 / (O2+Ar)=1-99 vol%, and the gas flow rates of oxygen and argon are 0.1-1 L / min, respectively. Preferably, the gas flow rate is 0.2 L / min.

[0019] Furthermore, in step 2), the crystal growth rate is 5 to 10 mm / h.

[0020] Furthermore, in step 2), during the crystal growth, the material rod rotates at a speed of 10 to 20 r / min. After the crystal grows to the expected length, it is slowly cooled to room temperature within 5 hours to prevent the crystal from cracking due to excessively rapid cooling.

[0021] Further, in step 2), the high temperature annealing includes: heating the grown aluminum-rare earth ion co-doped gallium oxide single crystal to 1300-1500°C in an argon atmosphere (at a heating rate of 1°C / min) and keeping the temperature constant for 20-150 hours to eliminate thermal stress in the crystal, and then cooling to room temperature. Preferably, the heating is heated to 1500°C and kept constant for 20 hours.

[0022] The third aspect of the present invention provides a method for preparing aluminum-rare earth ion co-doped gallium oxide crystals, namely a guided mode method, the method comprising the following steps:

[0023] S1: mixing a gallium source, an aluminum source, and a rare earth element source, isostatically pressing to obtain a cake, and sintering to obtain an aluminum-rare earth ion co-doped gallium oxide polycrystalline material;

[0024] S2: heating the aluminum-rare earth ion co-doped gallium oxide polycrystalline material under a protective atmosphere to obtain a melt;

[0025] S3: lowering the gallium oxide seed crystal to contact with the melt, performing crystal pulling and necking, shoulder growth, and equal diameter growth, and after demolding and cooling, obtaining an aluminum-rare earth ion co-doped gallium oxide ingot;

[0026] S4: performing high temperature annealing on the aluminum-rare earth ion co-doped gallium oxide crystal ingot to obtain an aluminum-rare earth ion co-doped gallium oxide crystal.

[0027] Furthermore, in step S1, the gallium source is gallium oxide, the aluminum source is aluminum oxide, and the rare earth element source is selected from at least one of erbium oxide (Er2O3), holmium oxide (Ho2O3), thulium oxide (Tm2O3) or ytterbium oxide (Yb2O3).

[0028] Furthermore, in step S1, during the isostatic pressing treatment, the pressure is 100-200 MPa, and the holding time is 20-60 min. Preferably, the pressure is 200 MPa, and the holding time is 60 min.

[0029] Furthermore, in step S1, during the sintering, the sintering temperature is 1500-1700° C., and the sintering time is 20-30 hours. Preferably, the sintering temperature is 1700° C., and the sintering time is 30 hours.

[0030] Furthermore, in step S2, the protective atmosphere is a mixed atmosphere of argon and carbon dioxide (CO2), Ar / (Ar+CO2)=30-70 vol%, and the total gas pressure is 0.01-1.08 MPa.

[0031] Furthermore, in step S2, in the heated material, when it is observed that the feed seam is full of melt (completely melted state, temperature is about 1800° C.), the temperature is continued to be raised by 50° C. and kept constant for 2 hours to wait for seeding.

[0032] Furthermore, in step S3, the pulling speeds of the crystal pulling and necking, shoulder growth, and equal diameter growth are 2 to 20 mm / h respectively.

[0033] Furthermore, in step S3, when the seed crystal is slightly melted, the pulling and necking operation is performed at a pulling speed of 3 mm / h. When the seed crystal is thinned to less than 1 mm, the pulling speed is increased to 10 mm / h, and the steady shoulder growth is ready to begin. After the crystal shoulders to the edge of the mold, it enters the equal diameter growth stage. When the crystal is pulled and grown to the required length, the crystal is pulled out of the mold.

[0034] Furthermore, in step S3, during the cooling, the cooling is performed to room temperature at a cooling rate of 50°C / h.

[0035] Further, in step S4, the high temperature annealing includes: heating the grown aluminum-rare earth ion co-doped gallium oxide single crystal to 1300-1500°C in an argon atmosphere (at a heating rate of 1°C / min) and keeping the temperature constant for 20-150 hours to eliminate thermal stress in the crystal, and then cooling to room temperature. Preferably, the heating is heated to 1500°C and kept constant for 30 hours.

[0036] Compared with the prior art, the present invention has the following characteristics:

[0037] 1) The ions co-doped with the rare earth ions in the present invention are Al 3+ . Due to Al 3+ When entering the gallium oxide lattice, it tends to form [AlO6] octahedron, and Al 3+ radius( CN=6) is smaller than the Ga it replaces 3+ ( CN=6), which can effectively compensate for the lattice distortion effect caused by the larger radius of the doped rare earth ions, increase the effective doping concentration of rare earth ions, and thus enhance the rare earth fluorescence effect. 3+ This strategy solves the problem of the difficulty in effectively doping rare earth ions in gallium oxide crystals and growing large-sized crystals, and successfully grows large-sized, high-quality rare earth-doped β-Ga2O3 laser crystals. In addition, Al 3+ with Ga 3+ In the same main group, with similar radius and electronic structure, Al 3+ Doping into the β-Ga2O3 lattice has little effect on the crystal properties.

[0038] 2) The present invention selects β-Ga2O3 crystal as the laser crystal matrix material, and dopes rare earth ions into the β-Ga2O3 lattice as the luminescent center. Among them, the thermal conductivity of the

[010] direction in the β-Ga2O3 crystal exceeds 28W / m·K, which is much higher than the traditional high thermal conductivity sesquioxide matrix materials (Lu2O3~12.8W / m·K, Sc2O3~16.5W / m·K, Y2O3~13.6W / m·K, etc.), and can effectively dissipate the heat generated by the laser, which is of strategic significance for the development of rare earth doped solid lasers. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The β-(Ga 0.985 Al 0.01 Er 0.005 )X-ray diffraction pattern of 2O3 crystals.

[0040] Figure 2 The β-(Ga 0.985 Al 0.01 Er 0.005 )Absorption spectrum of 2O3 crystal.

[0041] Figure 3 The β-(Ga 0.985 Al 0.01 Er 0.005 )2O3 crystals and β-(Ga 0.995 Er 0.005 )Emission spectrum of 2O3 crystals.

[0042] Figure 4 The β-(Ga 0.945 Al 0.05 Ho 0.005 )2O3 crystals and β-(Ga 0.995 Ho 0.005 )Emission spectrum of 2O3 crystals.

[0043] Figure 5 The β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3 crystals and β-(Ga 0.995 Tm 0.005 )Emission spectrum of 2O3 crystals.

[0044] Figure 6 The β-(Ga 0.895 Al 0.1 Yb0.005 )2O3 crystals and β-(Ga 0.995 Yb 0.005 )Emission spectrum of 2O3 crystals. DETAILED DESCRIPTION

[0045] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0046] Embodiment 1:

[0047] Aluminum-rare earth ion co-doped gallium oxide crystal β-(Ga 1-x-y Al x RE y )2O3, x = 0.01, y = 0.005, the rare earth ion doped is Er 3+ The specific chemical formula is β-(Ga 0.985 Al 0.01 Er 0.005 )2O3. The growth method is an optical floating zone method, and the preparation method includes the following steps:

[0048] (1) Selection and processing of raw materials

[0049] Weigh 5N-grade Ga2O3, Al2O3 and Er2O3 raw materials according to the stoichiometric ratio, and put the raw materials into a mixer to mix them thoroughly for 20 hours. Put the fully mixed raw materials into an oven at 220℃ and dry them for 10 hours to remove the bound water adsorbed in the raw materials. Put the dried raw materials into a corundum crucible and pre-sinter them at 1200℃ in an air environment in a muffle furnace for 20 hours to make Al 3+ and Er 3 + The pre-sintered raw material was fully ground in an agate mortar for 50 minutes, placed in a cylindrical mold, and cold isostatically pressed at 150MPa for 40 minutes to form a cylindrical rod. After demolding, it was placed in a muffle furnace again in an air environment at 1500℃ for a second sintering for 20 hours to obtain a hard β-(Ga 0.985 Al 0.01 Er 0.005 )2O3 polycrystalline ceramic rod, i.e., aluminum-rare earth ion co-doped gallium oxide polycrystalline ceramic rod;

[0050] (2) Crystal growth and annealing

[0051] a. The chemical formula is β-(Ga 0.985 Al 0.01 Er 0.005)2O3 gallium oxide polycrystalline ceramic rod is loaded into the optical floating zone method single crystal furnace, the loading rod and the lower gallium oxide seed crystal rotate coaxially, and the deviation from the center does not exceed 1mm. A mixed flow gas of O2 and Ar is introduced, wherein the flow rate of O2 is 0.2L / min, and the flow rate of Ar is 0.2L / min;

[0052] b. When the temperature rises to the point where the material rod and seed crystal are slightly melted, seeding begins. The upper material rod rotates counterclockwise at a speed of 12 r / min and a descending speed of 5 mm / h; the lower material rod rotates clockwise at a speed of 12 r / min and a descending speed of 5 mm / h. After the crystal grows to the expected length, it is slowly cooled to room temperature within 5 hours to prevent the crystal from cracking due to excessive cooling;

[0053] c. After the growth is completed, the growth of β-(Ga 0.985 Al 0.01 Er 0.005 )2O3 crystals are subjected to high temperature annealing. 0.985 Al 0.01 Er 0.005 )2O3 crystal was placed in a muffle furnace, and argon was introduced and the temperature was slowly raised to 1500℃ at a rate of 1℃ / min and kept constant for 20h to eliminate the thermal stress in the crystal, and then slowly cooled to room temperature to obtain β-(Ga 0.985 Al 0.01 Er 0.005 )2O3 single crystal, that is, aluminum-erbium ion co-doped gallium oxide single crystal.

[0054] like Figure 1 The β-(Ga 0.985 Al 0.01 Er 0.005 )2O3 crystal X-ray diffraction pattern. Al 3+ and Er 3+ The diffraction peak of the co-doped β-Ga2O3 crystal corresponds to the β-Ga2O3 crystal phase, and no other impurity phase is generated.

[0055] like Figure 2 The β-(Ga 0.985 Al 0.01 Er 0.005 )2O3 crystal absorption spectrum. Al 3+ and Er 3+ The absorption spectrum of co-doped β-Ga2O3 crystals is Er 3+ Absorption peaks and corresponding energy level transitions.

[0056] Comparative Example 1:

[0057] Aluminum-rare earth ion co-doped gallium oxide crystal β-(Ga 1-x-yAl x RE y )2O3, the preparation method thereof is different from that of Example 1 only in that:

[0058] Er doped alone 3+ β-Ga2O3 crystal, undoped with Al 3+ The specific chemical formula is β-(Ga 0.995 Er 0.005 )2O3.

[0059] like Figure 3 The β-(Ga 0.985 Al 0.01 Er 0.005 )2O3 crystal and the single Er doped crystal grown in Comparative Example 1 3+ β-Ga2O3 crystal, namely β-(Ga 0.995 Er 0.005 )2O3 crystal emission spectrum. Under the excitation of a 980nm semiconductor laser, the β-(Ga 0.985 Al 0.01 Er 0.005 The luminescence band of )2O3 crystal covers 1450nm~1650nm, and the main emission peak is located near 1550nm.

[0060] Compared with β-(Ga 0.995 Er 0.005 )2O3 crystal (Comparative Example 1 grown with Er doped 3+ β-Ga2O3 crystal), β-(Ga 0.985 Al 0.01 Er 0.005 )2O3 (Al-Er co-doped β-Ga2O3 crystal grown in Example 1) has an emission intensity that is increased by 3.8 times. This is because Al 3+ doping, Al into the β-Ga2O3 lattice 3+ Occupy Ga Ⅱ The smaller cation coordination radius and similar electronic structure in the β-Ga2O3 crystal structure make Al 3+ The occupied octahedral lattice shrinks and distorts, further affecting the surrounding [GaO6] octahedral structure, making the Er with a larger radius 3+ Easier to occupy Ga Ⅱ The point enters the β-Ga2O3 lattice, so Al 3+ Improved Er 3+ The effective doping concentration can significantly increase the fluorescence intensity.

[0061] Embodiment 2:

[0062] Aluminum-rare earth ion co-doped gallium oxide crystal β-(Ga 1-x-y Al x RE y )2O3, x = 0.05, y = 0.005, the rare earth ion doped is Ho 3+ The specific chemical formula is β-(Ga 0.945 Al 0.05 Ho 0.005 )2O3. The growth method is an optical floating zone method, and the preparation method includes the following steps:

[0063] (1) Selection and processing of raw materials

[0064] According to the stoichiometric ratio, weigh the raw materials of Ga2O3, Al2O3 and Ho2O3 with a purity of 5N grade, put the raw materials into the mixer and mix them thoroughly for 20 hours. The fully mixed raw materials are placed in an oven and dried at 220℃ for 10 hours to remove the adsorbed bound water in the raw materials. The dried raw materials are placed in a corundum crucible and pre-sintered at 1200℃ in an air environment in a muffle furnace for 20 hours. The pre-sintered raw materials are fully ground in an agate mortar for 50 minutes, placed in a cylindrical mold, and demolded after cold isostatic pressing at 150MPa for 40 minutes. Then, they are placed in a muffle furnace again and sintered for a second time at 1500℃ in an air environment for 20 hours to obtain hard β-(Ga 0.945 Al 0.05 Ho 0.005 )2O3 polycrystalline ceramic rod;

[0065] (2) Crystal growth and annealing

[0066] a. The chemical formula is β-(Ga 0.945 Al 0.05 Ho 0.005 )2O3 gallium oxide polycrystalline ceramic rod is loaded into the optical floating zone method single crystal furnace, the loading rod and the lower gallium oxide seed crystal rotate coaxially, and the deviation from the center does not exceed 1mm. A mixed flow gas of O2 and Ar is introduced, wherein the flow rate of O2 is 0.2L / min, and the flow rate of Ar is 0.2L / min;

[0067] b. When the temperature rises to the point where the material rod and seed crystal are slightly melted, seeding begins. The upper material rod rotates counterclockwise at a speed of 12 r / min and a descending speed of 5 mm / h; the lower material rod rotates clockwise at a speed of 12 r / min and a descending speed of 5 mm / h. After the crystal grows to the expected length, it is slowly cooled to room temperature within 5 hours to prevent the crystal from cracking due to excessive cooling;

[0068] c. After the growth is completed, the growth of β-(Ga 0.945 Al 0.05 Ho 0.005)2O3 crystals are annealed. 0.945 Al 0.05 Ho 0.005 )2O3 crystal was placed in a muffle furnace, argon was introduced, and the temperature was raised to 1500℃ at a rate of 1℃ / min and kept constant for 20h to eliminate the thermal stress in the crystal, and then slowly cooled to room temperature to obtain β-(Ga 0.945 Al 0.05 Ho 0.005 )2O3 single crystal, that is, aluminum-holmium ion co-doped gallium oxide single crystal.

[0069] Comparative Example 2:

[0070] Aluminum-rare earth ion co-doped gallium oxide crystal β-(Ga 1-x-y Al x RE y )2O3, the preparation method thereof is different from that of Example 2 only in that:

[0071] Ho doped alone 3+ β-Ga2O3 crystal, undoped with Al 3+ The specific chemical formula is β-(Ga 0.995 Ho 0.005 )2O3.

[0072] like Figure 4 The β-(Ga 0.945 Al 0.05 Ho 0.005 )2O3 crystal and the Ho-doped crystal grown in Comparative Example 2 3+ β-Ga2O3 crystal, namely β-(Ga 0.995 Ho 0.005 )2O3 crystal emission spectrum. Under the excitation of a 640nm semiconductor laser, the β-(Ga 0.945 Al 0.05 Ho 0.005 )2O3 crystal luminescence band covers 1100nm~1300nm, and the main emission peak is located near 1210nm.

[0073] Compared with β-(Ga 0.995 Ho 0.005 )2O3 crystal (comparative example 2 grown by single doping Ho 3+ β-Ga2O3 crystal), β-(Ga 0.945 Al 0.05 Ho 0.005 )2O3 (Al-Ho co-doped β-Ga2O3 crystal grown in Example 2) has an emission intensity that is increased by 8 times. 3+ After entering the lattice, Ho is greatly improved 3+The fluorescence emission intensity is significantly enhanced.

[0074] Embodiment 3:

[0075] Aluminum-rare earth ion co-doped gallium oxide crystal β-(Ga 1-x-y Al x RE y )2O3, x = 0.01, y = 0.005, the rare earth ion doped is Tm 3+ The specific chemical formula is β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3. The growth method is a guided mode method, and the preparation method includes the following steps:

[0076] (A) Ga2O3, Al2O3 and Tm2O3 with a purity of 5N were weighed according to the stoichiometric ratio, and the raw material powder was placed in a mixer and fully mixed for 20 hours, and then placed in a mold, and pressed in a cold isostatic press at 200MPa for 60 minutes. The pressed raw material was demoulded, placed in a muffle furnace and sintered at 1700℃ in air environment for 30 hours, so that the pressed raw material became hard β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3 polycrystalline ceramic block;

[0077] (B) Put β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3 polycrystalline material is placed in an iridium crucible, and the absolute pressure in the furnace is pumped down to 1×10 -4 Pa, introduce a mixed gas of 30% Ar and 70% CO2 by volume to a relative pressure of 0.1MPa to protect the crucible and inhibit the decomposition of gallium oxide at high temperatures. Raise the temperature and wait until the feed seam is filled with melt (completely melted, temperature is about 1800℃), then continue to raise the temperature by 50℃ and keep it constant for 2h before seeding;

[0078] (C) Lower the gallium oxide seed crystal at a temperature 10-20°C higher than the material temperature (the temperature in the fully molten state, i.e., 1800°C) to fully contact the melt in the crucible mold in step (B), and pull and neck the seed crystal at a pulling speed of 3mm / h when the seed crystal is slightly melted. When the seed crystal is thinned to less than 1mm, increase the pulling speed to 10mm / h, and prepare to start steady shoulder growth. After the crystal shoulders to the edge of the mold, it enters the equal diameter growth stage. When the crystal is pulled and grown to the required length, pull the crystal out of the mold and slowly cool it to room temperature at a cooling rate of 50°C / h to obtain β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3 ingot;

[0079] (D) After the growth is completed, β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3 ingot was placed in a muffle furnace and slowly heated to 1500℃ at a rate of 1℃ / min in an argon atmosphere and kept at this temperature for 30h to eliminate the thermal stress in the crystal. Then, the temperature was slowly cooled to room temperature to obtain the target β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3 crystals.

[0080] Comparative Example 3:

[0081] Aluminum-rare earth ion co-doped gallium oxide crystal β-(Ga 1-x-y Al x RE y )2O3, the preparation method thereof is different from that of Example 3 only in that:

[0082] Tm doping alone 3+ β-Ga2O3 crystal, undoped with Al 3+ The specific chemical formula is β-(Ga 0.995 Tm 0.005 )2O3.

[0083] like Figure 5 The β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3 crystal and the single doped Tm grown in Comparative Example 3 3+ β-Ga2O3 crystal, namely β-(Ga 0.995 Tm 0.005 )2O3 crystal emission spectrum. Under the excitation of 793nm semiconductor laser, the β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3 crystal luminescence band covers 1420nm ~ 1700nm, and the main emission peak is located near 1600nm.

[0084] Compared with β-(Ga 0.995 Tm 0.005 )2O3 crystal (comparative example 3 grown single doped Tm 3+ β-Ga2O3 crystal), β-(Ga 0.985 Al 0.01 Tm 0.005 )2O3 (Al-Tm co-doped β-Ga2O3 crystal grown in Example 3) has an emission intensity that is increased by 2.7 times. 3+ After entering the lattice, Tm is greatly increased3+ The fluorescence emission intensity is significantly enhanced.

[0085] Embodiment 4:

[0086] Aluminum-rare earth ion co-doped gallium oxide crystal β-(Ga 1-x-y Al x RE y )2O3, x = 0.1, y = 0.005, the rare earth ion doped is Yb 3+ The specific chemical formula is β-(Ga 0.895 Al 0.1 Yb 0.005 )2O3. The growth method is a guided mode method, and the preparation method includes the following steps:

[0087] (A) Ga2O3, Al2O3 and Yb2O3 with a purity of 5N were weighed according to the stoichiometric ratio, and the raw material powder was put into a mixer and mixed thoroughly for 20 hours, and then put into a mold, and pressed in a cold isostatic press at 200MPa for 40 minutes. The pressed raw material was demoulded, and placed in a muffle furnace for constant temperature sintering at 1500℃ in air environment for 30 hours, so that the pressed raw material became hard β-(Ga 0.895 Al 0.1 Yb 0.005 )2O3 polycrystalline ceramic block;

[0088] (B) Put β-(Ga 0.895 Al 0.1 Yb 0.005 )2O3 polycrystalline material is placed in an iridium crucible, and the absolute pressure in the furnace is pumped down to 1×10 -4 Pa, introduce a mixed gas of 40% Ar and 60% CO2 to a relative pressure of 0.05MPa. Heat the material until the feed seam is filled with melt (completely melted, temperature is about 1800℃), then continue to heat by 50℃, keep the temperature constant for 2h and wait for seeding;

[0089] (C) Lower the gallium oxide seed crystal at a temperature 10-20°C higher than the material temperature (the temperature in the fully molten state, i.e., 1800°C) to fully contact the melt in the crucible mold in step (B), and pull and neck the seed crystal at a pulling speed of 3mm / h when the seed crystal is slightly melted. When the seed crystal is thinned to less than 1mm, increase the pulling speed to 6mm / h, and prepare to start steady shoulder growth. After the crystal shoulders to the edge of the mold, it enters the equal diameter growth stage. When the crystal is pulled and grown to the required length, pull the crystal out of the mold and slowly cool it to room temperature at a cooling rate of 50°C / h to obtain β-(Ga 0.895 Al 0.1 Yb 0.005 )2O3 ingot;

[0090] (D) After the growth is completed, β-(Ga 0.895 Al 0.1 Yb 0.005 )2O3 ingot was placed in a muffle furnace and slowly heated to 1500℃ at a rate of 1℃ / min in an argon atmosphere and kept at this temperature for 30h to eliminate the thermal stress in the crystal. Then, the temperature was slowly cooled to room temperature to obtain the target β-(Ga 0.895 Al 0.1 Yb 0.005 )2O3 crystals.

[0091] Comparative Example 4:

[0092] Aluminum-rare earth ion co-doped gallium oxide crystal β-(Ga 1-x-y Al x RE y )2O3, the preparation method thereof is different from that of Example 4 only in that:

[0093] Yb doped alone 3+ β-Ga2O3 crystal, undoped with Al 3+ The specific chemical formula is β-(Ga 0.995 Yb 0.005 )2O3.

[0094] like Figure 6 The β-(Ga 0.895 Al 0.1 Yb 0.005 )2O3 crystal and the single doped Yb grown in Comparative Example 4 3+ β-Ga2O3 crystal, namely β-(Ga 0.995 Yb 0.005 )2O3 crystal emission spectrum. Under the excitation of a 905nm semiconductor laser, the β-(Ga 0.895 Al 0.1 Yb 0.005 The luminescence band of )2O3 crystal covers 960nm~1170nm, and the main emission peak is located near 1050nm.

[0095] Compared with β-(Ga 0.995 Yb 0.005 )2O3 crystal (comparative example 4 grown single doped Yb 3+ β-Ga2O3 crystal), β-(Ga 0.895 Al 0.1 Yb 0.005 )2O3 (Al-Yb co-doped β-Ga2O3 crystal grown in Example 4) has obvious Yb 3+ emission peak, while single-doped Yb 3+No Yb was detected in β-Ga2O3 crystals 3+ Fluorescence emission peak. Al 3+ After entering the lattice, the Yb 3+ The effective doping concentration of Yb 3+ Fluorescence emission peak.

[0096] The ions co-doped with the rare earth ions in the present invention are Al 3+ . Due to Al 3+ When entering the gallium oxide lattice, it tends to form [AlO6] octahedron, and Al 3+ radius( CN=6) is smaller than the Ga it replaces 3+ ( CN=6), which can effectively compensate for the lattice distortion effect caused by the larger radius of the doped rare earth ions, increase the effective doping concentration of rare earth ions, and thus enhance the rare earth fluorescence effect. 3+ This strategy solves the problem of the difficulty in effectively doping rare earth ions in gallium oxide crystals and growing large-sized crystals, and successfully grows large-sized, high-quality rare earth-doped β-Ga2O3 laser crystals. In addition, Al 3+ with Ga 3+ In the same main group, with similar radius and electronic structure, Al 3+ Doping into the β-Ga2O3 lattice has little effect on the crystal properties.

[0097] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. An aluminum-rare earth ion co-doped gallium oxide crystal, characterized in that: The chemical formula of the crystal is β-(Ga 1-x- y Al x RE y )2O3, Among them, 0.001 < x < 0.3, 0.001 < y < 0.1, and RE is at least one of Er, Ho, Tm, or Yb.

2. A method for preparing aluminum-rare earth ion co-doped gallium oxide crystals as claimed in claim 1, characterized in that: The method includes the following steps: 1) Mix a gallium source, an aluminum source, and a rare earth element source, and sequentially perform pre-sintering, isostatic pressing, and secondary sintering to obtain a polycrystalline gallium oxide ceramic rod co-doped with aluminum and rare earth ions. 2) Load the polycrystalline gallium oxide ceramic rod co-doped with aluminum and rare earth ions described in step 1) into an optical floating zone single crystal furnace for crystal growth under a protective atmosphere, and obtain a gallium oxide crystal co-doped with aluminum and rare earth ions after high-temperature annealing.

3. The method for preparing aluminum-rare earth ion co-doped gallium oxide crystal according to claim 2, characterized in that: In step 1), the gallium source is gallium oxide, the aluminum source is aluminum oxide, and the rare earth element source is selected from at least one of erbium oxide, holmium oxide, thulium oxide, or ytterbium oxide.

4. The method for preparing aluminum-rare earth ion co-doped gallium oxide crystal according to claim 2, characterized in that: In step 1), during the pre-sintering, the sintering temperature is 1000 - 1300 °C, and the sintering time is 10 - 20 h; during the isostatic pressing, the pressure is 100 - 200 MPa, and the pressure holding time is 20 - 60 min; during the secondary sintering, the sintering temperature is 1500 - 1700 °C, and the sintering time is 20 - 30 h.

5. The method for preparing aluminum-rare earth ion co-doped gallium oxide crystal according to claim 2, characterized in that: In step 2), the protective atmosphere is a mixed flowing gas of oxygen and argon; O2 / (O2 + Ar) = 1 - 99 vol%, and the gas flow rates of oxygen and argon are 0.1 - 1 L / min respectively; the crystal growth rate is 5 - 10 mm / h.

6. The method for preparing aluminum-rare earth ion co-doped gallium oxide crystal according to claim 2, characterized in that: In step 2), the high-temperature annealing includes: heating the grown gallium oxide single crystal co-doped with aluminum and rare earth ions to 1300 - 1500 °C in an argon atmosphere and keeping it at a constant temperature for 20 - 150 h, and then cooling it to room temperature.

7. A method for preparing aluminum-rare earth ion co-doped gallium oxide crystals as claimed in claim 1, characterized in that: The method includes the following steps: S1: Mix a gallium source, an aluminum source, and a rare earth element source, perform isostatic pressing to obtain a cake, and sinter to obtain a polycrystalline gallium oxide material co-doped with aluminum and rare earth ions. S2: Heat and melt the polycrystalline gallium oxide material co-doped with aluminum and rare earth ions under a protective atmosphere to obtain a melt. S3: Lower a gallium oxide seed crystal to contact the melt, perform crystal pulling necking, shoulder growth, and equal-diameter growth, and obtain a gallium oxide ingot co-doped with aluminum and rare earth ions after demolding and cooling. S4: Perform high-temperature annealing on the gallium oxide ingot co-doped with aluminum and rare earth ions to obtain a gallium oxide crystal co-doped with aluminum and rare earth ions.

8. The method for preparing aluminum-rare earth ion co-doped gallium oxide crystal according to claim 7, characterized in that: In step S1, the gallium source is gallium oxide, the aluminum source is aluminum oxide, and the rare earth element source is selected from at least one of erbium oxide, holmium oxide, thulium oxide, or ytterbium oxide.

9. The method for preparing aluminum-rare earth ion co-doped gallium oxide crystal according to claim 7, characterized in that: In step S1, during the isostatic pressing, the pressure is 100 - 200 MPa, and the pressure holding time is 20 - 60 min; during the sintering, the sintering temperature is 1500 - 1700 °C, and the sintering time is 20 - 30 h.

10. The method for preparing aluminum-rare earth ion co-doped gallium oxide crystal according to claim 7, characterized in that: In step S2, the protective atmosphere is a mixed atmosphere of argon and carbon dioxide, Ar / (Ar+CO2)=30~70vol%, and the total gas pressure is 0.01~1.08MPa; in step S3, the pulling speed of the crystal pulling necking, shoulder growth, and equal diameter growth is 2~20mm / h; in step S4, the high temperature annealing includes: heating the grown aluminum-rare earth ion co-doped gallium oxide single crystal to 1300~1500℃ and keeping the temperature constant for 20~150h in an argon atmosphere, and then cooling to room temperature.

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