Cobalt-doped magnesium borate rare earth laser crystal and preparation method and application thereof

Abstract

The invention discloses a cobalt-doped magnesium borate rare earth laser crystal and a preparation method and application thereof. The method comprises the following steps: mixing a magnesium-containing source, a rare earth source and a boron-containing oxygen compound according to a raw material ratio and a cobalt ion doping amount, and carrying out solid-phase heat treatment to obtain a polycrystal material; the rare earth source is at least one of a lanthanum source, a gadolinium source and a yttrium source; the polycrystalline material is subjected to melt solution heat treatment growth to obtain the cobalt-doped magnesium borate rare earth salt crystal. The molecular formula of the crystal is Co < 2 + >: LnMgB5O10, ln is at least one of La, Gd and Y; and Co < 2 + > replaces the lattice position of Mg ions. The novel laser crystal has good spectral performance, has a wide band between 600 nm and 900 nm, the peak value is about 712 nm, the half-peak width is 123 nm, laser output can be obtained by directly using a flash lamp or a commercial GaN semiconductor laser pump, and the crystal can be used as a good laser material for achieving tunable laser output.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal materials, and in particular relates to a cobalt-doped magnesium borate rare earth laser crystal and a preparation method and application thereof. Background Art

[0002] Tunable laser refers to such an effect: pump excitation activated ions doped into the solid laser matrix generate laser, and tunable laser output is obtained by using prism tuning method, FP standard tuning method, grating tuning method, filter tuning method and distributed feedback system tuning method.

[0003] In 1963, LF Johnson et al. used flash lamp pumping to dope Ni 2+ The first solid-state tunable laser operation was realized in MgF2 crystal (LF Johnson REDietz & H.J. Guggenheim, J.Phys.Rev.Lett.,11(1963)318). Subsequently, many tunable laser crystals appeared, such as Ti 3+ :Al2O3、Cr 3+ :Mg2SiO4、Cr 3+ :LiSrAlF6、Cr 3+ :BeAl2O4, etc., but due to various reasons, many tunable laser crystals are limited to laboratory tools and cannot be promoted to industrial applications.

[0004] The most studied and applied tunable laser crystals are Cr 3+ :BeAl2O4(Alexandrite), Ti 3+ :Al2O3 (doped with titanium sapphire) and Cr 3+ :LiCaAlF6、Cr 3+ :LiSrAlF6, but they also have some unavoidable defects, which limits their application scope.

[0005] Therefore, finding tunable laser crystal materials with a wider tunable range and that can be directly pumped by flash lamps and LDs has become one of the hot topics in the current laser crystal research field. Summary of the invention

[0006] In view of this, the present invention provides a cobalt-doped magnesium borate rare earth laser crystal and a preparation method and application thereof, the main purpose of which is to solve the technical problem of limited tunable range of laser crystal materials.

[0007] In one aspect, the present invention provides a cobalt-doped magnesium borate rare earth laser crystal, the molecular formula of which is:

[0008] Co 2+ :LnMgB5O10 Formula I;

[0009] In Formula I, Ln is at least one of the rare earth metal ions La, Gd and Y;

[0010] The Co 2+ is the doping ion in the crystal, the Co 2+ Replace the lattice position of Mg ions.

[0011] Co in Formula I of the present invention 2+ is a divalent cobalt ion, La is lanthanum metal, Gd is gadolinium metal, Y is yttrium metal, Mg is magnesium metal, and B is boron.

[0012] Optionally, the Co 2+ The doping concentration in the crystal is 0.05 at % to 5 at %.

[0013] Optionally, the Co 2+ The doping concentration in the crystal is selected from any one of 0.05, 0.10, 0.5, 1.0, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0, 3.2, 3.5, 3.8, 4.0, 4.2, 4.5, 4.8, 5.0 or a range between any two of them, and the unit is at%.

[0014] Optionally, the laser crystal is of monoclinic system and belongs to P21 / C space group.

[0015] Optionally, the unit cell parameters of the laser crystal are: α=γ=90°, β=92.01°~93.51°,

[0016] Optionally, the color of the crystal is purple; and the refractive index of the crystal is 1.3-1.5.

[0017] In a second aspect, the present invention provides a method for preparing the above-mentioned cobalt-doped magnesium borate rare earth salt crystals, the preparation method comprising the following steps:

[0018] S1: According to the raw material ratio and the doping amount of cobalt ions, a magnesium source, a cobalt source, a rare earth source, and a boron-oxygen compound are mixed to obtain a mixture; the mixture is subjected to solid phase heat treatment to obtain a polycrystalline material;

[0019] Wherein, the rare earth source is at least one of a lanthanum source, a gadolinium source and a yttrium source;

[0020] S2: The polycrystalline material is subjected to heat treatment in a molten solution to grow the cobalt-doped magnesium borate rare earth laser crystal.

[0021] The chemical reaction formula of each raw material in the present invention is Formula II;

[0022] 0.5Ln2CO3 +MgO+ 5H3BO3= LnMgB5O 10 + 0.5CO2+7.5H2O Formula II;

[0023] The raw material ratio in the present invention is the reaction ratio (molar ratio) between the materials.

[0024] Optionally, rare earth source: magnesium source: boron-oxygen compound = (0.3-0.7): (0.8-1.2): (3-7).

[0025] Optionally, rare earth source: magnesium source: boron-oxygen compound = (0.4-0.6): (0.9-1.1): (4-6).

[0026] Optionally, rare earth source: magnesium source: boron-oxygen compound = 0.5:1:5.

[0027] Optionally, the doping amount of the cobalt source is 0.05 at% to 5 at%, that is, the ratio of the number of cobalt atoms to the total number of atoms of all raw materials of the crystal is 0.05% to 5t%.

[0028] Optionally, the doping amount of the cobalt source is selected from any one of 0.05, 0.10, 0.5, 1.0, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0, 3.2, 3.5, 3.8, 4.0, 4.2, 4.5, 4.8, 5.0 or a range between any two of them, and the unit is at%.

[0029] Optionally, the cobalt source is selected from cobalt oxides and / or cobalt chlorides.

[0030] Optionally, the rare earth source is selected from carbonates of rare earth elements or oxides of rare earth elements, such as La2O3, Gd2O3, Y2O3, La2CO3, Gd2CO3, and Y2CO3.

[0031] Optionally, the magnesium source is selected from magnesium oxides, such as MgO.

[0032] The boron-oxygen compound in the crystal raw material of the present invention refers to a compound containing at least boron and oxygen.

[0033] Optionally, the boron-oxygen-containing compound is selected from boric acid or boron oxide, such as H3BO3.

[0034] The raw materials in the present invention can be selected from other types of sources according to actual needs.

[0035] In step S1 of the present invention, a high-temperature solid phase method is first used to prepare a variety of raw materials into polycrystalline materials; in step S2, a high-temperature melt solution growth method is used to grow the polycrystalline materials into target single crystal materials.

[0036] The technical principles of the high-temperature solid-phase method and the high-temperature melt solution growth method adopted in the present invention are existing technologies, but the temperature is difficult to control in the high-temperature solid-phase method, and it needs to match the performance of the raw materials. Especially in the high-temperature melt solution growth method, the flux is very important and it is difficult to select a material that matches the crystal material.

[0037] Optionally, in step S2, the flux used in the heat treatment of the molten solution is selected from alkali metal fluorides, alkaline earth metal fluorides, alkali metal oxides, alkaline earth metal oxides, alkali metal tungstates, alkaline earth metal tungstates, alkali metal molybdates, alkaline earth metal molybdates, alkali metal borates, alkaline earth metal borates, lead-containing oxides or lead-containing fluorides.

[0038] Optionally, in step S2, the flux used for the heat treatment of the molten solution is selected from Li-BFO mixed flux, PbF2 and / or PbO flux, Li2WO4 and / or K2WO4 flux, K3Mo3O 10 Any one of flux, LiF, NaF, KF, MgF2, CaF2; wherein the Li-BFO mixed flux is a flux system containing at least one element of Li, B, F and O.

[0039] Optionally, in step S1, the temperature of the solid phase heat treatment is 600-850°C.

[0040] Optionally, in step S1, the temperature of the solid phase heat treatment is selected from any value among 600, 650, 700, 750, 800, 850 or a range between any two of them, and the unit is °C.

[0041] Optionally, in step S2, the temperature of heat treatment of the molten solution is 900-1100°C.

[0042] Optionally, in step S2, the temperature of the heat treatment of the molten solution is selected from any value among 900, 950, 1000, 1050, 1100 or any range between two thereof, and the unit is °C.

[0043] Optionally, in step S2, the cooling rate of the heat treatment of the molten solution is 0.5-3°C / day; the crystal rotation speed is 3-30rpm, and the crystal pulling speed is 0-1mm / h.

[0044] Optionally, after the crystal growth is completed, the crystal is lifted out of the liquid surface and cooled to room temperature at a rate of 3 to 30° C. / h to obtain a single crystal of cobalt-doped magnesium borate rare earth salt.

[0045] Optionally, in step S2, the cooling rate of the heat treatment of the molten solution is selected from any value among 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0 or any range between two values, and the unit is ℃ / day.

[0046] Optionally, in step S2, the crystal rotation speed is selected from any value among 3, 5, 10, 15, 20, 25, 30 or any range between two values, in rpm.

[0047] In a third aspect, the present invention provides applications of the cobalt-doped magnesium borate rare earth salt crystals in the fields of physical medicine, spectroscopy, military and chemistry.

[0048] Optionally, the cobalt-doped magnesium borate rare earth salt crystal is used as a gain medium of a laser.

[0049] In a fourth aspect, the present invention provides a laser, wherein the gain medium material of the laser comprises a laser crystal; characterized in that the crystal is the above-mentioned cobalt-doped magnesium borate rare earth salt crystal.

[0050] Optionally, the cobalt-doped magnesium borate rare earth salt crystal is pumped by a flash lamp or a GaN semiconductor laser to output laser.

[0051] Optionally, the laser pump wavelength of the laser crystal is 440-460 nm.

[0052] Optionally, the output laser wavelength of the laser crystal is 600-900 nm.

[0053] Optionally, the peak value of the crystal is between 710 and 714 nm, and the half-peak width is 123 nm.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] 1) The cobalt ion-doped magnesium borate rare earth laser crystal Co provided by the present invention 2+ :LnMgB5O 10 (Ln is at least one of La, Gd and Y), Co 2+ is the doping ion in the crystal, Co 2+ Replace the lattice position of Mg ions; the crystal is purple, hard, has good thermal conductivity, mechanical properties, excellent optical properties and a high laser damage threshold.

[0056] 2) The cobalt ion-doped magnesium borate rare earth laser crystal Co provided by the present invention 2+ :LnMgB5O 10The crystal is pumped by a commercial GaN semiconductor laser. It has a wide spectral band between 600nm and 900nm, with a peak near 712nm and a half-peak width of 123nm. The crystal can be used as a better laser material to achieve tunable laser output. It can be widely used in biological military, laser radar, scientific research and other fields.

[0057] 3) The cobalt ion-doped magnesium borate rare earth laser crystal Co provided by the present invention 2+ :LnMgB5O 10 , is to use high temperature solution technology to grow crystals. Based on years of research experience, we have found the ideal flux suitable for the growth of this crystal: Li-BFO mixed flux, PbF2 and / or PbO flux, Li2WO4h and / or K2WO4 flux, K3Mo3O 10 Any of the fluxes grew high quality crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Co prepared in Example 1 of the present invention 2+ :LaMgB5O 10 Top view of the laser crystal;

[0059] Figure 2 Co prepared in Example 1 of the present invention 2+ :LaMgB5O 10 X-ray powder diffraction pattern of laser crystal;

[0060] Figure 3 Co prepared in Example 1 of the present invention 2+ :LaMgB5O 10 Fluorescence spectrum of the crystal. DETAILED DESCRIPTION

[0061] The present application is further described below in conjunction with specific embodiments. The following are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application discloses the following preferred embodiments, they are not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the above disclosed technical content to make some changes or modifications are equivalent to equivalent implementation cases and are within the scope of the technical solution.

[0062] Unless otherwise specified, the raw materials in the examples of the present application were purchased from commercial sources and used directly without any special treatment.

[0063] The sources of raw materials used in the embodiments of the present invention are shown in Table 1;

[0064]

[0065]

[0066] The crystal preparation method of the present invention comprises: firstly preparing a polycrystalline material by a high-temperature solid phase method, and then growing the polycrystalline material by a high-temperature melt solution growth method to obtain a target single crystal material.

[0067] The reaction formula of each raw material in the high temperature solid phase method of the present invention is shown in Formula II;

[0068] 0.5Ln2CO3+MgO+5H3BO3=LnMgB5O 10 +0.5CO2+7.5H2O formula II.

[0069] In the embodiment of the present invention, the ratio between the raw materials is the reaction ratio (molar ratio) between the materials, that is,

[0070] Rare earth source: magnesium source: boron-oxygen compound = (0.3-0.7): (0.8-1.2): (3-7).

[0071] Optionally, rare earth source: magnesium source: boron-oxygen compound = (0.4-0.6): (0.9-1.1): (4-6).

[0072] Preferably, the ratio of rare earth source: magnesium source: boron-oxygen compound = 0.5:1:5.

[0073] The Co of the crystal in the embodiment of the present invention 2+ The doping concentration is 0.05at% to 5at%.

[0074] The flux of the embodiment of the present invention is selected from any one of alkali metal fluorides, alkaline earth metal fluorides, alkali metal oxides, alkaline earth metal oxides, alkali metal tungstates, alkaline earth metal tungstates, alkali metal molybdates, alkaline earth metal molybdates, alkali metal borates, alkaline earth metal borates, lead-containing oxides, and lead-containing fluorides.

[0075] Preferably, the flux of the present invention is selected from Li-BFO mixed flux, PbF2 and / or PbO flux, Li2WO4 and / or K2WO4 flux, K3Mo3O 10 Any one of flux, LiF, NaF, KF, MgF2, CaF2; wherein the Li-BFO mixed flux is a flux system containing at least one element of Li, B, F and O.

[0076] Example (Li-BFO mixed flux system + 0.5at%Co 2+ )

[0077] Select magnesium source, cobalt source, lanthanum source and boron-oxygen compound raw materials from Table 1, and mix them according to La2O3:MgO:H3BO3=0.5:1:5.2+ The doping amount is 0.5at%, and the mixture is mixed to obtain a mixture; the mixture is heat treated by a high temperature solid phase method (temperature is 600-850°C) to obtain Co 2+ :LaMgB5O 10 Polycrystalline material.

[0078] Co 2+ :LaMgB5O 10 The polycrystalline material and Li-BFO mixed flux system are mixed in proportion, Co 2+ :LaMgB5O 10 Polycrystalline material: Li2O: H3BO3: LiF = 1:2:5:1 (molar ratio); using the flux method, in a φ60×50mm platinum crucible, the growth temperature is about 950℃, the cooling rate is 0.5℃ / day, the crystal speed is 5 rpm, after the growth is completed, the crystal is lifted from the liquid surface, the pulling speed is 1mm / h, and the rate of 3℃ / h is maintained to cool to room temperature, and a size of 25×25×10mm is grown. 3 High quality Co 2+ :LaMgB5O 10 Single crystal; Figure 1 Shown and Figure 2 shown.

[0079] ICP (inductively coupled plasma emission spectroscopy) analysis showed that Co 2+ The ion content is 0.045at%; the crystal block is cut from the crystal to 5.00×5.00×4.00mm 3 Spectral testing shows that there is a broad fluorescence band between 600nm and 900nm, with a peak near 712nm and a half-peak width of 123nm. Figure 3 As shown; this crystal can be used as a better laser crystal to achieve tunable laser output.

[0080] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A cobalt-doped magnesium borate rare earth laser crystal, characterized in that: Its molecular formula is Formula I; Co 2+ :LnMgB5O 10 Formula I; In Formula I, Ln is at least one of the rare earth metal ions La, Gd and Y; The Co 2+ is the doping ion in the crystal, the Co 2+ Replace the lattice position of Mg ions.

2. The cobalt-doped magnesium borate rare earth laser crystal according to claim 1, characterized in that: The Co 2+ The doping concentration in the laser crystal is 0.05 at % to 5 at %.

3. The cobalt-doped magnesium borate rare earth laser crystal according to claim 1, characterized in that: The laser crystal is a monoclinic crystal system and belongs to the P21 / C space group; Preferably, the unit cell parameters of the laser crystal are: α=γ=90°, β=92.01°~93.51°, Preferably, the refractive index of the laser crystal is 1.3-1.

5.

4. The method for preparing a cobalt-doped magnesium borate rare earth laser crystal according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: S1: According to the raw material ratio and the doping amount of cobalt ions, a magnesium source, a cobalt source, a rare earth source, and a boron-oxygen compound are mixed to obtain a mixture; the mixture is subjected to solid phase heat treatment to obtain a polycrystalline material; wherein the rare earth source is at least one of a lanthanum source, a gadolinium source, and a yttrium source; S2: The polycrystalline material is subjected to heat treatment in a molten solution to grow the cobalt-doped magnesium borate rare earth laser crystal.

5. The method for preparing a cobalt-doped magnesium borate rare earth laser crystal according to claim 4, characterized in that: In step S2, the flux used in the heat treatment of the molten solution is selected from alkali metal fluorides, alkaline earth metal fluorides, alkali metal oxides, alkaline earth metal oxides, alkali metal tungstates, alkaline earth metal tungstates, alkali metal molybdates, alkaline earth metal molybdates, alkali metal borates, alkaline earth metal borates, lead-containing oxides or lead-containing fluorides; Preferably, in step S2, the flux used for the heat treatment of the molten solution is selected from Li-BFO mixed flux, PbF2 and / or PbO flux, Li2WO4 and / or K2WO4 flux, K3Mo3O 10 Any one of flux, LiF, NaF, KF, MgF2, CaF2; wherein the Li-BFO mixed flux is a flux system containing at least one element of Li, B, F and O.

6. The method for preparing a cobalt-doped magnesium borate rare earth laser crystal according to claim 4, characterized in that: In step S1, the raw material ratio is a molar ratio of rare earth source, magnesium source, and boron-oxygen compound of (0.3-0.7): (0.8-1.2): (3-7); Preferably, in step S1, the doping concentration of the cobalt ions is 0.05 at% to 5 at%; Preferably, the cobalt source is selected from cobalt oxide or cobalt chloride; Preferably, the rare earth source is selected from carbonates of rare earth elements or oxides of rare earth elements; Preferably, the magnesium source is selected from magnesium oxides.

7. The method for preparing a cobalt-doped magnesium borate rare earth laser crystal according to claim 4, characterized in that: In step S1, the temperature of the solid phase heat treatment is 600-850°C; Preferably, in step S2, the temperature of the heat treatment of the molten solution is 900-1100°C; Preferably, in step S2, the cooling rate of the molten solution heat treatment is 0.5-3°C / day, the crystal rotation speed is 3-30rpm, and the crystal pulling speed is 0-1mm / h; after the crystal growth is completed, the crystal is lifted from the liquid surface and cooled to room temperature at a rate of 3-30°C / h to obtain a single crystal of cobalt-doped magnesium borate rare earth.

8. Application of the cobalt-doped magnesium borate rare earth laser crystal according to any one of claims 1 to 3 in the fields of physical medicine, spectroscopy, military and chemistry.

9. A laser, characterized in that: The gain medium material of the laser comprises a laser crystal; the crystal is the cobalt-doped magnesium borate rare earth laser crystal according to any one of claims 1 to 3.

10. A laser according to claim 9, characterized in that: The cobalt-doped magnesium borate rare earth laser crystal is pumped by a flash lamp or a GaN semiconductor laser to output laser light; Preferably, the laser pump wavelength of the laser crystal is 440-460 nm; the output laser wavelength of the laser crystal is 600-900 nm.

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