Rare earth halide with double perovskite structure and preparation method thereof

Abstract

The invention discloses a rare earth halide with a double-perovskite structure and a preparation method thereof. The preparation method comprises the following steps: (1) dissolving metal halide salt in a polar solvent to obtain a precursor solution; (2) mixing a surfactant with an organic solution to obtain an anti-solvent solution; (3) mixing the precursor solution with the anti-solvent solution to obtain a crystal; and (4) separating the crystal from the solution, and drying to obtain the rare earth halide microcrystal with the double perovskite structure. Compared with existing thermal injection and hydrothermal methods, the method does not need complex technological processes and high-temperature and high-pressure conditions, does not use hydrochloric acid and long-chain high-melting-point organic solvents, is energy-saving and environment-friendly, and can be used for batch preparation and industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of solid luminescent materials, and in particular to a double perovskite structure rare earth halide and a preparation method thereof. Background Art

[0002] Lead halide perovskite materials are difficult to meet people's growing demand for environmental friendliness and health due to their toxicity. Non-lead halides with double perovskite structure have attracted people's attention due to their good optoelectronic properties, and are expected to become a substitute for lead halide perovskite materials in the optoelectronic field. Among them, rare earth-based double perovskite metal halides can achieve full-spectrum luminescence from ultraviolet to visible to near-infrared and are more valued. However, the current preparation method of double perovskite rare earth halide microcrystals usually uses complex synthesis instruments and harsh environments of high temperature and high pressure, which undoubtedly increases the cost of synthesis. In addition, the high melting point solvents or hydrochloric acid used in the synthesis process are toxic and the waste is difficult to handle, which also causes a certain degree of environmental pollution. Therefore, there is an urgent need for a simple, efficient and green synthesis method of double perovskite rare earth halides. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a double perovskite structure rare earth halide and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art.

[0004] The present invention adopts the following technical solutions:

[0005] A method for preparing a double perovskite structure rare earth halide comprises the following steps:

[0006] (1) dissolving a metal halide salt in a polar solvent to obtain a precursor solution;

[0007] (2) mixing the surfactant with the organic solution to obtain an anti-solvent solution;

[0008] (3) mixing the precursor solution with the anti-solvent solution to obtain crystals;

[0009] (4) Separating the crystals from the solution and drying them to obtain double perovskite structured rare earth halide microcrystals.

[0010] Preferably, in step (1), the metal halide salt comprises a first halide salt, a second halide salt and a third halide salt, and the molar ratio of the first halide salt, the second halide salt and the third halide salt is 2:1:1.

[0011] Preferably, the first halide salt is cesium halide or organic halide; the second halide salt is sodium halide or potassium halide; and the third halide salt is rare earth halide.

[0012] Preferably, the organic halide is CsX, MAX, FAX, BAX or PEAX, wherein X is Cl, Br or I.

[0013] Preferably, the rare earth halide is LnX3, wherein Ln is Y, Sc, La, Ce, Pr, Nb, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu; and X is Cl, Br or I.

[0014] Preferably, in step (1), the polar solvent is deionized water.

[0015] Preferably, in step (2), the organic solution is a mixture of ethyl acetate and anhydrous ethanol in a volume ratio of 1:1.

[0016] Preferably, in step (3), the precursor solution and the anti-solvent solution are mixed by dripping the precursor solution dropwise into the rapidly stirred anti-solvent solution.

[0017] Preferably, in the step (4), the method for separating the crystals from the solution is centrifugation; and in the step (4), the method for drying the crystals is vacuum freezing.

[0018] A double perovskite structure rare earth halide is prepared using the above preparation method.

[0019] Compared with the prior art, the present invention has the following advantages: the present invention proposes a preparation method of a double perovskite structure rare earth halide and a halide obtained by the preparation method, the preparation method can prepare double perovskite structure rare earth halide microcrystals under open conditions at room temperature, the solvents used are all green solvents, compared with the current hot injection and hydrothermal methods, the present invention does not require complicated process flows and high temperature and high pressure conditions, and does not use hydrochloric acid or long-chain high-melting point organic solvents, is energy-saving and environmentally friendly, and can be prepared in batches and industrialized; the double perovskite rare earth halide microcrystals obtained by the present invention have good luminescence properties and have broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the crystal structure of Cs2NaTbCl6 double perovskite rare earth halide microcrystals obtained in Example 1;

[0021] Figure 2 The XRD detection spectrum of the Cs2NaTbCl6 double perovskite rare earth halide microcrystals obtained in Example 1;

[0022] Figure 3 The ultraviolet light-excited luminescence spectrum of the Cs2NaTbCl6 double perovskite rare earth halide microcrystals obtained in Example 1;

[0023] Figure 4 This is the X-ray excited luminescence spectrum of the Cs2NaTbCl6 double perovskite rare earth halide microcrystals obtained in Example 1. DETAILED DESCRIPTION

[0024] In order to facilitate the understanding of the technical solution of the present invention, a detailed description is given below in conjunction with the accompanying drawings and specific embodiments.

[0025] A method for preparing a double perovskite structure rare earth halide comprises the following steps:

[0026] (1) dissolving a metal halide salt in a polar solvent to obtain a precursor solution;

[0027] (2) mixing the surfactant with the organic solution to obtain an anti-solvent solution;

[0028] (3) mixing the precursor solution with the anti-solvent solution to obtain crystals;

[0029] (4) Separating the crystals from the solution and drying them to obtain double perovskite structured rare earth halide microcrystals.

[0030] Wherein, in step (1), the metal halide salt comprises a first halide salt, a second halide salt and a third halide salt, and the molar ratio of the first halide salt, the second halide salt and the third halide salt is 2:1:1. The first halide salt is cesium halide (CsX) or an organic halide; the second halide salt is sodium halide or potassium halide; and the third halide salt is a rare earth halide.

[0031] The organic halide is at least one of methylamine (MA), formamidine (FA), n-butylamine (BA), and phenylethylamine (PEA), that is, the organic halide is at least one of MAX, FAX, BAX, or PEAX, wherein X is Cl, Br, or I.

[0032] The rare earth halide is at least one of the halides of scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nb), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu), that is, the rare earth halide is LnX3, wherein Ln is Y, Sc, La, Ce, Pr, Nb, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu; and X is Cl, Br or I.

[0033] In the present invention, the polar solvent in step (1) is deionized water.

[0034] In the present invention, the organic solution in step (2) is a mixture of ethyl acetate and anhydrous ethanol, and the volume ratio thereof is 1: 1. The surfactant is at least one of tridecyl trimethyl ammonium halide and didodecyl dimethyl ammonium halide.

[0035] In the present invention, the method for mixing the precursor solution and the anti-solvent solution in step (3) is: dripping the precursor solution drop by drop into the rapidly stirred anti-solvent solution.

[0036] In the present invention, the method for separating the crystals and the solution in step (4) is centrifugation.

[0037] In the present invention, the method for drying the crystals in step (4) is vacuum freezing.

[0038] The present invention can be carried out in an open system, the reaction temperature can be 0-40° C., and the reaction time can be 1-10 seconds.

[0039] The analysis method in the following examples of the present invention is as follows:

[0040] The XRD spectrum test was carried out using a Bruker D8 Advance powder diffractometer, in which the radiation source was a Cu target.

[0041] The photo-stimulated fluorescence spectrum was analyzed by FLS1000 UV-visible spectrophotometer, and the excitation source was a xenon lamp.

[0042] X-ray excited fluorescence spectroscopy analysis was performed using an FLS1000 UV-visible spectrophotometer, with an excitation source of an X-ray tube with a voltage of 50 kV and a current of 200 μA.

[0043] Example 1

[0044] Preparation of Cs2NaTbCl6 double perovskite structure rare earth halide microcrystals:

[0045] According to the stoichiometric ratio of 2:1:1, 0.337 g of cesium chloride, 0.058 g of sodium chloride, and 0.374 g of terbium chloride hexahydrate were weighed in a beaker and 1 mL of deionized water was added and stirred until completely dissolved to obtain solution 1; 10 mL of anhydrous ethanol and ethyl acetate were added to another beaker according to a volume ratio of 1:1, and 0.0528 g of tridecyltrimethylammonium chloride was added thereto, and stirred until completely dissolved to obtain solution 2; under the stirring condition of 500 rpm, solution 1 was added dropwise to solution 2. The product was then transferred to a centrifuge tube, centrifuged at a speed of 6000 rpm for 5 minutes, the supernatant was removed, and dried in a vacuum freeze dryer for 2 hours to obtain the final product Cs2NaTbCl6 microcrystals.

[0046] Example 2

[0047] Preparation of Cs2NaTbCl6 double perovskite rare earth halide microcrystals:

[0048] According to the stoichiometric ratio of 2:1:1, 33.7 g of cesium chloride, 5.8 g of sodium chloride, and 37.4 g of terbium chloride hexahydrate were weighed in a beaker and 100 mL of deionized water was added and stirred until completely dissolved to obtain solution 1; 1000 mL of anhydrous ethanol and ethyl acetate were added to another beaker according to the volume ratio of 1:1, and 5.28 g of tridecyltrimethylammonium chloride was added thereto, and stirred until completely dissolved to obtain solution 2; under the stirring condition of 500 rpm, solution 1 was added dropwise to solution 2. The product was then transferred to a centrifuge tube, centrifuged at a speed of 6000 rpm for 5 minutes, the supernatant was removed, and dried in a vacuum freeze dryer for 2 hours to obtain the final product Cs2NaTbCl6 microcrystals.

[0049] Example 3: Cs2NaTb 0.95 Ce 0.05 Preparation of Cl6 double perovskite rare earth halide microcrystals

[0050] According to the stoichiometric ratio of 2:1:0.95:0.05, 0.337g of cesium chloride, 0.058g of sodium chloride, 0.355g of terbium chloride hexahydrate, and 0.012g of anhydrous cerium chloride were weighed in a beaker and 1mL of deionized water was added and stirred until completely dissolved to obtain solution 1; 10mL of anhydrous ethanol and ethyl acetate were added to another beaker according to a volume ratio of 1:1, and 0.0528g of tridecyltrimethylammonium chloride was added thereto, and stirred until completely dissolved to obtain solution 2; under the stirring condition of 500rpm, solution 1 was added dropwise to solution 2. The product was then transferred to a centrifuge tube, centrifuged at a speed of 6000rpm for 5 minutes, the supernatant was removed, and dried in a vacuum freeze dryer for 2 hours to obtain the final product Cs2NaTb 0.95 Ce 0.05 Cl6 microcrystals.

[0051] Example 4

[0052] The difference between Example 4 and Example 1 is that cesium chloride is replaced by cesium bromide or cesium iodide, and sodium chloride is replaced by sodium bromide or sodium iodide. The surfactant is didodecyl dimethyl ammonium halide.

[0053] Example 5

[0054] The difference between Example 5 and Example 1 is that cesium chloride is replaced by an organic halide; sodium chloride is replaced by a potassium halide; terbium chloride hexahydrate is replaced by other rare earth halides. The surfactant is a mixture of tridecyl trimethyl ammonium halide and didodecyl dimethyl ammonium halide.

[0055] It can be seen from the above examples that the present invention provides a method for preparing double perovskite structure rare earth halide, and the results of Examples 1-5 are tested and analyzed.

[0056] Taking Example 1 as an example, Figure 1 Schematic diagram of the crystal structure of Cs2NaTbCl6 microcrystals, which have a double perovskite structure.

[0057] The XRD pattern of Cs2NaTbCl6 microcrystals obtained in Example 1 is as follows Figure 2 As shown, it was observed that the peaks in the spectrum were sharp and free of impurity peaks, which could correspond one-to-one with the standard card, indicating that the Cs2NaTbCl6 microcrystalline sample of Example 1 was successfully obtained.

[0058] The Cs2NaTbCl6 microcrystals obtained in Example 1 were subjected to ultraviolet fluorescence testing, and their emission spectrum was as follows: Figure 3 When excited by ultraviolet light with a wavelength of 275 nm, the microcrystal emits green narrow-band light between 525 and 575 nm, which is the characteristic emission peak of trivalent terbium ions.

[0059] The Cs2NaTbCl6 microcrystals obtained in Example 1 were subjected to X-ray fluorescence testing, and the emission spectrum thereof was as follows: Figure 4 As shown. Under X-ray excitation, the microcrystal has a green narrow-band luminescence between 525-575nm, which is the characteristic emission peak of trivalent terbium ions.

[0060] The above are only preferred embodiments of the present invention. The protection scope of the present invention shall be based on the scope defined by the claims. Several improvements and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a double perovskite structure rare earth halide, characterized in that: The following steps are involved: (1) dissolving a metal halide salt in a polar solvent to obtain a precursor solution; (2) mixing the surfactant with the organic solution to obtain an anti-solvent solution; (3) mixing the precursor solution with the anti-solvent solution to obtain crystals; (4) Separating the crystals from the solution and drying them to obtain double perovskite structured rare earth halide microcrystals.

2. The method for preparing double perovskite rare earth halide according to claim 1, characterized in that: In the step (1), the metal halide salt includes a first halide salt, a second halide salt and a third halide salt, and the molar ratio of the first halide salt, the second halide salt and the third halide salt is 2:1:

1.

3. The method for preparing double perovskite rare earth halide according to claim 2, characterized in that: The first halide salt is cesium halide or organic halide; the second halide salt is sodium halide or potassium halide; and the third halide salt is rare earth halide.

4. The method for preparing double perovskite rare earth halide according to claim 3, characterized in that: The organic halide is CsX, MAX, FAX, BAX or PEAX, wherein X is Cl, Br or I.

5. The method for preparing double perovskite rare earth halide according to claim 3, characterized in that: The rare earth halide is LnX3, wherein Ln is Y, Sc, La, Ce, Pr, Nb, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu; and X is Cl, Br or I.

6. The method for preparing double perovskite rare earth halide according to claim 1, characterized in that: In the step (1), the polar solvent is deionized water.

7. The method for preparing double perovskite rare earth halide according to claim 1, characterized in that: In the step (2), the organic solution is a mixture of ethyl acetate and anhydrous ethanol in a volume ratio of 1:

1.

8. The method for preparing double perovskite rare earth halide according to claim 1, characterized in that: In the step (3), the precursor solution and the anti-solvent solution are mixed by dripping the precursor solution dropwise into the rapidly stirred anti-solvent solution.

9. The method for preparing double perovskite rare earth halide according to claim 1, characterized in that: In the step (4), the method for separating the crystals from the solution is centrifugation; in the step (4), the method for drying the crystals is vacuum freezing.

10. A double perovskite structure rare earth halide, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 9.

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