Rare earth iodate material, preparation method therefor and use thereof

Abstract

The present application discloses a rare earth iodate material, a preparation method therefor and a use thereof. The molecular formula of the rare earth iodate material is AxB1-x(IO3)3, A and B being independently selected from among trivalent rare earth elements; the crystal phase structure of the rare earth iodate material is a monoclinic phase. The material has a large atomic number, a large bandgap and stable physical and chemical properties, and therefore has strong absorption of X-rays and strong resistance to radiation damage. The present method adopts a specific cooling rate during a cooling process, to produce high-quality crystals. A direct X-ray detector prepared based on the rare earth iodate material AxB1-x(IO3)3 has excellent sensitivity at different electric field strengths, with a maximum sensitivity of 1301.5μCGy-1cm-2.

Description

A rare earth iodate material and its preparation method and application Technical Field

[0001] The present application relates to a rare earth iodate material and a preparation method and application thereof, belonging to the field of direct X-ray detectors. Background Art

[0002] X-rays are widely used in numerous fields, including medical CT imaging, security inspections, industrial nondestructive testing, and national defense. Consequently, X-ray detectors have garnered significant attention from numerous research institutes and companies worldwide. Commercial scintillators are mostly fabricated into indirect X-ray detectors, where the detection signal is generated by converting the incident X-rays twice, through the scintillator and then the photodetector. As an alternative, direct detection using scintillating semiconductors (converting X-rays directly into electrical signals) holds greater potential for developing compact CT devices with high-quality X-ray imaging. Traditional semiconductors, such as crystalline silicon, germanium, and amorphous selenium, dominate commercial direct X-ray detection applications due to their compatibility with mature micro- and nanofabrication technologies. However, most commercial semiconductor materials currently suffer from intrinsic defects or material preparation challenges. Low-atomic-number materials, such as silicon, germanium, amorphous selenium, and diamond, exhibit weak X-ray cutoff, limiting their detection performance. Materials composed of heavy atoms, such as mercury iodide, cadmium telluride, and cadmium zinc telluride, have relatively small band gaps, making it difficult to suppress thermal noise, which exacerbates dark current and results in poor resistance to radiation damage. Therefore, it is of great significance to find a semiconductor scintillating material with a large atomic number, a large bandgap and stable physical and chemical properties.

[0003] Oxyiodates, products of halides and oxides, are a promising candidate for our research. Using high-atomic-number rare earth metal cations ensures the material's radiation-cutting capability. Rare earth iodates generally possess wide band gaps and stable physical and chemical properties.

[0004] Summary of the Invention

[0005] According to the first aspect of the present application, there is provided a rare earth iodate material A x B 1- x (IO3)3, where A and B are independently selected from trivalent rare earth elements, and A and B can be at least one of Ce, Gd, Tb, or Tm. Selecting high-atomic-number rare earth metal cations ensures the material's radiation cutoff capability, thereby enabling the production of high-performance X-ray detectors. Rare earth iodates generally possess wide band gaps and stable physicochemical properties, enabling the fabrication of X-ray-sensitive and stable direct X-ray detectors, which have great potential for application.

[0006] A rare earth iodide material, the molecular formula of the rare earth iodide material is Ax B 1- x (IO3)3, 0≤x≤1, wherein A and B are independently selected from trivalent rare earth elements.

[0007] Optionally, the crystal phase structure of the rare earth iodate material is monoclinic.

[0008] Optionally, A and B are independently selected from at least one of Ce, Gd, Tb, and Tm.

[0009] Optionally, the crystal phase structure of the rare earth iodate material is monoclinic.

[0010] Optionally, the rare earth iodide material is a micron- to millimeter-scale single crystal.

[0011] Optionally, the size of the rare earth iodide material is 0.2 mm to 2 mm.

[0012] Optionally, the size of the rare earth iodide material single crystal is 0.8 mm to 2 mm.

[0013] Optionally, the size of the rare earth iodide material single crystal is independently selected from any value among 0.20 mm, 0.25 mm, 0.80 mm, 0.85 mm, 1.55 mm, 2.00 mm or a range between any two of the above values.

[0014] Optionally, the rare earth iodide material has an X-ray powder diffraction pattern as shown in FIG1 .

[0015] Optionally, the effective atomic number of the rare earth iodide material is 52.3 to 53.2.

[0016] Optionally, the resistivity of the rare earth iodate material is 3.00×10 10 ~1.50×10 11 .

[0017] According to the second aspect of the present application, there is provided a rare earth iodate material A x B 1- x (IO3)3 preparation method. The method is prepared by a hydrothermal method, especially in the cooling process, a specific cooling rate is adopted to obtain high-quality crystals.

[0018] A method for preparing a rare earth iodate material, the preparation method comprising:

[0019] In a closed reactor, a mixture containing an iodate source, a rare earth metal source and water is reacted to obtain the rare earth iodate material.

[0020] Optionally, the iodate source is selected from at least one of sodium iodate, potassium iodate and iodic acid.

[0021] Optionally, the rare earth metal source is selected from rare earth nitrates and / or rare earth oxides.

[0022] Optionally, the rare earth metal source is selected from at least one of anhydrous rare earth nitrates, hydrous rare earth nitrates and rare earth oxides.

[0023] Optionally, the mass ratio of the rare earth metal source to the iodate source is 1:2-6.

[0024] Optionally, the mass ratio of the rare earth metal source to the iodate source is 1:4.3.

[0025] Optionally, the mass ratio of the rare earth metal source to the iodate source is independently selected from any value of 1:2, 1:3, 1:4, 1:5, 1:6, or a range between any two of the above values.

[0026] Optionally, the mixture further comprises nitric acid.

[0027] Optionally, the volume ratio of the nitric acid to water is 0.01-2:10-100.

[0028] Optionally, the concentration of the rare earth metal source is 0.000005 mol / L to 0.00005 mol / L, and the concentration of the rare earth metal source is measured as the molar concentration of the rare earth metal element in the mixture.

[0029] Optionally, the concentration of the rare earth metal source is independently selected from any value among 0.000005 mol / L, 0.00001 mol / L, 0.00002 mol / L, 0.00003 mol / L, 0.00004 mol / L, 0.00005 mol / L, or a range between any two of the above values.

[0030] Optionally, the concentration of the iodate source is 0.000015 mol / L to 0.00015 mol / L, and the concentration of the iodate source is measured as the molar concentration of iodine element in the mixture.

[0031] Optionally, the concentration of the iodate source is independently selected from any value among 0.000015 mol / L, 0.00003 mol / L, 0.00005 mol / L, 0.00010 mol / L, 0.00015 mol / L, or a range between any two of the above values.

[0032] Optionally, the concentration of the nitric acid is chemically pure.

[0033] Optionally, the reaction temperature is 180° C. to 220° C., and the reaction time is 24 h to 120 h.

[0034] Optionally, the reaction temperature is independently selected from any value among 180°C, 190°C, 200°C, 210°C, 220°C or a range between any two of the above values.

[0035] Optionally, after the reaction is completed, the temperature is lowered;

[0036] The cooling rate is 0.1°C / hour to 2°C / hour.

[0037] Optionally, the cooling rate is independently selected from any value among 0.1°C / hour, 0.5°C / hour, 1.0°C / hour, 1.5°C / hour, 2°C / hour, or a range between any two of the above values.

[0038] Optionally, the duration of the reaction process and the cooling process conforms to the temperature variation diagram shown in FIG3 .

[0039] According to a third aspect of the present application, there is provided an application of the rare earth iodate material described above in a direct X-ray detector. The direct X-ray detector based on the rare earth iodate material has high sensitivity.

[0040] Application of a rare earth iodate material in a direct X-ray detector.

[0041] A direct X-ray detector comprising an electrode and a light absorbing layer;

[0042] The light absorbing layer is selected from one of the rare earth iodate materials mentioned above.

[0043] Optionally, the direct X-ray detector includes an upper electrode, a light absorbing layer and a lower electrode.

[0044] Optionally, the light absorbing layer is selected from rare earth iodate materials or polycrystalline pressed sheets.

[0045] Optionally, the thickness of the upper electrode is 5 μm to 10 μm.

[0046] Optionally, the light absorbing layer has a thickness of 0.1 mm to 2 mm.

[0047] Optionally, the upper electrode and the lower electrode are independently selected from at least one of Ag, Au, Cu, Cr, and ITO.

[0048] Optionally, the sensitivity of the direct X-ray detector is 34.6 μCGy -1 cm -2 ~1301.5μCGy-1 cm -2 .

[0049] Optionally, the direct X-ray detector has an X-ray sensitivity diagram as shown in FIG4 , which has a sensitivity of 34.6 μCGy -1 cm -2 ~1301.5μCGy -1 cm -2 .

[0050] Optionally, the sensitivity of the direct X-ray detector is independently selected from 34.6 μC Gy - 1 cm -2 、100μCGy -1 cm -2 , 500μCGy -1 cm -2 、1000μCGy -1 cm -2 、1301.5μCGy - 1 cm -2 Any value in or a range of values ​​between any two of the above.

[0051] According to a fourth aspect of the present application, a method for preparing a direct X-ray detector is provided.

[0052] A method for preparing a direct X-ray detector comprises the following steps:

[0053] Applying conductive silver paste evenly to the upper and lower surfaces of the rare earth iodate material and drying naturally to obtain a device unit of electrode / rare earth iodate material / electrode;

[0054] The rare earth iodate material A x B 1-x (IO3)3 is selected from the rare earth iodate material A described above x B 1-x (IO3)3.

[0055] The present invention proposes a rare earth iodate material A x B 1-x A (IO3)3 direct X-ray detector and a preparation method thereof, wherein the detector has high X-ray sensitivity.

[0056] The present invention discloses a rare earth iodate material A x B 1-x (IO3)3 direct X-ray detector, the device structure from top to bottom is electrode / rare earth iodate material / electrode, rare earth iodate material A x B 1-x(IO3)3 acts as a light-absorbing layer to absorb X-rays.

[0057] Furthermore, the electrode is made of metal Ag and has a thickness of 1 to 2 μm.

[0058] Based on rare earth iodate material A x B 1-x A method for preparing a (IO3)3 X-ray detector comprises the following steps:

[0059] (a) mixing rare earth nitrate pentahydrate (R(NO3)35H2O) and sodium iodate (NaIO3) in a mass ratio of 1:4.3;

[0060] (b) adding the raw material mixture obtained in step (a) into a hydrothermal kettle liner containing a mixed solution of water and nitric acid (the volume ratio of water to nitric acid is 30:1) to maintain a concentration of 0.000005 to 0.00005 mol / L, then placing the liner into the hydrothermal kettle shell, and placing the hydrothermal kettle in a temperature-controlled forced air drying oven;

[0061] (c) The temperature-controlled forced air drying oven was set to maintain constant temperature heating at 220°C, and then slowly cooled to room temperature at a rate of 0.1°C / hour to obtain millimeter-sized rare earth iodate material A. x B 1-x (IO3)3 single crystal;

[0062] (d) the rare earth iodate material A obtained in step (c) x B 1-x The (IO3)3 single crystal was kept at 60°C until dry.

[0063] The present invention discloses a rare earth iodate material A x B 1-x The preparation method of the (IO3)3 direct X-ray detector is to apply the conductive silver paste evenly to the rare earth iodate material A x B 1-x The upper and lower surfaces of the (IO3)3 single crystal are naturally dried to obtain a device structure of electrode / rare earth iodate material / electrode.

[0064] The beneficial effects of this application include:

[0065] 1) Rare earth iodate material A provided in this application x B 1-x (IO3)3 has a high atomic number, a large band gap and excellent physical and chemical properties, so it has strong absorption and cutoff of X-rays, which is conducive to the preparation of direct X-ray detectors that are sensitive to X-rays.

[0066] 2) Rare earth iodate material A provided in this application x B1-x The preparation method of (IO3)3 is prepared by a hydrothermal method, especially in the cooling process, a specific cooling rate is adopted to obtain high-quality crystals; the method is simple and efficient and suitable for large-scale industrial production.

[0067] 3) Rare earth iodate material A provided in this application x B 1-x The application of (IO3)3 in direct X-ray detectors has excellent sensitivity at different electric field strengths, with a maximum sensitivity of 1301.5μCGy -1 cm -2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 shows Ce(IO3)3 in Example 1, Tb(IO3)3 in Example 2, Gd(IO3)3 in Example 3, Tm(IO3)3 in Example 4, and Ce(IO3)3 in Example 5. 0.5 Gd 0.5 X-ray powder diffraction pattern of (IO3)3.

[0069] Figure 2 is a physical photo of the Tm(IO3)3 single crystal in Example 4 of the present application.

[0070] FIG3 is a curve showing the temperature variation over time for crystal growth in Examples 1 to 5 of the present application.

[0071] FIG4 shows the changes in X-ray sensitivity of the direct X-ray detectors prepared in Examples 1 to 5 of the present application under different electric field intensities. DETAILED DESCRIPTION

[0072] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0073] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0074] The analysis method in the examples of this application is as follows:

[0075] The detector performance was analyzed using Keithley 2450 high voltage source meter.

[0076] Example 1

[0077] This embodiment provides a method for preparing rare earth iodate material Ce(IO3)3 and a method for preparing a direct X-ray detector based on Ce(IO3)3 material. The specific steps are as follows:

[0078] (a) 0.123 g of cerium nitrate pentahydrate (Ce(NO3)35H2O) and 0.57 g of sodium iodate (NaIO3) were mixed in a mass ratio of 1:4.6;

[0079] (b) adding the raw material mixture obtained in step (a) to a hydrothermal kettle inner container filled with a mixed solution of water and nitric acid (the volume ratio of water to nitric acid is 30:1) to maintain a concentration of 0.000005 mol / L, then placing the inner container into the hydrothermal kettle outer container, and placing the hydrothermal kettle in a temperature-controlled forced air drying oven;

[0080] (c) A temperature-controlled forced air drying oven was set to maintain a constant temperature of 220°C for 120 h, and then slowly cooled to room temperature at a rate of 0.1°C / hour to obtain Ce(IO3)3 crystals;

[0081] (d) keeping the Ce(IO3)3 crystals obtained in step (c) at 60°C until dry.

[0082] (e) Apply conductive silver paste evenly to the upper and lower surfaces of the Ce(IO3)3 crystal obtained in step (d) with a thickness of 8 μm and 8 μm respectively, and dry naturally to obtain a device structure of electrode / iodate crystal / electrode.

[0083] Example 2

[0084] This embodiment provides a method for preparing a rare earth iodate material Tb(IO3)3 and a method for preparing a direct X-ray detector based on the Tb(IO3)3 material. The specific steps are as follows:

[0085] (a) 0.120 g of terbium nitrate pentahydrate (Tb(NO3)35H2O) and 0.57 g of sodium iodate (NaIO3) were mixed in a mass ratio of 1:4.75;

[0086] (b) adding the raw material mixture obtained in step (a) to a hydrothermal kettle inner container filled with a mixed solution of water and nitric acid (the volume ratio of water to nitric acid is 30:1) to maintain a concentration of 0.000005 mol / L, then placing the inner container into the hydrothermal kettle outer container, and placing the hydrothermal kettle in a temperature-controlled forced air drying oven;

[0087] (c) A temperature-controlled forced air drying oven was set to maintain a constant temperature of 220°C for 120 h, and then slowly cooled to room temperature at a rate of 0.1°C / hour to obtain Tb(IO3)3 crystals;

[0088] (d) keeping the Tb(IO3)3 crystals obtained in step (c) at 60°C until dry.

[0089] (e) Apply conductive silver paste evenly to the upper and lower surfaces of the Tb(IO3)3 crystal obtained in step (d) to a thickness of 8 μm and 8 μm, respectively, and dry naturally to obtain a device structure of electrode / iodate crystal / electrode.

[0090] Example 3

[0091] This embodiment provides a method for preparing a rare earth iodate material Gd(IO3)3 and a method for preparing a direct X-ray detector based on the Gd(IO3)3 material. The specific steps are as follows:

[0092] (a) 0.129 g of gadolinium nitrate pentahydrate (Gd(NO3)35H2O) and 0.57 g of sodium iodate (NaIO3) were mixed in a mass ratio of 1:4.4;

[0093] (b) adding the raw material mixture obtained in step (a) to a hydrothermal kettle inner container filled with a mixed solution of water and nitric acid (the volume ratio of water to nitric acid is 30:1) to maintain a concentration of 0.000005 mol / L, then placing the inner container into the hydrothermal kettle outer container, and placing the hydrothermal kettle in a temperature-controlled forced air drying oven;

[0094] (c) A temperature-controlled forced air drying oven was set to maintain a constant temperature of 220°C for 120 h, and then slowly cooled to room temperature at a rate of 0.1°C / hour to obtain Gd(IO3)3 crystals;

[0095] (d) keeping the Gd(IO3)3 crystals obtained in step (c) at 60°C until dry.

[0096] (e) Apply conductive silver paste evenly to the upper and lower surfaces of the Gd(IO3)3 crystal obtained in step (d) to a thickness of 8 μm and 8 μm, respectively, and dry naturally to obtain a device structure of electrode / iodate crystal / electrode.

[0097] Example 4

[0098] This embodiment provides a method for preparing a rare earth iodate material Tm(IO3)3 and a method for preparing a direct X-ray detector based on the Tm(IO3)3 material. The specific steps are as follows:

[0099] (a) 0.134 g of thulium nitrate pentahydrate (Tm(NO3)35H2O) and 0.57 g of sodium iodate (NaIO3) were mixed in a mass ratio of 1:4.3;

[0100] (b) adding the raw material mixture obtained in step (a) to a hydrothermal kettle inner container filled with a mixed solution of water and nitric acid (the volume ratio of water to nitric acid is 30:1) to maintain a concentration of 0.000005 mol / L, then placing the inner container into the hydrothermal kettle outer container, and placing the hydrothermal kettle in a temperature-controlled forced air drying oven;

[0101] (c) A temperature-controlled forced air drying oven was set to maintain a constant temperature of 220°C for 120 h, and then slowly cooled to room temperature at a rate of 0.1°C / hour to obtain Tm(IO3)3 crystals;

[0102] (d) keeping the Tm(IO3)3 crystals obtained in step (c) at 60°C until dry.

[0103] (e) Apply conductive silver paste evenly to the upper and lower surfaces of the Tm(IO3)3 crystal obtained in step (d) to a thickness of 8 μm and 8 μm, respectively, and dry naturally to obtain a device structure of electrode / iodate crystal / electrode.

[0104] FIG2 is a physical photograph of the Tm(IO3)3 single crystal in Example 4, showing that the single crystal has ultra-high transparency, reflecting its excellent crystallinity.

[0105] Example 5

[0106] This embodiment provides a rare earth iodate material Ce 0.5 Gd 0.5 Preparation method of (IO3)3 and Ce-based 0.5 Gd 0.5 The preparation method of the direct X-ray detector of (IO3)3 material comprises the following specific steps:

[0107] (a) 0.060 g of cerium nitrate pentahydrate (Ce(NO3)35H2O), 0.060 g of gadolinium nitrate pentahydrate (Gd(NO3)35H2O), and 0.57 g of sodium iodate (NaIO3) were mixed in a mass ratio of 1:1:9.5;

[0108] (b) adding the raw material mixture obtained in step (a) to a hydrothermal kettle inner container filled with a mixed solution of water and nitric acid (the volume ratio of water to nitric acid is 30:1) to maintain a concentration of 0.000005 mol / L, then placing the inner container into the hydrothermal kettle outer container, and placing the hydrothermal kettle in a temperature-controlled forced air drying oven;

[0109] (c) The temperature-controlled forced air drying oven was set to maintain constant temperature at 220°C for 120 h, and then slowly cooled to room temperature at a rate of 0.1°C / hour to obtain Tb 0.5 Gd 0.5 (IO3)3 crystals;

[0110] (d) Ce obtained in step (c) 0.5 Gd 0.5 The (IO3)3 crystals were kept at 60°C until dry.

[0111] (e) Apply the conductive silver paste evenly to the Ce obtained in step (d) 0.5 Gd0.5 The upper and lower surfaces of the (IO3)3 crystal are 8μm and 8μm respectively, and the device structure of electrode / iodate crystal / electrode is obtained by natural drying.

[0112] Example 6

[0113] The performance of the direct X-ray detectors prepared in Examples 1 to 5 was analyzed using a Keithley 2450 high voltage source meter. The specific analysis structure is shown in Table 1:

[0114] Table 1 shows the thickness, electrode area and resistivity data of the direct X-ray detectors prepared in Examples 1 to 5.

[0115] Figure 1 is Ce (IO3) 3 in Example 1, Tb (IO3) 3 in Example 2, Gd (IO3) 3 in Example 3, Tm (IO3) 3 in Example 4, Ce (IO3) 3 in Example 5 0.5 Gd 0.5 (IO3)3 has an X-ray powder diffraction pattern as shown in Figure 1.

[0116] FIG3 is a temperature change diagram of the crystal reaction process and the cooling process in Examples 1 to 5. The setting of the heat preservation section is beneficial to promoting crystal growth.

[0117] FIG4 shows the X-ray sensitivity changes of the direct X-ray detectors prepared in Examples 1 to 5 under different electric field intensities, with the maximum being 1301.5 μCGy -1 cm -2 .

[0118] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present 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 rare earth iodate material, characterized in that: The molecular formula of the rare earth iodate material is A x B 1-x (IO3)3, 0≤x≤1; Wherein, A and B are independently selected from trivalent rare earth elements.

2. The rare earth iodate material according to claim 1, characterized in that The crystal structure of the rare earth iodate material is monoclinic.

3. The rare earth iodate material according to any one of claims 1 to 2, characterized in that: A and B are independently selected from at least one of Ce, Gd, Tb, and Tm.

4. The rare earth iodate material according to any one of claims 1 to 3, characterized in that The rare earth iodate material is a single crystal in the micron to millimeter scale.

5. The rare earth iodate material according to any one of claims 1 to 4, characterized in that: The size of the rare earth iodate material is 0.2 mm to 2 mm.

6. The rare earth iodate material according to any one of claims 1 to 5, characterized in that: The effective atomic number of the rare earth iodate material is 52.3-53.

2.

7. The rare earth iodate material according to any one of claims 1 to 6, characterized in that: The resistivity of the rare earth iodate material is 3.00×10 10 ~1.50×10 11 .

8. The method for preparing the rare earth iodate material according to any one of claims 1 to 7, characterized in that: The preparation method comprises: In a closed reactor, a mixture containing an iodate source, a rare earth metal source and water is reacted to obtain the rare earth iodate material.

9. The preparation method according to claim 8, characterized in that The iodate source is selected from at least one of sodium iodate, potassium iodate and iodic acid.

10. The preparation method according to claim 8 or 9, characterized in that: The rare earth metal source is selected from rare earth nitrates and / or rare earth oxides.

11. The preparation method according to any one of claims 8 to 10, characterized in that: The mass ratio of the rare earth metal source to the iodate source is 1:2-6.

12. The preparation method according to any one of claims 8 to 11, characterized in that: The mass ratio of the rare earth metal source to the iodate source is 1:4.

3.

13. The preparation method according to any one of claims 8 to 12, characterized in that: Nitric acid is also included in the mixture.

14. The preparation method according to any one of claims 8 to 13, characterized in that: The volume ratio of the nitric acid to water is 0.01-2:10-100.

15. The preparation method according to any one of claims 8 to 14, characterized in that: The concentration of the rare earth metal source is 0.000005 mol / L to 0.00005 mol / L, and the concentration of the rare earth metal source is measured based on the molar concentration of the rare earth metal element in the mixture.

16. The preparation method according to any one of claims 8 to 15, characterized in that: The concentration of the iodate source is 0.000015 mol / L to 0.00015 mol / L, and the concentration of the iodate source is measured based on the molar concentration of iodine element in the mixture.

17. The preparation method according to any one of claims 8 to 16, characterized in that: The reaction temperature is 180° C. to 220° C., and the reaction time is 24 h to 120 h.

18. The preparation method according to any one of claims 8 to 17, characterized in that: After the reaction is completed, cool down; The cooling rate is 0.1°C / hour to 2°C / hour.

19. A direct X-ray detector, characterized in that: The direct X-ray detector includes an electrode and a light absorbing layer; The light absorbing layer is selected from one of the rare earth iodate materials according to any one of claims 1 to 7.

20. The direct X-ray detector according to claim 19, characterized in that: The direct X-ray detector includes an upper electrode, a light absorbing layer and a lower electrode.

21. The direct X-ray detector according to claim 19 or 20, characterized in that: The light absorbing layer is selected from rare earth iodate materials or polycrystalline pressed sheets.

22. The direct X-ray detector according to any one of claims 19 to 21, characterized in that: The thickness of the upper electrode is 5 μm to 10 μm.

23. The direct X-ray detector according to any one of claims 19 to 22, characterized in that: The thickness of the light absorbing layer is 0.1 mm to 2 mm.

24. The direct X-ray detector according to any one of claims 19 to 23, characterized in that: The upper electrode and the lower electrode are independently selected from at least one of Ag, Au, Cu, Cr, and ITO.

25. The direct X-ray detector according to any one of claims 19 to 24, characterized in that: The sensitivity of the direct X-ray detector is 34.6μCGy -1 cm -2 ~1301.5μCGy -1 cm -2 .

26. The method for preparing a direct X-ray detector according to any one of claims 19 to 25, characterized in that: include: Apply the conductive silver paste evenly to the upper and lower surfaces of the rare earth iodate material and let it dry naturally. to the device unit of electrode / rare earth iodate material / electrode; The rare earth iodate material is selected from the rare earth iodate material according to any one of claims 1 to 7.

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