Multi-temperature-zone annealing method for sulfur oxide scintillation ceramic

Abstract

The invention belongs to the field of a sulfur oxide ceramic annealing process, and discloses a sulfur oxide scintillation ceramic multi-temperature-zone annealing method. Comprising the following steps: (1) respectively putting sulfur oxide scintillation ceramic and a sulfur source into a crucible I and a crucible II; in the crucible I, the sulfur oxide scintillation ceramic is filled with ceramic powder with the same components as the sulfur oxide scintillation ceramic; (2) respectively placing a crucible I and a crucible II in a temperature zone I and a temperature zone II of a heating furnace, wherein the temperature zone I is communicated with the temperature zone II; and (3) starting an annealing program, and annealing the sulfur oxide scintillation ceramic in a vacuum atmosphere. According to the annealing method, the light output, the production yield, the crystallinity and the uniformity of the crystal size of the sulfur oxide scintillation ceramic can be improved.

Description

Technical Field

[0001] The invention belongs to the field of sulfide oxide ceramic annealing technology, in particular to a multi-temperature zone annealing method for sulfide oxide scintillating ceramics. Background Art

[0002] Rare earth ion doped oxysulfide scintillating ceramics (such as gadolinium oxysulfide scintillating ceramics) have the advantages of high density, high light yield, stable chemical properties, relatively simple preparation process, and no cleavage during processing. They have become ideal scintillator materials with excellent comprehensive performance for radiation inspection instruments or detectors such as X-CT, high-speed X-ray scanners and article security inspectors.

[0003] The preparation process of sulfur oxide scintillating ceramics is complicated, and the impurity phase is difficult to control; oxygen / sulfur vacancy defects are easily generated during powder calcination or high-temperature sintering of ceramics, resulting in reduced scintillation performance such as light output and afterglow. Therefore, annealing of ceramics is very necessary. Annealing treatment will have the following problems: (1) Currently, the most commonly used annealing methods are vacuum annealing, air annealing, inert atmosphere or weak reducing atmosphere annealing. However, since the S in the structure of oxysulfide scintillating ceramics is unstable, annealing in a high-temperature vacuum environment can easily make the sulfur vacancy defects more serious. In addition, oxysulfide scintillating ceramics are easily oxidized at high temperatures and are not suitable for long-term annealing in air.

[0004] (2) Local overheating of the ceramic during the annealing process will cause stress concentration inside the material, which will lead to cracks and reduce the production yield of oxysulfide scintillating ceramics.

[0005] (3) When annealing is performed in an air atmosphere, the ceramic may react with oxygen to generate oxide impurities (such as gadolinium oxide), thereby affecting the performance of the ceramic. Summary of the invention

[0006] The object of the present invention is to provide a multi-temperature zone annealing method for oxysulfide ceramics to solve at least one technical problem existing in the background technology.

[0007] To achieve the above object, the technical solution adopted by the present invention is: A multi-temperature zone annealing method for oxysulfide scintillating ceramics comprises the following steps: (1) placing the oxysulfide scintillating ceramic and the sulfur source into crucible I and crucible II respectively; in crucible I, filling the oxysulfide scintillating ceramic with ceramic powder having the same composition as the oxysulfide scintillating ceramic; (2) Place crucible I and crucible II in temperature zone I and temperature zone II of the heating furnace respectively, and connect temperature zone I and temperature zone II; (3) Start the annealing process and perform annealing of the sulfur oxide scintillating ceramic in a vacuum atmosphere.

[0008] Furthermore, the oxysulfide in the oxysulfide scintillating ceramic is RE2O2S, and RE is at least one of Gd, Tb, Y, La, Lu, Eu, Nd, Ce, Er, Pr, Yb, and Sm.

[0009] Furthermore, the sulfur source is a sulfur-containing compound that can generate sulfur vapor or sulfur-containing gas by heating; during the annealing process, the sulfur source is heated in the heating furnace temperature zone II to generate sulfur vapor or sulfur-containing gas, and the sulfur vapor or sulfur-containing gas passes through the connecting part between temperature zones I and II and enters temperature zone I to contact the sulfur oxide scintillating ceramic. By controlling the heating temperature and time of the sulfur source, the generation rate and amount of sulfur vapor can be effectively controlled, and then the sulfur pressure can be controlled.

[0010] Preferably, the sulfur-containing compound includes but is not limited to sublimated sulfur, sulfur, sulfate, bisulfite, sulfite, sodium thiosulfate, and the like.

[0011] It is further preferred that the sulfur source is sublimated sulfur, and the purity of the sublimated sulfur is not less than 98%.

[0012] Furthermore, the oxidized sulfide scintillating ceramic to be annealed is subjected to a polishing pre-treatment, preferably using a polishing machine to grind and polish the oxidized sulfide scintillating ceramic on both sides to a mirror surface, so as to remove impurities on the surface of the oxidized sulfide scintillating ceramic.

[0013] Furthermore, after landfilling, the outer surface of the oxysulfide scintillating ceramic is covered with ceramic powder.

[0014] Further preferably, the thickness of the ceramic powder filler between the sulfur oxide scintillating ceramic and the side wall of the crucible is 1~5 cm; the thickness of the ceramic powder filler covering the sulfur oxide scintillating ceramic is 1~5 cm; the thickness of the ceramic powder filler between the sulfur oxide scintillating ceramic and the bottom of the crucible is 0.5~2 cm.

[0015] Furthermore, the crucible I is an alumina crucible; the crucible II is a corundum crucible.

[0016] The present invention takes into account that too low an annealing temperature will lead to reduced performance, and too high a temperature will cause oxidation of the sulfur oxide scintillating ceramic, affecting the optical performance. Further, the annealing temperature of the temperature zone I is 800-1200°C; by adjusting the temperature of the temperature zone II, the sulfur pressure P of the temperature zone I during the annealing and heating process of the temperature zone I is controlled, 0<P≤0.02MPa.

[0017] Furthermore, the annealing procedure of the temperature zone I is: heating at a heating rate β1, 0<β1≤20℃ / min, until the temperature of the temperature zone I reaches T1, 600≤T1≤800℃, heating at a heating rate β2, 0<β2≤10℃ / min, until the temperature of the temperature zone I reaches T2, 800≤T2≤1200℃, and maintaining the constant temperature for 1~24h, wherein β1>β2, T1<T2.

[0018] More preferably, 3≤β1≤15℃ / min; 3≤β2≤8℃ / min; constant temperature for 2-12h.

[0019] It is further preferred to maintain the temperature for 3 to 8 hours.

[0020] Further, after the constant temperature of temperature zone I is finished, temperature zone I is cooled at a cooling rate V, 0<V≤20℃ / min, until the temperature of furnace chamber temperature zone I drops below 300℃, and the program is terminated.

[0021] More preferably, 5≤V≤10°C / min.

[0022] Furthermore, the sulfur pressure P of temperature zone I is controlled during the annealing heating process of temperature zone I, 0<P≤0.01MPa.

[0023] It is further preferred to control the sulfur pressure P in temperature zone I during the annealing heating process in temperature zone I to 500Pa≤P≤3800Pa.

[0024] Furthermore, the temperature of the temperature zone II is 300-1500°C.

[0025] Furthermore, the annealing procedure of the temperature zone II is: heating at a heating rate of 1-20°C / min to a temperature of 300-1500°C in the temperature zone II, and then regulating the generation rate and amount of sulfur vapor by changing the temperature and time, thereby controlling the sulfur pressure.

[0026] More preferably, the heating rate is 3-10°C / min.

[0027] More preferably, the heating rate is 5°C / min.

[0028] Furthermore, after annealing is completed, the ceramic powder is recovered and recycled.

[0029] Furthermore, after annealing, the annealed oxysulfide scintillating ceramic is washed with deionized water and then wiped with dilute nitric acid to remove surface impurities. It is further preferred that the concentration of the dilute nitric acid used does not exceed 10wt%, and it is further preferred that the concentration of the dilute nitric acid is 3-5wt%.

[0030] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts the method of placing a sulfur source in a vacuum sealing device for annealing, and realizes dual control of the ceramic annealing temperature and the sulfur source decomposition temperature through a dual-temperature zone temperature control system. Since the temperature of sulfur vapor or sulfur-containing gas generated by the decomposition of the sulfur source under high temperature is different, the sulfur partial pressure is controlled by controlling the temperature. As the temperature rises, the gas pressure of the sulfur vapor or sulfur-containing gas increases, so that some sulfur vacancies on the surface of the ceramic are evenly filled, thereby improving the optical properties of the sulfur oxide scintillating ceramic.

[0031] Considering that different sulfur-containing compounds decompose to produce sulfur vapor or sulfur-containing gas at different temperatures, and that too high an annealing temperature will cause the S and O elements in the sulfur oxide scintillating ceramic components to volatilize and generate oxides, thereby reducing the optical properties of the ceramics, and too high an annealing temperature will also cause thermal corrosion on the ceramic surface, causing the grains to become rough, requiring secondary grinding and polishing, which will also reduce the performance of the ceramics. The present invention creatively adopts dual-temperature zone heating control, and by adjusting the temperature control, the sulfur source is decomposed at a specific temperature, so that the sulfur source and the sulfur oxide scintillating ceramic to be annealed can be controlled separately in temperature, which can well avoid the above problems.

[0032] The present invention buries and covers the sulfide scintillating ceramics that need to be annealed with fillers, thereby avoiding the thermal stress generated by the direct contact between the surface of the sulfide scintillating ceramics being annealed and the crucible during the annealing process, creating a more uniform annealing environment, and being more conducive to the release of thermal stress, so that the ceramics have higher mechanical strength and avoid cracking during cutting and array processing. Therefore, the yield rate of the sulfide scintillating ceramics annealing processing using this annealing method is greatly improved compared with the traditional annealing method.

[0033] The present invention grinds and polishes the oxysulfide scintillating ceramics and removes impurities on the surface of the oxysulfide scintillating ceramics before annealing, which can improve the transmittance of the oxysulfide scintillating ceramics to a certain extent and further improve the yield rate of the oxysulfide scintillating ceramics produced by the present invention.

[0034] Placing a sulfur source in a vacuum-sealed device can reduce the oxidation reaction between ceramics and oxygen, which helps to improve the crystal structure and grain growth of ceramics. At high temperatures, the migration and recrystallization process of ceramic crystals are smoother, which is beneficial to the growth of ceramic grains and the rearrangement of grain boundaries, thereby improving the crystallinity of the ceramic and the uniformity of crystal size.

[0035] The present invention performs annealing under vacuum sealing conditions, uses a sulfur source to evaporate under high temperature to become sulfur vapor or sulfur-containing gas to create a sulfur-containing atmosphere condition, and after the annealing is completed, the sulfur vapor or sulfur-containing gas condenses, and there is no need to carry out tail gas treatment, and there is no waste gas pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0037] In the attached picture: Figure 1 It is a schematic diagram of the dual-temperature zone annealing device of the present invention.

[0038] Figure 2 This is a flow chart of the annealing process of the present invention.

[0039] Figure 3 : is a relative light output test chart of the ceramic before and after annealing in Example 2.

[0040] Figure 4 The XRD spectra of the ceramics after annealing in Example 3 and Comparative Example 1 are shown.

[0041] Figure 5 This is the SEM image of the ceramic after annealing in Example 5. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully below in conjunction with the accompanying drawings and preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0043] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0044] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0045] Example 1 A method for annealing oxysulfide scintillating ceramics, such as Figure 2 As shown, the following steps are included: (1) Use a polishing machine to perform double-sided grinding and polishing on the gadolinium oxysulfide scintillation ceramic to remove impurities on the surface of the gadolinium oxysulfide scintillation ceramic.

[0046] (2) Take a ceramic powder with the same composition as the gadolinium oxysulfide scintillating ceramic, such as Figure 1 As shown, the gadolinium oxysulfide scintillating ceramic is placed in an alumina crucible and ceramic powder is buried so that the ceramic powder completely wraps the gadolinium oxysulfide scintillating ceramic to be annealed, the thickness of the ceramic powder filling between the oxysulfide scintillating ceramic and the side wall of the crucible is 1 cm; the thickness of the ceramic powder filling covering the top is 1 cm; the thickness of the ceramic powder filling between the bottom of the crucible is 1 cm, and it is placed in the temperature zone I position of the double-temperature zone high-temperature tube furnace; Sublimed sulfur with a purity of 99% is placed in a corundum crucible as a sulfur source and placed in the temperature zone II position of a double-temperature zone high-temperature tube furnace.

[0047] (3) Annealing process setting: Evacuate the furnace chamber until the vacuum pressure reading is -0.1MPa, then perform annealing. Set the annealing process for the two temperature zones in the furnace chamber separately: The annealing program of the temperature zone I where the gadolinium oxysulfide scintillating ceramic to be annealed is set to increase the temperature at a rate of 10°C / min until the temperature of the temperature zone I reaches 800°C, then the heating rate is reduced to 8°C / min until the temperature of the temperature zone I reaches 1000°C, and the temperature is kept constant for 4 hours; The annealing program of temperature zone II where the sulfur source is placed is set to heat up at 5°C / min until the sulfur pressure in furnace chamber temperature zone I reaches 800Pa. The temperature of temperature zone II is regulated in the range of 300~1500°C to maintain the sulfur pressure in furnace chamber temperature zone I at 500~1000Pa; the end time of regulation is set to be consistent with the end time of constant temperature in temperature zone I. (4) Then, the dual temperature zones are cooled at a rate of 10°C / min at the same time until the furnace chamber temperature reaches 200°C. The program is terminated, and the temperature is automatically cooled to room temperature. The annealed gadolinium oxysulfide scintillating ceramic is taken out, and the ceramic powder and the residual sulfur powder on the tube wall are collected for reuse next time. Annealing is then completed.

[0048] (5) After washing the annealed ceramic with deionized water, wipe it with 5 wt% dilute nitric acid to remove surface impurities.

[0049] Example 2 A method for annealing oxysulfide scintillating ceramics, such as Figure 2 As shown, the following steps are included: (1) Use a polishing machine to perform double-sided grinding and polishing on the gadolinium oxysulfide scintillation ceramic to remove impurities on the surface of the gadolinium oxysulfide scintillation ceramic.

[0050] (2) Take a ceramic powder with the same composition as the gadolinium oxysulfide scintillating ceramic, such as Figure 1 As shown, the gadolinium oxysulfide scintillating ceramic is placed in an alumina crucible and ceramic powder is buried so that the ceramic powder completely wraps the gadolinium oxysulfide scintillating ceramic to be annealed, the thickness of the ceramic powder filler between the oxysulfide scintillating ceramic and the side wall of the crucible is 1 cm; the thickness of the ceramic powder filler covering the top is 2 cm; the thickness of the ceramic powder filler between the bottom of the crucible is 1 cm, and it is placed in the temperature zone I position of the double-temperature zone high-temperature tube furnace; Sublimed sulfur with a purity of 99% is placed in a corundum crucible as a sulfur source and placed in the temperature zone II position of a double-temperature zone high-temperature tube furnace.

[0051] (3) Annealing process setting: Evacuate the furnace chamber until the vacuum pressure reading is -0.1MPa, then perform annealing. Set the annealing process for the two temperature zones in the furnace chamber separately: The annealing program of temperature zone I where the gadolinium oxysulfide scintillating ceramic to be annealed is set to increase the temperature at a rate of 5°C / min until the temperature of furnace chamber temperature zone I reaches 800°C and keep the temperature constant for 4 hours; The annealing program of temperature zone II where the sulfur source is placed is set to heat up at 5°C / min until the sulfur pressure in furnace chamber temperature zone I reaches 800Pa. The temperature of temperature zone II is regulated in the range of 300~1500°C to maintain the sulfur pressure in furnace chamber temperature zone I at 500~1000Pa; the end time of regulation is set to be consistent with the end time of constant temperature in temperature zone I. (4) Then, the dual temperature zones are cooled at a rate of 10°C / min at the same time until the furnace chamber temperature reaches 200°C. The program is terminated, and the temperature is automatically cooled to room temperature. The annealed gadolinium oxysulfide scintillating ceramic is taken out, and the ceramic powder and the residual sulfur powder on the tube wall are collected for reuse next time. Annealing is then completed.

[0052] (5) After washing the annealed ceramic with deionized water, wipe it with 5 wt% dilute nitric acid to remove surface impurities.

[0053] Example 3 A method for annealing oxysulfide scintillating ceramics, such as Figure 2 As shown, the following steps are included: (1) Use a polishing machine to perform double-sided grinding and polishing on the gadolinium oxysulfide scintillation ceramic to remove impurities on the surface of the gadolinium oxysulfide scintillation ceramic.

[0054] (2) Take a ceramic powder with the same composition as the gadolinium oxysulfide scintillating ceramic, such as Figure 1 As shown, the gadolinium oxysulfide scintillating ceramic is placed in an alumina crucible and ceramic powder is buried so that the ceramic powder completely wraps the gadolinium oxysulfide scintillating ceramic to be annealed, the thickness of the ceramic powder filling between the oxysulfide scintillating ceramic and the side wall of the crucible is 2 cm; the thickness of the ceramic powder filling covering the top is 2 cm; the thickness of the ceramic powder filling between the bottom of the crucible is 2 cm, and it is placed in the temperature zone I position of the double-temperature zone high-temperature tube furnace; Sublimed sulfur with a purity of 99.9% is placed in a corundum crucible as a sulfur source and placed in temperature zone II of a double-temperature zone high-temperature tube furnace.

[0055] (3) Annealing process setting: Evacuate the furnace chamber until the vacuum pressure reading is -0.1MPa, then perform annealing. Set the annealing process for the two temperature zones in the furnace chamber separately: The annealing program of the temperature zone I where the gadolinium oxysulfide scintillating ceramic to be annealed is set to increase the temperature at a rate of 5°C / min until the temperature of the furnace chamber temperature zone I reaches 800°C, and then the heating rate is reduced to 3°C / min until the temperature of the furnace chamber temperature zone I reaches 1000°C, and the temperature is kept constant for 6 hours; The annealing program of temperature zone II where the sulfur source is placed is set to heat up at 5°C / min until the sulfur pressure in furnace chamber temperature zone I reaches 1200Pa. The temperature of temperature zone II is regulated in the range of 300~1500°C to maintain the sulfur pressure in furnace chamber temperature zone I at 1000~1500Pa; the end time of regulation is set to be consistent with the end time of constant temperature in temperature zone I. (4) Then, the dual temperature zones are cooled at a rate of 10°C / min at the same time until the furnace chamber temperature reaches 200°C. The program is terminated, and the temperature is automatically cooled to room temperature. The annealed gadolinium oxysulfide scintillating ceramic is taken out, and the ceramic powder and the residual sulfur powder on the tube wall are collected for reuse next time. Annealing is then completed.

[0056] (5) After washing the annealed ceramic with deionized water, wipe it with 5 wt% dilute nitric acid to remove surface impurities.

[0057] Example 4 A method for annealing oxysulfide scintillating ceramics, such as Figure 2 As shown, the following steps are included: (1) Use a polishing machine to perform double-sided grinding and polishing on the gadolinium oxysulfide scintillation ceramic to remove impurities on the surface of the gadolinium oxysulfide scintillation ceramic.

[0058] (2) Take a ceramic powder with the same composition as the gadolinium oxysulfide scintillating ceramic, such as Figure 1 As shown, the gadolinium oxysulfide scintillating ceramic is placed in an alumina crucible and ceramic powder is buried so that the ceramic powder completely wraps the gadolinium oxysulfide scintillating ceramic to be annealed, the thickness of the ceramic powder filling between the oxysulfide scintillating ceramic and the side wall of the crucible is 1 cm; the thickness of the ceramic powder filling covering the top is 1 cm; the thickness of the ceramic powder filling between the bottom of the crucible is 1 cm, and it is placed in the temperature zone I position of the double-temperature zone high-temperature tube furnace; Sublimed sulfur with a purity of 99.9% is placed in a corundum crucible as a sulfur source and placed in temperature zone II of a double-temperature zone high-temperature tube furnace.

[0059] (3) Annealing process setting: Evacuate the furnace chamber until the vacuum pressure reading is -0.1MPa, then perform annealing. Set the annealing process for the two temperature zones in the furnace chamber separately: Set the annealing program of temperature zone I where the gadolinium oxysulfide scintillating ceramic to be annealed to increase the temperature at a rate of 8°C / min until the furnace chamber temperature reaches 800°C, then reduce the heating rate to 3°C / min until the furnace chamber temperature reaches 1100°C and keep the temperature constant for 4 hours; The annealing program of temperature zone II where the sulfur source is placed is set to heat up at 10℃ / min until the sulfur pressure in furnace chamber temperature zone I reaches 2000Pa. The temperature of temperature zone II is regulated in the range of 300~1500℃ to maintain the sulfur pressure in furnace chamber temperature zone I at 1800~2300Pa; the end time of regulation is set to be consistent with the end time of constant temperature in temperature zone I. (4) Then, the dual temperature zones are cooled at a rate of 10°C / min at the same time until the furnace chamber temperature reaches 200°C. The program is terminated, and the temperature is automatically cooled to room temperature. The annealed gadolinium oxysulfide scintillating ceramic is taken out, and the ceramic powder and the residual sulfur powder on the tube wall are collected for reuse next time. Annealing is then completed.

[0060] (5) After washing the annealed ceramic with deionized water, wipe it with 5 wt% dilute nitric acid to remove surface impurities.

[0061] Example 5 A method for annealing oxysulfide scintillating ceramics, such as Figure 2 As shown, the following steps are included: (1) Use a polishing machine to perform double-sided grinding and polishing on the gadolinium oxysulfide scintillation ceramic to remove impurities on the surface of the gadolinium oxysulfide scintillation ceramic.

[0062] (2) Take a ceramic powder with the same composition as the gadolinium oxysulfide scintillating ceramic, such as Figure 1 As shown, the gadolinium oxysulfide scintillating ceramic is placed in an alumina crucible and ceramic powder is buried so that the ceramic powder completely wraps the gadolinium oxysulfide scintillating ceramic to be annealed, the thickness of the ceramic powder filling between the sulfur oxide scintillating ceramic and the side wall of the crucible is 1.5 cm; the thickness of the ceramic powder filling covering the top is 1.5 cm; the thickness of the ceramic powder filling between the bottom of the crucible is 1.5 cm, and it is placed in the temperature zone I position of the double-temperature zone high-temperature tube furnace; Sublimed sulfur with a purity of 99% is placed in a corundum crucible as a sulfur source and placed in the temperature zone II position of a double-temperature zone high-temperature tube furnace.

[0063] (3) Annealing process setting: Evacuate the furnace chamber until the vacuum pressure reading is -0.1MPa, then perform annealing. Set the annealing process for the two temperature zones in the furnace chamber separately: The annealing program of temperature zone I where the gadolinium oxysulfide scintillating ceramic to be annealed is set to increase the temperature at a rate of 10°C / min until the furnace chamber temperature reaches 1000°C and keep the temperature constant for 4 hours; The annealing program of temperature zone II where the sulfur source is placed is set to heat up at 5°C / min until the sulfur pressure in furnace chamber temperature zone I reaches 2500Pa. The temperature of temperature zone II is regulated in the range of 300~1500°C to maintain the sulfur pressure in furnace chamber temperature zone I at 2200~2800Pa. The end time of regulation is set to be consistent with the end time of constant temperature in temperature zone I. (4) Then, the dual temperature zones are cooled at a rate of 10°C / min at the same time until the furnace chamber temperature reaches 200°C. The program is terminated, and the temperature is automatically cooled to room temperature. The annealed gadolinium oxysulfide scintillating ceramic is taken out, and the ceramic powder and the residual sulfur powder on the tube wall are collected for reuse next time. Annealing is then completed.

[0064] (5) Wash the annealed ceramic with deionized water.

[0065] Example 6 A method for annealing oxysulfide scintillating ceramics, such as Figure 2 As shown, the following steps are included: (1) Use a polishing machine to perform double-sided grinding and polishing on the gadolinium oxysulfide scintillation ceramic to remove impurities on the surface of the gadolinium oxysulfide scintillation ceramic.

[0066] (2) Take a ceramic powder with the same composition as the gadolinium oxysulfide scintillating ceramic, such as Figure 1 As shown, the gadolinium oxysulfide scintillation ceramic is placed in an alumina crucible and ceramic powder is buried so that the ceramic powder completely wraps the gadolinium oxysulfide scintillation ceramic to be annealed, the thickness of the ceramic powder filling between the sulfur oxide scintillation ceramic and the side wall of the crucible is 3 cm; the thickness of the ceramic powder filling covering the top is 3 cm; the thickness of the ceramic powder filling between the bottom of the crucible is 2 cm, and it is placed in the temperature zone II position of the double-temperature zone high-temperature tube furnace; Sublimed sulfur with a purity of 99% is placed in a corundum crucible as a sulfur source and placed in temperature zone I of a double-temperature zone high-temperature tube furnace.

[0067] (3) Annealing process setting: Evacuate the furnace chamber until the vacuum pressure reading is -0.1MPa, then perform annealing. Set the annealing process for the two temperature zones in the furnace chamber separately: Set the annealing program of temperature zone I where the gadolinium oxysulfide scintillating ceramic to be annealed to increase the temperature at a rate of 10°C / min until the furnace chamber temperature reaches 800°C, then reduce the heating rate to 5°C / min until the furnace chamber temperature reaches 1000°C and keep the temperature constant for 4 hours; The annealing program of temperature zone II where the sulfur source is placed is set to heat up at 5°C / min until the sulfur pressure in furnace chamber temperature zone I reaches 3000Pa. The temperature of temperature zone II is regulated in the range of 300~1500°C to maintain the sulfur pressure in furnace chamber temperature zone I at 2800~3200Pa; the end time of regulation is set to be consistent with the end time of constant temperature in temperature zone I. (4) Then, the dual temperature zones are cooled at a rate of 15°C / min at the same time. When the furnace chamber temperature reaches 200°C, the program is terminated. After the temperature is automatically cooled to room temperature, the annealed gadolinium oxysulfide scintillating ceramic is taken out, and the ceramic powder and the residual sulfur powder on the tube wall are collected for reuse next time. The annealing is then completed.

[0068] (5) After washing the annealed ceramic with deionized water, wipe it with 5 wt% dilute nitric acid to remove surface impurities.

[0069] Example 7 A method for annealing oxysulfide scintillating ceramics comprises the following steps: (1) Use a polishing machine to perform double-sided grinding and polishing on the lanthanum gadolinium oxysulfide scintillation ceramic to remove impurities on the surface of the gadolinium oxysulfide scintillation ceramic.

[0070] (2) Take a ceramic powder with the same composition as the lanthanum gadolinium oxysulfide scintillating ceramic, such as Figure 1 As shown, the lanthanum gadolinium oxysulfide scintillation ceramic is placed in an alumina crucible, and ceramic powder is buried in it so that the ceramic powder completely wraps the gadolinium oxysulfide scintillation ceramic to be annealed, the thickness of the ceramic powder filler between the oxysulfide scintillation ceramic and the side wall of the crucible is 2 cm; the thickness of the ceramic powder filler covering the top is 2 cm; the thickness of the ceramic powder filler between the bottom of the crucible is 2 cm, and it is placed in the temperature zone I position of the double-temperature zone high-temperature tube furnace; Sublimed sulfur with a purity of 99% is placed in a corundum crucible as a sulfur source and placed in the temperature zone II position of a double-temperature zone high-temperature tube furnace.

[0071] (3) Annealing process setting: Evacuate the furnace chamber until the vacuum pressure reading is -0.1MPa, then perform annealing. Set the annealing process for the two temperature zones in the furnace chamber separately: The annealing program of temperature zone I, where the lanthanum gadolinium sulfide oxide scintillation ceramic to be annealed is placed, is set to heat up at a rate of 10°C / min until the furnace chamber temperature reaches 800°C, and then the heating rate is reduced to 5°C / min until the furnace chamber temperature reaches 1000°C, and the temperature is kept constant for 4 hours; The annealing program of temperature zone II where the sulfur source is placed is set to heat up at 10℃ / min until the sulfur pressure in furnace chamber temperature zone I reaches 3500Pa. The temperature of temperature zone II is regulated in the range of 300~1500℃ to maintain the sulfur pressure in furnace chamber temperature zone I at 3200~3800Pa; the end time of regulation is set to be consistent with the end time of constant temperature in temperature zone I. (4) Then, the dual temperature zones are cooled at a rate of 15°C / min at the same time. When the furnace chamber temperature reaches 200°C, the program is terminated. After the temperature is automatically cooled to room temperature, the annealed lanthanum gadolinium sulfide scintillation ceramic is taken out, and the lanthanum gadolinium sulfide powder and the residual sulfur powder on the tube wall are collected for reuse next time. Annealing is then completed.

[0072] Comparative Example 1 A method for annealing oxysulfide scintillating ceramics comprises the following steps: (1) Use a polishing machine to perform double-sided grinding and polishing on the gadolinium oxysulfide scintillation ceramic to remove impurities on the surface of the gadolinium oxysulfide scintillation ceramic.

[0073] (2) Take ceramic powder with the same composition as that of gadolinium oxysulfide scintillation ceramic, place the gadolinium oxysulfide scintillation ceramic in an alumina crucible, and bury the ceramic powder so that the ceramic powder completely wraps the gadolinium oxysulfide scintillation ceramic to be annealed. The thickness of the ceramic powder filling between the sulfur oxide scintillation ceramic and the side wall of the crucible is 2 cm; the thickness of the ceramic powder filling covering the top is 2 cm; the thickness of the ceramic powder filling between the crucible and the bottom of the crucible is 2 cm. Place it in the temperature zone I position of the dual-temperature zone high-temperature tube furnace; (3) Annealing treatment program setting: After adding insulation bricks at both ends of the corundum tube, annealing is performed directly in an air atmosphere, and the annealing program in the furnace chamber is set: The annealing program of the gadolinium oxysulfide scintillating ceramic to be annealed is set to heat up at a rate of 5°C / min until the furnace chamber temperature reaches 800°C, then the heating rate is reduced to 3°C / min until the furnace chamber temperature reaches 1000°C, and the temperature is kept constant for 6 hours; (4) The temperature is then lowered at a rate of 10°C / min until the furnace chamber temperature reaches 200°C. The program is terminated, and the temperature is automatically lowered to room temperature. The annealed gadolinium oxysulfide scintillating ceramic is taken out and the ceramic powder is collected for reuse next time. Annealing is then completed.

[0074] (5) After washing the annealed ceramic with deionized water, wipe it with 5 wt% dilute nitric acid to remove surface impurities.

[0075] The relative light output of the ceramics before and after annealing in Example 2 was tested using the scintillation performance testing platform SPM_Platform, with a NA22 source and a testing time of 180s. The test results are shown in Figure 3 As shown, it can be seen that the annealing in a sulfur-containing atmosphere in Example 2 has a significant effect on improving the light output of the gadolinium oxysulfide scintillating ceramic.

[0076] Figure 4 The XRD spectra of the ceramic after annealing in Example 3 and Comparative Example 1 are shown in the figure. It can be seen from the figure that the XRD diffraction peak of the ceramic annealed in the sulfur-containing atmosphere in Example 3 is sharp, the intensity is higher, the crystallinity is better, the diffraction peak position is completely consistent with the standard card, and there is no impurity phase.

[0077] Figure 5 This is the SEM image of the ceramic after annealing in Example 5. It can be seen from the image that the grain size distribution is uniform and there are no obvious cracks or pores.

[0078] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention.

Claims

1. A multi-temperature zone annealing method for oxysulfide scintillating ceramics, characterized in that: The following steps are involved: (1) Place sulfur oxide scintillating ceramic and sulfur source into crucible I and crucible II respectively; In crucible I, the oxysulfide scintillating ceramic is filled with ceramic powder having the same composition as the oxysulfide scintillating ceramic; (2) Place crucible I and crucible II in temperature zone I and temperature zone II of the heating furnace respectively, and connect temperature zone I and temperature zone II; (3) Start the annealing process and perform annealing of the sulfur oxide scintillating ceramic in a vacuum atmosphere.

2. The annealing method according to claim 1, characterized in that The oxysulfide in the oxysulfide scintillating ceramic is RE2O2S, and RE is at least one of Gd, Tb, Y, La, Lu, Eu, Nd, Ce, Er, Pr, Yb, and Sm.

3. The annealing method according to claim 1, characterized in that The sulfur source is a sulfur-containing compound that can generate sulfur vapor or sulfur-containing gas by heating; Preferably, the sulfur source is at least one of sublimated sulfur, sulfur, sulfate, bisulfite, sulfite, and sodium thiosulfate; Preferably, the sulfur source is sublimated sulfur, and the purity of the sublimated sulfur is not less than 98%.

4. The annealing method according to claim 1, characterized in that After landfilling, the outer surface of the oxysulfide scintillating ceramic is covered with ceramic powder.

5. The annealing method according to claim 4, characterized in that: The thickness of the ceramic powder filler between the sulfur oxide scintillation ceramic and the bottom of the crucible is 0.5-2 cm; the thickness of the ceramic powder filler between the sulfur oxide scintillation ceramic and the side wall of the crucible is 1-5 cm; the thickness of the ceramic powder filler covering the sulfur oxide scintillation ceramic is 1-5 cm.

6. The annealing method according to claim 1, characterized in that: The crucible I is an alumina crucible; the crucible II is a corundum crucible.

7. The annealing method according to any one of claims 1 to 6, characterized in that: The annealing temperature of the temperature zone I is 800-1200°C; by adjusting the temperature of the temperature zone II, the sulfur pressure P of the temperature zone I during the annealing heating process of the temperature zone I is controlled, 0<P≤0.02MPa.

8. The annealing method according to claim 7, characterized in that: The annealing procedure of the temperature zone I is: heating at a heating rate β1, 0<β1≤20℃ / min, until the temperature of the temperature zone I reaches T1, 600≤T1≤800℃, heating at a heating rate β2, 0<β2≤10℃ / min, until the temperature of the temperature zone I reaches T2, 800≤T2≤1200℃, and keeping the temperature constant for 1~24h, wherein β1>β2, T1<T2; Preferably, 3≤β1≤15℃ / min; 3≤β2≤8℃ / min; constant temperature for 2~12h.

9. The annealing method according to claim 7, characterized in that: After the constant temperature of temperature zone I is finished, temperature zone I is cooled at a cooling rate V, 0<V≤20℃ / min, until the temperature of furnace chamber temperature zone I drops below 300℃, and the program is terminated; Preferably, 5≤V≤10°C / min.

10. The annealing method according to any one of claims 7 to 9, characterized in that: Control the sulfur pressure P of temperature zone I during annealing and heating in temperature zone I, 0<P≤0.01MPa; It is preferred to control the sulfur pressure P in temperature zone I during the annealing heating process in temperature zone I to 500Pa≤P≤3800Pa.

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