Method for preparing novel hafnium calcium cerium scintillating material by solid phase method

Abstract

The invention discloses a method for preparing a novel hafnium calcium cerium scintillating material by a solid phase method. The novel hafnium calcium cerium scintillating material is a novel scintillator material with excellent performance. CaHfO3: Ce nanoscale powder is synthesized by adopting a solid-phase reaction method, lattice distortion of a matrix CaHfO3 can be caused by doping a small amount of Ce < 3 + > ions, and a cubic crystal system structure is not changed. When the molar concentration of the doped Ce < 3 + > is 0.9%, the emission peak value reaches the maximum; when the Ce < 3 + > content is 1.1%, the emission peak intensity is reduced. Meanwhile, the luminous intensity of the powder is influenced by the crystallinity and morphology size of a sample, and the powder with high crystallinity, uniform size and good dispersity has optimal luminous performance.

Description

Technical Field

[0001] The invention belongs to the technical field of novel scintillator materials, and in particular relates to a method for preparing a novel calcium cerium hafniumate scintillator material by a solid phase method. Background Art

[0002] Nuclear medicine imaging technology is an important means of medical technology detection. Since the 1950s, medical imaging technology has developed rapidly, especially the ray imaging technology based on scintillation detectors. With the growing demand for various medical imaging equipment, the demand for scintillators as the core sensitive components in detectors for detecting high-energy photons is huge.

[0003] Compared with scintillating crystals, scintillating ceramics can achieve uniform ion doping, tailorable size, good mechanical processing performance, simple process, and low preparation cost with the help of powder sintering theory and sintering process. At the same time, with the advancement of sintering technology, transparent scintillating ceramics have become a reality. As a strong competitor of single crystal scintillators, polycrystalline ceramic scintillators, (Y,Gd)2O3:Eu 3+ (YGO) material is a ceramic scintillator that has been successfully applied, but its luminescence decay time is long. Now the MHfO3 (M=Ca, Sr, Ba) material system doped with Ce ions is a very promising scintillating ceramic. The luminescence intensity of Ce doped with rare earth ions is large, the decay time is short, and the cubic crystal structure of the matrix is ​​easy to achieve transparency. The present invention provides a calcium hafnium salt (CaHfO3) doped with cerium ions (Ce3+), and this doping can significantly change the properties of the material, especially in terms of luminescence and scintillation characteristics. Due to its high density and high effective atomic number, CaHfO3:Ce is considered to be an attractive scintillating material that absorbs gamma rays and X-rays. It is widely used in instruments in the fields of medical imaging (such as PET), security inspection, astrophysics, high-energy physics and downhole logging. Summary of the invention

[0004] The purpose of the present invention is to propose a method for preparing a novel calcium cerium hafnate scintillating material by a solid phase method. The characteristics of the powder material have an important influence on the properties of the ceramic scintillator material. The present invention synthesizes CaHfO3:Ce ultrafine powder by a solid phase reaction method for the first time, and synthesizes CaHfO3:Ce nanoparticles with a nearly spherical shape, good dispersion, and a primary particle size of about 30nm. This method has low cost, simple process, high purity, few crystal surface defects, no particle agglomeration, good filling property, and is convenient for large-scale industrial production, and has certain practical significance.

[0005] The specific technical solution adopted by the present invention is as follows:

[0006] The present invention proposes a method for preparing a novel calcium cerium hafnate scintillating material by a solid phase method, wherein the general formula of the system composition is MHfO3 (M=Ca, Sr, Ba)-Ce. By comparing the precursors Hf(OH)4 and HfO2, it can be known that Hf(OH)4 is more suitable as a reaction precursor for preparing CaHfO3 nanopowder.

[0007] According to the present invention, the solid phase reaction method is used to prepare CaHfO3:Ce nanopowder, and the specific steps are as follows:

[0008] S1: Using CaO, Ce(NO3)3·6H2O, HfOCl2·8H2O, and NH3·H2O as raw materials, various raw materials are weighed on an electronic balance after calculating the precise stoichiometric ratio;

[0009] S2: The HfOCl2·8H2O raw material described in S1 is prepared into a 1 mol / L solution, and a 1 mol / L concentration of NH3·H2O solution is used for forward titration into a 500 ml beaker on a peristaltic pump. The mixed solution under the action of a magnetic stirrer presents a white, flocculent Hf(OH)4 precipitate; S3: After filtering the Hf(OH)4 precipitate described in S2, the white precursor needs to be washed twice with deionized water and anhydrous ethanol respectively to remove NH4 + , Cl - wait;

[0010] S4: placing the precipitate in S3 into an oven at 80°C for drying, and then calcining it at 1100°C in a box-type resistance furnace to obtain HfO2;

[0011] S5: dissolve Ce(NO3)3·6H2O in S1 in water, and then add excess ammonia water to obtain Ce(OH)3 precipitate;

[0012] S6: repeatedly washing the Ce(OH)3 precipitate described in S5 to obtain a precipitate, and placing the precipitate in a box-type resistance furnace and calcining it at 1100° C. to obtain CeO2;

[0013] S7: CaO, HfO2 obtained in S4, and CeO2 obtained in S6 are proportioned according to the general formula of the system composition CaHfO3-Ce, accurately weighed, and then placed in a polyurethane grinding pot for wet ball milling for 12 to 36 hours, with a rotation speed of 300 to 600 r / min, the grinding balls are high-purity ZrO2, and the ball milling medium is anhydrous ethanol. S8: The ball milled slurry described in S7 is dried in a vacuum drying oven at 90°C for 12 hours, ground with a mortar, sieved with 200 mesh, placed in an alumina crucible in a box-type resistance furnace, and calcined at 900 to 1100°C for 2 hours to synthesize a CaHfO3:Ce ultra-pure nano powder sample.

[0014] Beneficial effects:

[0015] The present invention prepares a cerium ion (Ce3+) doped calcium hafnium salt (CaHfO3) ceramic scintillating material for the first time. The Ce3+ doping molar content is controlled at 0-1.1 mol%. By comparison, it can be seen that the synthesis of CaHfO3:Ce using Hf(OH)4 as the starting material is better than the powder prepared using HfO2 as the raw material. The particle size of the former sample is more uniform, no agglomeration occurs, and the dispersion is better. When doped with Ce 3+ When the molar concentration is 0.9%, the emission peak reaches the maximum.

[0016] The MHfO3 (M=Ca, Sr, Ba) material system doped with Ce ions is a promising scintillation ceramic. The results of the present invention are helpful to meet the domestic demand for the replacement of new ceramic scintillation materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The XRD spectrum of the CaHfO3 powder synthesized by using HfO2 as a precursor in the present invention;

[0018] Figure 2 The XRD spectrum of the CaHfO3 powder synthesized by using Hf(OH)4 as a precursor in the present invention;

[0019] Figure 3 For the different Ce of the present invention 3+ XRD patterns of CaHfO3:Ce powders with different doping concentrations calcined at 1100℃ for 2h;

[0020] Figure 4 For the different Ce of the present invention 3+ Emission spectra of CaHfO3:Ce powders with different concentrations;

[0021] Figure 5 This is the SEM morphology of samples calcined at different temperatures for 2h in the present invention. DETAILED DESCRIPTION

[0022] In order to explain the content of the present invention more clearly, the present invention is described in detail below in conjunction with the accompanying drawings.

[0023] The present invention provides a method for preparing a novel calcium cerium hafniumate scintillating material by a solid phase method, and the specific implementation method is as follows:

[0024] Example 1:

[0025] (1) Weigh HfOCl2·8H2O according to Table 1 to prepare a solution. Titrate with 1 mol / L NH3·H2O solution, and stir the mixed solution under magnetic stirring to obtain a white, flocculent Hf(OH)4 precipitate;

[0026] Table 1 is the calculation data of the present invention

[0027] Chemical formula <![CDATA[CaHfO3]]> CaO <![CDATA[HfOCl2·8H2O]]> <![CDATA[Ce(NO3)3·6H2O]]> Molecular weight 266.97 56.08 409.517 434.2225 Mass / g 1g 0.421 1.126 0.012

[0028] (2) Wash the Hf(OH)4 precipitate with anhydrous ethanol several times to remove NH 4+ , Cl - etc. The precipitate was dried at 80℃ for 4h, and calcined at 1100℃ in a box-type resistance furnace to obtain the precursor HfO2, thereby obtaining two Hf precursors, namely Hf(OH)4 and HfO2;

[0029] (3) Ce(NO)3·6H2O was dissolved in water with a concentration of 0.5 mol% of Ce ions, and then an excess of ammonia water was added to obtain a Ce(OH)3 precipitate. The precipitate was washed repeatedly and the hydroxide was used as a precursor of Ce.

[0030] (4) Hf(OH)4 was used as the precursor of Hf and CaO, and wet ball milled in a polyurethane mill for 36 h at a speed of 300 r / min. The grinding balls were high-purity ZrO2 and the ball milling medium was anhydrous ethanol.

[0031] (5) Then dried in a vacuum drying oven at 90°C for 12 h, ground in a mortar, sieved with 200 mesh, placed in an alumina crucible and calcined in a box-type resistance furnace at 900°C for 2 h to synthesize a CaHfO3:Ce nanopowder sample;

[0032] (6) Using HfO2 as a Hf precursor, repeating steps (4) and (5) to obtain precursors of different Hf sources and CaO, and then synthesizing an ultrapure CaHfO3:Ce nanopowder sample after ball milling and calcination.

[0033] Example 2:

[0034] (1) Weigh HfOCl2·8H2O according to Table 1 to prepare a solution. Titrate with 1 mol / L NH3·H2O solution, and stir the mixed solution under magnetic stirring to obtain a white, flocculent Hf(OH)4 precipitate;

[0035] (2) Wash the Hf(OH)4 precipitate with anhydrous ethanol several times to remove NH 4+ , Cl - The precipitate was placed in an oven and dried at 120°C for 5 hours, and then calcined at 1100°C in a box-type resistance furnace to obtain the precursor HfO2, thereby obtaining two Hf precursors, namely Hf(OH)4 and HfO2;

[0036] (3) Ce(NO)3·6H2O was dissolved in water with a concentration of 0.7 mol% of Ce ions, and then an excess of ammonia water was added to obtain a Ce(OH)3 precipitate. The precipitate was washed repeatedly and the Ce(OH)3 precipitate was used as a Ce precursor.

[0037] (4) Precursors of different Hf sources and CaO were wet-milled in a polyurethane mill for 36 h at a speed of 300 r / min. The grinding balls were high-purity ZrO2 and the milling medium was anhydrous ethanol.

[0038] (5) Then dried in a vacuum drying oven at 90°C for 6 h, ground in a mortar, sieved with 200 mesh, placed in an alumina crucible and calcined in a box-type resistance furnace at 1000°C for 2 h to synthesize a CaHfO3:Ce nanopowder sample;

[0039] Example 3:

[0040] (1) Weigh HfOCl2·8H2O according to the data calculated in Table 1 to prepare a solution. Titrate with 1 mol / L NH3·H2O solution, and stir the mixed solution under magnetic stirring to obtain a white, flocculent Hf(OH)4 precipitate;

[0041] (2) Wash the Hf(OH)4 precipitate with anhydrous ethanol several times to remove NH 4+ , Cl - The precipitate was placed in an oven and dried at 80°C for 2h, and then calcined at 1100°C in a box-type resistance furnace to obtain the precursor HfO2, thereby obtaining two Hf precursors, namely Hf(OH)4 and HfO2;

[0042] (3) Ce(NO)3·6H2O was dissolved in water with a concentration of 0.9 mol% of Ce ions, and then an excess of ammonia water was added to obtain a Ce(OH)3 precipitate. The precipitate was washed repeatedly and the Ce(OH)3 precipitate was used as a Ce precursor.

[0043] (4) Precursors of different Hf sources and CaO were placed in a polyurethane mill and wet-milled for 24 h at a speed of 300 r / min. The grinding balls were high-purity ZrO2 and the milling medium was anhydrous ethanol.

[0044] (5) Then dried in a vacuum drying oven at 90°C for 2 h, ground in a mortar, sieved with 200 mesh, placed in an alumina crucible and calcined in a box-type resistance furnace at 1100°C for 2 h to synthesize a CaHfO3:Ce nanopowder sample;

[0045] Figure 4 For the different Ce of the present invention 3+ The emission spectrum of CaHfO3:Ce powder with high concentration. The more active Hf(OH)4 reacts with CaO as the precursor and is calcined at 1100℃ for 2h. The luminescence intensity of the sample is similar to that of Ce 3+ The content is related to Ce 3+ The luminescence performance is optimal when the content is 0.9%, and concentration quenching will occur when the content exceeds this value.

[0046] Example 4:

[0047] (1) Weigh HfOCl2·8H2O according to the data calculated in Table 1 to prepare a solution. Titrate with 1 mol / L NH3·H2O solution, and stir the mixed solution under magnetic stirring to obtain a white, flocculent Hf(OH)4 precipitate;

[0048] (2) Wash the Hf(OH)4 precipitate with anhydrous ethanol several times to remove NH 4+ , Cl - The precipitate was placed in an oven and dried at 80°C for 2h, and then calcined at 1100°C in a box-type resistance furnace to obtain the precursor HfO2, thereby obtaining two Hf precursors, namely Hf(OH)4 and HfO2;

[0049] (3) Ce(NO)3·6H2O was dissolved in water with a concentration of 1.1 mol% of Ce ions, and then an excess of ammonia water was added to obtain a Ce(OH)3 precipitate. The precipitate was washed repeatedly and the Ce(OH)3 precipitate was used as a Ce precursor.

[0050] (4) Precursors of different Hf sources and CaO were wet-milled in a polyurethane mill for 36 h at a speed of 300 r / min. The grinding balls were high-purity ZrO2 and the milling medium was anhydrous ethanol.

[0051] (5) Then dried in a vacuum drying oven at 90°C for 2 h, ground in a mortar, sieved with 200 mesh, placed in an alumina crucible and calcined in a box-type resistance furnace at 1200°C for 2 h to synthesize a CaHfO3:Ce nanopowder sample;

[0052] The present invention uses different Hf sources as precursors and solid phase reaction method to prepare CaHfO3:Ce nanopowders. The synthesis temperature of using Hf(OH)4 as a precursor is lower than that of using HfO2 as a precursor to prepare CaHfO3:Ce nanopowders, and the uniformity, dispersibility and optical properties of the powder particle size of the former are better than those of the latter.

Claims

1. A method for preparing a novel calcium cerium hafnate scintillating material by a solid phase method, wherein the system composition formula is CaHfO3-Ce. The characteristics of the powder material have an important influence on the properties of the ceramic scintillator material. The present invention synthesizes CaHfO3:Ce ultrafine powder by a solid phase reaction method for the first time, and synthesizes CaHfO3:Ce nanoparticles with a nearly spherical shape, good dispersibility, and a primary particle size of about 30 nm.

2. According to the method for preparing a novel calcium cerium hafnate scintillating material by a solid phase method as claimed in claim 1, the specific steps adopted by the present invention are as follows: According to the method for preparing a novel calcium cerium hafnate scintillating material by a solid phase reaction method of the present invention, the specific steps are as follows: S1: Using CaO, Ce(NO3)3·6H2O, HfOCl2·8H2O, and NH3·H2O as raw materials, various raw materials are weighed on an electronic balance after calculating the precise stoichiometric ratio; S2: The HfOCl2·8H2O raw material described in S1 is prepared into a 1 mol / L solution, and a 1 mol / L NH3·H2O solution is forward titrated into a 500 ml beaker using a peristaltic pump. The mixed solution under the action of a magnetic stirrer presents a white, flocculent Hf(OH)4 precipitate; S3: After filtering the Hf(OH)4 precipitate described in S2, the white precursor needs to be washed twice with deionized water and anhydrous ethanol respectively to remove NH4 + , Cl - wait; S4: placing the precipitate in S3 into an oven at 80°C for drying, and then calcining it at 1100°C in a box-type resistance furnace to obtain HfO2; S5: dissolve Ce(NO3)3·6H2O in S1 in water, and then add excess ammonia water to obtain Ce(OH)3 precipitate; S6: repeatedly washing the Ce(OH)3 precipitate described in S5 to obtain a precipitate, and placing the precipitate in a box-type resistance furnace and calcining it at 1100° C. to obtain CeO2; S7: CaO, HfO2 obtained in S4, and CeO2 obtained in S6 are mixed according to the general formula of the system composition CaHfO3-Ce, accurately weighed, and then placed in a polyurethane grinding jar for wet ball milling for 12 to 36 hours at a rotation speed of 300 to 600 r / min. The grinding balls are high-purity ZrO2 and the ball milling medium is anhydrous ethanol. S8: The ball-milled slurry described in S7 was dried in a vacuum drying oven at 90° C. for 12 h, ground in a mortar, sieved with 200 mesh, placed in an alumina crucible, and calcined in a box-type resistance furnace at 900-1100° C. for 2 h to synthesize a CaHfO3:Ce ultrapure nanopowder sample.

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