Preparation method of scandium oxide trace doped cubic phase dysprosium titanate

Abstract

The invention relates to the technical field of reactor and material preparation and processing, in particular to a preparation method of scandium oxide trace doped cubic phase dysprosium titanate, Sc2O3 is used as a doping agent for trace doping, so that the Dy-site average ion radius is reduced to a cubic phase range, chemical components are designed, and the scandium oxide trace doped cubic phase dysprosium titanate is prepared. And the dysprosium titanate material with a cubic phase structure is prepared by a high-temperature solid-phase reaction method. The material is good in structural thermal stability, low in thermal expansion coefficient, high in thermal conductivity and good in application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of reactor and material preparation and processing, and in particular to a method for preparing cubic phase dysprosium titanate doped with trace amounts of scandium oxide. Background Art

[0002] A fission reactor is a device that achieves nuclear energy utilization through nuclear fission reactions. During the operation of a nuclear reactor, the nuclear fuel undergoes a controllable self-sustaining chain fission nuclear reaction. In order to ensure the safe and stable operation of the nuclear reactor, control rods need to be inserted into the reactor. The control rod is the core component of a fission reactor. It controls the reaction rate in the reactor by absorbing neutrons to maintain the chain reaction. At the same time, it can disconnect the chain nuclear reaction in time in an emergency, which is of great significance to the safe and stable operation of the reactor. Boron carbide is currently the most widely used neutron absorber material. 10 B has a large neutron absorption cross section, no secondary radiation pollution, corrosion resistance, wear resistance, etc. However, due to 10 B absorbs neutrons and undergoes (n, α) nuclear reactions to produce a large number of α particles, which gather in the absorber to form bubbles, causing the absorber to irradiate and swell. Therefore, the research and development of Dy2TiO5 dysprosium titanate neutron absorption materials is in urgent need of research and development.

[0003] Dy2TiO5 dysprosium titanate is a multiphase material. As the temperature rises, it presents orthorhombic, hexagonal and cubic structures in turn. Cubic dysprosium titanate has been identified as a neutron absorption material because of its optimal anti-irradiation swelling rate, but the preparation and stability of its cubic phase are key issues restricting its application. Doping stabilizers is an effective way to prepare cubic Dy2TiO5. Lau, Risovany and others have successfully prepared cubic Dy2TiO5 by adding MoO3, but the relevant mechanism is not clear and cannot be verified experimentally.

[0004] According to investigation, there are two publicly published cubic phase dysprosium titanate preparation technologies: CN105161144A discloses a method for preparing dysprosium titanate core blocks, which are neutron absorption materials for nuclear reactor cores; and CN113213916 B discloses a fluorite structured dysprosium titanate reactor control rod and its preparation method. Both use MoO3 as a stabilizer, the relevant mechanism is not clear, and the structure is not stable.

[0005] With the continuous development of my country's nuclear industry, the demand for neutron absorbing materials with excellent performance and low cost is increasing. Finding and preparing neutron absorbing materials with excellent performance is an issue that has received widespread attention in the context of the continuous development of the nuclear industry. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing cubic phase dysprosium titanate doped with trace amounts of scandium oxide, which has a reasonable structural design and is convenient for promotion.

[0007] In view of the above-mentioned deficiencies in the prior art, the present invention uses scandium oxide (Sc2O3) as a dopant for trace doping and successfully prepares a dysprosium titanate material with a cubic phase structure.

[0008] A method for preparing cubic phase dysprosium titanate doped with scandium oxide, comprising the following steps:

[0009] S1. Weigh and mix the raw materials: weigh Dy2O3 powder, TiO2 powder and Sc2O3 powder according to a molar ratio of 0.945:1:0.055, and add them into a ball mill for ball milling and mixing;

[0010] S2, the ball-milled powder is dried and then compressed into tablets in a manual tablet press to obtain a sheet-like body;

[0011] S3, the sheet-like green body after tableting is placed in a high-temperature muffle furnace, and a sintering plan is designed through an automatic control program, and the sintering temperature curve is set as follows: heating from room temperature to 1350°C at a rate of 5-20°C / min and keeping it for 10 hours, then heating to 1550°C at a rate of 5-20°C / min and keeping it for 2-5 hours, and then cooling to room temperature at a rate of 10°C / min;

[0012] S4. Obtain a dysprosium titanate sample.

[0013] Preferably, in step S2, the pressure is 20-30 MPa and the holding time is 5-10 min.

[0014] As a preferred embodiment, the chemical composition of the prepared dysprosium titanate is: 1.89 Sc 0.11 The average radius of TiO5, Dy ions is That is, dysprosium titanate with a cubic structure is prepared.

[0015] The beneficial effects of the present invention are:

[0016] The present invention prepares a dysprosium titanate material with a cubic phase structure by using Sc2O3 as a stabilizer for trace doping. Since the doping amount of Sc2O3 is extremely small, its cubic phase structure is significantly stabilized, and the neutron absorption performance of dysprosium titanate is almost not affected. The material has good structural thermal stability, low thermal expansion coefficient, high thermal conductivity, and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 This is the XRD pattern of cubic phase dysprosium titanate slightly doped with Sc2O3 (after preparation and annealing);

[0019] Figure 2 This is the in-situ high temperature X-ray diffraction pattern of cubic phase dysprosium titanate slightly doped with Sc2O3;

[0020] Figure 3 is the thermal expansion coefficient of cubic phase dysprosium titanate slightly doped with Sc2O3 (room temperature to 600°C);

[0021] Figure 4 Thermal conductivity of cubic phase dysprosium titanate slightly doped with Sc2O3 (room temperature to 500°C);

[0022] Figure 5 These are the hardness test results of cubic phase dysprosium titanate micro-doped with Sc2O3. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] In the description of the embodiments of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0025] A method for preparing cubic phase dysprosium titanate doped with scandium oxide, characterized in that it comprises the following steps:

[0026] S1. Chemical composition design: According to the "A2TiO5 phase diagram", when the A-site ion radius is less than When the cubic structure of A2TiO5 is obtained, the molar ratio of the original reactants Dy2O3, TiO2 and Sc2O3 is designed to be 0.945:1:0.055 respectively. The chemical composition of the dysprosium titanate obtained is: Dy 1.89 Sc 0.11 The average radius of TiO5, Dy ions is It is in the required range of the cubic phase;

[0027] S2, weighing and mixing raw materials: weighing Dy2O3 powder, TiO2 powder, and Sc2O3 powder according to a molar ratio of 0.945:1:0.055, and adding them into a ball mill for ball milling and mixing;

[0028] S3, after the ball-milled powder is dried, it is pressed into a manual tablet press at a pressure of 20-30 MPa and a holding time of 5-10 min to obtain a sheet-like body;

[0029] S4. The pressed sheet body is placed in a high-temperature muffle furnace, and a sintering scheme is designed through an automatic control program. The sintering temperature curve is set as follows: heating from room temperature to 1350°C at a rate of 5-20°C / min and keeping warm for 10 hours → heating to 1550°C at a rate of 5-20°C / min and keeping warm for 2-5 hours → cooling to room temperature at a rate of 10°C / min;

[0030] S5. Obtain a dysprosium titanate sample.

[0031] As attached Figure 1 As shown, the X-ray diffraction technique shows that the Sc2O3 trace-doped dysprosium titanate sample obtained by the present invention has a stable single cubic phase structure; after annealing at 1000°C for 24h, the cubic phase structure of the Sc2O3 trace-doped dysprosium titanate does not change;

[0032] As attached Figure 2-3 As shown in the figure, the thermal expansion coefficient of Sc2O3-doped Dysprosium titanate is not higher than 8.52×10 -6 / K;

[0033] As attached Figure 4 As shown in Figure 2, the average thermal conductivity of Sc2O3-doped Dysprosium titanate was 1.96 W·m in the range of room temperature to 500°C measured by laser scintillation method. -1 ·K -1 ;

[0034] As attached Figure 5 As shown, the hardness of Sc2O3-micro-doped dysprosium titanate was measured by a microhardness tester to be 10.17±1.71 Gpa.

[0035] The present invention uses scandium oxide (Sc2O3) as a dopant for trace doping, reduces the average ion radius of the Dy position to the cubic phase range, designs the chemical components, and prepares a dysprosium titanate material with a cubic phase structure through a high-temperature solid-phase reaction method. The material has good structural thermal stability, low thermal expansion coefficient, high thermal conductivity, and good application prospects.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing cubic phase dysprosium titanate doped with scandium oxide, characterized in that: The following steps are involved: S1. Weigh and mix the raw materials: weigh Dy2O3 powder, TiO2 powder and Sc2O3 powder according to a molar ratio of 0.945:1:0.055, and add them into a ball mill for ball milling and mixing; S2, the ball-milled powder is dried and then compressed into tablets in a manual tablet press to obtain a sheet-like body; S3, the sheet-like green body after tableting is placed in a high-temperature muffle furnace, and a sintering plan is designed through an automatic control program, and the sintering temperature curve is set as follows: heating from room temperature to 1350°C at a rate of 5-20°C / min and keeping it for 10 hours, then heating to 1550°C at a rate of 5-20°C / min and keeping it for 2-5 hours, and then cooling to room temperature at a rate of 10°C / min; S4. Obtain a dysprosium titanate sample.

2. The method for preparing cubic phase dysprosium titanate doped with scandium oxide in a trace amount according to claim 1, characterized in that: In step S2, the pressure is 20-30 MPa and the holding time is 5-10 min.

3. The method for preparing a cubic phase dysprosium titanate doped with scandium oxide in a trace amount according to claim 1, characterized in that: The chemical composition of the prepared dysprosium titanate is: Dy 1.89 Sc 0.11 The average radius of TiO5, Dy ions is That is, dysprosium titanate with a cubic structure is prepared.

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