Method for growing uranium dioxide crystals by using borate fluxing agent

A technology of uranium dioxide and flux, which is applied in chemical instruments and methods, melts of self-melting solvents, and single crystal growth, etc., can solve the problems of difficulty in obtaining uranium dioxide crystals and the like

Inactive Publication Date: 2020-07-10
SHANGHAI INST OF TECH
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Problems solved by technology

[0005] The object of the present invention is to provide a method for growing uranium dioxide crystals using a borate f

Method used

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Embodiment Construction

[0017] The following is further described in detail through specific implementation methods:

[0018] Among the present invention, a kind of method utilizing borate flux to grow uranium dioxide crystal comprises the following steps:

[0019] (1) Flux Li 5 U(BO 3 ) 3 Li by stoichiometric ratio 2 CO 3 、H 3 BO 3 and UO 2 The powder is mixed and ground for 3h; in the present embodiment, Li 2 CO 3 99.99% pure, H 3 BO 3 99.99% pure, UO 2 99.99% pure.

[0020] (2) Put the mixed powder in step (1) into a platinum crucible, the thickness of the platinum crucible is 1mm, and the size is Ф40×H40mm. Seal the platinum crucible in Ar / 5%H 2 It is sintered at three stages of temperature under atmosphere; the sintering temperature of the first stage is sintering at 500°C for 12 hours, the sintering temperature of the second stage is sintering at 800°C for 12 hours, the sintering temperature of the third stage is sintering at 1250°C for 2 hours, and the mixture is taken out after ...

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Abstract

The invention belongs to the technical field of crystal preparation, and particularly discloses a method for growing uranium dioxide crystals by using a borate fluxing agent, which comprises the following steps: (1) mixing and grinding a fluxing agent Li5U (BO3)3 with Li2CO3, H3BO3 and UO2 powder in a stoichiometric ratio for 3 hours; (2) putting the mixed powder in the step (1) into a platinum crucible, and sintering at a three-stage temperature; (3) mixing fluxing agents Li5U (BO3) 3 and UO2 according to the molar ratio of 83 mol%: 1; preparing 17mol% of raw materials, fully mixing and grinding, loading into a platinum crucible, introducing Ar/5% H2, putting into a tubular resistance furnace, heating to 1235 DEG C, dissolving UO2 by using a Li5U(BO3) 3 fluxing agent, enabling the systemto reach a molten state, and slowly cooling to reach supersaturation to drive the crystal to grow, thereby obtaining the UO2 crystal. The scheme is mainly used for preparing the uranium dioxide crystal, and the problem that the ultrahigh-melting-point uranium dioxide crystal is difficult to grow by an existing melt method is solved.

Description

technical field [0001] The invention belongs to the technical field of crystal preparation, and specifically discloses a method for growing uranium dioxide crystals by using a borate flux. Background technique [0002] Uranium dioxide has semiconducting properties, and its resistivity decreases with increasing temperature. Uranium dioxide has been widely used in the manufacture of reactor fuel elements due to its characteristics of no anisotropic deformation when subjected to strong irradiation, no change in lattice structure at high temperatures, no volatilization and no chemical reaction with water. [0003] Uranium dioxide is one of the thermodynamically stable states in the uranium-oxygen system, which belongs to the cubic crystal system and has a face-centered cubic structure (fluorite type, space group Fm3m), a=547pm. At 100°C, the thermal conductivity is 0.09W / cm°C. It can slowly react with hydrochloric acid, sulfuric acid, and nitric acid at room temperature, and i...

Claims

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Application Information

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IPC IPC(8): C30B9/12C30B29/16
CPCC30B9/12C30B29/16
Inventor 徐家跃潘芸芳李志超冯海威周鼎田甜
Owner SHANGHAI INST OF TECH
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