Study On Preparation And Neutron-gamma Ray Shielding Performance Of Bismuth Borate Nanostructures

In recent years,human beings have become increasingly frequent activities in the environment of all kinds of rays with the rapid development of nuclear energy and nuclear technology.The face of neutron and gama rays with strong penetrating ability,the performance of the traditional shielding material has been unable to fully meet the requirements.Therefore,in order to meet further challenges,it is an important to research and development of a kind of material that can shield the neutron and gamma rays and has excellent mechanical properties.In this paper,bismuth borate crystals were successfully prepared by sol-gel method using H₃BO₃ and Bi（NO₃）_3.5H₂O as raw materials.Bismuth borate nanostructures with different morphologies were prepared by adjusting the reaction conditions.The study found that the mole ratio of Bi/B has a great influence on the phase and the product is the orthorhombic phase of B_i6B₁₀O₂₄ when the mole ratio of Bi/B is 1:2.Sintering time and sintering temperature affected the particle morphology of bismuth borate crystal.The product consists of a large number of nanoparticles with the size of 100 300 nm and exhibits good dispersion when the xerogel sintered at 600℃ for 3 h and the product presented the structure of nanometer flake when the xerogel sintered at 530℃ for 5 h.The mechanism of the formation of bismuth borate nanostructures with different morphologies was investigated,and it was found that the additives citrate and EDTA played an important role in the formation bismuth borate with different morphologies.The gamma ray shielding performance of bismuth borate nanopowdesr was tested by gamma-spectrometer,and the shielding performance of thermal neutrons was simulated by Monte Carlo program.It was found that the shielding performance increases with the increase of the powder content.When the powder content is the same,the mass attenuation coefficient of the gamma ray decreases with the increase of the ray energy because of the existence of the weak absorption area of the bismuth.The materialshowed the highest shielding performance at 105.3 keV.In addition,the shielding properties to gamma ray and thermal neutrons of bismuth borate nanostructures with different morphology are higher than those of the mixtures of Bi₂O₃ and B₂O₃ which shows that the shielding properties of the neutron and gamma ray arenot only related to the density of the material,but also to the size and morphology of particle.Particle nanocrystallization and improve the particle size of the regularity of the material can improve the shielding properties of materials.