The Effect Of Gd₂O₃ Doping On Thermal And Radiation Protection Performance Of La₂Zr₂O₇ Ceramic Material

With the rapid development of the social economy,the supply of conventional energy has been difficult to meet the needs of economic development,and the pollution brought seriously threatens the environment for human survival.In order to protect the environment and meet the needs of the country for nuclear power plants and military,nuclear reactors of various uses have emerged.In the face of the rapid development of the nuclear industry,traditional radiation protection materials have been difficult to meet the protection,there is an urgent need to develop a new type of radiation-proof material that is lead-free,and capable of long-term and stable service in high-temperature and irradiated environments.In this experiment,Gd_xLa_2-x-x Zr₂O₇?x=0.1,0.2,0.3,0.4,0.5,0.6,0.7?powder and ceramic materials were synthesized by solid state reaction using lanthanum oxide,gadolinium oxide and zirconium oxide as raw materials.This experiment used X-ray diffractometer?XRD??differential scanning calorimeter?DSC??field emission scanning electron microscope?SEM??Archimedes drainage method?high temperature thermal expansion instrument?Neumann-kopp law?laser thermal conductivity meter?ion implanter were used.The instrument and method characterize the phase structure,high temperature phase stability,microstructure morphology,density,thermal expansion coefficient,heat capacity thermal conductivity and radiation damage of the material.The XRD results show that the powder of Gd_xLa_2-xZr₂O₇?x=0.1,0.2,0.3,0.4,0.5,0.6,0.7?is completely sintered and the reaction is complete.The diffraction peaks of the synthesized products are consistent with the diffraction peak of strontium zirconate of a single cubic pyrochlore structure,which indicates that the gadolinium ions are completely dissolved in the lanthanum zirconate lattice.The DSC results show that the Gd_xLa_2-xZr₂O₇?x=0.1,0.2,0.3,0.4,0.5,0.6,0.7?has no obvious endothermic exothermic peak at room temperature to 1450?,which proves that the high temperature phase stability is good.The SEM results show that the Gd_xLa_2-x-x Zr₂O₇?x=0.1,0.2,0.3,0.4,0.5,0.6,0.7?is completely sintered,the grain boundary is clear,the grain size is generally between 3-5microns,and the material density is better.The relative density is between 94.6% and 97.49%.The thermal performance test results show that the average thermal expansion coefficient of Gd_xLa_2-xZr₂O₇?x=0.1,0.2,0.3,0.4,0.5,0.6,0.7?ceramic materials increases with the increase of the doping ratio of gadolinium ions,and the overall value is between9.67×10^-6K^-1.and 10.78×10^-6K^-1.In the temperature range from room temperature to 1027?,the heat capacity values of seven different gadolinium ion doping ratios of ceramics showed a decreasing trend with the increase of gadolinium ion doping ratio.In the range of room temperature to 1000?,the doping of gadolinium ions significantly reduces the thermal diffusivity and thermal conductivity of lanthanum zirconate ceramic materials,and the thermal diffusivity and thermal conductivity decrease with increasing doping ratio of gadolinium ions.When the doping ratio reaches x=0.6,the ceramic material obtains the lowest thermal diffusivity and thermal conductivity.The results of irradiation of the material show that the doping of gadolinium ions effectively enhances the radiation resistance of lanthanum zirconate ceramics.The trend is that as the doping ratio of gadolinium ions increases,the anti-radiation ability of cerium-doped ceramic materials is strengthened.After the gadolinium ion doped lanthanum zirconate ceramic material is irradiated,the thermal diffusivity and thermal conductivity decrease to some extent,and the thermal conductivity decreases by about31.4%at low temperature and low doping.The rate also showed a decrease of about 4.9%at high temperature and high doping.Among them,when the doping ratio of gadolinium ions reaches x=0.6,the lowest thermal conductivity is obtained.Through the research in this paper,it is proved that the gadolinium ion doped lanthanum zirconate ceramic material can be used for long-term service in high temperature and irradiation environment,and its radiation and heat insulation performance is excellent and stable.Among them,Gd_0.6La_1.4Zr₂O₇ ceramic material has the most comprehensive performance.