Preparation And Property Study Of Spinel-type High-entropy Oxide Materials

High-entropy alloys（HEAs）（also called"multi-principal alloys"）are alloys composed of five or more metal elements as main elements,and the atomic ratio of each main element is almost equal.Based on the four special"core effect"has many excellent properties.With continuous research,the concept of"high entropy"is introduced into the field of ceramic materials.Thanks to its excellent performance,high-entropy ceramics have been widely used in many fields,such as aerospace engine manufacturing,high-speed rail,maglev train engineering,and microwave absorbing materials.Therefore,research on high-entropy ceramics is very necessary.In terms of high-entropy oxides,in addition to expanding the system of high-entropy oxide ceramic materials,there are also reports on the special properties of high-entropy oxide ceramic materials.Spinel-type oxides have excellent and diverse physical properties.Spinel-type high-entropy oxide ceramics are prepared by doping a variety of divalent metal elements at the A site and changing the types of trivalent elements at the B site to obtain good catalytic performance.,A new functional ceramic with excellent mechanical properties and certain electrical properties.This article conducts in-depth research on the system of high-entropy oxides,mainly for spinel-type high-entropy oxides.(Co_0.2Ni_0.2Cu_0.2Zn_0.2Mg_0.2)B₂O₄（B=Fe,Ga,Al）spinel-type high-entropy oxide powders are prepared by solid-phase synthesis and sol-gel method.And on this basis,the bulk spinel high-entropy ceramics were sintered,and the formation conditions of the new spinel-type high-entropy ceramics and the relationship between the properties and the structure were explored.The best sintering temperature of(Co_0.2Ni_0.2Cu_0.2Zn_0.2Mg_0.2)Fe₂O₄ high-entropy ceramic is 1100℃,the best flexural strength is 165.3MPa,the elastic modulus is 110.7GPa,and the hardness is 758.004HV（98N）.The best sintering temperature of(Co_0.2Ni_0.2Cu_0.2Zn_0.2Mg_0.2)Ga₂O₄ high-entropy ceramics is 1200℃,the best flexural strength is 204.4MPa,the elastic modulus is 153.8GPa,and the hardness is 982.23HV（98N）.On this basis,high-entropy ceramics with unequal ratios of A-site elements were sintered.Compared with single-component Zn Fe₂O₄,high-entropy spinel oxide ceramics exhibit better dielectric properties and lower thermal conductivity.There is an inverse relationship between the thermal conductivity of ceramics and its configuration entropy.On the other hand,(Co_0.2Ni_0.2Cu_0.2Zn_0.2Mg_0.2)B₂O₄（B=Fe,Ga,Al）spinel-type high-entropy oxide nanofibers were prepared by the electrospinning method.The microscopic morphology differences of spinel high-entropy oxide nanofibers in different systems were explored,and the photocatalytic degradation performance of methylene blue was studied.It is found that the photocatalytic degradation efficiency or rate of high-entropy spinel oxide fibers is improved to a certain extent compared with single-component Zn Fe₂O₄ nanofibers.