Study On The Field-assisted Preparation Of Ultrafine Oxide Towns And Their Morphology Controllability

As an excellent P-type semiconductor material,nickel oxide is widely used in electrical,magnetic,chemical and other fields and is a functional material with great application prospects.The morphology,purity,particle size,dispersity and other microscopic appearance of nickel oxide products are closely related to the application performance.A single controlled reaction condition is difficult to meet the comprehensive performance requirements.The addition of additives will affect the purity of the product.Therefore,The paper is to adopt microwave-assisted heating,using urea as a homogeneous precipitator,to discuss the change of nickel oxide morphology in the microwave field,and to provide a reference for the further control of the morphology of nickel oxide.Microwave homogeneous precipitation method was used.Using Ni（NO₃）₂·6H₂O as the nickel source and CO（NH₂）₂ as the precipitant,with no additives,the heating method,the amount of urea,the concentration of nickel nitrate,the temperature of reaction,initial pH value of the solution,and calcination temperature on the morphology of the nickel oxide were investigated.The results show that:1)Microwave-assisted heating is superior to conventional water bath heating with faster reaction rate,the prepared precursor has a specific flower-like structure and the particle surface is smoother.2)The flower-like microsphere nickel oxide with a good dispersion、particle size of 1-2μm and BET specific surface area of 12.4414 m²/g was prepared when the nickel nitrate concentration is 0.1 mol/L,the urea content is 0.03 mol,the pH is 6 and the reaction is carried out at 90°C for 120 min,the calcined at 400°C for 120 min.3)The nickel oxide was characterized by SEM,TG-DTA,FT-IR and XRD,the results show that,the composition of flower-like microsphere nickel oxide precursors and its calcined product after firing at 400°C for 2 hours is Ni₂（OH）₂CO₃ and cubic phase NiO.4)In the self-assembly process of flower-like microsphere structure:A variety of products of urea decomposition products have a greater impact on the formation of nanoplatelets.Nanoplatelets are assembled into a flower-like microsphere structure under the induction of electrostatic forces,with flower-like microspheres as the backbone,the nucleus is attached to the nanoplatelets,and the flower-like microspheres are gradually encapsulated and filled into spherical structures.Superfine nickel oxide nanoparticles were prepared by microwave hydrothermal method.Using Ni（NO₃）₂·6H₂O as the nickel source and CO（NH₂）₂ as the precipitant,the amount of urea,nickel nitrate concentration,reaction temperature and reaction time of the spherical nickel oxide were investigated.The results show that:1)The spherical nickel oxide with a BET specific surface area of 32.3944 m²/g was prepared when the concentration of nickel nitrate is 0.15mol/L,the amount of urea is 0.04mol,and the reaction is carried out at 130°C for 120 min,the calcined at 400°C for 120 min.It was agglomerated from particles with an average particle size of 150nm.2)The concentration of nickel nitrate has a great influence on the morphology of the product.By changing the concentration of nickel nitrate,the morphology of the nickel oxide precursor can be changed from petaloid to walnut to spherical structure.3)The nickel oxide was characterized by SEM,TG-DTG,FT-IR,XRD,the results show that,The composition of nickel oxide precursor and its calcined product after firing at 400°C for120 min is Ni₂（OH）₂CO₃and cubic phase NiO.