Preparation Of Carbon Nitride Powder And Its Field Emission Performance

Field emission display(FED)is an emerging type of flat panel display that combines the advantages of cathode ray tube(C RT)high-definition and liquid crystal display(LCD)thin low-power flat panel displays.Carbon nitride is a covalent compound similar to silicon nitride proposed by the theory of prediction,and has a large polymerization energy and mechanical stability.In addition to having good mechanical properties and chemical stability,carbon nitride may also have a smaller electron affinity than diamond,so the potential for field emission has attracted attention.In this paper,carbon nitride powders were prepared by solvothermal method.Carbon nitride powders were deposited on the surface of different substrates to form field emission cathodes.The field emission performance of cathode samples with different substrates was tested.The effect of changes in process conditions on the field emission performance was investigated.Firstly,solvothermal method was used to synthesize graphite phase carbon nitride powder materials with cyanuric chloride and sodium azide as raw materials and dichloromethane as solvent.The crystal structure,composition and morphology of the product were characterized by XRD,SEM,EDS,FTIR and TGA.The effects of reaction parameters such as reaction temperature,reaction time,mass of reactants and amount of organic solvent on the synthesis of the product were investigated.The best process was obtained:reaction temperature 200°C,reaction time 15 h,amount of solvent 20 ml.Synthet ic carbon nitride is mainly spherical or spherical.Secondly,according to the principle of electrophoresis,the formulation of electrophoretic fluid was designed.Titanium,graphite and carbon cloth were selected respectively.Electrodeposition of carbon nitride powder on the substrate was used to prepare the field emission cathode.The electrophoresis process parameters were studied.The results show that:(1)When using titanium as substrate,the effects of parameters such as electrophoresis time,electrophoretic voltage,concentration of electrophoretic solution,carbon nitride content,and heat treatment temperature on the field emission cathode are studied to obtain the best experimental conditions:electrophoresis time 3min,electrophoretic voltage 30 V,titanium powder,iodine and carbon nitride in the electrophoretic solution were 10 mg,20mg,15 mg,respectively,and the heat treatment temperature was 400°C.The turn-on field is 5.20 V/mm and the emission current density is 105mA/cm~2 under electric field of 14 V/mm.(2)When using carbon cloth as a substrate,the influence of parameters such as electrophoresis time,electrophoretic voltage,electrophoretic concentration,and carbon nitride content on the performance of the field emission cathode was stud ied.The optimal experimental conditions were as follows:electrophoresis time 3 min,electrophoresis voltage 45 V,titanium powder,iodine and carbon nitride in the electrophoresis solution were 10 mg,20 mg,and 20 mg.The turn-on field is 0.23 V/mm and the emission current density is 300mA/cm~2 under electric field of 1.2 V/mm.(3)When graphite was used as substrate,the effects of electrophoretic time,electrophoretic voltage,electrophoretic concentration,and carbon nitride content on the performance of the field emission cathode were studied.The best experimental conditions were as follows:electrophoresis time 6min,electrophoresis voltage 60 V,electrophoresis liquid titanium powder,iodine and carbonitride 10 mg,20mg,20 mg.The turn-on field is 3.15V/mm and the emission current density is 200mA/cm~2 under electric field of 8 V/mm.Again,the solvothermal method is used to grow carbon nitride powders directly on carbon cloth and graphite substrates to prepare field emission cathodes.The process parameters such as reaction temperature,reaction time and solvent amount are changed,and the structure and shape of the sample are determined.The characterization of the appearance and properties explored the combined effect of process parameter conditions on the emission performance of the sample field.The results showed that:(1)Carbon nitride were grown on carbon cloth to prepare field emission cathodes.The field emission performance of the samples was best when the reaction temperature was 200°C,the reaction time was 15 h,and the amount of solvent was 20 ml.The turn-on field is 0.35 V/mm and the emission current density is 160mA/cm~2 under electric field of 1.4 V/mm.(2)Carbon nitride were grown on a graphite substrate to prepare field emission cathodes.The field emission performance of the sample was the best when the reaction temperature was 220°C.,the reaction time was 15 hours,and the solvent amount was 25 ml.The turn-on field is 4.08 V/mm and the emission current density is 290mA/cm~2 under electric field of 18 V/mm.