Study On Preparation,shaping And Luminescence Properties Of BN And BCNO Ceramics Based On Organic Precursors

The emergence of counterfeit banknotes,fake legal documents,ID cards,medicines,and other counterfeit products has become a growing security concern.Many information encryption solutions have been developed to ensure information security and defend the legitimate rights and interests of the market and consumers.Anti-counterfeiting technique based on fluorescence,which is often used to protect legitimate products.The following properties are required for mature fluorescent anticounterfeiting technology: 1)the optical properties and stability of the materials employed,and 2)the complexity of the anti-counterfeiting pattern or shapes,both of which will improve the method’s non-replication.Fluorescent anti-counterfeiting technology is in high demand these days,which necessitates the development of new materials with good fluorescent properties as well as easy processes that allow anticounterfeiting materials to produce complicated patterns or shapes.Fluorescent boron carbon oxynitride（BCNO）,a newly developed type of oxynitride phosphor,has gotten a lot of attention as a potential fluorescent anti-counterfeiting candidate.The favourable properties of BCNO include cheap raw materials,simple synthesis process,high quantum yield,as well as tunable photoluminescence wavelength.In this research,precursor decomposition and direct ink writing（DIW）technology were used to successfully prepare BCNO with complicated geometric shapes,the following are the specific contents:1.DIW and precursor decomposition techniques were used to prepare BN and BCNO fluorescent ceramic monoliths.The precursor salts used for ceramic preparation were prepared from boric acid（B source）and melamine（N source）as raw materials.The precursor salt powders,deionized water,photoinitiator 1173 and PEG400 DA photosensitive resin are mixed evenly to prepare a water-based precursor slurry suitable for DIW printing.PEG400 DA was employed as a binding agent for printing ink and as a carbon source for the production of ceramics in this study.The above-prepared precursor slurry was put into the barrel of the DIW printer,the precursor slurry is printed and cured by DIW to obtain ceramic green bodies,which are sintered under nitrogen and air conditions to obtain BN and BCNO monoliths.2.By changing the sintering temperature,sintering time,sintering rate and the content of PEG400 DA in the precursor slurry,the effects of synthesis conditions on the structure and fluorescence properties of BCNO were studied.3.In order to solve the problem that the organic dye Rhodamine B（RhB）will cause fluorescence quenching due to aggregation,BN monoliths were immersed in Rhodamine B solution as an adsorption carrier to prepare BN/RhB composites,and the effect of changing the types of solvents and solution concentrations on the structure and fluorescence properties of BN/RhB composites were studied,as well as the stability in water and thermal stability of BN/RhB composites.4.A preliminary study about the use of BCNO monoliths as an anti-counterfeiting material in the field of optical anti-counterfeiting is done.