Abstract: Room temperature phosphorescent metal-free carbon dots (CDs) embedded in a continuous SiO2 network (CDs@SiO2) are made by a method comprising in part grinding biomass and a source of SiO2 into a powder and soaking the powder with an acidic aqueous solution; washing the powder with deionized water; reacting the powder with an alkaline aqueous solution to form an aqueous solution of CDs from the biomass and Na2SiO3 from the source of SiO2; lowering the pH of the aqueous solution to a value sufficient to cause gelation; and aging the aqueous solution so that the Na2SiO3 forms mono-silicic acid (H4SiO4), which polymerizes to form a continuous SiO2 network composed of Si—O tetrahedrons (gel). The method can further comprise calcination of the CDs, wherein the CDs are multi-confined by a continuous SiO2 network composed of Si—O tetrahedrons. The metal-free CDs are useful in anti-counterfeiting encryption and fingerprint detection systems.

Abstract: The present invention relates to a process for preparing rare earth trichromatic phosphor, comprising the following steps: (1) providing precursors for at least one composition formula selected from the group consisting of CaBPO5:xEu:yTb, CaAlrB1-rPO5:xEu:yTb and Ca2B5O9Cl:xEu:yTb, wherein x=0.02–0.05 (mole ratio), y=0.001–0.01 (mole ratio) and r=0.5–0.8; (2) grinding and mixing the precursors; and (3) calcining the product obtained in step (2) at 800–1000° C. for 3–5 hours. According to the present process, only one matrix material and two rare earth reactive ions (Eu3+ and Tb3+) are required to synthesize rare earth trichromatic phosphor. That is to say, no reducing reagent is needed; and absence of reducing agent(s) reduces environmental pollution.

Abstract: The present invention relates to a process for preparing rare earth trichromatic phosphor, comprising the following steps: (1) providing a matrix material doping with both europium (Eu) and terbium (Tb); (2) grinding and mixing the said matrix material; and (3) making the product obtained in step (2) to react at 800-1000° C for 3-5 hours. According to the present process, only one matrix material and two rare earth reactive ions (Eu3+, Tb3+) are desired to synthesize rare earth trichromatic phosphor. That is to say, no reducing reagent is needed and thus no pollution is brought.