Figure 2. (a) Multicolor downshifting tuning of NaGdF4 nanoparticles by varying activator compositions. (b) Multicolor upconversion tuning of NaYF4 nanoparticles by varying the concentration of Er 3+ and Yb3+. (c) Multicolor downshifting tuning of YVO4 nanoparticles by varying the concentrations of Dy3+, Eu3+, and Sm3+
續Color-changing sparksThe phases of the spark are readily explained by a cooler starting phase, which exhibits black-body emission (orange-white), a very hot phase that leads to vapor-phase combustion and intense green emission of erbium monoxide in the gas phase... ...tellurium for blue and sodium-soaked silica powder for yellow sparks.