Effect Of Plasmon-enhancement On Luminescent Properties Of Doped Multiferroic Fluoride Nanoparticles

BaMgF₄ and BaMnF₄ multiferroic materials have good ferroelectric and ferromagnetic properties, at the same time, they also belong to the fluoride, So have the potential of upconversion luminescence materials because of low phonon energy; good transparency and very short cut-off wavelength（such as the BaMgF₄ cut-off wavelength is 126nm）, in this case, they can become a multifunctional material set light, magnetic, electrical integration. In this work, we use multiferroic fluoride material as matrix material, to study its luminescent properties, and then demonstrate their excellent characteristics for highly improved fluorescence emission by plasmon field enhancement. These results provide the beneficial reference to the Synthesis of ferroelectric luminescent fluoride and noble metal hybrid nanostructures and explore a new efficient luminescent materials.Respectively using the hydrothermal method and coprecipitation method to prepare Na YF4:Yb, Er particles, screening out a method of synthesis of more suitable as a matrix material with nuclear shell structure. After respectively using optical deposition and chemical deposition method to prepare Na YF4:Yb, Er@Ag composite, obtained a synthesis method, that is relatively simple, efficient and controllable high by comparison. Ba MF4（M=Mg, Mn） nanoparticles were synthesized using a hydrothermal method, taking Yb3+, Tm3+ doping on BaMgF₄. Innovatively We synthesized Ba Mn F4@Ag and BaMgF₄:Yb3+,Tm3+@Ag hybrid nanostructures via a chemical-reduction method. The samples were characterized by XRD, SEM and fluorescence spectrometer.（1） Respectively using the hydrothermal method and coprecipitation method to prepare Na YF4:Yb, Er particles. It is found that although the materials prepared by coprecipitation with small particle size, good lighting effect, but which is easy to produce the impurity and dispersion is not good, so it is not suitable as a nuclear shell structure of nuclear materials. Respectively using optical deposition and chemical deposition method to prepare Na YF4:Yb, Er@Ag composite, Although it can make the fluorescence enhancement by optical deposition, but the silver particles size is not well controlled, so this method is eliminated. When use the chemical deposition method, Ag NO3 0.005 g, at the 529 nm luminescence enhancement nearly doubled, at 660 nm luminescence enhancement of nearly four times.（2） Taking Yb3+, Tm3+ doping on BaMgF₄, and observed on Tm3+ conversion luminescence under the excitation of 980 nm. The ratio between Ag NO3 and Ba MF4 nanoparticles is 0.01, while BaMgF₄:Yb3+, Tm3+@Ag fluorescence enhancement effect is the best, the average photoluminescence intensity reaches a maximum value of 30× that from 346 nm, 21× from 362 nm, 21× from 450 nm and 6× from 475 nm. With increasing the concentration of Ag+, the size of Ag nanoparticles increases from 10 nm to 30 nm, and caused serious coacervate, then the fluorescence enhanced by gradually weakened.（3） BaMnF₄ nanoparticles were synthesized using a hydrothermal method. As seen in SEM images, the BaMnF₄ samples are composed of a great deal of clavate morphologies, and c. 200 nm long, 30 nm wide. From the excitation and emission spectra of the Ba Mn F4, we could get the 695 nm emission peak under 465 nm excitation. Ba Mn F4@Ag samples were successfully prepared by chemical reduction, molar ratio of Ag NO3 and BaMnF₄ were 0.01, 0.05, 0.08. The proportion in the 0.01, the sample could be attached to the surface of Ag particles, with particle size about 10 nm. To increase the proportion, then particle size of Ag particles increased from 10 nm to 40 nm. Found in the spectrum of the test, gradually decreases with increasing coating ratio, the fluorescence enhancement was larger, when the ratio was 1:0.01, the photoluminescence intensity reached a maximum value.