Synthesis and Fluorescence Properties of Eu ^(2+)-Doped KMgF_3 Nanoparticles

The phase diagram of a cetyltrimethyl ammonium bromide （CTAB）/n-butanol/n-octane/KNO3-Mg（ NO3）2 system was drawn. Nanoparticles of Eu^2＋ -doped KMgF3 were prepared from the quaternary microemulsions of cetyltrimethyl ammonium bromide（ CTAB）, a-butanol, n-octane and water. The X-ray diffraction（XRD） patterns were indexed to a pure KMgF3 cubic phase. The environmental scanning electron microscopic（ESEM） images show the presence of spherical Eu^2＋ -doped KMgF3 nanoparticles with a diameter of ca. 20 nm. The emission of KMgF3： Eu^2＋ nanoparticles peaks at 360 nm. The excitation band was observed at 250 nm with a blue shift of ca. 70 nm compared with that of KMgF3： Eu^2＋ single crystal. The preparation method of nano-KMgF3： Eu^2＋/PMMA composite films was inquired into.

Optical Spectroscopy Properties of KMgF_3 :Eu^(2+) Nanocrystals and Powder Synthesized by Microemulsion and Solvothermal Process

Nanocrystals and powders of KMgF3 doped with Eu^2＋ were synthesized by the microemulsion method and the selvothermal process, respectively. The emission and excitation spectra of KMgF3： Eu^2＋ phosphors were measured and compared with those of the samples synthesized through a solid state reaction, Bridgman-Stockbarger method, and mild hydrothermal technique. The KMgF3： Eu^2＋ samples synthesized by means of the microemulsion method and the solvothermal process show only a sharp emission peak located at 360 nm in the emission spectra, which arises from the f→f（ ^6P7/2→^8S7/2 ） transition of Eu^2＋ The broad emission bands appear at 420 nm, which arises from Eu^2＋←O^2- cannot be observed（ in the mild hydrothermal and single crystal samples, the emission peak at 420 nm besides the emission of Eu^2＋ at 360 nm is observed）. In the excitation spectrum of the KMgF3 ： Eu^2＋ samples synthesized by the microemulsion method and the solvothermal process, the excitation peaks show an intensive blue shift. The blue shift can be attributed to the lower oxygenic content in the KMgF3 ： Eu^2＋ samples synthesized by the microemulsion method and the selvothermal process.

Spectroscopic Studies on Charge Transfer from Ce^(3+) to Yb^(3+) in KMgF_3∶Ce,Yb Nanocrystals

Nanocrystals of KMgF3 single-doped and codoped with Ce^3＋ or/and Yb^3＋ were synthesized separately by the mi-croemulsion method. The X-ray diffraction（XRD） patterns were indexed to show that the KMgF3 crystal system was unchanged. The fluorescent spectra of KMgF3： Ce, Yb polycrystal powders were studied and compared with those of the Ce,Yb doped KMgF3 crystals produced using the high-temperature solid phase method. The diffuse reflection spectra and infrared emission of KMgF3： Ce, Yb were investigated. From the results, the authors could confirm that there were charge transfer processes from Ce^3＋ to Yb^3＋ in both KMgF3： Ce,Yb nanocrystals and polycrystal powders.