Facile Synthesis and Magneto-Luminescence Study of Alliance of Iron-oxide and NaGdF4:RE3+ into Nanoentity

N. SHRIVASTAVA; D. MURACA; U. ROCHA; M.S. MORENO; C. JACINTO DA SILVA; H. FELINTO BRITO; M. KNOBEL; S. SHARMA

Congreso; XVI Brazil MRS meeting; 2017

Reported nanorice of Iron-oxide/SiO2/NaGdF4:RE3+ (RE = 5%Ce, 5%Tb, x%Dy; x =1, 5 and 10) has been synthesized using a single reaction microwave synthesisprocedure, incorporating Iron oxide@SiO2 as seeds. The hexagonal phase as b-NaGdF4 was confirmed by powder X-ray diffraction and high-resolutiontransmission electron microscopy. The nanocrystals (~ 30 nm) displayferromagnetic properties at 300 K and 2 K. Zero field cooling/field cooling(ZFC/FC) measurements show a clear magnetic contribution of rare-earthelements. During the down-conversion emission, energy transfer process likeCe3+->Gd3+->Tb3+Dy3+ occurred, in which Gd3+ ions play an importantintermediate role along with Tb3+.The excitation spectra of all the samples consistof a broad band at around 250 nm and two sharp lines at about 275 nm and 310nm, which can be attributed to the Ce3+(4f-5d) transition and Gd3+(8S7/2) ->6IJtransition and Gd3+ (8S7/2->6PJ transition, respectively. The presence and intensityof Ce3+ and Gd3+ excitation peaks in the excitation spectra indicate the existenceof energy transfer from Ce3+ and Gd3+ to the luminescent ions. Excitation into theCe3+ band at 260 nm yields weak and sharp emission of Gd3+ at 310 nm, weakemission of Ce3+(300-400 nm) and strong emission color lines of RE3+ (400-700nm). The emission peaks (400-700 nm) are composed of the characteristictransitions of Tb3+ (5D4->7FJ, J = 6.3), and Dy3+ (4F9/2-6H15/2, 6H13/2), respectively.Tunable multicolor down-conversion emissions are achieved from ironoxide/SiO2/NaGdF4:RE3+ nanocrystals under a ultraviolet excitation. The CIEchromacity shows the green-yellow region, depending on concentration of Dy. Theoverall characteristics show strong magnetic behavior and considerableluminescence emission of the nanocrystals.