174 resultados para BAFBR-EU2


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Long lasting phosphorescence (LLP) was observed in Eu2+, Ce3+ co-doped strontium borate glasses prepared under the reducing atmosphere due to the emission of both Eu2+ and Ce3+. The methods of photoluminescence, thermoluminescence and phosphorescence were used to study the samples, and possible mechanism was suggested. The co-doping of Ce3+ ions poisoned the phosphorescence emission of Eu2+ because of the competition to obtain the trapped electron. The phosphorescence of Ce3+ in the sample decays more quickly than that of Eu2+, which is suggested for the reason that the emission energy of Ce3+ is higher or the distance between Ce3+ and electron traps of the glasses is longer.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this study, KMgF3:Eu2+ luminescent nanocrystals (NCs) were prepared in water/cetyltrimethylammonium bromide (CTAB)/2-octanol microemulsions. The KMgF3:Eu2+ NCs were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), fluorescence spectrum, infrared spectroscopy (IR) and elementary analysis. The results showed that the size of the KMgF3:Eu2+ NCs was hardly affected by water content and surfactant (CTAB) concentration. The emission spectrum showed that the position of the 362 nm peak is due to the K+ sites substituted Eu2+. Two emission peaks located at 589 and 612 nm can be attributed to Eu3+, which exist at two different types of Eu3+ centers: one is Eu3+ at a K+ site, the other is clustering of Eu3+ ions in the interstices of KMgF3 host lattice.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

M2B5O9X: Re(M = Ca, Sr, Ba; X = Cl, Br; Re = Eu, Th) phosphors were synthesized via solid state method. The products were characterized with X-ray powder diffraction and luminescence spectrometer. The luminescent properties as well. as the influences of the matrix composition and other doping ions on the luminescence of the rare earth ions of the co-doped phosphors were investigated. The coexistence of Eu3+, Eu2+ and Th3+ were observed in these matrices. The phenomenon may be explained by the electron transfer theory. The sensitization of Ce3+ ion improves the intensity of emission of Eu2+, and Tb3+. The competition between electron transfer among conjugate rare earth ions and energy migration might be the reasons for the observation. We predict a novel trichromatic phosphor co-doped with Eu3+ Tb3+ in M2B5O9X.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Europium-doped barium fluoride cubic nanocolumns were synthesized from the quaternary water in oil reverse microemulsions In this process, the aqueous cores of water/cetyl trimethyl ammonium bromide (CTAB)/n-butanol/n-octane reverse microemulsions were used as microreactors for the precipitation of europium doped barium fluoride. XRD analysis shows that under the dopant concentration of 0.06% (molar fraction), the products are single phase. The result products are cubic column-like with about 30 similar to 50 nm edge length of cross section, and about 200 nm of length obtained from the transmission electron microscopy (TEM), and atomic force microscopy (AFM). Under the 0.06 % (molar fraction) of dopant concentration I the fluorescence of Eu2+ and Eu3+ under the 589 of excitation wavelength is observed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Ca BPO5 RE( RE=Eu,Tb) , , . , ,Eu3+ ,Tb3+ Eu2 + , Eu2 + 40 2 nm 42 8nm. Ce3+ ,Eu3+ ,Tb3+ Eu2 + , Ce3+ Eu3+

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A semiempirical method for the evaluation of the barycenter of energy of 4f(N-1)5d configurations is presented. The environmental factors affecting the barycenter are given to be the bond volume polarization, fractional covalence of the chemical bond between the central ion and the nearest anion, and presented charge of the nearest anion in the chemical bonds. The barycenter energies of 4f(N-1)5d configurations of Eu2+ and Ce3+ are calculated in various crystals, and the results are in good agreement with the experimental values. A relationship is found between the barycenter of energy of the 4f(N-1)5d configuration on Eu2+ method offers the advantage of applicability to a broad class of luminescence materials and initiates a link between macroscopic properties and microscopic structure.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A new blue phosphorescent glass-ceramic, Eu2+ and Nd3+, co-doped CaO-Al2O3-B2O3, was synthesized. After the irradiation with ultraviolet (UV) light, the glass-ceramic emitted blue long-lasting phosphorescence (LLP) with a spectrum peaking at about 464 nm ascribed to the characteristic 4f(6)5d(1) -> 8S(7/2) transition of Eu2+. This phosphorescence can be seen in the dark 1 h after the irradiation. However, the transparent Eu2+ and Nd3+ co-doped CaO-Al2O3-B2O3 glass did not show the phosphorescence. By the X-ray diffraction diffusion (XRD) data, alpha-CaAl2B2O7 was demonstrated to be the crystallites in the glass-ceramic. We think that alpha-CaAl2B2O7:Eu2+ Nd3+ crystallites produced during the heat treatment of the glass contribute to the LLP of the glass-ceramic.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The Sr2Mg(BO3)(2) phosphors doped respectively with Tm3+, Tb3+ and Dy3+ as activator were prepared by high temperature solid-state reaction. All the thermo luminescence curves of the phosphors consisted of two isolated peaks and the Dy3+ activated sample exhibited the strongest thermo luminescence intensity. The kinetic parameters of the thermoluminescence of Sr2Mg(BO3)(2):0.04 Dy were calculated employing the peak shape method and 3 dimensional thermo luminescent emission spectra were observed peaking at 480, 579, 662 and 755 nm due to the characteristic transition of Dy3+. In addition, the pre-irradiation heat-treatment and the thermoluminescence dose response of Sr2Mg(BO3)(2):0.04 Dy were investigated.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Eu2+,Ce3+KMgF3,.,,..,KMgF3,Eu2+Ce3+,Ce3+;KMgF,Ce3+Eu2+,Eu2+.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

KMgF3EuEu3+Eu2+100%,0.29%.,KMgF3X1 h100 h;KMgF3Eu2+X,360 nm.,KMgF3,,,103Gy,30 d.KMgF3Eu2+360 nm.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Sr4Al14O25RE3+(RE=Eu,Ce,Tb),Eu3+,Ce3+Tb3+,Ce3+Tb3+;Eu3+,Ce3+Tb3+,Eu2+;Tb3+5D35D4,;Ce3+Tb3+

Relevância:

10.00% 10.00%

Publicador:

Resumo:

BaMgAl10 O17R(R =Eu ,Mn) , , 16 5nm ,Mn2 + 170 2 40nm ,Eu2 + 4f 5d 2 10 40 0nm

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The crystal field splitting of 5d level of EU2+ and Ce3+ in halide crystals has been studied. Our results indicate that the 10Dq splitting can be directly related to the homopolar part of average energy gap, the coordination number of central (doped) ion, the charge of neighboring anions and bond ionicity between central ion to nearest anions. A relation between the 10Dq splitting and the above mentioned factors is presented. Our calculated results are in reasonable agreement with diverse experiments.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The complex fluoride LiBaF3 and LiBaF3:M(M = Eu, Ce) is solvothermally synthesized at 180 degreesC and characterized by means of X-ray powder diffraction, scanning electron microscopy, thermogravimetric analysis and infrared spectroscopy. In the solvothermal process, the solvents, molar ratios of initial mixtures and reaction temperature play important roles in the formation of products. The excitation and emission spectra of the LiBaF3:M(M= Eu,Ce) have been measured by fluorescence spectrophotometer. In the LiBaF3: Eu emission spectra, there is one sharp line emission located at 360 nm arising from f --> f transition of Eu2+ in the host lattice, and typical doublet 5d-4f emission of Ce3+ in LiBaF3 powder is shown.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The different ions doped KMgF3 single crystals are prepared by the vertical Bridgman method. The near-infrared absorption spectra for different parts of all as-growth crystals indicate that there is the best transparency in middle part. The correlation between the vibronic frequencies of Eu2+ and the site displacement of Cu+ co-doped ions is firstly studied, which indicates that Cu+ ions replace the site of the Mg2+ ions. The co-doped Eu2+ counteracts the charge misfit causing by the replacement of Mg2+ with Cu+. The overlapping of the emission spectra of the Eu2+ and the excitation spectra of the Cu+ results in the energy transfer from Eu2+ to Cu+.