Luminescence properties of Tm^3＋/Yb^3＋, Er^3＋/Yb^3＋ and Ho^3＋/Yb^3＋ activated calcium tungstate

CaWO4 phosphor activated by the Tm3+/Yb3+,Er3+/Yb3+ and Ho3+/Yb3+ ions were synthesized by a traditional high-temperature solid-state method.The crystal structures and morphologies of the products were characterized by X-ray powders diffraction method(XRD) ,infrared spectra(FT-IR) and scanning electron microscopy(SEM) .The samples were found to show up-conversion luminescence properties.CaWO4 doped with Tm3+/Yb3+ showed blue luminescence characteristic of Tm(III) ion in the range of 460-485 nm,corresponding to the 1G4→3H6 electronic transition.CaWO4 doped with Er3+/Yb3+ showed strong green luminescence at 510-565 nm(2H11/2,4S3/2→4I15/2) and weak red luminescence at 640-685 nm(4F9/2→4I15/2) of Er(III) ion.CaWO4 doped with Ho3+/Yb3+ phosphor emitted green luminescence at 525-560 nm(5S2,5F4→5I8) and red luminescence at 630-670 nm(5F5→5I8) and at 730-770 nm(5S2,5F4→5I7) ,which is the characteristic of Ho(III) ion.     

Dy^3＋在（LaO）3BO3和（GdO）3BO3中的光致发光

研究了Ｄｙ＾３＋在（ＬａＯ）３ＢＯ３和（ＧｄＯ）３ＢＯ３中的光致发光;探讨了基质晶体结构、稀土离子ＲＥ＾３＋的电荷半径比（Ｚ／ｒ）和Ｄｙ＾３＋含量对（Ｄｙ＾３＋）发光强度及发光颜色的影响;分析了（ＧｄＯ）３ＢＯ３中Ｂｉ＾３＋对Ｄｙ＾３＋发光的敏化作用及Ｄｙ＾３＋４Ｆ９／２→＾６Ｈ１３／２超灵敏跃迁发射的自身浓度猝灭机理。     

Luminescence characteristics of Ca_4YO(BO_3)_3 doped with Bi~(3+),Dy~(3+) and Pr~(3+) ions

The photoluminescence(PL) properties of Ca4YO(BO3)3 doped with Bi3+,Dy3+,and Pr3+ ions were investigated.These compounds were prepared using a typical solid-state reaction.The excitation and emission spectra were measured using a spectrofluorometer.For Ca4YO(BO3)3:Bi3+,the excitation spectrum showed the bands at about 228,309,and 370 nm which correspond to the 1S0→1P1 transition and the 1S0→3P1 transition of Bi3+ ions.The emission band at 390 nm corresponded to the 3P1→1S0 transition of Bi3+ ions.For Ca4YO(BO3)3:Bi3+,Dy3+,energy transfer occurred from Bi3+ to Dy3+ somewhat.In Ca4YO(BO3)3:Bi3+,Dy3+,Pr3+,the excitation band at 367 nm was enhanced obviously due to the energy migration from Bi3+ to Pr3+,which converted efficiently the emission of semiconductor InGaN based light-emitting diode(LED).Therefore,the emission of Dy3+ ions was enhanced due to the energy migration from the process of Bi3+→Pr3+→Dy3+.It resulted in the good color rendering.     

Novel phosphors of Eu~(3+), Tb~(3+) or Tm~(3+) activated LaBGeO_5

Rare earth borogermanates as a group of stable compounds provided various potential properties important for modern sciences. Among the properties of interests, luminescence was manifested due to the variability of rare earth elements and the compounds constituted an important group of potential candidate. In this work, novel phosphors of Eu3+, Tb3+ or Tm3+ doped LaBGeO5 with the stillwellite type structure were synthesized by the solid state reaction method. Their X-ray and UV excitation luminescent proper...     

Quenching mechanism of Er~(3+) emissions in Er~(3+)-and Er~(3+)/Yb~(3+)-doped SrAl_(12)O_(19) nanophosphors

Nanoscaled SrAl12O19:Er3+ and SrAl12O19:Yb3+,Er3+ phosphors were synthesized by a combustion method.The emission intensities of every sample were compared by a new method with the emission of codoped Gd3+ ions as a reference.Compared with their bulk material prepared by the solid-state reaction method,a higher Er3+ quenching concentration,as high as 20%,was observed in the nanoscaled phosphors for both visible(VIS) and near infrared(NIR) emissions.The higher quenching concentration in both VIS and NIR regio...     

Study of Complexes Formed by Adrenaline with Nd~(3+),Gd~(3+) and Tm~(3+)

The solution reaction mechanisms,composition,donor atoms,properties of coordinate link and stability ofthe complexes on the systems of adrenaline with Na~(3+),Gd~(3+)and Tm~(3+)have been studied by pH-potentiometrictitration and electronic spectroscopy.Adrenaline perturbs the f-f electronic transition of Nd~(3+)and Tm~(3+)sothat the absorption spectra of their complexes are shifted toward longer wavelengths.The absorption spectra ofthe complexes formed by the three f-block element ions with adrenaline are shifted toward shorter wavelengthswith the increase of PH in Δγ=350～650 nm     

Optical Spectroscopy of Er^3 , Er^3＋/Yb^3 ＋ Co-doped Bi2O3-GeO2-B2O3-ZnO Glasses

Optical Spectroscopy of Er~(3 ), Er~(3 )/Yb~(3 ) Co-doped Bi_2O_3-GeO_2-B_2O_3-ZnO Glasses     

Luminescent properties and energy transfer mechanism from Tb~(3+) to Eu~(3+) in CaMoO_4:Tb~(3+),Eu~(3+) phosphors

A series of CaMoO_4:Tb~(3+),Eu~(3+) phosphors were prepared by the method of precipitation. The structure and morphology of the phosphors were characterized by the X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM). The photoluminescence properties of the prepared products were researched, and the energy transfer from Tb~(3+) to Eu~(3+) in CaMoO_4 phosphors was studied. By adjusting the doping concentration of Eu~(3+) ions in CaMoO_4:Tb~(3+),Eu~(3+) phosphors, the emitting color of the phosphors could be easily tuned from green to red. With Tb~(3+) doped in the phosphors, the red luminescence of Eu~(3+) by near UV excitation was significantly enhanced. The energy transfer efficiency, rate and average distance between Tb~(3+) and Eu~(3+) in CaMoO_4:5%Tb~(3+),x%Eu~(3+)(mole percent) phosphors(x=0.3–10) were calculated. It was found that the interaction type between Tb~(3+) and Eu~(3+) was electric dipole-dipole interaction in the phosphors.     

Energy transfer from Ce~(3+) to Tb~(3+) and Eu~(3+) in zinc phosphate glasses

Ce3+,Eu3+ and Tb3+ singly doped and Ce3+/Eu3+ and Ce3+/Tb3+ co-doped zinc phosphate glasses were prepared by sintering P2O5,ZnO,Ce2(C2O4)3·10H2O and Eu2O3/Tb4O7 mixtures at 1200 °C in the air for 2 h and then annealing at 450 °C for 10 h.The obtained glasses were homogeneous and transparent.The glasses without Ce3+ were colorless and those with Ce3+ showed slightly yellow.The singly doped glasses showed strong emissions and excitations from doped trivalent rare earth ions.Strong energy transfer from Ce3+ to Tb3+ was observed for Ce3+/Tb3+ coped samples.There were also some very weak evidences for the energy transfer from Ce3+ to Eu3+.     

Separation of Tb~(3 ) , Dy~(3 ) , Ho~(3 ) , Er~( 3 ) with Solvent Impregnated Resins Containing Di-(2,4,4-trimethylpentyl) Phosphinic Acid

Separation of Tb~(3 ) , Dy~(3 ) , Ho~(3 ) , Er~( 3 ) with Solvent Impregnated Resins Containing Di-(2,4,4-trimethylpentyl) Phosphinic Acid     

Remarkable red-shift of upconversion luminescence and anti-ferromagnetic coupling in NaLuF_4:Yb~(3+)/Tm~(3+)/Gd~(3+)/Sm~(3+) bifunctional microcrystals

Lanthanide doped bifunctional materials are potentially important for developing multifunctional devices. Here, NaLuF_4:Yb~(3+)/Tm~(3+)/Gd~(3+)/Sm~(3+) optical-magnetic bifunctional microcrystals were successfully synthesized by hydrothermal method, which could emit ~480 nm blue light from the ~1G_4→~3H_6 electronic transition and ~800 nm infrared light from the ~3H_4→~3H_6 electronic transition of Tm~(3+) ion, under the excitation of 980 nm infrared light. By doping Sm~(3+) ion into Na Lu F4:Yb~(3+)/Tm~(3+)/Gd~(3+), the infrared emission peak centered at 800 nm would shift obviously to longer wavelength. This indicated that Sm~(3+) ion could efficiently tune the energy level gaps of Tm~(3+) ions in Na Lu F4 host which was demonstrated based on the crystal field theory. In addition, these NaLuF_4:Yb~(3+)/Tm~(3+)/Gd~(3+)/Sm~(3+) microcrystals presented unique ferromagnetic property instead of usually reported paramagnetic property. Importantly, the ferromagnetic property decreased with increasing the concentration of Gd~(3+) ion. This was in good agreement with Swift's theoretical investigation that the coexistence of light rare earth(Gd~(3+)) and heavy rare earth(Yb~(3+)/Tm~(3+)) would lead to the anti-ferromagnetic coupling in the sub-lattices.     

Specific features of Eu~(3+) and Tb~(3+) magnetooptics in gadolinium-gallium garnet (Gd_3Ga_5O_(12))

We reported magnetooptical properties of Eu3+(4f(6)) and Tb3+(4f(8)) in single crystals of Gd3Ga5O12 (GGG), Y3Ga5O12 (YGG), and Eu3+(4f(6)) in Eu3Ga5O12 (EuGG) for both ions occupying sites of D2 symmetry in the garnet structure. Absorption, luminescence, and magnetic circular polarization of luminescence (MCPL) spectra of Tb3+ in GGG and YGG and absorption and magnetic circular dichroism (MCD) of Eu3+ in EuGG were studied. The data were obtained at 85 K and room temperature (RT). Magnetic susceptibility of...     

Luminescent Properties of Eu~(3+) and Bi~(3+) and Their Interaction in LaBO_3 and GdBO_3

Under the excitation of UV light and cathode ray,the dependence of the excitation and emission spectraand luminescent lifetime of Eu~(3+)and Bi~(3+)on composition and structure in LABO_3 and GdBO_3 has been stu-died.The results indicate that the emission spectra of Eu~(3+)in LaBO_3 with aragonite structure and in GdBO_3with YBO_3 structure are quite different.Under 254 nm excitation,Eu~(3+)emission is sensitized by Bi~(3+)inGdBO_3 matrix.In other case Eu~(3+)emission is quenched by Bi(3+).     

Broadband Cr~(3+)-sensitized upconversion luminescence of LiScSi_2O_6:Cr~(3+)/Er~(3+)

Broadband sensitization is an effective strategy to enhance the upconversion luminescence(UCL) of lanthanide ions.Herein,novel UC materials LiScSi_2 O_6:Cr~(3+)/Er~(3+)(LSS:Cr~(3+)/Er~(3+)) were synthesized by high-temperature solid state reaction and their luminescent properties were investigated.LSS:Cr~(3+)/Er~(3+)has the broadband absorption in the spectral range of 600-800 nm,and meanwhile shows green UC emissions of Er~(3+)upon pumping Cr~(3+) by the 690 nm laser.The UCL of LSS:Cr~(3+)/Er~(3+)belongs to the twophoton process and is attributed to the energy transfer upconversion mechanism.The effects of the Cr~(3+)and Er~(3+)concentration as well as the Yb~(3+)introduction were also studied.LSS:Cr~(3+)/Yb~(3+)/Er~(3+) exhibits the interesting dual-mode UCL,capable of generating the UCL of Cr~(3+) upon pumping Yb~(3+)ions and the UCL of upon pumping Cr~(3+) ions.This research might promote the development of novel broadband Cr~(3+)-sensitized UC materials.     

Spectroscopy Study on Crystal Structure of Ce（NO3）3 （phen）2 and Interactions of Ce（NO3）3 （phen）2 with DNA

Inrecentyears ,Komiyaetal.[1] havefoundthatrareearthsionsmaybeoneofthestrongestcutre agentsofnucleicacids .Theexperimentalresults ,thatrareearthsrepresscancersonwholeanimalbodiesandonhumanbodies(invitro) ,indicatedthatrareearthselementsactuallyhavestrongf…     

Efficient near-infrared quantum cutting by Ce~（3＋）-Yb~（3＋） couple in GdBO_3 phosphors

Ce3+ and Yb3+ co-activated GdBO3 phosphors were prepared by a conventional solid-state reaction method. X-ray powder diffraction, photoluminescent spectra and decay curves were used to characterize their structural and luminescent properties. An efficient near-infrared (NIR) quantum cutting (QC) from the phosphors was observed, which involved the emission of two low-energy NIR photons (around 971 nm) from an absorbed ultra-violet (UV) photon at 358 nm via a cooperative energy transfer (CET) from Ce3+ to Yb3+ ions. The theoretical quantum efficiency was calculated and the maximum efficiency approached up to 164% before reaching the critical concentration quenching threshold. Our results demonstrated that these phosphors might find potential application in improving the efficiency of silicon based solar cells.     

Optical studies of Y_3(Al,Ga)_5O_(12):Ce~(3+),Cr~(3+),Nd~(3+) nano-phosphors obtained by the Pechini method

The Y3(AI,Ga)_5O_(12):Ce~(3+),Cr~(3+),Nd~(3+)(YAGG) nano-phosphors with homogeneous particle-size distribution,low aggregation and average crystalline size of about 65 nm were obtained using a modified Pechini method.Only slight aggregation of the crystallites occurs after post-annealing at 1100℃.The intense Ce~(3+)bands in the excitation spectra of the Ce~(3+),Cr~(3+),Nd~(3+)co-doped materials monitoring the Cr~(3+) emission at 690 nm indicate energy transfer from Ce~(3+) to Cr~(3+).Weak Nd~(3+) lines are observed,as well.In addition,the emission of Nd~(3+)at 1060 nm with excitation of Ce~(3+) and Cr~(3+) confirms the Ce~(3+)/Cr~(3+)to Nd~(3+)energy transfer.The short average luminescence decay times for the Ce~(3+) emission indicate the Ce~(3+)/Cr~(3+)to Nd~(3+)energy transfer.Eventually,the Y_3(AI,Ga)_5O_(12):Ce~(3+),Cr~(3+),Nd~(3+) nano-phosphors exhibit persistent luminescence originating from the 4f~3→4f~3 transitions of Nd~(3+) which matches well to the first biological window to be used in bioimaging applications.