Ultraviolet excitation of rare-earth-doped YSZ crystals

Abstract

The optical properties of nominally pure and Er³⁺- or Pr³⁺ -doped yttria-stabilized zirconia single crystals were investigated under UV light excitation. In the excitation spectra of both types of doped crystals, a broad UV band is observed. Under excitation with light of different wavelengths inside this band, the luminescence features of the doped crystals are different. YSZ: Pr³⁺ samples exhibit the characteristic 4f → 4f emission of the Pr³⁺ ions. In YSZ: Er³⁺ crystals, both the Er³⁺ ion and the intrinsic luminescence are observed. Host to Er³⁺ ion radiative energy-transfer is also demonstrated. No dependence of the transfer process with the excitation wavelength was found. These results suggest that the UV band in Er³⁺ -doped crystals is associated with the lattice-dopant ion interaction rather than with the 4f5d interconfigurational band of the Er^3? ions.     

Dual mode emission and harmonic generation in ZnO-CaO-Al2O3: Er nano-composite

Er³⁺ doped ZnO-CaO-Al₂O₃ nano-composite phosphor has been synthesized through combustion method and its emission and harmonic generation properties have been studied. The X-ray diffraction and thermal analysis techniques have been used to prove the dual phase (ZnO and CaO-Al₂O₃) nature of the phosphor. The phosphor has shown up-conversion emission on near-infra-red (976 nm) excitation and down-conversion emission on 355 nm excitation in presence of Er³⁺ and thus behaves as a dual mode phosphor. On excitation with 976 nm diode laser, material shows color tunability (calcination of composite material at different temperatures). Formation of ZnO nanocrystals on heat treatment of as-synthesized sample has shown its characteristic emission at 388 nm and also the energy transfer from ZnO to Er³⁺ ions. The low temperature emission measurements have been carried out and the results have been discussed. Phosphor has shown strong second harmonic generation (SHG) at 532 nm on 1064 nm and at 266 nm on 532 nm excitation.     

Energy transfer between Sm and Er in orthophosphate YPO4

The energy transfer between Sm³⁺ and Er³⁺ ions in yttrium orthophosphate is studied. This choice of ions is based on the possibility of quantum cutting processes and the host material is selected according to the position of the 5d bands of the Sm³⁺ ion. The Sm³⁺ and Er³⁺ doped and Sm³⁺, Er³⁺ co-doped YPO₄ have been synthesized. Spectroscopic studies were done in the ultraviolet and vacuum ultraviolet ranges. The energy transfer between Sm³⁺ and Er³⁺ is very efficient but it does not lead to Er³⁺ visible emission. Whatever the excitation wavelength, the emission of co-doped samples mainly occurs in the infrared range.     

Upconversion properties of Er^3＋/Yb^3＋ co-doped TeO2-Nb2O5-Li2O glasses

The Er^3＋/Yb^3＋ co-doped TeO2-Nb2O5-Li2O glass is prepared by conventional melting method, and its upconversion spectra are measured. The intense green upconversion luminescence upon excitation with a 976 nm laser diode is observed with the naked eyes. The dependence of luminescence intensity on the ratio of Yb^3＋/Er^3＋ is discussed in detail, and the relationship between the ratio of green luminescence intensity to red luminescence intensity and the ratio of Yb^3＋/Er^3＋ is also studied, The luminescence intensity increases with the ratio of Yb^3＋/Er^3＋ increasing. The ratio of Yb^3＋/Er^3＋ plays a more important role than the concentration of Er^3＋ in determining the upconversion luminescence intensity. The ratio of green luminescence intensity to red luminescence intensity reaches a maximum when ratio of Yb^3＋/Er^3＋ is 3. Thus the glass could be one of the potential candidates for LD pumping solid-state lasers.     

Upconverted VUV luminescence of Nd and Er doped into LiYF4 crystals under XeF-laser excitation

The upconverted VUV (185 nm) and UV (230 and 260 nm) luminescence due to 5d-4f radiative transitions in Nd³⁺ ions doped into a LiYF₄ crystal has been obtained under excitation by 351/353 nm radiation from a XeF excimer laser. The maximum upconversion efficiency, defined as the ratio of intensity for 5d-4f luminescence to overall intensity for 5d-4f and 4f-4f luminescence from the ⁴D_3/2 Nd³⁺ level, has been estimated to be about 70% under optimal focusing conditions for XeF laser radiation. A redistribution of intensity between three main components of 5d-4f Nd³⁺ luminescence is observed under changing the excitation power density, which favors the most long-wavelength band (260 nm) at higher excitation density level. The effect is interpreted as being due to excited state absorption of radiation emitted. The upconverted VUV and UV luminescence from the high-lying ²F(2)_7/2 4f level of Er³⁺ doped into a LiYF₄ crystal has also been obtained under XeF-laser excitation the most intense line being at 280 nm from the spin-allowed transition to the ²H(2)_11/2 4f level of Er³⁺, but the efficiency of upconversion for Er³⁺ emission is low, less than 5%.     

Er3+，Er3+/Yb3+掺杂氟化镧超微材料的光谱特性与上转换发光

采用共沉淀法制备了Er³⁺掺杂和Er³⁺/Yb³⁺共掺杂LaF₃超微材料,所制备的样品的颗粒呈球形,尺寸为250nm左右.计算得到Er³⁺单掺杂样品中对应着⁴S_3/2和⁴F_9/2能级的发光量子效率分别为67.0%和71.9%.研究发现,随着Yb³⁺离子浓度的增加 关键词： 3+')" href="#">Er³⁺ 3+')" href="#">Yb³⁺ 发光 能量传递     

Infrared-to-visible upconversion in Er and Er/Yb activated Sb2O4 nanopowders prepared by sol-gel route

We prepared Er³⁺ doped and Er³⁺/Yb³⁺ codoped Sb₂O₄ nanocrystals by the sol-gel method. The Raman, X-ray diffraction (XRD), transmission electron microscope (TEM), and photoluminescence spectra of the samples were studied. The phonon energy of the Sb₂O₄ nanocrystals is very low (the maximum value being 461 cm⁻¹). The upconversion (UC) red emission of the Er³⁺/Yb³⁺ codoped sample is very strong at 975 nm laser diode excitation. The Sb₂O₄ nanocrystals will be a promising luminous material.     

Yb3+敏化的Er3+/Ho3+共掺碲酸盐玻璃的上转换发光研究

用高温熔融法制备了系列Er³⁺/Yb³⁺共掺，Ho³⁺/Yb³⁺共掺，和Er³⁺/Yb³⁺/Ho³⁺三掺碲酸盐玻璃，在975nm激光抽运下三种掺杂玻璃中都出现了较强的绿光和红光上转换.研究了Yb³⁺离子对Er³⁺和Ho³⁺离子上转换发光强度的影响以及Yb³⁺→Er关键词： 3+/Yb³⁺/Ho³⁺共掺')" href="#">Er³⁺/Yb³⁺/Ho³⁺共掺 碲酸盐玻璃 光谱性质 上转换     

The up-conversion properties of Yb and Er doped Y4Al2O9 phosphors

Er³⁺ doped and Yb³⁺/Er³⁺ co-doped Y₄Al₂O₉ phosphors are prepared by the sol-gel method. The effect of dopant concentration on the structure and up-conversion properties is investigated by X-ray diffraction (XRD) and photoluminescence, respectively. XRD pattern indicates that the sample structure belongs to monoclinic. Under 980 nm excitation, the green and red up-conversion emissions are observed and the emission intensities depended on the Yb³⁺ ion concentration. The green up-conversion emissions decrease with the increase of Yb³⁺ concentration, while red emission increases as Yb³⁺ concentration increases from 0 to 8 at% and then decreases at high Yb³⁺ concentration. The mechanisms of the up-conversion emissions are discussed and results shows that in Er³⁺ and Yb³⁺/Er³⁺ co-doped system, cross-relaxation (CR) and energy transfer (ET) processes play an important role for the green and red up-conversion emissions.     

Energy transfer from the host to Er<Superscript>3+</Superscript> dopants in semiconductor SnO<Subscript>2</Subscript> nanocrystals segregated in sol–gel silica glasses

Undoped and Er³⁺-doped glass–ceramics of composition (100−x)SiO₂–xSnO₂, with x = 5 or 10 and with 0.4 or 0.8 mol% of Er³⁺ ions, were synthesised by thermal treatment of precursor sol–gel glasses. Structural studies were developed by X-Ray Diffraction. Wide band gap SnO₂ semiconductor quantum-dots embedded in the insulator SiO₂ glass are obtained. The mean radius of the SnO₂ nanocrystals, ranging from 2 to 3.2 nm, is comparable to the exciton Bohr radius. The luminescence properties have been analysed as a function of sample composition and thermal treatment. The results show that Er³⁺ ions are partially partitioned into the nanocrystalline phase. An efficient UV excitation of the Er³⁺ ions by energy transfer from the SnO₂ nanocrystal host is observed. The Er³⁺ ions located in the SnO₂ nanocrystals are selectively excited by this energy transfer mechanism. On the other hand, emission from the Er³⁺ ions remaining in the silica glassy phase is obtained by direct excitation of these ions.     

Energy transfer and infrared-to-visible upconversion luminescence of Er/Yb-codoped halide modified tellurite glasses

We report on the energy transfer and frequency upconversion spectroscopic properties of Er³⁺-doped and Er³⁺/Yb³⁺-codoped TeO₂-ZnO-Na₂O-PbCl₂ halide modified tellurite glasses upon excitation with 808 and 978 nm laser diode. Three intense emissions centered at around 529, 546 and 657 nm, alongwith a very weak blue emission at 410 nm have clearly been observed for the Er³⁺/Yb³⁺-codoped halide modified tellurite glasses upon excitation at 978 nm and the involved mechanisms are explained. The quadratic dependence of fluorescence on excitation laser power confirms the fact that the two-photon contribute to the infrared to green-red upconversion emissions. And the blue upconversion at 410 nm involved a sequential three-photon absorption process.     

Synthesis and Characterization of Monodispersed SiO2@Y3Al5O12:Er3+ Core-Shell Particles

Submicron core-shell structure particles SiO₂@Y₃Al₅O₁₂:Er³⁺, which silica spherical particles was coated with an yttrium aluminum garnet (Y₃Al₅O₁₂) layer doped with Er³⁺, were prepared by the modified Pechini-Type sol-gel method for the first time. The structure and morphology of samples were detected by the X-ray powder diffraction (XRD) measurement, field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The results indicate that well-crystallized garnet nanocrystallines were formed on the surface of the silica particles. The luminescent spectra in near infrared and visible region of the core-shell structured SiO₂@Y₃Al₅O₁₂:Er³⁺ powders were also investigated and compared with those of the pure Y₃Al₅O₁₂:Er³⁺ and the Er³⁺ doped silicate glass. The results show that mono-dispersed SiO₂@Y₃Al₅O₁₂:Er³⁺ core-shell spherical particles with the near infrared, red and green luminescent emissions under the excitation of 980 nm laser diode have been successfully synthesized.     

Up-conversion white light of Tm/Er/Yb tri-doped CaF2 phosphors

Tm³⁺/Er³⁺/Yb³⁺ tri-doped CaF₂ phosphors were synthesized using a hydrothermal method. The phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and up-conversion (UC) emission spectra. After annealing, the phosphors emitted white light under a 980 nm continuous wave diode laser (CW LD 2 W) excitation. As the excitation power density changed in the range of 20-260 W/cm², the chromaticity coordinates of the UC light of the phosphor Ca_0.885Tm_0.005Er_0.01Yb_0.1F₂ fell well in the white region of the 1931 CIE diagram. For the proportion of red, green and blue (RGB) in white light is strict, key factors for achieving UC white light, such as host materials, rare earth ions doping concentrations, annealing temperatures, as well as the excitation power densities, were investigated and discussed.     

Enhanced 1.53-μm and lowered upconversion luminescence in Er-doped Ga2O3-GeO2-Bi2O3-Na2O glass by codoping rare earths

Spectroscopic properties and energy transfer (ET) in Ga₂O₃-GeO₂-Bi₂O₃-Na₂O (GGBN, glass doped with Er³⁺ and rare earths (RE³⁺; RE³⁺=Ce³⁺, Tb³⁺) have been investigated. Intense 1.53-μm emission with the peak emission cross-section achieved to 7.58×10⁻²¹ cm² from Er³⁺-doped GGBN glass has been obtained upon excitation at 980 nm. Effects of RE³⁺ (RE³⁺=Ce³⁺, Tb³⁺) codoping on the optical properties of Er³⁺-doped GGBN glass have been investigated and the possible ET mechanisms involved have also been discussed. Significant enhancement of the 1.53 μm emission intensity and decrease of upconversion (UC) fluorescence with increasing Ce³⁺ concentration have been observed. The incorporation of Tb³⁺ into Er³⁺-doped GGBN glass could significantly decrease the UC emission intensity, but meanwhile decrease the 1.53 μm emission intensity due to the ET from Er³⁺:⁴I_13/2 to Tb³⁺:⁷F₂. The results indicate that the incorporation of Ce³⁺ into Er³⁺-doped GGBN glass can effectively improve 1.53-μm and lower UC luminescence, which makes GGBN glass more attractive for use in C-band optical fiber amplifiers.     

Optical temperature sensor based on up-conversion fluorescence emission in Yb3+:Er3+ co-doped ceramics glass

Yb3+:Er3+co-doped oxy-fluoride ceramics glass has been prepared.The mechanism of up-conversion emissions about Er3+was discussed,and the temperature properties of green up-conversion fluorescence between 303 and 823 K were investigated.The results show that the sensitivity of this sample reaches its maximum value,about 0.0047 K 1,when the temperature is 383 K,indicating that this kind of sample can be used as high temperature and high sensitivity optical temperature sensor.     

Infrared and visible emission of Er in combustion-synthesized CaAl2O4 phosphors

New near-infrared luminescent, monoclinic CaAl₂O₄:Er³⁺ phosphor was prepared by using the combustion route at furnace temperatures as low as 500 °C in a few minutes. Combustion synthesized phosphor has been well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive analysis of X-ray (EDAX) mapping studies. The luminescence spectra of Er³⁺-doped calcium aluminate were studied at UV (380 nm), vis (488 nm) and IR (980 nm) excitation. Upon UV and vis excitation, the CaAl₂O₄:Er³⁺ phosphor exhibits emission bands at ~523 nm and at ~547 nm, corresponding to transitions from the ²H_11/2 and ⁴S_3/2 erbium levels to the ⁴I_15/2 ground state. A strong luminescence at 1.55 μm in the infrared (IR) region due to ⁴I_13/2→⁴I_15/2 transition has been observed in CaAl₂O₄:Er³⁺ phosphor upon 980 nm CW pumping. In the spectrum of IR-excited up-conversion luminescence, green (~523 and ~547 nm) and red (662 nm) luminescence bands were present, the latter associated with the ⁴F_9/2→⁴I_15/2 transitions of Er³⁺ ions. Both excited state absorption and energy transfer may be proposed as processes responsible for the population of the ⁴S_3/2 and ⁴F_9/2 erbium levels upon IR excitation. The mechanisms responsible for the up-conversion luminescence are discussed.     

Er3+/Ce3+共掺碲铋酸盐玻璃的制备及光谱特性提高研究

采用高温熔融退火法制备了系列 80TeO₂-10Bi₂O₃-10TiO₂-0.5Er₂O₃-xCe₂O₃ (x=0,0.25, 0.5,0.75,1.0 mol%)和(80-y) TeO₂-10Bi₂O₃-10TiO₂-yWO₃-0.5Er₂O₃-0.75Ce₂O₃ (y=3,6,9,12 mol%)的碲铋酸盐玻璃.测试了玻璃样品400-1700 nm范围内的吸收光谱, 975 nm抽运下的上转换发光谱和1.53 μm波段荧光谱, 以及808 nm激励下的Er³⁺离子荧光寿命和无掺杂玻璃样品的Raman光谱, 并结合Judd-Ofelt理论和McCumber理论计算了Er³⁺离子光谱参数.结果表明, 在掺Er³⁺碲铋酸盐玻璃中引入Ce³⁺离子进行Er³⁺/Ce³⁺共掺, 通过Er³⁺离子⁴I_11/2能级与Ce³⁺离子²F_5/2 能级间基于声子辅助的能量传递过程,可以有效抑制Er³⁺离子上转换发光并明显增强其 1.53 μm波段荧光;同时,在现有Er³⁺/Ce³⁺共掺玻璃组分基础上引入WO₃, 可进一步提高1.53 μm波段荧光并展宽其荧光发射谱. 研究结果对于获取优异光谱特性的宽带掺Er³⁺光纤放大器玻璃基质具有实际意义.     

Optical parameters of Nd3＋：Er3＋：yb3＋ co-doped borosilicate glasses and their energy transfers at high temperature

This paper reports that a series of Nd³⁺:Er³⁺:Yb³⁺ co-doped borosilicate glasses have been prepared and their absorption spectra measured. The J--O intensity parameters Ω_k (k=2, 4, 6), spontaneous radiative lifetime τ_rad, spontaneous transition probability A, fluorescence branching ratio β and oscillator strength f_ed of the Nd³⁺ ions at room temperature are calculated based on Judd--Ofelt (J--O) theory. The temperature dependence of the up-conversion photoluminescence characteristics in a Nd³⁺:Er³⁺:Yb³⁺ co-doped sample is studied under a 978 nm semiconductor laser excitation, and the energy transfer mechanisms among Yb³⁺, Er³⁺ and Nd³⁺ ions are analysed. The results show that the J--O intensity parameters Ω₂ increase when the Nd³⁺ concentration of the Nd³⁺:Er³⁺:Yb³⁺ co-doped borosilicate glasses increases. The possibility of spontaneous transition is small and lifetimes are long at levels of ⁴F_5/2 and ⁴F_3/2. The intensity of Nd³⁺ emissions at 595, 691, 753, 813 and 887 nm are markedly enhanced when the sample temperature exceeds 400 K. The reasons being the cooperation of the secondary sensitization from Er³⁺ to Nd³⁺ and the contribution of a multi-phonon.     

Upconversion emission enhancement in Er/Yb-codoped BaTiO3 nanocrystals by tridoping with Li ions

Er³⁺/Yb³⁺/Li⁺-tridoped BaTiO₃ nanocrystals were prepared by a sol-gel method to improve the upconversion (UC) luminescence of rare-earth doped BaTiO₃ nanoparticles. Effects of Li⁺ ion on the UC emission properties of the Er³⁺/Yb³⁺/Li⁺-tridoped BaTiO₃ nanocrystals were investigated. The results indicated that tridoping with Li⁺ ion enhanced the visible green and red UC emissions of Er³⁺/Yb³⁺-codoped BaTiO₃ nanocrystals under the excitation of a 976 nm laser diode. X-ray diffraction and decay time of the UC luminescence were studied to explain the reasons of the enhancement of UC emission intensity. X-ray diffraction results gave evidence that tridoping with Li⁺ ion decreased the local symmetry of crystal field around Er³⁺, which increased the intra-4f transitions of Er³⁺ ion. Moreover, lifetimes in the intermediate ⁴ S_3/2 and ⁴I_11/2 (Er) states were enhanced by Li⁺ ion incorporation in the lattice. Therefore, it can be concluded that Li⁺ ion in rare-earth doped nanocrystals is effective in enhancing the UC emission intensity.     

Ce3+对Er3+/Yb3+共掺TeO2-WO3-ZnO玻璃发光性能的影响

在Er³⁺/Yb³⁺共掺TeO₂-WO₃-ZnO玻璃中引入Ce³⁺，研究了Ce³⁺对Er³⁺1.5μm发射性能及其上转换发光性能的影响。结果表明，随Ce³⁺浓度的增加Er³⁺1.5μm波段的荧光强度先增强后降低，优化的Ce³⁺掺杂浓度在2.07×10²⁰/cm³左右；1.5μm波段的荧光寿命则随Ce³⁺浓度的增加有轻微降低，从3.4ms降到3.0ms，但Ce³⁺浓度的增加对1.5μm波段的荧光半高宽基本无影响；Er³⁺/Ce³⁺间的交叉弛豫Er³⁺(⁴I_11/2)+Ce³⁺(²F_5/2)→Er³⁺(⁴I_13/2)+Ce³⁺(²F_7/2)使玻璃的上转换发光强度大大降低，但在过高的Ce³⁺浓度下，Er³⁺/Ce³⁺间的另一交叉弛豫Er³⁺(⁴I_13/2)+Ce³⁺(²F_5/2)→Er³⁺(⁴I_15/2)+Ce³⁺(²F_7/2)则使Er³⁺⁴I_13/2能级粒子数减少，导致1.5μm波段荧光强度和荧光寿命降低. 关键词： 碲钨酸盐玻璃 发光性能 3+离子')" href="#">Er³⁺离子 3+离子')" href="#">Ce³⁺离子 交叉弛豫