棒状结构NaGdF_(4):Yb^(3+),Er^(3+)上转换发光性能的研究

以乙二胺四乙酸二钠(EDTD-2Na)为螯合剂,采用水热法合成了棒状结构的NaGdF_(4):Yb^(3+),Er^(3+)纳米粉末。分别借助X射线衍射(XRD)、荧光光谱仪(PL)和扫描显微镜(SEM)对其晶体结构、发光强度和表面形貌进行分析和表征。探究了稀土前驱体、水热温度和水热时间的实验条件对NaGdF_(4):Yb^(3+),Er^(3+)纳米粉末上转换发光强度的影响;研究了氟源和钠源对NaGdF_(4):Yb^(3+),Er^(3+)晶体形貌和上转换发光强度的改善;同时,采用煅烧处理的方法,进一步探究样品的形貌和发光强度收到的影响。实验结果表明NH4F与NaOH作为氟源和钠源及200℃煅烧1 h得到的棒状结构NaGdF_(4):Yb^(3+),Er^(3+)的发光强度最好,色坐标(CIE)绿色发光强度从84%提升到94.88%。

高热稳定CaGdAlO_(4)∶Er^(3+)/Yb^(3+)荧光粉的上转换发光及其温度传感性能

获得具有良好热稳定性和发光性能的非接触式光学温度传感材料是目前的研究热点之一,本工作通过高温固相法制备了Er^(3+)/Yb^(3+)共掺CaGdAlO_(4)∶Er_(x),Yb_(0.10)(x=0.006、0.008、0.010、0.012、0.014)荧光粉,尺寸大小分布在0.6~4.2μm。在980 nm激光激发下,该荧光粉在500~700 nm发射谱由两个发射带组成,528和550 nm处两个较强的绿光发射带,归属于Er^(3+)的^(2)H_(11/2)→^(4)I_(15/2)、^(4)S_(3/2)→^(4)I_(15/2)能级跃迁,663 nm处较弱的红光发射带,归属于Er^(3+)的^(4)F_(9/2)→^(4)I_(15/2)能级跃迁。上转换发光强度最大组分为CaGdAlO_(4)∶Er_(0.010),Yb_(0.10)。300~573 K变温发射谱表明,基于荧光强度比FIR_(528/550)参数,温度传感绝对灵敏度S_(A)从44.4×10^(-4) K^(-1)(@300 K)先增大到52.0×10^(-4) K^(-1)(@445 K)随后减小到49.0×10^(-4) K^(-1)(@573 K)。相对灵敏度S_(R)则从0.95×10^(-2) K^(-1)(@300 K)单调减小到0.27×10^(-2) K^(-1)(@573 K)。冷热循环实验表明该材料的热重复性优于98%。结果表明,CaGdAlO_(4)∶Er_(0.010),Yb_(0.10)荧光粉在光学温度传感领域具有潜在的应用前景。

Effect of Er substituting sites on upconversion luminescence of Er^(3+)-doped BaTiO_3 films

Erbium-doped BaTiO3 films on LaNiO3/Si substrates were fabricated by sol-gel method. The crystalline structure, morphologies and upconversion （UC） luminescence properties of films were respectively investigated by X-ray diffraction （XRD）, atomic force microcopy （AFM） and photoluminescence （PL）. The results indicate that both of the microstructure and luminescence are found to be dependent on Er^3＋ substituting sites. The samples with A-site substitution have smaller lattice constants, larger grains and smoother surface than those with B-site substitution. The photoluminescence spectra show that both of the samples have two stronger green emission bands centered at 528 and 548 nm and a weak red emission band centered at 673 nm, which correspond to the relaxation of Er^3＋ from ^2H11/2, ^4S3/2, and ^4F9/2 levels to the ground level ^4I15/2, respectively. Compared with B-site doped films, A-site doped films have a stronger integrated intensity of green emissions and a weaker relative intensity of red emissions. The differences could be explained by the crystalline quality and cross relaxation （CR） process.

Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体的光谱分析及中红外发射增强

采用非化学计量配比的提拉法成功生长出Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体、Er^(3+)/Yb^(3+):SrLaGaO_(4)和Er^(3+):SrLaGaO_(4)晶体并进行了详细的光谱分析,同时对纯的SrLaGaO_(4)晶体进行了热学性能分析。与Er^(3+):SrLaGaO_(4)晶体相比,Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体不仅展示了更好的吸收特性,而且还表现出较弱的近红外发射,以及优异的中红外发射;Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体中2.7μm铒激光下能级4I13/2的荧光寿命显著减少,而上能级4I11/2的寿命略微下降,成功抑制了自终止效应。此外,本工作还研究了Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体中Yb^(3+)的敏化作用和Pr^(3+)离子的去激活作用以及能量传递机制。总之,引入Yb^(3+)和Pr^(3+)有利于在Er^(3+)/Yb^(3+)/Pr^(3+):SrLaGaO_(4)晶体中实现增强的2.7μm发射,这使其成为中红外激光有前途的候选材料。

LD脉冲泵浦Er^(3+)/Yb^(3+):Lu_(2)Si_(2)O_(7)晶体百kHz激光器

目前1.5μm激光二极管(Laser Diode,LD)泵浦的铒镱共掺玻璃/晶体被动调Q微型激光器广泛应用于激光测距、激光雷达等领域。随着激光器输出重频的增加,玻璃面临突出的热效应问题,晶体的热导率是玻璃的10倍以上,有望能够实现比玻璃基质更高重频的激光输出。报道了一种通过LD脉冲端面泵浦Er^(3+)/Yb^(3+):Lu_(2)Si_(2)O_(7)晶体的百kHz人眼安全激光器。通过实验优化增益介质掺杂浓度和长度、泵浦光斑尺寸和调Q晶体初始透过率等实验参数,同时适当缩短脉宽,优化泵浦占空比,提高了输出重频的稳定性。最终获得了重频为100 kHz、单脉冲能量0.7μJ、脉冲宽度240 ns、光束质量M^(2)=1.61的1537 nm脉冲激光输出。实现了输出脉冲频率与泵浦的一致,保证了输出重频的稳定性,有效解决了输出重频具有随机性、不稳定、不可控等问题。

3μm波段Er^(3+)∶ZBLAN光纤激光器研究进展及展望

3µm激光处于分子指纹区,在医疗外科、气体检测、军事应用等领域都有重要的应用价值。Er^(3+)∶ZBLAN光纤激光器具有效率高、可集成的优点,是3µm激光的主要输出方式。本文从铒离子跃迁产生3µm激光出发,围绕Er^(3+)∶ZBLAN光纤激光器,介绍了3µm激光产生的结构原理及能级系统,总结了实现该波段高功率连续输出和脉冲输出的技术方案和研究进展,重点介绍了基于不同材料可饱和吸收体的调Q和锁模激光器实验研究,并对目前实现3µm波段高功率输出需要解决的问题进行了分析,最后对Er^(3+)∶ZBLAN激光器的发展方向进行了展望。

高掺Er^(3+)上转换纳米晶发光性质多维调控研究进展

近年来,高掺Er^(3+)纳米晶的上转换发光研究取得了显著进展。与传统发光材料相比,这类材料具有多波段激发、穿透能力强的激发波段、光色动态可调以及对外场刺激响应灵敏等特点,在光信息安全、温度探针、生物成像等领域展现出巨大应用潜力。本文综述了高掺杂Er^(3+)纳米晶发光性质的多维调控策略,涵盖基质组成、结构设计以及能量传递机制的深入解析,详细探讨了发光强度增强、光色调控、动力学过程调节和激发波段拓宽等方面的最新研究成果。此外,本文还探究了外场激励对高掺杂Er^(3+)体系发光性能的调控机制,详细分析了温度、压力及金属表面电场等关键因素的影响,并从提升多光子跃迁概率和减少无辐射能量损失等角度揭示发光增强机理。最后,总结了激发模式调控高掺杂Er^(3+)上转换发光的有效方法,并对未来发展方向进行了展望。

KYb_(2)F_(7):2%Er^(3+)荧光材料的制备、发光机制及温度传感性能

采用简易水热法制备了正交相KYb_(2)F_(7):2%Er^(3+)上转换荧光材料。利用X射线衍射仪和扫描电子显微镜确定所合成样品均为六角状纯相材料。在980 nm激光激发下,KYb_(2)F_(7):2%Er^(3+)荧光材料展现了位于527 nm和545 nm的两个绿光发射峰和位于655 nm处的红光发射峰,且上转换发光出现少见的以红光为主的现象。变温光谱结果表明,545 nm和655 nm处的发射强度随温度升高均呈现热猝灭。基于热耦合测温原理,对Er^(3+)的^(2)H_(11/2)→^(4)I_(11/2)和^(4)S_(3/2)→^(4)I1_(1/2)两个热耦合能级进行温度传感性能研究,计算了发光温度计的发光强度比(LIR)、绝对灵敏度(S_(a))、相对灵敏度(S_(r))、温度不确定度(δ_T)和可重复度(R),其中最大相对灵敏度在313 K时为0.99%·K^(-1),最小温度不确定度在313 K时为0.73 K,可重复度超过99%,确保了该温度计的可靠性。实验结果表明KYb_(2)F_(7):2%Er^(3+)荧光材料在温度传感方面具有潜在应用价值。

Preparation and Luminescence of Er^(3+) Doped Oxyfluoride Glass Ceramics Containing LaF_3 Nanocrystals

Er^3＋ doped transparent oxyfluoride glass ceramics version and near infrared luminescence behavior of Er^3＋ in containing LaF3 nanocrystals were prepared and the up-conglasses heat-treating time and temperature, the size （varied from 0 to 19 and glass ceramics were investigated. With increasing nm） and crystallinity （varied from 0 to 47%） of LaF3 nanocrystals in the glass ceramics are increased. The up-conversion luminescence intensity of Er^3＋ ions in the glass ceramics is much stronger than that in the glasses The near infrared emission of Er^3＋ ions in and increased significantly with increasing heat-treating time and temperature the glass ceramics is found to be similar to that in the glasses.

Preparation and Optical Properties of Er^(3+)-Doped Gadolinium Borosilicate Glasses

Er^(3+)-doped Gd_2O_3 -SiO_2 -B_2O_3 -Na_2O glasses were prepared, and formation range of glass of Gd_2O_3 -SiO_2 -B_2O_3 system was experimentally obtained. It is found that the glass phase can be formed only when the content of SiO_2 is 0～50%(molar fraction), Gd_2O_3 is 0～30%(molar fraction) and B_2O_3 is above 20%(molar fraction) in this glass system. The glass can also be obtained but becomes translucent at the contents of 60%(molar fraction) SiO_2 and 30% Gd_2O_3 , or at the contents of 60%(molar fraction) SiO_2 and 30%(molar fraction) B_2O_3. There is no glass phase formed in other glass components. Glass forming ability for Gd_2O_3 content of 10%, was characterized by the value of β, the parameter of crystallization tendency, which is 0.32～1.76, obtained from the differential thermal analysis. The absorption and emission cross section, the J-O parameters Ωt_((2,4,6)) and radiative transition probabilities were calculated by using the theory of McCumber and Judd-Ofelt. The emission properties at 1.5 μm of the samples are discussed with the product of full width at half maximum and stimulated emission cross section. It can be seen that the value of the FWHM×σ_e^(peak) product in the prepared glass is more than those of germanate, silicate and phosphate glasses. Furthermore, the maximum value of the product among these glasses reported in this work is close to that of oxyfluoride silicate glass. Therefore, the Er^(3+)-doped gadolinium borosilicate glass in this paper is a candidate for broadband erbium doped fiber amplifiers.

不同激发波长下NaLaF_(4):Er^(3+)/Yb^(3+)的上转换光谱调控研究

为探究不同激发波长(980 nm、1 550 nm)对NaLaF_(4):Er^(3+)/Yb^(3+)上转换发光材料光谱调控的规律和机理,采用水热-固相两步反应法合成一系列不同Er^(3+)/Yb^(3+)掺杂浓度的NaLaF_(4)荧光粉。利用X射线衍射仪(XRD)、荧光分光光度计对材料进行测试,分析其发光性能与机理。结果表明,样品在980 nm激发下呈绿色发光,上转换发光强度随Er^(3+)/Yb^(3+)掺杂浓度增加而呈现先增后减的规律,该发光过程为双光子过程;而在1 550 nm激发下呈红色发光,上转换发光强度随Er^(3+)掺杂浓度增加而呈增强趋势,但随Yb^(3+)浓度增加而降低,发光过程为三光子过程。因此,通过调节激发光波长,在同组分NaLaF_(4):Er^(3+)/Yb^(3+)荧光粉中实现颜色可控的绿、红色发光,对设计新型光谱调控手段和探索新的发光材料具有一定的理论指导意义。

溶剂热法制备NaScF_(4):Yb^(3+)/Er^(3+)及其发光性能的研究

利用溶剂热法在油酸(OA),正辛醇(OC)及乙二醇(EG)三溶剂中成功制备出NaScF_(4):Yb^(3+)/Er^(3+)纳米颗粒。调节三种溶剂的不同比例观察对样品晶相、结构、尺寸及发光强度的影响。此外,我们使用了X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、荧光光谱仪对样品进行了表征。通过XRD证明在OA、OC、EG分别为16mL,12mL、4mL时成功合成出了纯相的NaScF_(4):Yb^(3+)/Er^(3+)纳米颗粒。SEM图进一步证明样品形貌均匀,分散性较好,粒径较小,颗粒尺寸为37.62±9.36nm。此外,样品的荧光光谱表明样品在980nm激光激发下能发射出红色荧光。因此,该方法下制备的NaScF_(4):Yb^(3+)/Er^(3+)尺寸较小,形貌较均匀,拥有强的红色发射且该材料有望用于生物成像、信息储存,防伪等领域。

Preparation and Optical Properties of Er^3+:Na2O-Al2O3-SiO2 Transparent Glass-Ceramics

Na2O-Al2O3-SiO2 glass-ceramics doped with Er^3＋ ions were synthesized by the conventional melt quenching technique at a low melting temperature.The samples were characterized by differential scanning calorimetry（DSC）,X-ray diffraction（XRD）,scanning electron microscopy（SEM）,UV-vis-NIR scanning spectrophotometry,and fluorescence spectrometry.The results show that the main crystalline phase of glass-ceramics is nepheline.The best heat-treatment process is at 520 ℃ for 2 h.Because the up-conversion luminescence and near infrared luminescence properties of glass doped with Eu^3＋ are studied in detail.

Upconversion luminescence of Y_2O_3:Er^(3+), Yb^(3+) nanoparticles prepared by a homogeneous precipitation method

Y2O3： Er^3＋, Yb^3＋ nanoparticles were synthesized by a homogeneous precipitation method without and with different concentrations of EDTA 2Na. Upconversion luminescence spectra of the samples were studied under 980 nm laser excitation. The results of XRD showed that the obtained Y2O3：Er^3＋,Yb^3＋ nanoparticles were of a cubic structure. The average crystallite sizes calculated were in the range of 28-40 nm. Green and red upconversion emission were observed, and attributed to ^2H11/2,^4S3/2→^4I15/2 and ^4F9/2→^4I15/2 transitions of the ion, respectively. The ratio of the intensity of green emission to that of red emission drastically changed with a change in the EDTA 2Na concentration. In the sample synthesized without EDTA, the relative intensity of the green emission was weaker than that of the red emission. The relative intensities of green emission increased with the increased amount of EDTA 2Na used. The possible upconversion luminescence mechanisms were discussed.

Theoretical Analyses of 4f^11→4f^105d Excitation Spectra of Er^3＋ Doped in LiYF4

Spectral terms and J-spectral multiplet of low-spin 4f105d configuration of Er3+ were obtained with the method of ligand field theory. According to the selection rules for dipole transitions, the excitation spectra of Er3+ doped in LiYF4 in vacuum ultraviolet region (120～160 nm) of the spectrum were theoretically interpreted by applying the crystal field model, and the six bands were assigned to the spin-allowed transitions from the ground state (4I15/2) to J-spectral multiplet of low-spin 4f105d configuration of Er3+ion.

Synthesis and upconversion luminescence properties of NaYF_4:Yb^(3+)/Er^(3+) microspheres

Cubic NaYF4：Yb^3＋（20%）/Er^3＋（1%） microspheres were synthesized by EDTA-assisted hydrothermal method. Under 980 nm excitation, ultraviolet （^4G11/2→^4I15/2）, violet （^2H9/2→^4I15/2）, green （^4F7/2→^4I15/2, 2H11/2→^4I15/2, and ^4S3/2→^4I15/2）, and red （^4F9/2→^4I15/2） upconversion fluorescence were observed. The number of laser photons absorbed in one upconversion excitation process, n, was determined to be 3.89, 1.61, 2.55, and 1.09 for the ultraviolet, violet, green, and red emissions, respectively. Obviously, n=3.89 indicated that a four-photon process was involved in populating the ^4G11/2 state, and n=2.55 indicated that a three-photon process was involved in populating the ^4F7/2/^2H11/2/^4S3/2 levels. For the violet and red emissions, the population of the states ^2H9/2 and ^4F9/2 separately came from three-photon and two-photon processes. The decrease of n was well explained by the mechanism of competition between linear decay and upconversion processes for the depletion of the intermediate excited states.

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.

Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

Preparation and characterization of BaLiF_3:Er^(3+) nanoparticles by the hydrothermal microemulsion synthesized method

Nanoparticles of BaLiF3：Er^3＋ were prepared from the quaternary microemulsions of Cetyltrim-Enthyl Ammonium Bromide （CTAB）, n-butanol, n-octane, and water, using the hydrothermal-microemulsion technique. The complex fluorides were characterized by means of X-ray power diffraction, Environmental Scanning Electron Microscopy （ESEM）, and fluorescence spectra. The positions and intensifies of the peaks in the XRD pattern of the final products indicate the formation of BaLiF3·Er^3＋. No other peaks or impurities were detected. The average size of the nanoparticles, calculated with the Debye-Scherrer equation was 98.45 nm, which was in agreement with the result of ESEM. The infrared fluorescence spectra consisted of four peaks with a predominant peak located at 1540 nm.

Optical temperature sensor based on up-conversion fluorescence emission in Yb^(3+):Er^(3+) co-doped ceramics glass

yb^3＋：Er^3＋ co-doped oxy-fluoride ceramics glass has been prepared. The mechanism of up-conversion emissions about Er^3＋ 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.