Er3+/Tm3+/Yb3+共掺氟氧化物玻璃的上转换白光性质

采用高温固相法制备了Er3+/Yb3+、Tm3+/Yb3+和Er3+/Tm3+/Yb3+共掺杂的氟氧化物玻璃SiO2-Al2O3-Na2O-ZnF2,研究了980nm近红外激光激发下的上转换发光性质。研究表明,Er3+/Yb3+共掺样品呈现了上转换绿光和红光发射,Tm3+/Yb3+共掺样品呈现了强的上转换蓝光发射和弱的红光发射,Er3+/Tm3+/Yb3+三掺样品呈现了上转换白光发射。对上转换发光强度和激光功率的研究表明上转换绿光和红光发射是两光子吸收过程,上转换蓝光发射是三光子吸收过程。     

掺Er3+硅酸盐玻璃上转换发光特性研究

研究了掺Er^3＋硅酸盐玻璃的吸收光谱和上转换光谱，应用Judd-Ofelt理论计算了Er^3＋强度参数Ωλ（λ=2、4、6）、跃迁振子强度、自发辐射几率、荧光分支比．上转换光谱分析表明：在522、545、658nm处有较强的绿光和红光，分别对应于^2H11／2→^4I15／2、^4S3／2→^4I15／2、^4F9／2→^4I15／2的跃迁，发光曲线拟合斜率分别为1．67，1．94，1．76；上转换发光机制主要是激发态吸收和能量转换，且均为双光子吸收过程．     

氟化物玻璃中Yb^3＋敏化稀土离子的上转换发光

研究了氟化物玻璃中Ｙｂ＾３＋敏化Ｐｒ＾３＋、Ｔｍ＾３＋、Ｅｒ＾３＋和Ｈｏ＾３＋产生的上转换发光,在波长为８８０ｎｍ光的激发下,Ｙｂ＾３＋敏化Ｐｒ＾３＋产生波长为４８２,５２０,５２９,６０５和６３５ｎｍ的荧光。     

YAG:Er3+粉体的sol-gel燃烧法合成与上转换发光研究

以柠檬酸作为络合剂和燃料,用sol-gel燃烧法,制备了(Y1-xErx)3Al5O12粉体(x=0.001、0.005、0.01、0.05、0.1).在800℃,粉体直接由无定形相转变为YAG单相.采用980nm的半导体激光器激发,YAGEr3+发出较强的红绿光,且有两个主发射峰552.5nm和675nm.随着掺杂量的增加,发光强度先增加后减小,当Er3+掺杂量为5%(x=0.05)时,上转换发光强度最大.另外,对其上转换发光机制进行了讨论.     

980nm LD激发下Tm3+和Yb3+共掺杂的PGETYA玻璃上转换发光的研究

制备了一种Tm3+和Yb3+共掺杂的PGETYA氟氧玻璃材料,其组分为61.97PbF2-30.98GeO2-3Al2O3-0.05Tm2O3-4Yb2O3.测量了该玻璃系统在980nmLD激发下的上转换发光光谱,观察到很强的476nm的蓝色荧光,它来源于1G4→3H6的跃迁.同时,还有两个较弱的红色荧光来源于1G4→3H4和3F3→3H6的跃迁.测量并讨论了蓝色和红色上转换荧光强度与LD工作电流的关系.     

NaYF4:Er3+六棱柱的水热合成及上转换发光性能

以氟化钠、硝酸钇、硝酸铒为原料,利用水热法合成NaYF4:Er3+材料。利用X射线粉末衍射仪(XRD)、场扫描电子显微镜(SEM)、红外吸收(FT-IR)以及发光光谱等手段对产物的物相结构、形貌和荧光性能进行分析。结果表明,NaYF4:Er3+为六角棱柱晶体,属于六方晶系,具有P63/m(176)空间点群结构。在980nm光激发下,NaYF4:Er3+展现出强的上转换光,波长在520nm和539nm为绿光发射,对应为Er3+离子的2 H11/2→4/I15/2和4S3/2→4/I15/2跃迁发射,而652nm为红光发射,则对应于Er3+离子的4F9/2→4/I15/2跃迁发射。     

棒状结构NaGdF4:Yb3+,Er3+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NaGdF₄:Yb³⁺,Er³⁺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NaGdF₄:Yb³⁺,Er³⁺纳米粉末上转换发光强度的影响;研究了氟源和钠源对NaGdF₄:Yb³⁺,Er³⁺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NaGdF₄:Yb³⁺,Er³⁺的发光强度最好,色坐标(CIE)绿色发光强度从84%提升到94.88%。     

OH- 对 Tm3+/Yb3+ 共掺碲酸盐玻璃上转换发光的影响

研究了Tm3 /Yb3 共掺碲酸盐玻璃的Raman光谱、红外光谱和上转换发光光谱,分析了OH-对Tm3 上转换发光的影响。结果表明,氧氯碲酸盐玻璃的声子能量高于氧氟碲酸盐玻璃的声子能量,但是Tm3 /Yb3 共掺氧氟碲酸盐玻璃的上转换发光强度高于Tm3 /Yb3 共掺氧氯碲酸盐玻璃。分析认为这主要是由于OH-的影响,在氧氟碲酸盐玻璃中OH-的浓度较低,导致Tm3 的荧光寿命高,从而提高Tm3 的上转换发光。在一定程度上,OH-对Tm3 上转换发光的影响大于声子能量对Tm3 上转换发光的影响。研究结果有助于进一步提高Tm3 的发光效率。     

Er3+掺杂GdVO4纳米粒子的制备及发光性能研究

用水热法制备了Er3+掺杂GdVO4纳米荧光粉,通过X射线衍射(XRD)、荧光(FL)光谱、红外光谱仪(FTIR)对合成样品的结构和发光性能进行表征。探讨了焙烧温度、pH值以及络合剂对GdVO4∶Er3+纳米晶的结构和发光的影响。在760nm近红外光和380nm紫外光激发下激发样品,出现了较强的525nm、553nm特征绿光上转换和下转换发射。其中525nm和553nm分别来自于Er3+离子的2 H11/2→4I15/2和4S3/2→4I15/2跃迁产生。     

热处理温度对β-NaYF4:Yb3+、Er3+纳/微米颗粒上转换发光性能的影响

采用溶剂热法和热分解法分别制备纳/微米的β-NaYF4:20%Yb3+,2%Er3+晶体.根据两种不同粒径颗粒的TG-DTA测试分析,对其进行不同温度的热处理。通过XRD、SEM、FT-IR以及PL等手段研究不同热处理温度对两种粒径的颗粒的尺寸、形貌以及上转换发光性能的影响.研究结果表明,随着热处理温度的升高,纳/微米颗粒的发光性能主要呈现出先升高后下降的趋势。与未作热处理样品对比发现,适当的热处理(580℃)可以提高纳米颗粒的发光强度,却不利于改善微米颗粒发光性能。分析认为,结晶质量的提高、缺陷浓度的降低以及有机配体的去除,导致了纳/微米颗粒的发光性能的逐步提高。而过高处理温度(>580℃)引起的相转变(β→α)和表面Na2CO3的生成又大大降低了稀土离子的发光效率。热处理过程中颗粒之间的不同团聚程度是造成纳/微米颗粒发光性能差异变化的主要原因。     

CeO2∶Er3+纳米晶的合成及上转换发光特性研究

采用燃烧法制备得到CeO2∶Er3+纳米晶粉末.用X射线衍射仪(XRD)、高分辨透射电子显微镜(HRTEM)和荧光分光光度计等对CeO2∶Er3+纳米晶的结构、形貌和上转换发光特性进行了研究.结果表明:所得到的纳米晶粒度均匀、结晶完好,属于立方萤石结构.上转换发光光谱的研究表明:在980nm红外光激发下,可以发现上转换荧光,分别来自于Er3+离子的2H11/2,4S3/2→4 I15/2和4 F9/2→4I15/2跃迁.     

New binary PbF2-AlF3 glasses

New binary glass PbF₂-AlF₃ (AlF₃ 30–60 mole %) is developed by rapid quenching technique. PbF₂-AlF₃ glass, which is resistant to moisture and of low toxicity, is expected to have a transmission loss minimum in 3–4 μm wavelength region. Infrared absorption edge of the glass is originated from AlF₃ absorption band around 18 μm. Refractive index of PbF₂-AlF₃ glass is measured as 1.66 the value decreases with increasing AlF₃ content. Crystallization temperature (280–330°C) and thermal expansion coefficient (13?16×10^?6) are also affected by AlF₃ content. Activation energy of crystallization is determined, by DTA measurement, as about 80 kcal/mole. It is suggested from these data that PbF₂-AlF₃ glass has a potentiality for the achievement of infrared transmitting optical fibers.     

Crystalline spectra of Pr3+ in CdF2

We report the first observation of line structure in the cathodoluminescence spectrum of cadmium fluoride crystals doped with trivalent praseodymium ions. CdF₂:Pr shows luminescence from ³P₁, ³P₀ and ¹D₂ to low lying levels of Pr³⁺ (³H, ³F). Anomalous temperature dependence of the emission decay measurements was observed. The decay-time constants decreased when the temperature was lowered within the range 300°–77°K. Possible mechanism for this phenomena is discussed.     

硼酸铋玻璃中Er3+和Yb3+的光谱特性

采用熔体冷却法制备了单掺Er3+和Yb3+的硼酸铋玻璃,并利用理论方法计算了硼酸铋玻璃中Er3+和Yb3+的光谱参数.详细分析了硼酸铋玻璃中Er3+和Yb3+离子光谱参数与玻璃组成和掺杂浓度的关系,并研究了Yb3+离子的辐射陷阱效应.实验表明,掺Er3+和Yb3+的硼酸铋玻璃是一种具有潜在发展前途的固体激光器和光纤放大器用激光材料.     

Evolution of electrical and optical properties of CdF2: Er3+ during the conversion to the semiconducting state

The electrical and optical properties are studied at different steps of the conversion of CdF₂: Er³⁺ to the semiconducting state. The conversion is achieved by annealing the crystal under Hydrogen atmosphere.The conducting properties are better than those obtained after conversion under Cd vapor, the lowest resistivity being 0.17Ωcm. The comparison between optical and electrical parameters lead us to conclude to a conduction via impurity banding.The study of the fluorescence spectra recorded before and after conversion allows the observation of a new centre, which is probably of cubic symmetry.     

Excitation diffusion due to photon trapping in GeGaSe glasses heavily doped with Er3+

The photoluminescence (PL) in erbium doped GeGaSe glasses with stoichiometric composition Ge₂₈Ga_6.2Se_64.5S_0.8:Er_0.5 has been investigated in bulk samples and coarse and fine powders with varying average particle size 〈L〉. The shape of PL spectra and PL decay time are found to depend strongly on 〈L〉 at large 〈L〉 ≥ 500 μm. In fine powders with 〈L〉 ≤ 200 μm the PL decay time does not depend on 〈L〉 and is very close to the theoretical calculation of the lifetime using the Judd–Ofelt theory. In addition, the PL spectra do not depend on 〈L〉 ≤ 200 μm, and the shape of spectra closely follows the predictions of McCumber theory. The 〈L〉-independent decay time values and PL spectra are observed only in fine powders with 〈L〉 ≤ 200 μm.     

Diffusion process applied in fabrication of ion-exchanged optical waveguides in novel Er3+ and Er3+/Yb3+-doped silicate glasses

Planar optical waveguides fabricated in erbium doped glasses are promising photonics components operating at 1.5 μm, above all as optical amplifiers or waveguide lasers. In this study we focused on the influence of chemical compositions of Er³⁺ and Er³⁺/Yb³⁺-doped silicate glasses on the properties important for the sought applications, i.e., waveguiding and spectroscopic properties of the fabricated waveguides. Optical waveguides were fabricated by routine K⁺ ↔ Na⁺ ion exchange in a set of the glasses that had various contents of the RE ions. Waveguiding properties were studied by means of Dark Mode Spectroscopy at 671 nm while the chemical composition of the waveguides was determined using Scanning Electron Microscopy (SEM-EDAX). Surface concentrations of the lasing RE ions were determined by Rutherford Backscattering Spectroscopy (RBS) and related to the resultant photoluminescence properties. On the bases of the obtained experimental results the relations between composition of the substrates, especially content of the active ions, and experimental procedures will be presented with regards to real fabrication processes. Diffusion processes will be characterized by diffusion coefficients.     

Interactions of Cr2+ with the F− ligands in CdF2:Cr2+

Superhyperfine structure s.h.f.s. resulting from the Cr²⁺ - F^? interaction was studied in Cr²⁺ doped CdF₂ crystals. The s.h.f.s. observed can be described with by the following spin-Hamiltonian

$\text{H}\text{=}\text{g}{}_{\mathrm{eff}}\text{β}\text{HS}{}_{\mathrm{z}}\text{+ST}{}_{\mathrm{i}}\text{I+ST}{}_{\mathrm{j}}\text{I}$

The constants calculated are $\text{T}{}_{\mathrm{i\perp }}\text{≈}\text{T}{}_{\mathrm{i}}\text{= 50}\text{MHz}$$\text{T}{}_{\mathrm{j\perp }}\text{≈}\text{T}{}_{\mathrm{j}}\text{= 5}\text{MHz}$. The measurements were made with an ESR spectrometer at X band at 4.2 OK.     

Fluorine motion in PbF2: Fe3+ studied by ESR

The Fe³⁺ ion is used as an ESR probe to detect the mobility of the F^? ions in the superionic conductor PbF₂. At room temperature the ESR spectrum is characterized by a superhyperfine structure with ¹⁹A = 22 G. At rising temperature the s.h.f. structure collapses due to vacancy-diffusion with a hopping rate of about 4.10⁸.s^?1.     

Yb3+、Er3+和Eu3+共掺杂TiO2纳米带的制备与表征

通过离子交换和水热两步合成过程简单制备了Yb3+、Er3+和Eu3+共掺杂锐钛矿型TiO2纳米带。该3种离子共掺杂未导致TiO2结构和形貌发生变化。光学特性测试结果表明,由于稀土离子掺杂浓度低,Eu3+掺杂未改变由Yb3+和Er3+产生的上转换发射峰位,但可观察到因上转换发光激发的Eu3+荧光发射峰;Eu3+荧光光谱也未受到Yb3+和Er3+掺杂的影响。通过对掺杂样品上转换发光机理的考察证实,上转换发光过程是双光子过程,但TiO2和Eu3+掺杂对此发光过程有明显影响。