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1.
利用溶胶-凝胶法制备了Dy3+掺杂的YAl3(BO3)4荧光粉。通过X射线衍射仪(XRD)、荧光(FL)光谱仪对所合成样品的结构和发光性能进行表征。研究了Dy3+离子掺杂浓度和焙烧温度对YAl3(BO3)4∶Dy3+荧光粉的结构和发光性能的影响。结果表明:Y1-xAl3(BO3)4∶Dy3x+在Dy掺杂摩尔分数为x=0.05,焙烧温度为1 100℃时的发光强度最大。Y0.95Al3(BO3)4∶Dy30.+05荧光粉在774 nm波长光激发下,最强发射峰位于575nm。该荧光粉可将700~900 nm和290~450 nm范围内的光转换为染料敏化电池吸收的575 nm附近可见光。  相似文献   

2.
The electronic structure of the Tm3+ in YAl3(BO3)4 crystals has been investigated by means of low temperature absorption and emission spectroscopy in the 5000-30,000 cm−1 range. The assignment of the lines composing the observed manifolds to transitions between the Stark levels of Tm3+ is complicated by the presence of extra features having different origins. The energy levels scheme of the doping ion has been compiled after a careful analysis of the spectra by reproducing the observed transitions by means of theoretical calculations based on a Hamiltonian, including the free ion and the crystal field (CF) terms. The agreement between experimental and calculated energy values was reasonably good, the overall r.m.s. deviation being 16 cm−1. The resulting CF parameters have been tabulated and compared with those reported in literature for other rare earth ions doped in YAB. The analysis of trends observed along the lanthanide series evidences some inconsistencies and the necessity of a systematic investigation of these systems.  相似文献   

3.
Radioluminescence and thermally stimulated luminescence measurements on Lu2O3, Lu2SiO5 (LSO) and Lu2SiO5:Ce3+ (LSO:Ce) reveal the presence of intrinsic ultraviolet luminescence bands. Characteristic emission with maximum at 256 nm occurs in each specimen and is attributed to radiative recombination of self-trapped excitons. Thermal quenching of this band obeys the Mott-Seitz relation yielding quenching energies 24, 38 and 13 meV for Lu2O3, LSO and LSO:Ce, respectively. A second intrinsic band appears at 315 nm in LSO and LSO:Ce, and at 368 nm in Lu2O3. Quenching curves for these bands show an initial increase in peak intensity followed by a decrease. Similarity in spectral peak position and quenching behavior indicate that this band has a common origin in each of the samples and is attributed to radiative recombination of self-trapped holes, in agreement with previous work on similar specimens. Comparison of glow curves and emission spectra show that the lowest temperature glow peaks in each specimen are associated with thermal decay of self-trapped excitons and self-trapped holes. Interplay between the intrinsic defects and extrinsic Ce3+ emission in LSO:Ce is strongly indicated.  相似文献   

4.
The Yb3+ to Er3+ energy transfer in yttrium aluminum borate (YAB) crystal is investigated with the rate equation without considering the back energy transfer. The energy transfer coefficients (W25) in the crystals with different Yb3+ concentrations are determined and compared with those in other crystals. The transfer efficiencies and the micro-parameters of energy transfer and migration are also determined. The results show that the energy transfer from Yb3+ to Er3+ in YAB crystal is very efficient and the Yb3+–Er3+ co-doped YAB crystal may be a good candidate for the 1.55 μm laser media.  相似文献   

5.
Influence of the partial substitution of paramagnetic Fe3+ ions by diamagnetic Ga3+ ions in the trigonal crystal GdFe3 (BO3)4 on its optical and magnetic properties is studied and discussed in connection with problems common for all antiferromagnets containing 3d 5 ions. Polarized optical absorption spectra and linear birefringence of GdFe3 (BO3)4 and GdFe2.1Ga0.9 (BO3)4 single crystals have been measured in the temperature range 85–293 K. Specific heat temperature dependence (2–300 K) and structure of GdFe2.1Ga0.9 (BO3)4 crystal have been also studied. As a result of substitution of 30% Fe to Ga the Neel temperature diminishes from 38 till 16 K, the strong absorption band edge shifts on 860 cm-1 (0.11 eV) to higher energy and the d-d transitions intensity decreases substantially larger than the Fe concentration does. Strong absorption band edge is shown to be due to Mott-Hubbard transitions. Correlation between position of the strong absorption band edge and the Neel temperature of antiferromagnets has been revealed. Properties of the doubly forbidden d-d transitions in the studied crystals and in other antiferromagnets are explained within the framework of the model of the exchange-vibronic pair absorption, which is theoretically analyzed in detail. The model permitted us to determine the connection between parameters of d-d absorption bands (intensity, width and their temperature dependences), on the one hand, and the exchange, spin-orbit and electron-lattice interactions, on the other hand.  相似文献   

6.
唐桦明  唐强  毛日华  谢建才 《发光学报》2018,39(12):1807-1813
为了分析材料在低温下的陷阱能级,获得更多有关缺陷结构的信息,研制了一套由STM32微控制器为核心的低温热释光发光谱测量系统。设计了低温样品室,采用液氮冷却样品;STM32通过控制加热电流,实现样品以恒定速率升温,从而获得低温热释光发光曲线或三维热释光谱。温度测量范围为85~400 K,升温速率范围为0.1~10 K/s。设计了由STM32控制X射线及紫外光源的驱动电路,用于样品的激发。采用高灵敏度CCD实现对三维热释光谱的测量,采用单光子计数器获取二维热释光发光曲线。利用该系统测试了(Lu,Y)2SiO5:Ce3+(LYSO:Ce3+)单晶闪烁体与SrSO4:Dy3+粉末样品的热释光谱及辐射发光光谱。观察到LYSO:Ce3+在108,200,380 K左右的热释光峰,发光波长位于390~450 nm之间,是明显的宽带峰。在低温下由于基质的自陷激子(STE)发射所形成的发射峰在166 K时发生猝灭。在309 K时,Ce3+发射峰展宽为单一发射峰;SrSO4:Dy3+发光峰温度为178,385 K,发光波长由Dy3+离子的能级跃迁决定,在480,575,660,750 nm处呈现窄带发光峰。结果表明,系统人机交互界面友好,实验数据可靠,智能化程度高,操作简单。  相似文献   

7.
稀土掺杂发光材料一直是科研领域研究的热点,被广泛应用于白光LED、温度传感、显示显像、新能源和激光等领域。基质的结构对于稀土离子光致发光特性有非常重要的影响,在众多发光基质材料中,硼酸盐具有透光范围宽、光学损伤阈值高、较好的热稳定性和化学稳定性等优点。碱土-稀土金属硼酸盐Sr3Y2(BO3)4具有出色的光学性能,对其发光性能的研究具有重要意义。稀土离子Eu3+具4f6电子层,是一种典型的下转换发光中心离子,常被选作红色发光材料的激活剂。Dy3+具4f9电子层,也是一种典型的下转换发光中心离子,在紫外光激发下,在蓝色光区和橙色光区有较强的荧光发射。采用高温固相法合成了Sr3Y2(BO3)4∶Eu3+/Dy3+荧光粉,通过XRD和SEM对样品的结构和形貌进行了表征,XRD结果表明,1 0...  相似文献   

8.
A high-quality Cr 3+:CdWO4 single crystal at a size of approximatelyΦ25×80 mm is grown using the Bridgman method with CdO,WO3,and Cr2O3 as raw materials and their molar ratio of 100:100:0.5.The temperature gradient of solid-liquid interface at growth is approximately 50?C/cm and the growth rate is 0.05 mm/h.The X-ray diffraction(XRD),absorption,excitation,and emission spectra of different parts of the as-grown and O2-annealed crystals are investigated.Two strong broad optical absorption bands of about 472 and 708 nm are observed,and they are associated with the transitions 4 A2→ 4 T1 and 4 A2→ 4 T2.The weak 4 T2→ 2 E transition(the R-line)at 632 nm is also observed.The crystal-field parameter Dq and the Racah parameters B and C are estimated to be 1 412.4,776.8,and 3 427.6 cm? 1,respectively,according to the absorption spectra and crystal-splitting theory.A broadband fluorescence at about 1 000 nm due to 4 T2→ 4 A2 transition is produced by exciting the samples at 675 nm.After being annealed in an O2 atmosphere,the crystals become more transparent,while the effective light absorption of Cr 3+ ions is evidently enhanced and the emission intensity is also strengthened due to the reduction of oxygen vacancies in the CdWO4 crystal after annealing.  相似文献   

9.
We report the group delay dispersion of Yb3+:YAl3(BO3)4 (Yb:YAB) crystal measured by a white-light interferometer, and compare with that calculated from the Sellmeier formulae provided by the crystal supplier, over the wavelength range from 1000 nm to 1080 nm. The data should be useful for the dispersion compensation for femtosecond pulse generation in Yb:YAB lasers.  相似文献   

10.
A pulsed, tunable dye laser was used to selectively excite Nd3+ ions in nonequivalent crystal field sites in NdAl3(BO3)4 crystals and energy transfer between ions in different types of sites was studied by monitoring the time evolution of the fluorescence spectrum. The results show that the energy transfer rate varies as t-12 and increases with temperature. The predictions of various models of phonon-assisted energy transfer are compared to the results.  相似文献   

11.
D.C. electrical conductivity, DTA and coulometric studies on (NH4)3 H(SO4)2 single crystals are made. Conductivity is markedly anisotropic with maximum along c1 direction. A sudden jump in the conductivity plot along c1 direction at 413 K is supported by a large endothermic peak in DTA, confirming the presence of transition at this temperature. The values of activation energy calculated from conductivity measurements indicated that the charge carriers are protons. This was further confirmed by coulometric experiment where the gas evolved was hydrogen, as established by a gas chromatograph and the volume of H2 released agreed with that expected from electrolysis. The mechanism of protonic conduction in this crystal is discussed.  相似文献   

12.
EPR spectra of Gd3+-doped Ce2(SO4)3.8H2O and La2(SO4)3.9H2O single crystals have been measured with an X-band spectrometer at room and low temperatures. The absolute signs of spin Hamiltonian parameters have been determined for the La2(SO4)3.9H2O host from intensities of lines at liquid helium temperature; for the Ce2(SO4).8H2O host the lines broaden considerably below 60 K, not permitting the determination of absolute signs of spin Hamiltonian parameters. The data are analysed using a rigourous least-squares procedure, fitting simultaneously all lines obtained for several orientations of the external magnetic field. The zero-field splittings have been computed for both the hosts. The characteristics of EPR spectra of Gd3+ in these hosts are compared with those obtained in other rare-earth trisulphate octahydrate hosts.  相似文献   

13.
Growth conditions and electron paramagnetic resonance investigations of two well oriented KSm(WO4)2 and KEr(WO4)2 single crystals have been presented and discussed. Hyperfine structure of Sm3+ ion was detected and analyzed for angular and temperature dependences. EPR spectra of KEr(WO4)2 and its angular dependence showed the presence of 5 magnetically nonequivalent Er centers in the crystal. A change in the type of magnetic interactions was analyzed using mixed (Gaussian and Lorentzian) fits of the EPR spectra.  相似文献   

14.
Yb3+掺杂KY(WO4)2激光晶体生长、结构与光谱分析   总被引:1,自引:0,他引:1       下载免费PDF全文
采用顶部籽晶提拉法(TSSG)生长出Yb:KY(WO4)2(Yb:KYW)激光晶体.对预烧后的原料及晶体进行了XRD分析,结果表明,分别在920℃和600℃预烧8h后的熔质和助熔剂基本上形成一相,抑止了实验中的挥发问题;所生长的晶体为β-Yb:KYW,计算其晶格常数为a=1.063nm,b=1.034nm,c=0.755nm,β=130.75°.测得不同厚度样品的吸收光谱,结果表明样品在933nm和981nm有较强的吸收峰,计算出主峰981nm的吸收截面σ关键词: Yb:KYW TSSG法 晶体结构 光谱参数  相似文献   

15.
The effect of pressure on the phase transformations in Sm2(MoO4)3, Gd2(MoO4)3 and Eu2(MoO4)3 crystals has been studied in situ using synchrotron radiation. All three isostructural compounds undergo a structural phase transition at 2.2-2.8 GPa to a new phase, which is interpreted as a possible precursor of amorphization. Amorphization in these crystals occurs irreversibly over a wide pressure range, and its mechanism, interpreted as a chemical decomposition, is found to be weakly affected by the degree of hydrostaticity.  相似文献   

16.
EPR studies are reported on single crystals of ammonium cobalt sulphate and ammonium nickel sulphate containing Mn2+ ions. In each case only one magnetic complex of Mn2+ ion is found. The resonance lines in the case of Mn2+ doped ammonium nickle sulphate are characterised by a strong angular dependence of line intensities. The resonance lines in both the cases are fitted to a spin-Hamiltonian corresponding to orthorhombic symmetry.  相似文献   

17.
crystal with the size up to Φ 13 mm×44 mm was grown successfully by the Czochralski technique and its optical properties were presented. The absorption cross-section and emission cross-section were presented. Also, the potential laser gain near 1.9 μm was investigated. In the framework of the Judd-Ofelt (J-O) theory, the intensity parameters were calculated to be: Ω2=11.375×10−20 cm2, Ω4=5.077×10−20 cm2 and Ω6=6.524×10−20 cm2. The spectroscopic parameters of this crystal such as the oscillator strengths, radiative transition probabilities, radiative lifetime as well as the branching ratios were calculated, too. This crystal is promising as a tunable infrared laser crystal.  相似文献   

18.
The luminescence of Yb3+ in the oxyborate Li2Lu5O4(BO3)3 is reported. At low temperature, in addition to the usual ytterbium infrared emission, this phosphor presents an emission in the ultraviolet () which corresponds to the transition from the charge transfer state (O-Yb) to the 4f levels of Yb3+. The temperature quenching Tq50% is equal to 120 K. The infrared emission studied at room temperature is located between 950 and 1100 nm.Europium emission quenching in the Li2Yb5O4(BO3)3 phase is related to Eu→Yb transfer by cross-relaxation. The reverse Yb→Eu transfer by cooperative sensitization is highlighted in the codoped Li2Lu5O4(BO3)3 compound.  相似文献   

19.
测量了Tm3+:NaY(WO4)2晶体的吸收光谱、发射光谱和激发光谱,利用J_O理论计算了钨酸钇钠晶体的强度参数:Ω2=7.21304×10-20cm2,Ω4=0.504766×10-20cm2,Ω6=0.977784 ×10-20cm2,以及Tm3+光学参数包括各能级的荧光寿命和荧光分支  相似文献   

20.
Cadmium selenide nanocrystals along with dysprosium ions are doped in silica matrices through sol-gel route. The optical bandgap and size of the CdSe nanocrystals are calculated from the absorption spectrum. The size of the CdSe nanocrystallites is also evaluated from the TEM measurements. The fluorescence intensities are compared for SiO2-Dy3+ and CdSe-doped SiO2-Dy3+. The fluorescence intensity of Dy3+ is considerably increased in the presence of CdSe nanocrystals.  相似文献   

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