共查询到20条相似文献,搜索用时 31 毫秒
1.
D. H. Zhou X. D. Xu D. Y. Shen D. Z. Li J. Q. Di C. T. Xia F. Wu J. Xu 《Laser Physics》2011,21(11):1876-1879
Optical properties of Ho3+-doped Lu3Al5O12 and (Lu,Y)3Al5O12 crystals were investigated and compared. Substitution of Y for Lu in the host garnet Lu3Al5O12 results in broad absorption and emission spectra, and improvements in the laser behavior of Ho3+. Pumped by Tm:fiber laser, a maximum output power of 5.02 and 5.73 W of Ho-doped Lu3Al5O12 and (Lu,Y)3Al5O12 have been obtained, respectively. The center lasing wavelength are 2124.5 and 2123.0 nm for Lu3Al5O12 and (Lu,Y)3Al5O12, respectively. 相似文献
2.
Guodong Tang Chipui Tang Xiaonong Xu Yun He Li Qiu Liya Lv Zhihe Wang Youwei Du 《Solid State Communications》2010,150(35-36):1706-1709
The magnetothermopower have been studied in Lu-doped Ca3?xLuxCo4O9+δ. A strong magnetic field suppression of thermopower indicates large spin entropy contribution. The magnetothermopower for doped samples are overall enhanced compared with that for undoped Ca3Co4O9+δ, providing an experimental evidence for the enhancement of spin entropy. Magnetic results confirm that Co4+ concentration is reduced by Lu doping. We suggest that the reduction in Co4+ concentration results in the enhanced spin entropy. 相似文献
3.
Yu. V. Zorenko I. V. Konstankevich V. I. Gorbenko P. I. Yurchishin 《Journal of Applied Spectroscopy》2002,69(5):769-776
The possibility of obtaining scintillators with a high effective atomic number of the element Z
ef based on Lu3Al5O12:Ce3+ singlecrystal films (SCF) on doping with La3+ and Sc3+ ions on Y3Al5O12 substrates has been investigated. It is established that the SCF of (LuLaY)3Al5O12:Ce3+ (Z
ef = 58.9 and = 6.67 g/cm2) does not rank below those of Y3Al5O12:Ce3+ (Z
ef = 29 and = 4.52 g/cm2) in the conversion efficiency of radiation at the band with max = 515 nm. This allows their use as screens of xray images with a space resolution of 0.75–1.00 m. It is suggested that in the SCF of Lu3Al5O12 the isoelectronic impurities of lanthanum and scandium form radiative recombination centers of the type LaLu, ScLu, and ScAl as well as the centers Lu as a consequence of the effect of replacement of some Lu3+ ions by the La3+ ions to octanodes of the garnet lattice. The low efficiency of Ce3+ radiation in the SCF of (LuSc)3(AlSc)5O12:Ce is explained by substantial losses due to excitation of the recombination luminescence in the UV region of the centers formed by the isoelectronic impurities of scandium and to the possible existence of the channel of energy excitation dissipation related to the transitions between extrema of the allowed energy bands and activator levels. 相似文献
4.
At 4.2-350 K, the steady-state and time-resolved emission and excitation spectra and luminescence decay kinetics were studied under excitation in the 2.5-15 eV energy range for the undoped and Ce3+-doped Lu3Al5O12 (LuAG) single-crystalline films grown by liquid phase epitaxy method from the PbO-based flux. The spectral bands arising from the single Pb2+-based centres were identified. The processes of energy transfer from the host lattice to Pb2+ and Ce3+ ions and from Pb2+ to Ce3+ ions were investigated. Competition between Pb2+ and Ce3+ ions in the processes of energy transfer from the LuAG crystal lattice was evidenced especially in the exciton absorption region. Due to overlap of the 3.61 eV emission band of Pb2+ centres with the 3.6 eV absorption band of Ce3+ centres, an effective nonradiative energy transfer from Pb2+ ions to Ce3+ ions takes place, resulting in the appearance of slower component in the luminescence decay kinetics of Ce3+ centres and decrease of the Ce3+-related luminescence intensity. 相似文献
5.
Yu. Zorenko T. Voznyak V. Gorbenko T. Zorenko A. Voloshinovskiĭ V. Vistovsky M. Nikl K. Nejezchleb V. Kolobanov D. Spasskiĭ 《Optics and Spectroscopy》2008,104(1):75-87
The nature of the intrinsic luminescence of the lutetium aluminum garnet Lu3Al5O12 (LuAG) has been analyzed on the basis of time-resolved spectral kinetic investigations upon excitation of two model objects, LuAG single crystals and single-crystal films, by pulsed X-ray and synchrotron radiations. Due to the differences in the mechanisms and methods of crystallization, these objects are characterized by significantly different concentrations of LuAl antisite defects. The energy structure of luminescence centers in LuAG single crystals (self-trapped excitons (STEs), excitons localized near antisite defects, and LuAl antisite defects) has been established. For single-crystal LuAG films, grown by liquid-phase epitaxy from a Pb-containing flux, the energy parameters of the following luminescence centers have been determined: STEs in regular (unperturbed by the presence of antisite defects) sites of the garnet lattice and excitons localized near Pb2+ ions. The structure of the luminescence centers, related to the background emission of impurity Pb2+ ions, has also been established in the UV and visible ranges. It is suggested that, in contrast to the two-halide hole self-trapping, a self-trapped state similar to STEs in simple oxides (Al2O3, Y2O3) is formed in LuAG; this state is formed by self-trapped holes in the form of singly charged O? ions and electrons localized at excited levels of Lu3+ cations. 相似文献
6.
V. Venkatramu D. Falcomer A. Speghini M. Bettinelli C.K. Jayasankar 《Journal of luminescence》2008,128(5-6):811-813
The concentration-dependent luminescence properties of sol–gel-derived nanocrystalline Lu3(1?x)Er3xGa5O12 powders (where x=0.01, 0.05 and 0.1) have been studied. Laser-excited luminescence spectra, emission decays and upconversion luminescence of Er3+-doped Lu3Ga5O12 nanocrystalline samples have been measured. The decay curve of the (2H11/2,4S3/2) emission exhibits a non-exponential behavior presumably due to cross-relaxation process. Moreover, near-infrared to visible upconversion luminescence has been observed in the green region for 1.0 mol% Er3+ ions in Lu3Ga5O12 nanocrystals upon 815 nm excitation. The power dependence of the anti-Stokes luminescence suggests that upconversion is probably achieved through the sequential absorption of two photons. To the best of our knowledge, this is the first report on the preparation and optical properties of Er3+-doped Lu3Ga5O12 in the form of nanocrystalline powders. 相似文献
7.
In the temperature range 4.2–350 K, the steady-state and time-resolved emission and excitation spectra and luminescence decay kinetics are studied for the undoped Y2SiO5 and Lu2SiO5 single crystalline films grown by liquid phase epitaxy method from the PbO-based flux and, owing to that, containing lead ions substituting for Y3+ or Lu3+ ions. Luminescence characteristics of Pb-related centers of different types are identified. On the basis of the results obtained, we suggest that the ultraviolet emission of Pb-related centers arises from the Pb2+ ions substituting for Y3+ or Lu3+ ions in the Y1 and Lu1 lattice sites of the X2 structure. Possible hypotheses on the origin of the intense complex lead-related blue emission are discussed. We propose phenomenological models describing the excited-state dynamics of the studied luminescence centers. We also determine characteristic parameters of the corresponding relaxed excited states, in particular, the energy separations between the excited states and the rates of the radiative and non-radiative transitions from these states. 相似文献
8.
The Pr3+ d–f luminescence was investigated in the single crystalline films (SCF) of Lu3Al5−xGaxO12:Pr garnet solid solution at x = 1–3, grown by the liquid phase epitaxy (LPE) method from the melt-solution based on the PbO–B2O3 flux. The shape of CL spectra and decay kinetics of Pr3+ ions in Lu3Al5−xGaxO12 SCFs strongly depend on the total gallium concentration x and distribution of Ga3+ ions between the tetrahedral and octahedral position of the garnet host. The best scintillation properties of Lu3Al5−xGaxO12:Pr SCF are achieved at the nominal Ga content in melt-solution in the x = 2–2.5 range. 相似文献
9.
Shanmugam Aravazhi Dimitri Geskus Koop van Dalfsen Sergio A. Vázquez-Córdova Christos Grivas Uwe Griebner Sonia M. García-Blanco Markus Pollnau 《Applied physics. B, Lasers and optics》2013,111(3):433-446
Single-crystalline KY1?x?y?z GdxLuyYbz(WO4)2 layers are grown onto undoped KY(WO4)2 substrates by liquid-phase epitaxy. The purpose of co-doping the KY(WO4)2 layer with suitable fractions of Gd3+ and Lu3+ is to achieve lattice-matched layers that allow us to engineer a high refractive-index contrast between waveguiding layer and substrate for obtaining tight optical mode confinement and simultaneously accommodate a large range of Yb3+ doping concentrations by replacing Lu3+ ions of similar ionic radius for a variety of optical amplifier or laser applications. Crack-free layers, up to a maximum lattice mismatch of ~0.08 %, are grown with systematic variations of Y3+, Gd3+, Lu3+, and Yb3+ concentrations, their refractive indices are measured at several wavelengths, and Sellmeier dispersion curves are derived. The influence of co-doping on the spectroscopy of Yb3+ is investigated. As evidenced by the experimental results, the lattice constants, refractive indices, and transition cross-sections of Yb3+ in these co-doped layers can be approximated with good accuracy by weighted averages of data from the pure compounds. The obtained information is exploited to fabricate a twofold refractive-index-engineered sample consisting of a highly Yb3+-doped tapered channel waveguide embedded in a passive planar waveguide, and a cladding-side-pumped channel waveguide laser is demonstrated. 相似文献
10.
Photoluminescence of undoped and Cr3+-doped β-Ga2O3 was investigated. The transparent, undoped β-Ga2O3 film was successfully prepared by thermal conversion from GaOOH. The film exhibited predominant green luminescence in response to ultraviolet light excitation at 250 nm. This luminescence behavior, which was proposed to result from the oxygen defect centers, was used in examining excitation and emission mechanisms for Cr3+ ions doped in β-Ga2O3. It was found that red luminescence of Cr3+ surpasses green luminescence of the host lattice, as evidenced by the dependence of the spectral structure on the Cr3+ concentration. The excitation of Cr3+ was then suggested to be caused by the energy transfer from Ga3+O6 octahedra present in the monoclinic β-Ga2O3 lattice. 相似文献
11.
The effects of the excitation wavelength, Ce3+ concentration and chemical substitution on the thermal quenching of Y3Al5O12:Ce3+ (YAG:Ce3+) phosphors were investigated over a temperature range from 30 to 250 °C. The quenching behavior exhibits a complex dependence on the excitation wavelength and Ce3+ concentration, which can be attributed to temperature-dependent absorption strength of the different f-d absorption bands and thermally activated concentration quenching with or without energy migrations between Ce3+ ions, respectively. With increasing Lu3+content the luminescence of (Y, Lu)3Al5O12:Ce3+ phosphors shows a pronounced blueshift, and simultaneously the temperature quenching is obviously improved due to a decrease in Stokes shift. 相似文献
12.
Chesta Ruttanapun Pornjuk Srepusharawoot Santi Maensiri 《Chinese Journal of Physics (Taipei)》2018,56(1):252-260
This study aims to investigate the effect Fe ions doped into Ca12Al14O33 (C12A7, 12CaO-7Al2O3) cement compound on its thermal and optical properties. Polycrystalline samples of Ca12Al14?xFexO33 (where x?=?0.0, 0.5, and 1.0) were prepared via a solid state reaction in an oxygen atmosphere. The lattice constant of Ca12Al14O33 determined using an XRD technique was in excellent agreement with first-principles calculations. With increasing Fe concentrations, the lattice constants were found to have increased. Additionally, the optical gaps of Ca12Al14?xFexO33, (x?=?0, 0.25, 0.5, and 1.0) were 3.9?eV, 3.77?eV, 3.75?eV and 3.63?eV, respectively. It was clearly seen that the optical gap decreased with increasing Fe concentrations. As revealing by first-principles calculations, the optical gap was directly related to the electronic transition from the occupied electronic state of extra-framework O2? ions (as free O2? ions inside nano-cage) to the conduction band. Moreover, we also found that the thermal conductivity Ca12Al14?xFexO33 was reduced when the larger atomic mass and atomic radii Fe was substituted into Al sites. Hence, this indicated that Fe3+-substitution into Al3+ sites of Ca12Al14O33 cement directly affected both its optical gap and thermal conductivity. 相似文献
13.
Yu. V. Zorenko I. V. Konstankevych V. V. Mikhailin V. N. Kolobanov D. A. Spasskii 《Optics and Spectroscopy》2004,96(3):390-397
Comparative studies of the luminescence of Y3Al5O12:Ce and Lu3Al5O12:Ce single-crystal films and their volume analogues—Y3Al5O12 and Y3Al5O12:Ce single crystals, excited by synchrotron radiation with energy E=120–150 eV, have been performed. The films were grown from melt-solution by liquid-phase epitaxy and the crystals were grown from melt. The single-crystal films and single crystals studied are characterized by different degrees of structural order, in particular, different concentrations of substitutional defects of the Y Al 3+ and LU Al 3+ types. It was ascertained that the bands at 260 and 250 nm in the intrinsic luminescence spectra of Y3Al5O12:Ce and Lu3Al5O12:Ce single-crystal films and single crystals are due to the emission of self-trapped excitons. The luminescence band with λmax=300 nm and τ=0.36 μs, which is present in the luminescence spectrum of single crystals and absent in the spectra of single-crystal films, is due to the recombination of electrons with holes localized at Y Al 3+ centers. It is shown that an efficient energy transfer by excitons to activator ions occurs in Y3Al5O12 and Lu3Al5O2 single-crystal films doped with Ce3+ ions. 相似文献
14.
Xinmin Zhang Boowon Park Jongsu Kim Jungjun Lee Jinchul Choi 《Journal of luminescence》2010,130(1):117-120
Orange-emissive Ce3+/Eu2+ co-doped Sr3Al2O5Cl2 phosphors were synthesized by a solid-state reaction. The large overlap between the emission spectrum of blue Sr3Al2O5Cl2:Ce3+ and the excitation spectrum of orange Sr3Al2O5Cl2:Eu2+, and the shortening trend in lifetime of Ce3+ donors with increasing Eu2+ concentration in Sr3Al2O5Cl2:Ce3+, Eu2+ provide the strong evidence of energy transfer from Ce3+ to Eu2+ ions. It supports that the orange emission intensity of the optimal co-doped phosphor is 1.5 times stronger than that of single Eu2+-doped one. The Sr3Al2O5Cl2:Ce3+, Eu2+ phosphor is a promising orange-emitting phosphor for warm-white-light-emitting diode because of its effective excitation in the near ultraviolet range. 相似文献
15.
Ultraviolet, visible and infrared spectral measurements were used to investigate prepared undoped and rare-earth doped (2.5%) bismuth silicate glasses (80% Bi2O3–20%SiO2) before and after being subjected to gamma irradiation (8?Mrad). The base bismuth silicate glass reveals strong extended UV–near visible absorption bands which are attributed to the presence of trace iron impurities in the raw materials together with absorption due to sharing of Bi3+ ions. The RE-doped samples show the same strong UV–near visible bands as the undoped glasses beside extra narrow characteristic bands mostly in the visible and near-infrared regions due to the respective studied rare-earth ions. The base undoped and all RE-doped samples except CeO2 sample reveal quite resistance to the effect of gamma irradiation due to heavy atomic mass Bi3+ ions present in high content (80%) and the rare-earth ions are known to be weakly affected due to the known 5s, 5p shielding. The exceptional effect of CeO2-doped sample is related to the ability of Ce3+ ions to change its oxidation state through photochemical reaction by irradiation or exchange with Fe3+ present as trace iron impurities. The FT infrared spectra of the prepared glasses reveal characteristic absorption bands which are related to the silicate groups together with the sharing of vibrational modes due to Bi–O groups. The IR spectra are slightly affected by gamma irradiation indicating the stability of the structural network groups consisting of SiO4 and BiO6 units. 相似文献
16.
Mössbauer absorption spectra have been measured for Cr3+ doped Al2O3?Fe 2 57 O3 systems for different values of the Cr3+ concentration at room temperature. The cross relaxation between Fe3+ and Cr3+ ions, which destroys the paramagnetic hyperfine structure of Fe57 observed in undoped Al2O3?Fe 2 57 O3, is thoroughly studied. The experimental results suggest a new kind of cross-relaxation process involving three spins, i.e. two Fe3+.ions and one Cr3+. The process, though it is a higher-order one, is highly effective because it is energy-conserving. 相似文献
17.
The UV–Visible, Fourier transform infrared (FTIR) and Raman and electron spin resonance (ESR) spectra of undoped lead phosphate and MoO3-doped glassy samples have been investigated. The UV–VIS absorption spectra were re-measured after successive gamma irradiation. Before irradiation, undoped sample exhibited strong ultraviolet absorption, which was attributed to co-absorption due to trace iron impurities (mainly Fe3+ ions) and lead Pb2+ ions. With the introduction of MoO3 in progressive amounts, extra visible bands were recorded at about 400–440, 540, 750 and 870?nm. These bands are most likely correlated with the presence of Mo3+, Mo4+ and Mo5+ ions in the host glass. In the undoped specimen, gamma irradiation produced UV absorption bands that increased slightly with irradiation but no visible bands were recorded. Samples containing high MoO3 content showed some resistance to irradiation with no bands in the visible region being observed. FTIR absorption spectra of the undoped and MoO3-doped samples revealed the formation of metaphosphate and pyrophosphate structural units. Highly MoO3-doped samples exhibited additional bands due to molybdate groups. Raman and ESR spectra were in agreement with UV–VIS and IR data, indicating the presence of molybdenum ions in lead phosphate glass, as Mo3+, Mo4+ and Mo6+ with different ratios. However, such glassy systems favor the trivalent species. 相似文献
18.
Tb-activated scintillating glasses with Ln2O3 (Ln=Y, Gd, Lu) concentrations up to 40 mol% have been prepared. The effects of Ln3+ ions on the density, thermal properties, transmission, and luminescence properties under both UV and X-ray excitation have been investigated. Glasses containing Gd2O3 or Lu2O3 exhibit a density of more than 6.0 g/cm3. Energy transfer from Gd3+ to Tb3+ takes place in Gd-containing glass and as a result the Gd-containing glass shows a light yield 2.5 times higher than the Y- or Lu-containing glass. The effect of the substitution of fluorine for oxygen on the optical properties was also investigated. 相似文献
19.
Growth and the luminescence properties of a lutetium gadolinium garnet doped with Ce3+ and Pr3+ ions
S. V. Nizhankovsky A. Ya. Dan’ko Yu. V. Zorenko V. V. Baranov L. A. Grin’ V. F. Tkachenko P. V. Mateichenko 《Physics of the Solid State》2011,53(1):127-130
Crystals of lutetium gadolinium garnet solid solutions (Lu1 − x
Gd
x
)Al5O12 (0 ≤ x ≤ 0.6) doped with Ce3+ and Pr3+ ions have been prepared by the horizontal directional crystallization method, and their optical and luminescence properties
have been investigated. It has been established that the introduction of gadolinium into the lutetium garnet lattice leads
to a decrease in the antisite luminescence (LuAl centers) in the UV spectral range and to sensitization of the Ce3+ ion luminescence. By contrast, the presence of gadolinium results in the quenching of the Pr3+ luminescence due to the nonradiative excitation transfer from Pr3+ ions to Gd3+ ions. 相似文献
20.
采用溶胶-凝胶(sol-gel)工艺制备0.1 mol% Er3+掺杂Al2O3体系和SiO2-Al2O3复合体系粉末. 实验结果表明:5 mol%的SiO2复合加入Al2O3抑制γ→θ和θ→α相转变. 掺0.1 mol%Er3+:Al2O3体系粉末,900℃烧结,在1.47—1.63μm波段内光致发光(PL)谱为中心波长1.53 μm、半高宽56 nm的单一宽峰,1000—1200℃烧结,劈裂为多峰PL谱. 掺0.1 mol%Er3+:SiO2-Al2O3复合体系粉末,在高达1200℃烧结,仍保持中心波长1.53 μm的单一宽峰PL谱,由于—OH更完全的脱除,PL强度较900℃烧结Al2O3体系,SiO2-Al2O3复合体系均提高1个数量级.
关键词:
2-Al2O3复合体系')" href="#">SiO2-Al2O3复合体系
掺铒
溶胶-凝胶工艺
光致发光 相似文献