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1.
We present luminescence, luminescence excitation and luminescence time resolved spectra of La2Be2O5:Pr3+ system. We used high pressure spectroscopy approaches, with high pressure applied in diamond anvil cell (DAC) and sapphire anvil cell (SAC), for detailed analysis of luminescence related to the 4f5d → 4f2 and 4f2 → 4f2 transitions. We present effect of up-converted luminescence related to 4f5d → 4f2 transition excited with 488 nm. We also discussed possibility of existence of praseodymium trapped exciton (PTE) states in La2Be2O5:Pr3+ system. Lack of the PTE is attributed to high quantity of bulk modulus of this material. 相似文献
2.
Basic study of single crystal fibers of Pr:Lu3Al5O12 scintillator for gamma-ray imaging applications
Takayuki Yanagida Kei KamadaNoriaki Kawaguchi Yutaka FujimotoKentaro Fukuda Yuui YokotaValery Chani Akira Yoshikawa 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,652(1):256-259
Single-crystalline fibers were grown from 0.25, 0.70, and 1.50 mol% Pr-doped Lu3Al5O12 (LuAG) melts by the micro-pulling down (μ-PD) method with a diameter of 0.3-0.5 mm and a length of about 200 mm. They were cut to 10 mm long specimens, and their scintillation properties, including light yield and decay time profile, were examined. These results were compared with corresponding properties of the specimens (0.8×0.8×10 mm3) cut from the bulk crystals produced by conventional Czochralski (CZ) growth. The μ-PD-grown fibers demonstrated relatively low light yield and had the same decay time constant when compared with those of the samples cut from the CZ-grown crystals. The fiber crystals were used to assemble scintillating arrays with dimensions of Ø 0.5×10 mm2×20 pixels and Ø 0.3×10 mm2×30 pixels coated by a BaSO4 reflector. After optical coupling with a position sensitive photomultiplier tube, the fiber-based arrays demonstrated acceptable imaging capability with a spatial resolution of about 0.5 mm. 相似文献
3.
Paper presents luminescence spectra and time resolved spectra of KMgF3:Eu2+ system obtained at different temperatures and pressures, under excitation with 325 nm. At temperatures between 200 K and 292 K the spectra consist of sharp line peaked at 27,830 cm−1 related to 6P7/2 → 8S7/2 transition in Eu2+ accompanied by the phonon sideband. Under pressure the red spectral shift with the rate equal to −0.6 cm−1/kbar is observed. Luminescence decay is single-exponential with the lifetime equal to 5.2 ms independent of pressure and temperature. The emission spectra obtained at temperatures lower than 125 K consist of 5 sharp lines peaked at 27,590 cm−1, and 27,670 cm−1, 27,722 cm−1, 27,766 cm−1 and 27,809 cm−1, that relative intensity depends on temperature. Pressure shift of these lines was found to be equal to −0.6 cm−1/kbar; the same as 6P7/2 → 8S7/2 transition in Eu2+, whereas their lifetime is shorter and is equal to 0.7 ms at 100 K. These new lines disappear at temperature greater than 200 K. We tentatively related them to the luminescence of Eu2+-F center (fluorine vacancy with electron) complex. 相似文献
4.
Takayuki Yanagida Mitsuhiro SatoKei Kamada Yutaka FujimotoYuui Yokota Akira Yoshikawa Valery Chani 《Optical Materials》2011,33(3):413-418
Pr:LuAG single crystalline scintillators with different Pr3+ concentration, 0.1, 0.18, and 0.22 mol% were grown by the Czochralski method. The crystals were cut to dimensions of 2.2 × 2.2 × 15 mm3 and polished, simulating sensors for Positron Emission Tomography (PET). Their absorption coefficients were examined, and the absorption strength was found to be proportional to the Pr concentration. The α-ray induced emission spectra of the samples demonstrated two emission lines peaking at 310 and 370 nm. The emission intensities in the radio luminescence spectra were also proportional to the Pr content. The absolute light yields and intrinsic energy resolution under γ-ray irradiation were evaluated at +20, 0, and −20 °C using avalanche photodiode as a photodetector. Pr 0.22% doped crystal had strongest light output of 16 400 ph/MeV, and its intrinsic energy resolution was around few % at several hundred keV. When coupled with PMT, the decay time was around 25 ns, and it was almost independent on concentration. 相似文献
5.
The nature of intrinsic luminescence of Y3Ga5O12 (YGG) and (LaLu)3Lu2Ga3O12 (LLGG) single crystals grown from a melt was determined. In the case of a YGG single crystal containing YGa antisite defects with a concentration of 0.25–0.275 at.% the intrinsic luminescence was considered as a superposition of luminescence of self-trapped excitons (STE), luminescence of excitons localized near antisite defects (LE(AD) centers) and luminescence caused by a recombination of an electron with a hole captured at YGa antisite defects. Due to a large (2–3%) concentration of LuLa antisite defects in LLGG single crystals the intrinsic luminescence was a superposition mainly of the LE(AD) center emission and the recombination luminescence of LuLa antisite defects. The energy structure of the mentioned centers in YGG and LGGG hosts was determined from the excitation spectra of their luminescence under excitation by synchrotron radiation in the range of the fundamental absorption edge of these garnets. 相似文献
6.
Concentration dependant emission spectra and fluorescence dynamic profiles have been investigated in PrxLa1−xAlO3 single crystals in order to better understand processes responsible for concentration quenching of the praseodymium 3P0 and 1D2 emissions. The cross-relaxation transfer rates were experimentally determined as a function of Pr3+ concentration. Decays were modeled and nearest-neighbor trapping rates were calculated. 相似文献
7.
CaTiO3:Pr3+ films have been prepared by pulsed-laser deposition method on SiO2-buffered Si substrates, and their microstructure and photoluminescence properties have been compared with those of the films deposited directly on bare Si substrates. The SiO2 buffer layers were prepared using thermal oxidization and HF-etching. Photoluminescence intensities of CaTiO3:Pr3+ films on the SiO2-buffered Si substrates are significantly higher (up to 800%) than those of the films on bare Si substrates, which is attributed to the low refractive index and low light absorption of the SiO2 buffer layer. This study reveals that the presence of the buffer layer is effective in improving the red emission brightness of CaTiO3:Pr3+ films without sacrificing the surface roughness. 相似文献
8.
Makoto Sugiyama Yutaka FujimotoTakayuki Yanagida Daisuke Totsuka Shunsuke KurosawaYoshisuke Futami Yuui YokotaValery Chani Akira Yoshikawa 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2012,664(1):127-131
Er-doped Lu3Al5O12 (Er:LuAG) single crystalline scintillators with different Er concentrations of 0.1, 0.5, 1, and 3% were grown by the micro-pulling-down (μ-PD) method. The grown crystals were composed of single-phase material, as demonstrated by powder X-ray diffraction (XRD). The radioluminescence spectra measured under 241Am α-ray excitation indicated host emission at approximately 350 nm and Er3+ 4f-4f emissions. According to the pulse height spectra recorded under γ-ray irradiation, the 0.5% Er:LuAG exhibited the highest peak channel among the samples. The γ-ray excited decay time profiles were well fitted by the two-component exponential approximation (0.8 μs and 6-10 μs). 相似文献
9.
E. van der Kolk O.M. Ten KateJ.W. Wiegman D. BinerK.W. Krämer 《Optical Materials》2011,33(7):1024-1027
A high resolution luminescence study of NaLaF4: 1%Pr3+, 5%Yb3+ and NaLaF4: 1%Ce3+, 5%Yb3+ in the UV to NIR spectral range using a InGaAs detector and a fourier transform interferometer is reported. Although the Pr3+(3P0 → 1G4), Yb3+(2F7/2 → 2F5/2) energy transfer step takes place, significant Pr3+1G4 emission around 993, 1330 and 1850 nm is observed. No experimental proof for the second energy transfer step in the down-conversion process between Pr3+ and Yb3+ can be given. In the case of NaLaF4: Ce3+, Yb3+ it is concluded that the observed Yb3+ emission upon Ce3+ 5d excitation is the result of a charge transfer process instead of down-conversion. 相似文献
10.
Manganese is a very important microelement performing a large number of biological functions in human body. We have detected by spectroscopic measurements manganese in mineral kyanite. In this paper we present laser-induced time-resolved luminescence and optical absorbance spectra of orange, Mn containing kyanite. It was proven the orange color is caused by Mn3+. Several luminescence lines and bands were found and ascribed to Mn4+ and Mn3+, emission centers. The spectroscopic technique can be utilized for detection of small amounts of manganese in minerals. 相似文献
11.
An investigation of spectroscopic properties of (SrTiO3-TiO2):Pr3+ eutectic and, for comparison, of bulk SrTiO3:Pr3+ and TiO2:Pr3+crystals is presented. Luminescence spectra have been measured under both 450 nm and 350 nm excitation wavelength. For UV excitation they are characterized by a dominant red luminescence corresponding to transition from the 1D2 level of Pr3+ ions. The mechanism responsible for quenching of blue (from 3P0 state) and intensification of red luminescence is proposed to be thermally-induced radiationless relaxation involving a low-lying Pr3+-Ti4+ intervalence charge transfer state. Measured decay constants of 1D2 excited state of Pr3+ are compared with values obtained for other praseodymium doped titanate hosts. 相似文献
12.
M.R.N. SoaresC. Nico J. RodriguesM. Peres M.J. SoaresA.J.S. Fernandes F.M. CostaT. Monteiro 《Optical Materials》2011,34(1):27-29
Single crystal fibres of Pr3+-doped tetragonal yttria stabilized zirconia were grown by the laser floating zone method. The fibres show strong red luminescence at room temperature under ultraviolet optical pumping, which is due to the transition between the 1D2 and 3H4 multiplets of the Pr3+ ion. Additionally, in the infrared spectral range main transitions were found at ∼1140 nm and 1560 nm. Their intensity ratio was shown to be dependent on the excitation wavelength, suggesting the presence of multiple Pr3+-related centres. 相似文献
13.
YGG:Tb thin films were successfully prepared by Pechni sol-gel process. The structure, surface morphology, evolution of film crystallization and their luminescent properties were investigated. We find the annealing process is very important to the YGG:Tb film crystallization. Uniform crack-free films can be obtained by conventional annealing for 1 h after rapid thermal treating for 10 min at 800 °C. The excitation and emission spectra of photoluminescence (PL) were used to characterize the luminescent properties. The excitation spectrum of YGG:Tb is dominated by the 4f-4f5d transition of Tb3+at 260 nm. The emission peaks of phosphor thin film lie at 488 and 543 nm. It can be used as a promising phosphor material for FED or ELD application. 相似文献
14.
Guan-Xi LiuRui Zhang Quan-Lan XiaoShao-Yu Zou Wen-Fang PengLi-Wei Cao Jian-Xin Meng 《Optical Materials》2011,34(1):313-316
Bi3+,Nd3+ co-doped Gd2O3 were prepared by solid state reaction and the optical properties were investigated. The results show that the near-infrared emission of Nd3+ ions is significantly enhanced by the introducing of Bi3+ in co-doped samples. An efficient energy transfer from Bi3+ to Nd3+ corresponds to the near-infrared emission enhancement. The energy transfer efficiency reaches 64.1% for the sample with the strongest near-infrared emission, which has the optimized doping concentrations of 0.5% for Bi3+ and 2% for Nd3+. The interesting optical properties make Bi3+,Nd3+ co-doped Gd2O3 promising as the luminescent down-conversion layers in front of c-Si solar cells to enhance the performance of the solar cells. 相似文献
15.
A.M. Srivastava A.A. SetlurH.A. Comanzo W.W. BeersU. Happek P. Schmidt 《Optical Materials》2011,33(3):292-298
The photoluminescence and excitation spectra of Pr3+ activated LaPO4 has been investigated in the 1.6-300 K temperature region. At room temperature, the luminescence of LaPO4:Pr3+ is composed of the interconfigurational 4f15d1 → 4f2 emission transitions. However, in the 1.6-60 K temperature range, the emission spectrum also consists of the intraconfigurational emission transitions that emanate from the 1S0 state. A radiative lifetime of 145 ns is measured for the Pr3+1S0 → 1I6 emission transition in LaPO4. This is one of the shortest radiative lifetime observed for this transition in a solid. The energy position of the Pr3+1S0 state in LaPO4 is established by high-resolution emission spectrum at 46 375 ± 5 cm−1. A detailed analysis of the thermal quenching of the 1S0 lifetime and emission intensity is presented. It is proposed that the lowest energy state of the relaxed 4f15d1 configuration is situated energetically below that of the 1S0 state. 相似文献
16.
Very small nanoparticles (size 3-5 nm) of Y2Sn2O7, Y2Sn2O7:Tb3+ and Sb3+ co-doped Y2Sn2O7:Tb3+ were prepared at a relatively low temperature of 700 °C. Y2Sn2O7 host is characterised by an emission around 436 nm, which is arising from the oxygen vacancies present in the lattice. Tb3+ emission improves significantly when Sb3+ ions are co-doped with Y2Sn2O7:Tb3+ nanoparticles. Incorporation of Sb3+ ions at the Y3+ site of Y2Sn2O7 lattice and associated lattice distortion around Tb3+/Y3+ ions brought about by the difference in the stable coordination number of Sb3+ and Y3+ ions are responsible for the improved Tb3+ emission from the co-doped samples. 相似文献
17.
In this work, two Tb3+ activated green phosphors: Y2O3:Tb3+ and YBO3:Tb3+ were prepared by hydrothermal method. Photoluminescence properties of both phosphors were studied in details. Both phosphors exhibit similar luminescent characteristics symbolized by the dominant green emission at 545 nm. Concentration quenching occurs at the Tb3+ concentration of 1.60 atomic% and 2.57 atomic% for Y2O3:Tb3+ and YBO3:Tb3+, respectively. Luminescence decay properties were characterized to better understand the mechanism of concentration quenching. Based on the calculation, the concentration quenching in both phosphors was caused by the dipole–dipole interaction between Tb3+ ions. 相似文献
18.
A well oriented YVO4 single crystal, with 5% Yb3+ and 2% Tm3+ nominal doping, was investigated using the Raman and EPR techniques.The EPR measurements suggest that Yb3+ ions occupy eight-coordinated Y3+ sites forming bisdisphenoids of the D2d symmetry. An inhomogeneous distribution of rare-earth ions leads to a significant distortion of the local point symmetry (C1). It seems that strong dipole–dipole interactions between Yb3+ ions are responsible for the distortion. As a result, two types of ytterbium magnetic centers appear. They correspond to paired magnetic centers and distorted isolated paramagnetic centers that are strongly sensitive to the magnetic field directions and some imperfections of the crystal. Pair centers can be recorded through the rotation around the c-crystal axis, whereas isolated centers can be measured when the crystal is rotated around the a-crystal axis. With the increasing temperature, the ytterbium signal disappeared at about 23 K and a group of narrow lines became visible. These lines, observed in the range of 240–550 mT, correspond to the Gd3+ (S = 7/2) ions, doped to the structure unintentionally from the basic materials. 相似文献
19.
Hyun Kyoung Yang Byung Kee Moon Jung Hyun Jeong Ki-wan Jang Soung Soo Yi 《Thin solid films》2010,518(22):6219-6222
The effects of Li-doped CaTiO3:Pr3+ thin films have been investigated by varying the lithium ion concentrations from 0 to 5 wt.%. The films have been deposited on Si (100) substrate using a pulsed laser deposition technique. Structural properties of these films have been studied by the measurement of their XRD, SEM, and AFM. The variation of Li+ concentration influences the crystallinity and surface morphology of the CaTiO3:Pr3+ thin films. As Li+ content increases from 0 to 1 wt.%, the crystallinity and intensity of emission increases. The dominant emission is from 1D2 → 3H4 transition at 613 nm. The 1D2 emission quenching has also been observed in highly doped sample and is related to the cross-relaxation process between Pr3+ ions. 相似文献
20.
Scintillation properties of Tm-doped Lu3Al5O12 single crystals 总被引:1,自引:0,他引:1
Makoto Sugiyama Yutaka Fujimoto Takayuki Yanagida Daisuke Totsuka Yuui Yokota Akira Yoshikawa 《Optical Materials》2011,34(2):439-443
Using the micro-pulling-down (μ-PD) method, Tm-doped Lu3Al5O12 (Tm:LuAG) single crystals were grown to examine their scintillation properties. In transmittance spectra, they exhibited about 80% transparency in the wavelengths longer than 320 nm and five absorption lines due to Tm3+ 4f–4f transitions were observed. 241Am α-ray excited radioluminescence spectra were measured and intense 4f–4f emission peaks were observed with the host emission. When excited by 137Cs γ-Ray to obtain pulse height spectra, Tm 1% doped LuAG showed the highest light yield coupled with a photomultiplier (PMT) or a silicon avalanche photodiode (Si-APD). The light yield was estimated to be 5800 and 7300 photons/MeV for PMT and Si-APD, respectively. Decay time profiles consist of two exponential components and the fast and slow components are considered to be attributed to the host and the combination of the host and Tm3+ 4f–4f emission, respectively. 相似文献