共查询到20条相似文献,搜索用时 31 毫秒
1.
A phosphor Tb3+-doped ZnWO4 (ZWO:Tb) phosphors were prepared by a hydrothermal method. X-ray powder diffraction (XRD) analysis revealed that the as-obtained sample is pure ZnWO4 phase. The excitation and emission spectra indicated that the phosphor could be well excited by ultraviolet light (272 nm) and emit blue light at about 491 nm and green light at about 545 nm. Significant energy transfer from WO42− groups to Tb3+ ions has been observed. Two approaches to charge compensation are investigated: (a) 2Zn2+ = Tb3+ + M+, where M+ is a monovalent cation like Li+, Na+ and K+ acting as a charge compensator; (b) 3Zn2+ = 2Tb3+ + vacancy. Compared with two charge compensation patterns in the ZnWO4:Tb3+, it has been found that ZnWO4:Tb3+ phosphors used Li+ as charge compensation show greatly enhanced bluish-green emission under 272 nm excitation. 相似文献
2.
The electronic structures of luminescence centers in ZnWO4, ZnWO4:Mo, and ZnWO4:Cd crystals are calculated by the configuration interaction method using embedded cluster approach. Dependencies of energies of the ground and excited electronic states of the centers on vibration coordinates are computed. The energies and oscillator strengths of radiative transitions in the luminescence centers of regular and doped zinc tungstate crystals are obtained. Formation of emission spectra of ZnWO4, ZnMoO4, and CdWO4 are analyzed using results of the calculations. 相似文献
3.
Scintillation properties of ZnWO4, bismuth doped ZnWO4 and antimon doped ZnWO4 were studied. Decay time, light yield and their temperature dependence are reported. 相似文献
4.
5.
Xu Chun Song E. Yang Rong Ma Hai Fang Chen Zhong Li Ye Min Luo 《Applied Physics A: Materials Science & Processing》2009,94(1):185-188
ZnWO4 nanorods with a bundle-like structure were synthesized at 180°C for 12 h by a hydrothermal technology from Na2WO4⋅2H2O and ZnSO4⋅7H2O in the presence of sodium dodecyl sulfate (SDS). The as-synthesized bundle-like structure of ZnWO4 nanorods was characterized by various techniques: TEM, XRD and EDS. The luminescence properties of the bundle-like structure
of the ZnWO4 nanorods were investigated by photoluminescence (PL) spectroscopy. 相似文献
6.
钨酸铅(PWO)晶体是一种综合性能非常优异的无机闪烁晶体,并且在高能物理研究领域已获得重要应用,但光输出偏低的缺点严重制约了它在非高能物理领域的应用.本文采用氟化铅作为掺杂剂,用Bridgman方法生长出了光输出比普通PWO晶体高出2—3倍的新型PWO晶体.紫外和X射线荧光光谱的测试结果表明,这种新型晶体的发光波长比纯PWO晶体红移了大约134 nm,即为553 nm,衰减时间也从几十纳秒延长到100 ns以上,且光输出随积分时间的增加而增强.此外,发射波长和光输出沿晶体生长方向存在明显的位置依赖性,初期 相似文献
7.
Aleksandr Kalinko Alexey Kotlov Alexei Kuzmin Vladimir Pankratov Anatoli I. Popov Liana Shirmane 《Central European Journal of Physics》2011,9(2):432-437
The photoluminescence spectra and luminescence excitation spectra of pure microcrystalline and nano-sized ZnWO4 as well as the Zn
x
Ni1−x
WO4 solid solutions were studied using vacuum ultraviolet (VUV) synchrotron radiation. The samples were also characterized by
x-ray powder diffraction. We found that: (i) the shape of the photoluminescence band at 2.5 eV, being due to radiative electron
transitions within the [WO6]6− anions, becomes modulated by the optical absorption of Ni2+ ions in the Zn
x
Ni1−x
WO4 solid solutions; and (ii) no significant change in the excitation spectra of Zn0.9Ni0.1WO4 is observed compared to pure ZnWO4. At the same time, a shift of the excitonic bands to smaller energies and a set of peaks, attributed to the one-electron
transitions from the top of the valence band to quasi-localized states, were observed in the excitation spectrum of nano-sized
ZnWO4. 相似文献
8.
《Current Applied Physics》2014,14(9):1171-1175
ZnO/WO3 core–shell nanowires were synthesized by thermal evaporation of a mixture of ZnO and graphite powders (ZnO:C = 1:1) followed by sputter-deposition of WO3. The sensing properties of multiple networked ZnO-core/WO3-shell nanorod sensors toward H2 gas was examined. The responses of pristine ZnO and ZnO-core/WO3-shell nanorods to 1000 ppm H2 at room temperature under UV illumination were ∼236% and ∼645%, respectively. The responses of the core–shell nanowires increased from ∼118 to ∼645% with increasing the UV illumination intensity from 0 mW/cm2 to 1.2 mW/cm2. The enhanced sensing performance of the ZnO-core/WO3-shell nanowires induced by encapsulation with WO3 was explained based on a combination of surface depletion and potential barrier-controlled carrier transport models. The origin of the enhanced sensing properties of ZnO-core/WO3-shell nanorods toward H2 under UV illumination was also discussed. 相似文献
9.
Ytterbium-and erbium-doped single crystals of scheelite-like double tungstates NaGd(WO4)2, NaLa(WO4)2, and NaBi(WO4)2 and scheelite CaWO4 have been grown by the Czochralski method. The dopant concentrations in crystals are measured, and the coefficients of dopant
distribution are determined to range from 0.45 to 3. The lifetimes of the Er3+ states 4
I
11/2 and 4
I
13/2 and the Yb3+ state 2F5/2 are measured, and the absorption and luminescence spectra of the crystals are studied in the vicinity of 1.0 and 1.5 μm.
The data obtained are compared with the corresponding characteristics of other crystals. The possible use of the crystals
studied as active media of solid-state lasers operating in the range 1.0 and 1.5 μm is discussed.
__________
Translated from Optika i Spektroskopiya, Vol. 92, No. 4, 2002, pp. 657–664.
Original Russian Text Copyright ? 2002 by Subbotin, Zharikov, Smirnov. 相似文献
10.
11.
V. Jambunathan X. Mateos M. C. Pujol J. J. Carvajal C. Zaldo U. Griebner V. Petrov M. Aguiló F. Díaz 《Applied physics. B, Lasers and optics》2014,116(2):455-466
We present the crystal growth, optical spectroscopy, and room temperature continuous-wave (CW) laser operation of monoclinic Ho:KLu(WO4)2 crystals. Macro defect-free crystals of several dopant concentrations were grown by top-seeded solution growth slow-cooling method. The evolution of unit cell parameters with holmium doping level and temperature was studied using X-ray powder diffraction. The spectroscopic properties were characterized in terms of room- and low-temperature optical absorption and photoluminescence. From low-temperature optical absorption measurements, the energy of the Stark levels was determined. Calculation of the emission and gain cross sections is presented. CW laser action was realized for 3 and 5 at. % Ho-doped KLu(WO4)2 by in-band pumping using a Tm:KLu(WO4)2 pump laser. A maximum output power of 507 mW with a slope efficiency of ~38 % with respect to the incident power was achieved at 2,080 nm with the Ho:KLu(WO4)2 laser. 相似文献
12.
Nanosized Zn–WO3 and ZnWO4 materials have been prepared by microwave irradiation method. The physico-chemical characterization of the prepared nanomaterials was carried out by X-ray diffraction (XRD) and high resolution-scanning electron microscopy (HR-SEM) techniques. The size and shape of the ZnWO4 material can be controlled by changing the temperature. The XRD analysis revealed the formation of monoclinic phase of the calcined nanopowder. The HR-SEM images showed the sphere and plate shape particles. The electrochemical behavior of the ZnWO4 modified electrodes was investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) techniques. The synthesized material shows the pseudocapacitance. The specific capacitance of 35.70 F/g was achieved for the Zn–WO3 nanopowder. 相似文献
13.
The elastic and photo-elastic characteristics of four laser crystals KY(WO4)2, KGd(WO4)2, KYb(WO4)2, and KLu(WO4)2 are presented. The first pair was reported early, and the last two materials have been investigated for the first time. The full matrix of elastic constants of these monoclinic crystals has been determined. Also, acousto-optical figure of merit for all the basic geometries of isotropic diffraction has been measured. It is proved that potassium rare-earth tungstates has rather good acousto-optical properties and particularly can take place of fused silica in technical applications required high power laser radiation. All the results demonstrate good prospect of these optically bi-axial laser crystals for development of new effective acousto-optical devices. 相似文献
14.
Alexander A. Kaminskii Ludmila Li Andre V. Butashin Vladimir S. Mironov Alexsei A. Pavlyuk Sergey N. Bagayev Ken-ichi Ueda 《Optical Review》1997,4(2):309-315
Monoclinic KY(WO4)2:Pr3+, Tm3+:KY(WO4)2:Er3+, Yb3+ single crystals are grown by low-gradient Czochralski technique. Stimulated emission at 1.0223μm wavelength in the new lasing 1D2→3F3 channel of Pr3+ ions in KY(WO4)2 at room temperature under Xe-flashlamp pumping is excited. Full sets of Stark-level energies for Pr3+ ions in KY(WO4)2 and KGd(WO4)2 crystals at 77 K are determined. 4f2-4f2 intensity-transitions for the KY(WO4)2:Pr3+ are analyzed preliminarily. All observed at present and earlier one-micron Pr3+-ion, induced transitions in the 1D2→3F3 and 1D2→3F4 channels are identified. In yttrium and gadolinium sensitized-tungstates a two-micron (3H4→3H6) low-threshold generation of Tm3+ ions at cryogenic temperatures is achieved.All authors cooperate with the Joint Open Laboratory for Laser Crystals and Precise Laser Systems at the Institute of Crystallography and Institute of Laser Physics, Russian Academy of Sciences. 相似文献
15.
H. Wang C. Tu Z. You F. Yang Y. Wei Y. Wang J. Li Z. Zhu G. Jia X. Lu 《Applied physics. B, Lasers and optics》2007,88(1):57-60
NaGd(WO4)2:Yb3+, Ho3+ single crystals have been grown by the Czochralski technique along the (0 0 1) orientation. Conversion of the infrared (IR)
radiation at 980 nm into the visible emission in NaGd(WO4)2 crystals containing several different concentrations of Yb3+ and Ho3+ has been investigated. The NaGd(WO4)2: 8 at. % Yb3+, 4 at. % Ho3+ system exhibits intense red upconverted emission originating from the 5F5
level. The upconversion mechanism in a Ho3+-Yb3+ system under near infrared excitation is discussed. It is concluded that the green emission is excited by energy transfers
from Yb3+ to Ho3+, whereas excited state absorption is involved in the excitation of red emission. The emission cross-section of the 5F5→5I8 transition at about 660 nm was estimated by using the Füchtbauer–Ladengurg formula.
PACS 78.55.Hx; 78.20.-e 相似文献
16.
C. Luz Lima G. D. Saraiva P. T. C. Freire M. Maczka W. Paraguassu F. F. de Sousa J. Mendes Filho 《Journal of Raman spectroscopy : JRS》2011,42(4):799-802
Temperature‐dependent Raman studies on Na2WO4and Na2MoO4 crystals were performed in order to obtain information on structural changes induced by temperature evolution. The stability of the cubic phase of Na2WO4and Na2MoO4crystals was assessed and our results indicate that this phase is stable in the 8–823 K and 15–773 K ranges for Na2WO4 and Na2MoO4, respectively. The crystal of Na2WO4 shows a phase transition occurring at 833 K. Na2MoO4undergoes a sequence of three phase transitions, which were observed at 783–803, 823–913 and 943–950 K. In both crystals, a strong first‐order phase transition occurs as indicated by the behavior of the Raman modes: the Raman bands split and new bands appear below 100 cm−1. These transitions are connected with tilting and/or rotations of the WO4and MoO4 tetrahedra, which leads to a disorder at the WO4and MoO4 sites. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
17.
L. N. Limarenko Yu. V. Zorenko M. M. Batenchuk Z. T. Moroz M. V. Pashkovskii I. V. Konstankevich 《Journal of Applied Spectroscopy》2000,67(2):287-294
We analyze the optical characteristics of crystals within the framework of a model representation that presupposes the entry
of the background impurity of iron ions in two valence states, Fe3+ and Fe2+, into regular lattice nodes. The spectral manifestation of intrinsic defects of vacancy-type structure depending on the conditions
of crystal growth and heat treatment is comprehensively investigated. With allowance for the specific features of the technology
applied, we have tested the technique suggested in scientific periodicals for bleaching ZnWO4 and CdWO4 crystals by doping with nonisovalent ions, in particular, with Sb and Ag impurities.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 211–216, March–April, 2000.
The work was carried out with support from INTAS-UKRAINE within the framework of the project INTAS-UA-95-0166. 相似文献
18.
A method has been proposed to analyze the dynamics of interband two-photon absorption in a nonlinear medium excited by a sequence
of picosecond laser pulses of variable intensity and continuous probe radiation. Induced absorption leading both to hysteresis
in the dependence of the absorption on the intensity of laser pump radiation and to the opacity of crystals at the pump wavelength
has been revealed in initially transparent ZnWO4 and PbWO4 crystals irradiated by a train of 523.5-nm pulses with a duration of 20 ps at pump intensities of 5 to 140 GW/cm2. The kinetics of an increase in absorption and its subsequent relaxation at a 523.5-nm picosecond excitation of the crystals
have been measured with continuous 633-nm probe radiation. An exponential component of the increase in absorption with the
time constant τ = 2−3.5 and 8–9.5 μs depending on the direction of the linear polarization of pump radiation has been revealed
at 300 K in ZnWO4 and PbWO4 crystals, respectively. The absorption relaxation kinetics in the crystals are complicated and approach an exponential at
a late stage with the constant τ = 40−130 and 12–80 ms for the ZnWO4 and PbWO4 crystals, respectively. 相似文献
19.
A. García-Cortés M.D. Serrano C. Zaldo C. Cascales G. Strömqvist V. Pasiskevicius 《Applied physics. B, Lasers and optics》2008,91(3-4):507-510
The nonlinear refractive index (n2) of several NaT(WO4)2 (T?=?Y, La, Gd, Lu and Bi) and NaY(MoO4)2 femtosecond laser crystals has been measured using the z-scan technique. These tetragonal crystals with structural local disorder present significant n2 values, which should allow their efficient laser pulsed operation by Kerr-lens mode locking, especially NaBi(WO4)2, 68×10-16 cm2/W (for σ light), which is about twice than for the others. This difference is attributed to the high polarizability associated with the lone electron pair of Bi3+. 相似文献
20.
通过透射光谱、光产额(LY)和光致发光等发光性能测试,研究了F,Y双掺钨酸铅(PbWO4 ,简称PWO)晶体的发光性能,并利用热释光曲线和正电子湮没寿命谱对F,Y双掺PWO晶 体中的缺陷种类和变化进行了分析. 结果表明:与未掺杂晶体相比,双掺样品在350nm附近 的透过率大大提高,吸收边向短波方向移动约30nm,光致发光谱中出现位于350nm的发光峰 ,双掺样品的LY(100ns内)为未掺杂PWO的2.7倍左右.晶体中主要存在的缺陷为(WO3)-
关键词:
F
Y双掺钨酸铅闪烁晶体
高光产额
热释光
正电子湮没寿命谱 相似文献