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1.
The spectral parameters of Nd3+ ions in Nd:LaCa4O(BO3)3 crystal have been investigated based on Judd-Ofelt theory. The spectral parameters were obtained: the intensity parameters
Ωλ are Ω2 =1.98 × 10–20 cm2, Ω4 =2.39 × 10–20 cm2, Ω6 =1.38 × 10–20 cm2, the radioactive lifetime is 655 μs, the quantum efficiency is 10%, and the fluorescence branch ratios were calculated: β1 = 0.51, β2 = 0.42, β3 = 0.066, β4 = 0.003.
Electronic Publication 相似文献
2.
The spectral parameters of Er3+ in Yb3+/Er3+:KY(WO4)2 crystal with space group C2/c have been investigated based on Judd-Ofelt theory. The spectral parameters were obtained: the intensity parameters are: 2 = 6.33 × 10–20 cm2, 4 = 1.35 × 10–20 cm2, 6 = 1.90 × 10–20 cm2. The radiative lifetime and the fluorescence branch ratios were calculated. The emission cross section e (at 1536 nm) is 2.0 × 10–21 cm2. 相似文献
3.
The spectral parameters of Nd3+ ions in Nd:KLa(WO4)2 crystal have been investigated based on Judd-Ofelt theory. The spectral parameters were obtained: the parameters of oscillator
strengths
are Ω2=3.0887×10–20 cm2, Ω4=1.0375×10–20 cm2, Ω6=1.0422×10–20 cm2, the radiative lifetime is 685 μs, the quantum efficiency is 30.7%, and the fluorescence branch ratios were calculated: β1=0.432, β2=0.475, β3=0.089, β4=0.004.
Electronic Publication 相似文献
4.
M. M. Sinha 《Bulletin of Materials Science》2002,25(6):459-462
In recent years, the fluorite-structured solid solutions with the general formula, (MF2)1-x(RF3)x (M = Ca, Sr, Ba, Pb and R is a rare-earth element or Y), have been the subject of numerous experimental studies focussed
on their superionic properties. The overall cubic crystal symmetry (space group Fm3m) is conserved up to x ≶ xmax, where xmax ⊁ 0.4-0.5 depending on M and R. The zone centre phonons and phonon dispersion along three symmetry directions of the mixed
superionic compound (BaF2)1-x(LaF3)x have been investigated by applying de Launey angular force model for x ≶ xmax. The calculated results are compared and explained with available experimental results. 相似文献
5.
Jinhao Wang Yueping Zhang Haiping Xia Jiawei Sheng 《Bulletin of Materials Science》2009,32(2):183-186
The growth of Nd3+ doped lithium niobate crystals using Bridgman method has been reported in this paper. By means of the optimum conditions
such as proper feed materials, sealed platinum crucibles, growth rate of 1–1·5 mm/h and temperature gradient of 30–35°C/cm
across the solid-liquid interface under the furnace temperature of 1300°C, single crystals containing Nd3+ ion with 0·54 mol% concentration were obtained. X-ray diffraction and ICP-AES were used to characterize the crystals and
its composition. The absorption, emission and fluorescence lifetime are also measured. Based on the Judd-Ofelt theory, we
obtained the optical parameters of the crystal such as the luminescent quantum efficiency, the radioactive lifetimes, the
branching ratios and the emission cross-section. 相似文献
6.
Nd3+ : Sr3Ga2Ge4O14 crystals have been grown by the modified Bridgman method. The growth defects, such as striations, scattering particles and
dislocations were investigated. Some featherlike striations were observed in as-grown crystals. EPMA analysis suggested that
these inclusions were caused by the segregation of Nd2O3 from the melt. Chemical etching results showed that the dislocation density was in the range of 103 ∼ 105/cm2. 相似文献
7.
The superconducting properties of iodine-intercalated high-temperature superconducting Bi2Sr2Ca2Cu3O10+x
phase (Bi-2223) were systematically studied. It was found that for samples containing a significant amount of Bi2Sr2CaCu2O8+x
, iodine intercalation results in the dramatic decrease of the inter-granular critical current density, as well as a significant
decrease of the critical temperature (T
c), the critical current density in the grains (J
cg), and of the amount of Bi-2223. For samples with a large amount of Bi-2223, T
c changes insignificantly, whereas J
cg can even increase. We argue that the different behavior of the superconducting parameters is the result of various oxygen
concentrations, and we explain the effect of iodine intercalation based on the parabolic dependence between T
c and the number of holes per CuO2 layer. The H(T) curves (determined from the peak position in the loss signal of ac susceptibility) for intercalated samples deviate significantly
from the quasi 2D-like behavior, pointing toward an enhancement of the 3D fluctuations of vortices. For the change in the
values and dimensionality of the flux pinning in the process of the intercalation, we attempted a qualitative explanation
based on the models proposed in literature. 相似文献
8.
Optical absorption and fluorescence spectra of Eu3+ ions in Al(NO3)3-SiO2 sol-gel glass have been investigated using the Judd- Ofelt theory. JO intensity parameters (ω
λ
) and subsequent radiative properties for5
D
0 ↔7
F
1,2,4,6 transitions are determined. The lifetime (τr) of5
D
0 state is computed and along with JO parameters are compared with their corresponding values in other glasses prepared by
conventional technique. A structural analysis, using IR and XRD spectra and non- linear parametrization of the silica gel
glass is carried out. The study reveals the glass to be a very good third order non- linear amorphous optical material. 相似文献
9.
Eu3+ activated CaSiO3, (Ca, Ba) SiO3 and (Ca, Sr) SiO3 have been prepared by sol-gel technique. Residual solvent and organic contents in the gel were removed by firing at 100°C
for 3–4 h at 300 and 600°C for 2 h. Small exothermic shoulder around 850 to 875°C, as observed in DTA curve, corresponds to
crystallization temperature of the doped calcium silicate. Influence of firing temperature on the luminescence of Eu3+ shows the maximum emission intensity in gel fired at 850°C. Photoluminescence emission peak is observed at 614 nm due to5D0 →7F2 transition of Eu3+ ion in (Ca, Ba) SiO3 and (Ca, Sr) SiO3 phosphors, when excited by 254 nm. The (Ca, Ba) SiO3 material is proposed as an efficient red phosphor. 相似文献
10.
The growth of mixed crystals of Ba
x
Ca1−x
(IO3)4 were carried out with simple gel method. The effect of various parameters such as pH of gel solution, gel concentration,
gel setting time, concentration of reactants on the growth was studied. Crystals having different morphologies and habits
were obtained. The grown crystals were characterized by XRD, FT-IR, EDAX, TGA, DTA and DSC. 相似文献
11.
Emission spectral results of Pr3+ & Ho3+ ions doped Ca4GdO(BO3)3 powder phosphors are reported here. XRD, SEM and FTIR measurements have been carried out for them. The emission spectrum
of Pr3+: Ca4GdO(BO3)3 has shown an emission transition 1D2 → 3H4 at 606 nm with λexci = 480 nm (3H4 → 3P0) and Ho3+: Ca4GdO(BO3)3 phosphor has shown an emission transition 5S2 → 5I8 at 549 nm with λexci = 447 nm (5I8 → 5F1). Emission performances of these two phosphors have been explained in terms of energy level diagrams. 相似文献
12.
Polycrystalline sample of Pb2Sb3LaTi5O18, a member of tungsten- bronze (TB family, was prepared using a high temperature solid- state reaction technique. XRD analysis
indicated the formation of a single-phase orthorhombic structure. The dielectric studies revealed the diffuse phase transition
and the transition temperature was found to be at 52° C. Impedance plots were used as tools to analyse the sample behaviour
as a function of frequency. Cole-Cole plots showed Debye relaxation. The activation energy was estimated to be 0·634 eV from
the temperature variation of d.c. conductivity. The nature of variation of d.c. conductivity with temperature suggested NTCR
behaviour. 相似文献
13.
G. Aka E. Reino P. Loiseau D. Vivien B. Ferrand L. Fulbert D. Pelenc G. Lucas-Leclin Patrick Georges 《Optical Materials》2004,26(4):431-436
We have taken advantage of congruent melting behavior of the nonlinear rare-earth oxoborate Ca4REO(BO3)3 family to perfect a process of collective fabrication of self-frequency doubling microchip laser based on Nd:GdCOB (Ca4Gd1−xNdxO(BO3)3) crystals. The process goes from Czochralski boule to 1 × 3 mm2 chips perfectly oriented (better than 0.1°) to the phase matching direction (θ=90°, φ=46°) in the XY principal plane, with dielectric mirrors directly deposited on both faces of the chips. 20 mW of self-frequency doubling output power at 530 nm was performed under 800 mW of diode laser as incident pump power at 812 nm. In addition, new compositions from the solid solution Ca4Gd1−xYxO(BO3)3 (Gd1−xYxCOB) (x=0.13, 0.16, 0.44) have been grown by the Czochralski pulling method, in order to achieve noncritical phase matching (NCPM) second harmonic generation of 4F3/2 → 4I9/2 Nd3+ doped laser hosts. Three types of laser wavelengths have been chosen: Nd:YAP (YAlO3) at 930 nm, Nd:YAG (Y3Al5O12) at 946 nm, and Nd:ASL (NdySr1−x Lax−yMgx Al12−xO19) at 900 nm. Angular acceptance measurements of these three types of compositions present very large values, compared to pure GdCOB or YCOB oriented in critical phase matching configurations. 相似文献
14.
Z. Liu S. F. Wang Y. L. Zhou S. Q. Zhao K. J. Jin Z. H. Chen H. B. Lu G. Z. Yang 《Journal of Superconductivity and Novel Magnetism》2005,18(4):557-560
Chemical solution deposition is a promising technique for fabrication of high-temperature superconducting films and oxide
buffer layers due to its reproducibility and low cost. In this work, Y2O3 buffer layers were prepared on (100) LaAlO3 substrates by mental organic deposition method using trifluoroacetate. The resulting Y2O3 films crystallized as a single phase at 900°C and showed a low degree ofc-axis orientation. The scanning electron micrography showed that the surface of the films was smooth with a uniform grain
size of approximately 10 nm. 相似文献
15.
V. A. Ivanshin I. N. Kurkin A. M. Leushin L. K. Aminov 《Journal of Superconductivity and Novel Magnetism》2007,20(2):131-133
We have calculated the crystalline electric field (CEF) splitting of the energy levels of Yb3+ (4f13) in the clean Yb-based heavy fermion compound YbRh2Si2. The data of inelastic neutron scattering and electron spin resonance measurements in YbRh2Si2, together with relevant structural, thermodynamic, and magnetic properties, were used as input in the calculations of the
possible CEF level scheme in this non-Fermi-liquid compound. Two possible sets of the CEF parameters with the Γ6 or Γ7 ground-state symmetry are discussed.
PACS: 71.27.+a; 75.20.Hr; 76.30.−v. 相似文献
16.
Mingxia Zhao Zhiju Zhao Lixia Yu Liqin Yang Junbing Jiang Xuan Li Guanghua Li 《Journal of Materials Science: Materials in Electronics》2018,29(3):1832-1836
A series of Sr3La(PO4)3:Eu2+/Mn2+ phosphors were synthesized by a solid state reaction. The phase and the optical properties of the synthesized phosphors were investigated. The XRD results indicate that the doped Eu2+ and Mn2+ ions do not change the phase of Sr3La(PO4)3. The peak wavelengths of Eu2+ single doped and Eu2+/Mn2+ codoped Sr3La(PO4)3 phosphors shift to longer wavelength due to the larger crystal field splitting for Eu2+ and Mn2+. The increases of crystal field splitting for Eu2+ and Mn2+ are induced by the substitution of Sr2+ by Eu2+ and Mn2+ in Sr3La(PO4)3 host. Due to energy transfer from Eu2+ to Mn2+ in Sr3La(PO4)3:Eu2+/Mn2+ phosphors, tunable luminescence was obtained by changing the concentration of Mn2+. And the white light was emitted by Sr3La(PO4)3:3.0 mol%Eu2+/4.0 mol%Mn2+ and Sr3La(PO4)3:3.0 mol%Eu2+/5.0 mol%Mn2+ phosphors. 相似文献
17.
Caixuan Xu Anming Hu Naomichi Sakai Izumi Hirabayashi Mitsuru Izumi 《Journal of Superconductivity and Novel Magnetism》2007,20(4):309-314
Single domain GdBa2Cu7-δ (Gd123) bulk superconductors were fabricated in air by top-seeding melt-texture growth. Performance of the air-processed
Gd123 was successfully enhanced by addition of both BaCO3 and BaCuO2−x
, which suppress the formation of Gd1+x
Ba2−x
Cu3O7-δ solid solutions. The optimum doping amount ranges from 0.05 to 0.15, M BaCO3 and 0.05 to 0.1, M BaCuO2−x
per molar Gd123. The distribution of the second phase particles was observed by scanning electron microscopy. A narrow band
formed by Gd2BaCuO5 particle concentration appeared around the seeding zone in both a–b plane and c-growth sector in Gd123 single grain. Trapped magnetic field density reached 0.67, T for sample with 24 mm in diameter and
8, mm in thickness and a high critical current density J
c up to 91,200, A/cm2 was achieved at 77, K under self-field. 相似文献
18.
Zaifa Yang Changjian Ji Gongnian Zhang Guimei Han Hui Wang Hongxia Bu Denghui Xu Jiayue Sun 《Journal of Materials Science: Materials in Electronics》2018,29(15):12632-12638
A series of single-phase Sr3YNa(PO4)3F:Dy3+ phosphors were successfully synthesized via a conventional solid state reaction process. The powder X-ray diffraction patterns were utilized to confirm the phase composite and crystal structure. The phosphor could be excited by the ultraviolet visible light in the region from 300 to 420 nm, and it shown two dominant emission bands peaking at 484 nm (blue light) and 580 nm (yellow light) which originated from the transitions of 4F9/2→6H15/2 and 4F9/2→6H13/2 of Dy3+, respectively. The optimum dopant concentration of Dy3+ ions was confirmed to be 7 mol% in Sr3YNa(PO4)3F:Dy3+ system and the concentration quenching mechanism is dipole–dipole interaction. The lifetime values of Dy3+ ions at different concentrations (x?=?0.03, 0.05, 0.07, 0.09 and 0.11) were determined to be about 0.855, 0.759, 0.686, 0.606 and 0.546 ms, respectively. The thermal stability of luminescence of Sr3YNa(PO4)3F:0.07Dy3+ phosphor was also investigated and the activated energy was deduced to be 0.228 eV, which shows good thermal stability. The chromaticity coordinates fall in the white-light region calculated by the emission spectrum. These results show that Sr3YNa(PO4)3F:Dy3+ phosphor can be a promising white emitting phosphor for white LEDs. 相似文献
19.
K. P. Singh V. P. S. Awana S. Balamurugan M. Shahabuddin H. K. Singh M. Husain H. Kishan E. R. Bauminger I. Felner 《Journal of Superconductivity and Novel Magnetism》2008,21(1):39-44
Nano particle of Fe3O4 (nFe3O4) up to 6 at% were doped in the superconducting MgB2 samples. Despite the strong ferromagnetic nature of Fe3O4, both the ac susceptibility and the resistivity measurements show that up to 4 at% of Fe3O4, T
c
=38 K is not changed, whereas for 6% T
c
decreases by 6 K. This indicates that a low concentration of Fe does not substitute either the Mg or B sites and probably
occupies the intergrain spaces. For 0.5% doped Fe3O4, an increase in J
c
with respect to the pure MgB2 samples is observed in the lower field and temperature regions (H<2 T and 20 K) indicating an enhanced flux pinning and the magnetic activation, i.e., the interaction between the magnetic
dipole of Fe ion and the vortices is weak in comparison to the effective pinning potential. Whereas, at H>2 T, J
c
of the doped samples is always less than that of MgB2, and the activation is dominant in comparison with the effective pinning potential provided by the doping. Flux jumps are
observed in lower T and H regions for the samples doped up to 1% nFe3O4 only. Magnetization plots of higher Fe content samples exhibited clear paramagnetic background. Mossbauer measurements for
the higher (4, 6 at%) nFe3O4 doped MgB2 samples show that at RT, the hyperfine field for both samples is ∼100 kOe and ∼120 kOe at 90 K. This means that the nFe3O4 particles decompose and form possibly an intermetallic Fe-B phase in the matrix. 相似文献
20.
NbTe2 is a member of transition metal dichalcogenide (TMDC) group. Single crystals of niobium ditelluride (NbTe2) have been grown by a chemical vapour transport technique using iodine as transporting agent. The composition of the grown
crystals was confirmed on the basis of energy dispersive analysis by X-ray (EDAX) and remaining structural characterization
was also accomplished by X-ray diffraction (XRD) studies. Lattice parameters, volume and X-ray density have been carried out
for the grown crystals. The particle size for a number of reflections has been calculated using Scherrer’s formula. 相似文献