共查询到20条相似文献,搜索用时 13 毫秒
1.
Lipeng Jiang Xiyan Zhang Shiqi Zhu He Tang Qingxi Li Wenmin Zhang Xiaoyun Mi Liping Lu Hongwei Liu Xiuling Liu 《Journal of Materials Science: Materials in Electronics》2018,29(11):9045-9051
Y3?yAl5?xGaxO12:Ce3+y phosphors were prepared by high temperature solid state reaction method. The crystal structures, the influence of Ga3+ concentration on the photoluminescence (PL), cathodoluminescence, thermal stability and morphology of the phosphors were studied in detail. The results indicated that diffraction angle of the samples decreased gradually with the increase of Ga3+ ions content in XRD pattern. The emission peak of the spectra show a progressive blue-shift, the intensity increased first and then decreased and the optimal Ga3+ concentration in Y2.94Al5?xGaxO12:Ce3+0.06 phosphors is x?=?0.75. The critical concentration of Ce3+ in YAGG:Ce3+ phosphors is affected with the ratio of Ga3+ to Al3+ and the Y2.9Al4.25Ga0.75O12:Ce3+0.1 phosphor showed the best performance on PL. However, the optimum concentration of Y3?yAl5?xGaxO12:Ce3+y phosphors is x?=?1.5 and y?=?0.04 when they were excited by cathode ray. 相似文献
2.
Shumian Xu Sha-sha Liu Cong Zhao Tao Han Dachuan Zhu 《Journal of Materials Science: Materials in Electronics》2017,28(14):10061-10066
The Ba2P2O7:Tb3+, R (R?=?Eu2+, Ce3+) phosphors were synthesized by use of a co-precipitation method. Crystal phase, excitation and emission spectra of sample phosphors are analyzed by means of XRD and FL, respectively. The emission spectra of Ba2P2O7:Ce3+, Tb3+ phosphors exhibit four linear peaks attributed to the 5D4?→?7FJ (J?=?6–3) transition of Tb3+ while four broad emission bands are observed in the emission spectra of Ba2P2O7:Eu2+, Tb3+ phosphors. The effects of Eu2+ concentration on the luminescent properties of Ba2P2O7:Tb3+, R (R?=?Eu2+, Ce3+) are studied. Ce3+ affects the luminescent properties of Ba2P2O7:Ce3+, Tb3+ phosphors just as the sensitizer. However, Eu2+ is considered both as the sensitizer and the activator in Ba2P2O7:Eu2+, Tb3+ phosphors. The chromaticity coordinates of Eu2+ and Tb3+ co-doped phosphors gather around the white light field with the CCT approximate to 5000 K, indicating that the luminescent property of Ba2P2O7:Eu2+, Tb3+ phosphors may approach to a desired level needed for white LED application. 相似文献
3.
Lixin Yang Xiaoyun Mi Jiangang Su Huiling Zhang Nengli Wang Zhaohui Bai Xiyan Zhang 《Journal of Materials Science: Materials in Electronics》2017,28(14):9975-9982
Novel broadband luminescence phosphors Ca2?xNaMg2V3O12:xEu3+ have been successfully prepared via the conventional high-temperature solid-state reaction. The effects of concentrations of doped Eu3+ and introducing Li+, K+ on the luminescent properties of phosphor were studied. X-ray diffraction, GSAS structural refinement and photoluminescence spectra were used to characterize the samples. The refinement data ensured where the doped Eu3+ ions occupied the lattice site in the host. Under 355 nm excitation, the emission peak of Ca2NaMg2V3O12:Eu3+ phosphors are located at 610 nm (red) ascribed to the electric dipole transition of Eu3+ from 5D0 → 7F2. In the range of 400–575 nm, Ca2NaMg2V3O12:Eu3+ phosphors have broad emission bands attributed to charge transfer of \({\text{VO}}_4^{3 - }\) group. Energy transfer mechanism, energy transfer efficiency and critical distance (Rc) of \({\text{VO}}_4^{3 - }\) → Eu3+ would be analyzed. The emitting color of Ca2NaMg2V3O12:Eu3+ could be tunable from blue-green to near white light. 相似文献
4.
Zheng-Wei Yu Xiao-Yu Sun Zhen-Qing Wang 《Journal of Materials Science: Materials in Electronics》2018,29(7):5282-5286
We fabricated a series of Y3Al5O12:Mn4+ and Y1?yLuyAl5O12:Mn4+ phosphors by a solid state reaction. The phase and the optical properties of the synthesized phosphors were investigated. Under the excitation at 465 nm, Y3Al5O12:Mn4+ phosphors show emission bands locating at deep red regions, which is induced by the spin- and parity-forbidden 2Eg → 4A1g transitions of Mn4+. The substitution of Y3+ by Lu3+ decreases the lattice parameter and thus strengthens the crystal field strength, which gives rise to the blue shift of emission band for Y1?yLuyAl5O12:Mn4+ phosphors. Due to the compensation of red light by Y3Al5O12:Mn4+ or Y1?yLuyAl5O12:Mn4+ phosphor, the values of correlated-color-temperature for fabricated LEDs are decreased, which leads to the suitable application for them in indoor illumination. 相似文献
5.
Hualing Yu Jia Zhang Zhangyin Zhai 《Journal of Materials Science: Materials in Electronics》2017,28(19):14149-14155
In this paper, a series of Eu2+ activated Sr5(1?x)Ba5x(PO4)3Cl (0?≤?x?≤?100%) phosphors were prepared by solid-state reaction method, and their luminescence properties under near-ultraviolet excitation were investigated. For Eu2+-activated Sr5(PO4)3Cl, a strong emission band located at 445 nm is observed upon 365 nm excitation, which could be attributed to the 4f 65d 1–4f 7 transition of different Eu2+ centers. When the Ba2+ is introduced into the Sr5(PO4)3Cl:Eu2+, the emission band of Eu2+ is broadened largely. The fluorescence lifetimes for different Eu2+ centers were determined by the decay curves and time-resolved spectra. The excitation spectra of the as-prepared samples cover a wide wavelength range from 240 to 420 nm, which can well match the emission wavelength of the near ultraviolet LED chip. The investigation of the thermal luminescence stability reveals that the introduction of Ba2+ could improve the thermal quenching properties. 相似文献
6.
Subrata Das A. Amarnath Reddy S. Surendra Babu G. Vijaya Prakash 《Journal of Materials Science》2011,46(24):7770-7775
Potassium calcium borate, KCaBO3:Eu3+ phosphors with various Dy3+ concentrations (0–3 wt%) were synthesized by solid state reaction and studied for the first time. Under various UV–violet
excitations, the obtained single monoclinic phased Dy3+–Eu3+ co-doped KCaBO3 polycrystalline phosphors emit a combination of yellow–blue and red–orange wavelength giving intense white light, which can
easily be controlled by varying the concentration of Dy3+. The increase in white light emission with the increase of Dy3+ concentration indicates the efficient energy inter-ion transfer from Dy3+ to Eu3+ ions. Furthermore, the observed emission lifetimes and the intense white light emission are suggestive exploration for the
present phosphor for potential optoelectronic applications such as white light-emitting phosphor for blue LEDs chips. 相似文献
7.
CaTi1−x
Zr
x
O3: Pr3+ phosphors have been synthesized by sol-gel and solid state methods, with x = 1/300, 2/300, 3/300, 4/300, 5/300, 6/300, 7/300, respectively. Powder X-ray diffraction (XRD), UV-visible absorption spectra,
photoluminescent spectra (PL), and scanning electron microscopy (SEM) images are used to characterize the powder samples.
The inverse absorption at 610 nm appearing in the UV-visible absorption spectra is due to the 1
D
2 → 3
H
4 characteristic emission of Pr3+. Changes in the emission spectra at 610 nm were agreed with those in UV-visible absorption spectra. The strongest red excitation
obtained from CaTi1−x
Zr
x
O3: Pr3+ (x = 4/300) and CaTi1−x
Zr
x
O3: Pr3+ (x = 5/300) possesses the strongest emission at 610 nm, similar to the intensities of Ca(Ti1−x
Zr
x
)O3: Pr3+ (x = 3/300, 4/300, 6/300), which may be corresponded to the cell parameters of CaTi1−x
ZrxO3: Pr3+. 相似文献
8.
Zhanchao Wu Jianxin Shi Jing Wang Menglian Gong Qiang Su 《Journal of Materials Science: Materials in Electronics》2008,19(4):339-342
An efficient blue–green emitting phosphor, Sr4Al14O25:Eu2+, was prepared by solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Sr4Al14O25:Eu2+. Field-emission scanning electron-microscopy (FE-SEM) observation indicated that the microstructure of the phosphor consisted
of irregular fine grains with an average size of about 8–10 μm. Photoluminescence measurements showed a broad absorption band between 300 and 450 nm which was efficiently excited by near-ultraviolet
(NUV) LEDs (350–410 nm) and a strong emission band peaking at 491 nm. A bright blue–green LED with chromatic coordination
(0.176, 0.412) was fabricated by incorporating the phosphor with an InGaN-based NUV chip, which indicates that Sr4Al14O25:Eu2+ is a good candidate phosphor for application in white LEDs. 相似文献
9.
A. S. Saidov Sh. N. Usmonov K. T. Kholikov D. Saparov 《Technical Physics Letters》2007,33(10):853-855
Epitaxial layers of n-type solid solutions of the (Si2)1 ? x (CdS)x system (0 ≤ x ≤ 0.01) were grown by liquid phase epitaxy from a tin-based solution melt confined between two horizontal p-type single crystal silicon substrates. The photosensitivity spectra of p-Si/n-(Si2)1 ? x (CdS)x structures have been measured. A photoresponse peak at E ≈ 2.35 eV (1.25 eV below the top of the valence band of silicon) has been observed, which is probably related to an impurity level due to CdS molecules. 相似文献
10.
We report the optical and electrical properties of a-Si:H and a-Si1 − x
C
x
:H (x = 0.06, 0.17, 0.25,0.32) amorphous films produced by plasma deposition at constant hydrogen content. IR absorption data are
used to evaluate the density of Si-H and C-H bonds and the hydrogen concentration in the films. The activation energy for
conduction and the carrier mobility in the films are determined from the temperature dependence of their electrical conductivity. 相似文献
11.
M. M. Kasumov 《Technical Physics Letters》2010,36(10):895-898
The mass spectrum of the products of arc discharge in helium between graphite electrodes has been studied for various values
of the gas flow rate. As the gas flow rate increases, the intensity of C60±, C70±, C84± and C90± fullerene peaks increases and that of the C2− and C3+ cluster radicals decreases, but the total decay in radicals amounts to only 21% of the total growth of fullerenes. From this
it follows that a contribution to the formation of fullerenes from the neutral clusters (which are taken into account for
the first time) significantly exceeds the contribution due to small radical species. 相似文献
12.
The homogeneity range of EuMnO3 has been determined using x-ray diffraction analysis of single-and mixed-phase Eu2?x MnxO3+δ samples (0.90≤x≤1.20, Δx = 0.02) prepared from oxide mixtures by solid-state reactions in air between 900 and 1400°C. The results have been used to construct a partial phase diagram of the Eu-Mn-O system in air. The dependences of unit-cell parameters on x and synthesis temperature are presented for the samples synthesized at 1100 and 1400°C and for EuMnO3, respectively. The solubility of europium oxide in EuMnO3 is tentatively attributed to structural defects, and that of managanese oxides is interpreted in terms of structural defects, oxygen nonstoichiometry of europium manganite, the disproportionation reaction 2Mn3+ = Mn2+ + Mn4+, and partial substitution of the resulting Mn2+ for Eu3+ on the cuboctahedral site of the perovskite-like structure. To check these assumptions, systematic studies of the oxygen nonstoichiometry and structure of Eu2?x MnxO3+δ solid solutions synthesized at different temperatures are needed. 相似文献
13.
G. H. Mhlongo O. M. Ntwaeaborwa M. S. Dhlamini H. C. Swart K. T. Hillie 《Journal of Materials Science》2010,45(19):5228-5236
The successful incorporation of ZnO nanoparticles in Pr3+-doped SiO2 using a sol–gel process is reported. SiO2:Pr3+ gels, with or without ZnO nanoparticles, were dried at room temperature and annealed at 600 °C. On the basis of the X-ray
Diffraction (XRD) results, the SiO2 was amorphous regardless of the incorporation of Pr3+ and nanocrystalline ZnO or annealing at 600 °C. The particles were mostly spherical and agglomerated as confirmed by Field
Emission Scanning Electron Microscopy. Thermogravimetric analysis of dried gels performed in an N2 atmosphere indicated that stable phases were formed at ≥900 °C. Absorption bands ascribed to 3H4-3P(J = 0,1,2), 1I6 and 1D2 in the UV–VIS region were observed from SiO2:Pr3+ colloids. The red cathodoluminescent (CL) emission corresponding to the 3P0 → 3H6 transition of Pr3+ was observed at 614 nm from dried and annealed SiO2:Pr3+ powder samples. This emission was increased considerably when ZnO nanoparticles were incorporated. The CL intensity was measured
at an accelerating voltage of 1-5 keV and a fixed beam current of 8.5 μA. The effects of accelerating voltage on the CL intensity
and the CL degradation of SiO2:Pr3+ and ZnO·SiO2:Pr3+ were also investigated using Auger electron spectroscopy coupled with an Ocean Optics S2000 spectrometer. 相似文献
14.
Guo-Guang Yao Cui-Jin Pei Peng Liu Hui-Yu Xing Long-Xi Fu Bai-Cheng Liang 《Journal of Materials Science: Materials in Electronics》2017,28(18):13283-13288
New temperature stability Ba1?xSrxV2O6 (0.35?≤?x?≤?0.55) microwave dielectric ceramics prepared by the conventional solid-state route were investigated. X-ray diffraction confirmed that all the specimens formed a solid solution single phase with orthorhombic structure. The microwave dielectric properties strongly depended on the compositions, densification and microstructure of the specimens. Furthermore, partial Sr ions substitution for Ba ions in Ba1?xSrxV2O6 lattices not only successfully improved the temperature stability of BaV2O6-based ceramic but also promoted the sinterability of SrV2O6-based one. Out of these compositions, Ba0.5Sr0.5V2O6 sintered at 625?°C exhibited a near-zero τf together with a low permittivity εr?~?11.5 and a quality factor Q?×?f?~?14 100 GHz, which also showed good chemical compatibility with Al electrodes. 相似文献
15.
T. N. Kol’tsova 《Inorganic Materials》2010,46(3):242-250
The phase equilibria in the “CaAl2Si3O10”-Na2Al2Si3O10-H2O system are analyzed using structural and thermal analysis data, and the ideal gonnardite structure is modeled. The results
suggest that, to ensure a better correlation with the structures of the zeolites in this series, a new structural model of
the gonnardite-based solid solution must be selected, with the structure rotated through 45° about the c axis in the ab plane. 相似文献
16.
Epitaxial layers of (Si2)1?x(ZnS)x (0.08≤x≤0.92) solid solutions were grown by liquid phase epitaxy from a tin-based solution melt confined between two horizontal polycrystalline silicon substrates. The morphology, photoelectric properties, and current-voltage characteristics of the epilayers have been studied. The obtained (Si2)1?x(ZnS)x layers exhibit homogeneous depth-concentration profiles of components. The photo-sensitivity interval extends from 1.05 to 3.0 eV, which makes the obtained structures a promising material for photo-and optoelectronic devices. 相似文献
17.
Bin Yang Shuangming Li Xin Li Songke Feng Zhenpeng Liu Hong Zhong 《Journal of Materials Science: Materials in Electronics》2018,29(22):18949-18956
Sn1?xMnxTe (x?=?0, 0.09, 0.15, 0.20) bulk materials were prepared by melt spinning combined with spark plasma sintering process. Nanoscale grains were obtained, and the solid solubility of Mn was much enhanced by the ultrafast-cooling synthesis technique. The maximum of Seebeck coefficient and power factor are 242 µVK?1 and 19.97 µW cm?1K?2 at 873 K with the doping concentration of 15 at% Mn. A large amount of grain boundaries and doped atoms improve the scattering of heat-carrying phonons in a wide range of frequencies, and the scattering mechanisms are also explained by theoretical calculation. As a result, the minimum of lattice thermal conductivity is 0.66 µVK?1 at 873 K, the corresponding figure of merit is 1.26 for Sn0.85Mn0.15Te sample. This value is improved by 35% comparing with previously reported result. Our work indicates that melt spinning process is effective to develop SnTe related thermoelectric materials with excellent thermoelectric properties, which has the widespread commercial value and the prospects for development. 相似文献
18.
Yan Wang Jinghong Ma Dong Liang Meimei Zhou Fuxiang Li Ruifeng Li 《Journal of Materials Science》2009,44(24):6736-6740
Super-acid catalyst, SO4 2?/ZrO2–SiO2, with high zirconium loading was synthesized and the nature of the surface acid was investigated by FT-IR of pyridine adsorption. With the increasing ZrO2 content, the Lewis and Brønsted acid sites increased and reached the maximum when Zr/Si (molar ratio) = 1.3. The sample with Zr/Si = 1.3 showed the strongest IR adsorption band in the S=O stretching region (1,300–1,400 cm?1). Pyrosulfate and monosulfate species existed on the surface of the catalysts and the acidic strength could be enhanced by induction effect of their S=O groups. And there were two kinds of Brønsted acid sites on the surface of the catalysts. 相似文献
19.
20.
Cr x Ge1? x (x ~ 0.08) films were grown on GaAs (001) and Ge (001) substrates using molecular beam epitaxy (MBE) method, and their magnetic and transport properties have been studied in the temperature range between 1.8 and 300 K. All of the films exhibited weak paramagnetic behavior. Transport measurements showed that magnetoresistance ratio and the anomalous Hall resistance depend on the Cr concentration x and the kinds of substrate. 相似文献