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1.
Given the recent increased interest in phosphor materials and their applications, we analyzed a new NaPbB5O9:Dy3+ phosphor material with different concentrations of Dy3+. In particular, we investigated the crystal structure, morphology, and luminescence properties of these materials. X-ray diffraction analyses confirmed the formation of NaPbB5O9:Dy3+ phosphor powder. The functional groups present in the phosphor materials were examined by Fourier transform infrared spectroscopy. Scanning electron microscope images showed that the size of the grains was in the micrometer range. Photoluminescence spectra were recorded at different excitation wavelengths for the phosphor materials and we analyzed the variation in the intensity of the emission bands with different concentrations of Dy3+ ions. The color co-ordinates were calculated and used to characterize the color of the phosphor. We found that the emission colors of the Dy3+-doped NaPbB5O9 powders depended on the Dy3+ ion doping concentration and the excitation wavelength. 相似文献
2.
BaMgAl10O17:Eu2+ phosphors were synthesized by the flux method. When the appropriate amounts of fluxes are added, the synthesis temperature reduced by at least 200 °C compared with the conventional solid-state reaction method. SEM images demonstrated that addition of the flux in the process of phosphor synthesis benefitted the size and morphology of BaMgAl10O17:Eu2+ phosphor particles. Photoluminescence measurements under VUV excitation indicated that the luminescent intensity of the phosphor enhanced by adding the flux system (BaF2+Li2CO3). Addition of the flux system can not only enhance the luminescence efficiency and improve the stability, but also control the morphology and grain size of the phosphor. Replacement of Ba2+ by Li+ could generate traps, which result in slightly longer decay time. 相似文献
3.
Haoyi Wu Yihua Hu Bodai Zeng Zhongfei Mou Liuyong Deng 《Journal of Physics and Chemistry of Solids》2011,72(11):1284-1289
The long afterglow phosphors Sr1.97−xBaxMgSi2O7:Eu2+0.01, Dy3+0.02 (x=0, 0.4, 0.8, 1.2, 1.6 and 1.97) were synthesized via high temperature solid-state reaction. The phase identification reveals that the crystal plane spacing becomes greater with the decrease in the Sr/Ba ratio. Phase transition occurs when x=1.97. A nonlinear relationship between the emission peak and the crystal plane spacing is obtained with the decrease of the Sr/Ba ratio. This ascribes to the splitting of the 5d level of the Eu2+ and the change of the crystal field strength. The duration of the afterglow becomes shorter with the decrease of the Sr/Ba ratio. It may ascribe to deeper trap depth, lower trap concentration and the embarrassment of the transfer of carriers. 相似文献
4.
Different compositions in the Lu2Si2O7-Sc2Si2O7 system have been synthesized following the ceramic method. All XRD patterns are compatible with the thortveitite structure (β-RE2Si2O7 polymorph). Unit cell parameters change linearly with composition, which indicates a complete solid solubility of Sc2Si2O7 in Lu2Si2O7. 29Si MAS NMR spectra show a decrease of the 29Si chemical shift with increasing Sc content. A correlation reported in the literature to predict 29Si chemical shifts in silicates is applied here to obtain the theoretical variation in 29Si chemical shift values in the system Lu2Si2O7-Sc2Si2O7 and the results compare favourably with the values obtained experimentally. The FWHM values of the 29Si MAS NMR curves indicate a random distribution of Lu and Sc in the structure of the intermediate members. Finally, the IR study of the system confirms the solubility of Sc2Si2O7 in Lu2Si2O7, showing the splitting of several modes in the intermediate members and a linear shift of the frequency on going from one end-member to the other. 相似文献
5.
The luminescence properties of (Y0.9Eu0.1)VO4 phosphor with Na2CO3 flux prepared using the solid-state reaction were investigated. The XRD patterns show that all of the peaks are attributed to the YVO4 phase. The best crystallinity was obtained with 2 wt% Na2CO3 flux addition. The surface morphology of (Y0.9Eu0.1)VO4 phosphor changed from fluffy to a bar shape structure after Na2CO3 flux addition due to the tetragonal crystal system of YVO4. The calcined powders emit bright red luminescence centered at 618 nm due to the 5D0→7F2 electric dipole transition under an excitation wavelength of 318 nm; its intensity was increased about 15% with 2 wt% Na2CO3 flux addition. Red shift behavior was observed for the charge transfer state (CTS) absorption, which was due to the grain size of (Y0.9Eu0.1)VO4 phosphor increasing with increasing flux content. For 2 wt% Na2CO3 flux addition, the red emission of the (Y0.9Eu0.1)VO4 phosphor had CIE chromaticity coordinates of (0.66, 0.34), which are very close to the NTSC system standard red chromaticity coordinates of (0.67, 0.33). 相似文献
6.
Li2O-Nb2O5-ZrO2-SiO2 glasses mixed with different concentrations of V2O5 were crystallized. The samples were characterized by XRD, SEM and DTA techniques. The SEM pictures indicated that the samples contain well defined and randomly distributed crystal grains. The X-ray diffraction studies have revealed the presence of several crystalline phases in these samples. Optical absorption, ESR and photoluminescence spectral studies on these samples have indicated that a considerable proportion of vanadium ions do exist in V4+ state in addition to V5+ state and the redox ratio seems to be increasing with increase in the concentration of crystallizing agent V2O5. The infrared spectral studies have pointed out the existence of conventional SiO4, ZrO4, NbO6, VO structural units in the glass ceramic network. The study of dielectric properties suggested a decrease in the insulating character of the glass ceramics with increase in the crystallizing agent. A.C. conductivity in the high temperature region seems to be connected mainly with the polarons involved in the process of transfer from V4+↔V5+ ions. 相似文献
7.
Wei Zhao Zhen Jia E Lei Liguo Wang Zhaoyang Li Yejing Dai 《Journal of Physics and Chemistry of Solids》2013
〈001〉 textured Bi4Ti3O12 platelets with micro scale size were synthesized by a facile molten salt method. The photocatalytic activities of the as-prepared samples were measured with the photodegradation of methylene blue at room temperature under visible light irradiation. The Bi4Ti3O12 with the aspect ratio of 35 exhibited good absorption in the visible light region and the photodegradation against methylene blue was higher than that of anatase TiO2 reference, showing that the high degree of preferred {001} facets on the plate surface benefits the electronic transmission. In addition, the layer-pervoskite structure facilitates the mobility of the photogenerated carriers and hampers their recombination. The above results indicated that the large specific surface area of the as-prepared samples could attribute to the presence of a number of oxygen vacancies and then lead to the good photo-electric property. This work proposed an alternative way to tailor the structure of micro-sized platelets to get excellent properties comparable to the nano materials. 相似文献
8.
Photocatalytic activity of Nb2O5/SrNb2O6 heterojunction on the degradation of methyl orange 总被引:1,自引:0,他引:1
Jingcheng Xing Zhichao Shan Jianjiang Bian Wendeng Wang 《Journal of Physics and Chemistry of Solids》2008,69(1):23-28
The pure SrNb2O6 powders were prepared at 1400 °C by a conventional solid-state method and characterized by X-ray powder diffraction and UV-vis diffuse reflection spectrum. The powders of Nb2O5 and SrNb2O6 were ball-milled together and annealed to form the Nb2O5/SrNb2O6 composite. Photocatalytic activities of the composites were investigated on the degradation of methyl orange. The results show that the proportion of Nb2O5 to SrNb2O6 and the annealing temperature greatly influence the photocatalytic activities of the composites. The best photocatalytic activity occurs when the weight proportion of Nb2O5 to SrNb2O6 is 30% and the annealing temperature is 600 °C. The tremendously enhanced photocatalytic activity of the Nb2O5/SrNb2O6 composite compared to Nb2O5 or SrNb2O6 is ascribed to the heterojunction effect taking place at the interface between particles of Nb2O5 and SrNb2O6. The powders also show a higher photocatalytic activity than commercial anatase TiO2. 相似文献
9.
Jungang Zhang Changtai Xia Qun Deng Hongsheng Shi Jun Xu 《Journal of Physics and Chemistry of Solids》2006,67(8):1656-1659
Tin oxide doped β-Ga2O3 single crystals are recognized as transparent conductive oxides (TCOs) materials. They have a larger band gap (4.8 eV) than any other TCOs, thus can be transparent in UV region. This property shows that they have the potential to make the optoelectronic device used in even shorter wavelength than usual TCOs. β-Ga2O3 single crystals doped with different Sn4+ concentrations were grown by the floating zone technique. Their optical properties and electrical conductivities were systematically studied. It has been found that their conductivities and optical properties were influenced by the Sn4+ concentrations and annealing. 相似文献
10.
Zheng Wen-Chen Wu Shao-Yi Zhao Bei-JunZhu Shi-Fu 《Journal of Physics and Chemistry of Solids》2002,63(5):895-897
The substitutional sites of Co2+ ions in Co2+-doped CuG1−xAlxSe2 (including CuGaSe2 where x=0 and CuAlSe2 where x=1) semiconductors are studied by analyzing the composition x dependence of optical spectral parameters reported in the previous literature for these materials. From the studies, we suggest that Co2+ occupy I-group cation site rather than III-group cation site. The suggestion is discussed. 相似文献
11.
K RuckW Pitschke G Krabbes M WolfD Eckert K.-H Müller 《Journal of Physics and Chemistry of Solids》2002,63(10):1901-1907
Phases of the composition Ca1−x−yMgxCu2+yO3 have been prepared for the first time. The compounds are isostructural with the known end-members CaCu2O3 and MgCu2O3 showing a two-leg spin-ladder-like connection of copper and oxygen atoms within the Cu2O3-layer. Opposite the spin ladders this layer is folded, which results in a long-range antiferromagnetic ordering of these phases. The Néel temperature can be adapted by variation of x in Ca1−x−yMgxCu2+yO3 between 24 and 80 K. Several structural features, which influence the magnetic ordering, are discussed. 相似文献
12.
B.V. Raghavaiah 《Journal of Physics and Chemistry of Solids》2004,65(6):1153-1164
PbO-Sb2O3 glasses added with different concentrations of As2O3 (10-55 mol%) were prepared to understand their IR spectra, elastic properties (Young's modulus E, Shear modulus G, microhardness H), optical absorption and dielectric properties (constant ε, loss tan δ, ac conductivity σac over a moderately wide range of frequency and temperature and breakdown strength in air medium at room temperature). Results have indicated that the structure of the PbO-Sb2O3-As2O3 glass is more rigid when the concentration of As2O3 is around 40 mol%. 相似文献
13.
M.G. Brik 《Journal of Physics and Chemistry of Solids》2006,67(4):738-744
Exchange charge model of crystal field [B.Z. Malkin, in: A.A. Kaplyanskii, B.M. Macfarlane (Eds.), Spectroscopy of Solids Containing Rare-earth Ions, North-Holland, Amsterdam, 1987, pp. 33-50.] was used to analyze the energy level schemes of Ni2+ ion at both possible positions (octahedral and tetrahedral) in Ca3Sc2Ge3O12. The crystal field parameters were calculated from the crystal structure data; the crystal field Hamiltonian was diagonalised in the complete basis consisting of 25 wave functions of all LS terms of the Ni2+ ion. Results of calculations are in a good agreement with experimental data. From the experimental spectra available in the literature, the Huang-Rhys parameter S=3.5 and effective phonon energy were evaluated for the octahedral Ni2+ ion. 相似文献
14.
Jung-Jin KimKwang Hyun Ryu Kiyoshi SakaueHikaru Terauchi Chul-Hyun Yo 《Journal of Physics and Chemistry of Solids》2002,63(11):2037-2045
Chemical Li ion extraction processes have been carried out for pristine LiCoO2, LiCo0.95Ga0.05O2, and LiCo0.9Ga0.1O2 compounds by swirling them in 0.35 M H2SO4 solution. It is confirmed from XRD patterns that the compounds maintain the two-dimensional framework with pristine-type structure even after the acid treatment up to 12 h. The Ga-substituted compounds keep Li ions for longer time on the acid treatment rather than the LiCoO2. The average oxidation state of Co ions increases with the Li+ ion extraction time up to 3.45+. The local structure refinements for the chemically Li+ ion extracted compounds have been investigated by Co K-edge X-ray absorption spectroscopy. The extraction causes the increase of Debye-Waller (DW) factor or static disorder around the Co ion. The DW factor of the Co-Co bond pair less increases with the extraction time for the LiyCo0.95Ga0.05O2, and LiyCo0.9Ga0.1O2 compounds than that for the LiCoO2. The Ga-substituted compounds are more stable against acid treatments than the LiCoO2, since more basic Ga3+ ion retards the structural distortion of the CoO6 octahedra against the Li ion extraction. 相似文献
15.
Huaming Yang Xiangchao Zhang Chenghuan Huang Wuguo Yang Guanzhou Qiu 《Journal of Physics and Chemistry of Solids》2004,65(7):1329-1332
Mechanochemical reaction of ZnO and α-Fe2O3 in a planetary mill formed an amorphous precursor, which was subsequently heated to successfully produce zinc ferrite (ZnFe2O4) nanocrystallites. The amorphous precursor and nanocrystallites were characterized by differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Calcination of the precursor powder at 600 °C led to the formation of ZnFe2O4 nanocrystallites of about 22 nm in crystal size, and most of particle was about 10-50 nm in diameter. Effect of calcination temperature on the crystal size of the nanoparticles was investigated. The mechanism of nanocrystallite growth was primarily investigated. The activation energy of ZnFe2O4 nanocrystallite formation during thermal treatment was calculated to be 18.5 kJ/mol. 相似文献
16.
J. Feng B. Xiao J.C. Chen C.T. Zhou Y.P. Du R. Zhou 《Solid State Communications》2009,149(37-38):1569-1573
AgCuO2 and Ag2Cu2O3 are new types of semiconductor materials. A theoretical study is presented for both the electronic and optical properties of these new photovoltaic materials in the framework of density functional theory (DFT). The calculated cohesive energy is −3.606 eV/atom and −3.723 eV/atom for Ag2Cu2O3 and AgCuO2, respectively. Electronic calculations indicate that AgCuO2 is a small band gap semiconductor and Ag2Cu2O3 is metallic in nature. The valency state of Cu is divalent in Ag2Cu2O3 and trivalent in AgCuO2. The largest absorption coefficient of CuO2 is 332 244, which is significantly greater than that of CuInSe2, CdTe, GaAs, etc. 相似文献
17.
Junji Awaka Norihito Kijima Shoichi Nagata 《Journal of Physics and Chemistry of Solids》2008,69(7):1740-1746
High-purity powder specimens of AgCa2Mn2V3O12 and NaPb2Mn2V3O12 have been successfully synthesized by solid-state chemical reaction. The Rietveld refinements from X-ray powder diffraction data verified that these compounds have the garnet-type structure (space group , No. 230) with the lattice constant of a=12.596(2) Å for AgCa2Mn2V3O12 and a=12.876(2) Å for NaPb2Mn2V3O12. Calculation of the bond valence sum supported that Mn is divalent and V is pentavalent in these garnets. Estimation of the quadratic elongation and the bond angle variance showed that the distortions of the MnO6 octahedra and the VO4 tetrahedra are significantly suppressed. Our new results of AgCa2Mn2V3O12 and NaPb2Mn2V3O12 are compared to those of AgCa2M2V3O12 and NaPb2M2V3O12 (M=Mg, Co, Ni, Zn). 相似文献
18.
Paul M Forster 《Journal of Physics and Chemistry of Solids》2004,65(1):11-16
A novel layered hydrotalcite-like material, Co7(H2O)2(OH)12(C2H4S2O6), has been prepared hydrothermally and the structure determined using single crystal X-ray diffraction (a=6.2752(19) Å, b=8.361(3) Å, c=9.642(3) Å, α=96.613(5)°, β=98.230(5)°, γ=100.673(5)°, R1=0.0551). The structure consists of brucite-like sheets where 1/6 of the octahedral sites are replaced by two tetrahedrally coordinated Co(II) above and below the plane of the layer. Ethanedisulfonate anions occupy the space between layers and provide charge balance for the positively charged layers. The compound is ferrimagnetic, with a Curie temperature of 33 K, Curie-Weiss θ of −31 K, and a coercive field of 881 Oe at 5 K. 相似文献
19.
20.
Yoshiyuki Yoshida Kotaro Iwata Naofumi Aso 《Journal of Physics and Chemistry of Solids》2011,72(5):559-561
We have measured magnetization curves and powder neutron diffraction of double-layered Ruddlesden-Popper type ruthenate Sr3−xCaxRu2O7 (x=1.5, 2.0 and 3.0). The field dependence of the magnetization revealed that the transition field of metamagnetic transition along the b-axis shifted to lower fields and that the transition became broad with increasing Sr content. The slope of the magnetization curve also increased with increasing Sr content below the metamagnetic transition. These results indicate that an itinerant component is partly introduced by the Sr substitution. From the magnetic reflection, on cooling below TN, an additional reflection was observed at (0 0 1) for each x, and the amplitude increased with decreasing temperature. The observed diffraction patterns are very similar to those of Ca3Ru2O7. We conclude that the magnetic structure of the antiferromagnetic ordered phase is basically the same structure with that of Ca3Ru2O7. 相似文献