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1.
The absorption spectra of Y3Ga5O12:(Fe3+), Y3Ga5O12:(Bi3+) and Y3Ga5O12:(Bi3+, Fe3+) are presented to 40,000 cm-1. Assignments are discussed and the transitions analysed in terms of their involvement in the large Faraday rotation observed in bismuth substituted iron garnets. 相似文献
2.
119Sn Mössbauer spectroscopy shows that the reaction of metallic tin with niobium titanium phosphate, NbTiP3O12, results in the accommodation of Sn2+ in two types of sites within channels in the NbTiP3O12 structure. The Sn2+ absorptions are characterised by highly positive chemical isomer shifts which decrease as increasing concentrations of Sn2+ are incorporated within the NbTiP3O12 structure. At very high tin concentrations the Mössbauer spectra show the presence of some unreacted elemental tin. The119Sn Mössbauer data are endorsed by X-ray powder diffraction data and are discussed in terms of the incorporation of highly ionic Sn2+ species. 相似文献
3.
三基色荧光粉中, 红色荧光粉性能较差, 为获得性能优良的红色荧光粉, 本文采用高温固相法合成了Eu2+, Cr3+单掺杂及共掺杂的碱土金属多铝酸盐MAl12O19 (M =Ca, Sr, Ba) 发光体. 实验表明, 在以上三种基质中均存在Eu2+→Cr3+的能量传递, 利用能量传递可以有效将Eu2+的蓝光或绿光转换为红光. 三种碱土金属多铝酸盐基质的晶体结构相似,但Eu2+, Cr3+发光受晶体场影响,导致在不同的基质中Eu2+, Cr3+间能量传递效率不同.通过光谱分析及能量传递效率计算发现, 相同掺杂浓度下,CaAl12O19中Eu2+→Cr3+的能量传递效率最高,SrAl12O19次之, BaAl12O19最低.红光转换率在CaAl12O19中最高. 相似文献
4.
N. I. Kadyrova Yu. G. Zaynulin A. P. Tyutyunnik N. V. Melnikova A. A. Mirzorakhimov 《Bulletin of the Russian Academy of Sciences: Physics》2016,80(6):620-623
AMn3V4O12 (A = Ca, Ce, and Sm) compounds with a perovskite structure are synthesized at high pressures and temperatures. The crystalline structure of these compounds (space group \(Im\bar 3\)Z = 2) is determined via X-ray analysis. If ions in the A sublattice are changed in the order Ca2+–Sm3+–Ce3+, the valence is redistributed from Ca2+Mn32+V44+O12 to Sm3+Mn32+V43.75+O12, and to Ce3+Mn32+V43.75+O12. The temperature dependences of the electrical resistivity are studied. 相似文献
5.
O. Volkova K. Klimov O. Savelieva N. Tristan E. Goodilin B. Buechner A. Vasiliev 《Journal of magnetism and magnetic materials》2006
Magnetic and transport properties of double distorted perovskites CaCuMn6O12 and CaCu2Mn5O12 are studied in a range 2–300 K. The leading role in magnetism of these compounds belongs to antiferromagnetic exchange interaction of Cu2+ in square coordination with Mn3+/Mn4+ in octahedral coordination. The values of saturation magnetization indicate that Mn3+ ions in square coordination are coupled ferromagnetically with Mn3+/Mn4+ in octahedral coordination. The colossal magnetoresistance in the pellet samples is due assumingly to intergranular spin-polarized tunneling of current carriers. 相似文献
6.
Ch. Sauer U. Köbler W. Zinn H. Stäblein 《Journal of Physics and Chemistry of Solids》1978,39(11):1197-1201
Mössbauer effect measurements on 57Fe in LaFe12O19 at room temperature and at 4.2 K in an external magnetic field of 10 T confirm the suggestion of Lotgering[2] that the replacement of Ba2+ in BaFe12O19 by La3+ is accompanied by a valence change of Fe3+ to Fe2+ in the 2a-sublattice. The corresponding Fe2+-subspectrum has been detected. The increased hyperfine fields of the 12k- and 2b-sites in LaFe12O19 are discussed in terms of the different exchange paths between the iron sublattices. 相似文献
7.
Absorption of Bi12GeO20 and Bi12SiO20 single crystals doped with Mn and Cr were investigated before and after illumination with visible light. Pronounced photochromic effects were found. The effects are explained in terms of light induced charge transfer Mn4+→Mn5+ and Cr3+→Cr2+. 相似文献
8.
Xianju Zhou Kaining Zhou Yingmao Li Zhiliang Wang Qiaochun Feng 《Journal of luminescence》2012,132(11):3004-3009
Y3Al5O12:Ce3+, Pr3+ and Y3Al5O12:Ce3+, Tb3+ nano-particles have been synthesized by polymer-assisted sol–gel method. Crystal structure, luminescent properties and energy transfer of the phosphors are analyzed. XRD study of polycrystalline powders shows that all the samples are of YAG phase without impurity. Photoluminescence (PL) emission and excitation spectra illustrate that in YAG:Ce, Pr phosphors, energy transfer occurs mutually between Ce3+ and Pr3+, while in YAG:Ce, Tb systems, only one-way path energy transfer of Tb3+→Ce3+ is observed. 相似文献
9.
Spinel-Li4Ti5O12 is successfully synthesized by a solid phase synthesis. The Li4Ti5O12 powders with various dopants (Al3+, Cr3+, Mg2+) synthesized at 800 °C are in accordance with the Li4Ti5O12 cubic spinel phase structure. The dopants are inserted into the lattice structure of Li4Ti5O12 without causing any changes in structural characteristics. In order to study the effect on various dopants, the hybrid supercapacitor is prepared by using un-doped Li4Ti5O12 and doped Li4Ti5O12 in this work. The electrochemical performance of the hybrid supercapacitor is characterized by impedance spectroscopy and cycle performance. The results show Cr3+ and Mg2+ dopants enhance the conductivity of Li4Ti5O12. Also, Al3+ substitution improves the reversible capacity and cycling stability of Li4Ti5O12. It is found that effect of dopant on the electrochemical performance of Li4Ti5O12 as electrode material for hybrid supercapacitor where the EDLC and the Li ion secondary battery coexist in one cell system. 相似文献
10.
Mössbauer spectra of 57Fe in LaFe12O19 show that the substitution of La3+ for Ba2+ or Sr2+ in XFe12O19 is associated with a valency change of Fe3+ to Fe2+ at the 2a or 4f2 site. Temperature dependences of the hyperfine fields at the various sublattices are given. 相似文献
11.
12.
J. A. Hodges 《Hyperfine Interactions》1983,16(1-4):767-770
Measurements of the enhanced superhyperfine interaction linking the electron spin of an impurity EPR ion and the nuclear moments of Van Vleck host lattice ions are reported for Ru3+ in Tm3Al5O12 and for Ru3+ and Yb3+ in Tm3Ga5O12. The Ru3+ results appear to be the first reported where this interaction is large enough to give rise to a well resolved superhyperfine structure. For Yb3+ the observed temperature dependent line narrowing evidences the role of Tm spin fluctuations. 相似文献
13.
Ce3+ activated aluminate based phosphors prepared by combustion synthesis are reported here. The emission of Ce3+ ion is observed around 321–354 nm in the ultraviolet region of the spectrum. The intensity of strong photoluminescence emission peak of Ce3+ ion increases when Mg is added to CaAl12O19 phosphor. The Ce3+ emission in CaAl12O19:Ce,Mg phosphor may be useful for scintillation application. 相似文献
14.
K.V. Ivanovskikh A. Meijerink A. Speghini C. Ronda M. Bettinelli 《Journal of luminescence》2010,130(5):893-16384
The silicates Ca3Sc2Si3O12, Ca3Y2Si3O12 and Ca3Lu2Si3O12, both undoped and doped with Pr3+ ions, have been synthesized by solid-state reaction at high temperature. The luminescence spectroscopy and the excited state dynamics of the materials have been studied upon VUV and X-ray excitation using synchrotron radiation. All doped samples have shown efficient 5d-4f emission upon direct VUV excitation of 5d levels, but only Ca3Sc2Si3O12:Pr3+ shows luminescence upon interband VUV or X-ray excitation. The VUV excited emission spectra of Ca3Y2Si3O12:Pr3+ and Ca3Lu2Si3O12:Pr3+ show features attributed to emission from two distinct sites accommodating the Pr3+ dopant. The decay kinetics of the Pr3+ 5d-4f emission in Ca3Sc2Si3O12:Pr3+ upon VUV excitation across the band gap are characterized by decay times in the range 25-28 ns with no significant rise after the excitation pulse. They appear to be faster upon X-ray irradiation than for VUV excitation. Weak afterglow components are attributed to defect luminescence. 相似文献
15.
The stability and the possible application of our recently reported SiC heterofullerenes inspire the investigation of their further stabilization through ion encapsulation. The endohedral complexes X@C12Si8, where X=Li+, Na+, K+, Be2+, Mg2+, Ca2+, Al3+, and Ga3+, are probed at the MPWB1K/6-311G? and B3LYP/6-311G* levels of theory. The optimized geometries show the expanding or contracting capability of C12Si8 in order to accommodate metal ion guests. The inclusion energies indicate the stability of the complexes compared to the components. Meanwhile, the calculated binding energies show the stabilization of C12Si8 through the inclusion of Be2+, Mg2+, Al3+, and Ga3+. The host-guest interaction that is probed through NBO atomic charges supports the obtained results. This study refers to “metal ion encapsulation” as a strategy for stabilization of SiC heterofullerenes. 相似文献
16.
H. G. Bohlen H. Ossenbrink W. von Oertzen P. Wust H. Hafner K. Wannebo 《Zeitschrift für Physik A Hadrons and Nuclei》1978,285(4):379-388
Measuring energy spectra of nuclei afterγ-decay of excited states in flight the spin alignment of12C2+ states has been measured. Inelastic scattering,16O(16C,12C2+)16O and the reaction12C(16O,12C2+)16O leading to12C2+ (4.43 MeV) state have been studied. Characteristic line shapes of the12C2+ peak were observed using a Q3D magnetic spectrometer. The magnetic substate (m-states) population has been deduced from the spectra as function of reaction angle. A comparison of the measuredm-state population with reaction models shows that the first reaction is consistent with inelastic scattering although discrepancies remain. Discrepancies are also obtained if the reaction12C(16O,12C2+)16O is interpreted using a FRDWBA transfer calculation. At least 1/3 of the cross section can be attributed toα-transfer. A calculation which couples transfer and inelastic scattering channels seems to be necessary. 相似文献
17.
F. Iga Y. Takakuwa T. Takahashi M. Kasaya T. Kasuya T. Sagawa 《Solid State Communications》1984,50(10):903-905
Single phase TmB12, YbB12 and LuB12 were successfully obtained by the arc-melting and floating zone methods. The XPS measurements of these compounds have indicated that (1) only YbB12 is a valence fluctuating compound with the valency of +2.9 at room temperature, (2) the correlation energy between Yb2+ and Yb3+ ions is about 6.0 eV, (3) Tm and Lu ions in the dodecaborides are in a trivalent state, and (4) the binding energy of the 4f level in TmB12 and LuB12 is 5.0 and 7.7 eV, respectively. 相似文献
18.
Yu. Zorenko V. Gorbenko T. Voznyak T. Zorenko B. Kuklinski R. Turos-Matysyak M. Grinberg 《Optics and Spectroscopy》2009,106(3):365-374
The processes of excitation energy transfer in phosphors based on single-crystal Tb3Al5O12:Ce (TbAG:Ce) and Tb3Al5O12:Ce,Eu (TbAG:Ce,Eu) garnet films have been investigated. These films are considered to be promising materials for screens for X-ray images and luminescence converters of blue LED radiation. The conditions for excitation energy transfer from the matrix (Tb3+ cations) to Ce3+ and Eu3+ ions in TbAG:Ce and TbAG:Ce,Eu phosphors have been analyzed in detail. It is established that a cascade process of excitation energy transfer from Tb3+ ions to Ce3+ and Eu3+ ions and from Ce3+ ions to Eu3+ ions is implemented in TbAG:Ce,Eu via dipole-dipole interaction and through the Tb3+ cation sublattice. 相似文献
19.
Tin-119 and iron-57 Mössbauer spectroscopy show that the incorporation of tin and iron into the white oxide NbTiP3O12 to form black compounds of composition Sn0.5NTiP3O12 and Fe0.33NbTiP3O12 involves the accomodation of Sn2+ and Fe2+ in two types of sites in the NbTiP3O12 host lattice. The change in colour is associated which charge transfer arising from the transfer of electrons from the incorporated metal to the host lattice and the partial reduction of Nb5+ to a lower oxidation state.The compound SbTiP3O12 has been synthesised and shown by antimony-121 Mössbauer spectroscopy to contain Sb5+. The resistance of the SbTiP3O12 structure to the incorporation of tin and iron is associated with the reluctance of Sb3+ to adopt octahedral coordination. 相似文献
20.
Linuan Yin Ying Li Jun Wang Yu Zhai Yumei Kong Jingqun Gao Guangxi Han Ping Fan 《Journal of luminescence》2012,132(11):3010-3018
In this progress report, seven kinds of novel carefully designed and fabricated up-conversion luminescence agents, Er3+:Y3Al5O12, Er3+:YbnY3?nAl5O12, Er3+:Y3BaAl5?aO12, Er3+:Y3GabAl5?bO12, Er3+:Y3Al5NxO12?x, Er3+:Y3Al5FyO12?y and Er3+:YbnY3?nBaGabAl5?a?bNxFyO12?x?y, are successfully synthesized using sol–gel methods. After that, their corresponding photocatalysts, Er3+:Y3Al5O12/TiO2, Er3+:YbnY3?nAl5O12/TiO2, Er3+:Y3BaAl5?aO12/TiO2, Er3+:Y3GabAl5?bO12/TiO2, Er3+:Y3Al5NxO12?x/TiO2, Er3+:Y3Al5FyO12?y/TiO2 and Er3+:YbnY3?nBaGabAl5?a?bNxFyO12?x?y/TiO2, are also prepared by sol–gel coating process. The obtained up-conversion luminescence agents and photocatalysts were characterized by using XRD, XPS, SEM, UV–vis and fluorescence spectrophotometer. Synchronously, several kinds of organic dyes are used to test their photocatalytic degradation using prepared photocatalysts. It indicates that the up-conversion luminescence ability of Er3+:Y3Al5O12 can be improved obviously through doping of some elements. And then, the photocatalytic activity of TiO2 is markedly enhanced by modified up-conversion luminescence agents which can transform much visible light into ultraviolet light. 相似文献