共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
CaSiO3:Ce,Mn体系中Ce3+→Mn2+的能量传递研究 总被引:1,自引:0,他引:1
本文研究了CasiO3:Ce,Mn体系中Ce3+和Mn2+的发光及Ce3+→Mn2+的能量传递特性.分别采用Forster-Dexter电多极相互作用理论和Inokuti-Hirayama能量传递理论,研究了该体系中Ce3+→Mn2+的高效无辐射能量传递情况.结果表明,Ce3+→Mn2+的高效能量传递是以电偶极—偶极相互作用为主的电偶极—偶极和偶极—四极相互作用的共同结果. 相似文献
3.
A. Vázquez-Olmos R. Redón A.L. Fernández-Osorio J.M. Saniger 《Applied Physics A: Materials Science & Processing》2005,81(6):1131-1134
Nanocrystalline Mn3O4 hausmannite has been easily prepared from manganese(II) acetate tetrahydrated, dissolved in a mixture of N,N’-dimethylformamide (DMF) and water (10%) at room temperature, without post-treatment of heating. Stability of the Mn3O4 colloidal dispersion was monitored by UV-visible electronic absorption spectroscopy. X-ray powder diffraction (XRD) pattern demonstrates its good phase purity. Analysis by transmission electron microscopy (TEM) image shows homogeneous nanorods with a narrow size distribution, being the average diameter and length of 6.58 nm and 17.44 nm, respectively. Moreover, the facility of the hausmannite nanorods to adhere to glass wall in this solvent mixture has allowed the formation of thin films which were analyzed by atomic force microscopy (AFM). PACS 81.07.Bc; 81.16.Be; 61.46.+w 相似文献
4.
Iron-manganese oxide catalysts are known to influence the production of short chain hydrocarbons in the Fischer-Tropsch-synthesis process. XRD, XRF, gravity measurements and Mössbauer-effect spectroscopy has been used to study a catalytic precursor made by coprecipitation of iron and manganese oxides. The sample is characterized as a mixture of two compounds with the same iron to manganese ratio. The two compounds are cubic spinels with the same crystallographic parameters, however, one compound is a defect spinel while the other is not. In the Mössbauer studies the defect spinel shows superparamagnetic relaxation behavior—fluctuations of the magnetization vector along two opposite easy directions, while the non-defect spinel shows evidence of collective excitations—fluctuations of the magnetization vector in directions close to the easy direction. These properties are related to the particle sizes. 相似文献
5.
Junji Awaka Shuji Ebisu Masakazu Ito Shoichi Nagata 《Journal of Physics and Chemistry of Solids》2012,73(3):471-477
Ferrimagnetism has been extensively studied in garnets, whereas it is rare to find the antiferromagnet. Present work will demonstrate antiferromagnetism in the two Mn–V-garnets. Antiferromagnetic phase transition in AgCa2Mn2V3O12 and NaPb2Mn2V3O12 has been found, where the magnetic Mn2+ ions locate only on octahedral A site. The heat capacity shows sharp peak due to antiferromagnetic order with the Néel temperature TN=23.8 K for AgCa2Mn2V3O12 and TN=14.2 K for NaPb2Mn2V3O12. The magnetic entropy change over a temperature range 0–50 K is 13.9 J K?1 mol-Mn2+-ions?1 for AgCa2Mn2V3O12 and 13.6 J K?1 mol-Mn2+-ions?1 for NaPb2Mn2V3O12, which are in good agreement with calculated value of Mn2+ ion with spin S=5/2. The magnetic susceptibility shows the Curie–Weiss behavior over the range 29–350 K. The effective magnetic moment μeff and the Weiss constant θ are μeff=6.20 μB Mn2+-ion?1 and θ=?34.1 K (antiferromagnetic sign) for AgCa2Mn2V3O12 and μeff=6.02 μB Mn2+-ion?1 and θ=?20.8 K for NaPb2Mn2V3O12. 相似文献
6.
7.
The kinetics of order-disorder transformation in Ni3(Mn, Al) alloys prequenched from 700°C has been studied by neutron-diffraction analysis. Within the framework of the I. M. Lifshits model, it is shown that in Ni3(Mn, Al) alloys containing 2.0 and 4.3 at.% aluminum, ordering proceeds by the homogeneous mechanism at 400° and by nucleation and growth at 450°. The causes are discussed of the sharp speedup of the order-disorder transformation in its first stage in aluminum-doped Ni3Mn alloy as compared with the binary alloy.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 24–28, April, 1977. 相似文献
8.
Photorefractive recording in LiNbO(3):Mn 总被引:4,自引:0,他引:4
The dynamic range, sensitivity, and dark decay of holographic recording of wavelength 458 nm in LiNbO(3) crystals doped with 0.2-at. % Mn with different oxidation states have been measured. The measured sensitivity is 0.5 cm/J and is found to be independent of the oxidation state, and the largest M/# obtained is 12/mm (extraordinary light polarization; light wavelength, 458 nm). This combination of very large M/# and high sensitivity is in strong contrast with results for LiNbO(3):Fe for which a direct trade-off exists between M/# and sensitivity. The activation energy of the dark decay of holograms stored in these LiNbO(3):Mn crystals is ~1.0 eV , which is characteristic of proton compensation and leads to a projected lifetime of holograms of three years at room temperature. 相似文献
9.
10.
11.
12.
13.
本文研究了具有长余辉发光特性的红色Mg3BO3F3:Mn2+,R3+(R=Eu,Sm,Dy)的阴极射线发光性能,以及R3+离子的掺杂对Mg3BO3F3:Mn2+的发射光谱、色坐标等的影响. 相似文献
14.
D.V. Azamat A.G. Badalyan A. Dejneka V.A. Trepakov L. Jastrabik Z. Frait 《Journal of Physics and Chemistry of Solids》2012,73(7):822-826
A high-frequency (49 and 70 GHz) electron paramagnetic resonance (EPR) study is reported on SrTiO3 single crystals doped with 0.5-at% of manganese. EPR spectra originating from the S=2 ground state of Mn3+ ions are shown to belong to the different types of Jahn–Teller centers that arise as a result of varied ordering of the oxygen vacancies due to the reducing process. The present results indicate the strong covalent reduction of the density of unpaired spins (Fermi term) at the manganese nucleus for the various types of centers. 相似文献
15.
16.
测量了α-Al2O3: Mn单晶中子辐照前后的三维热释发光谱.观察到α-Al2O3: Mn:Mn单晶γ射线照射后测量的三维热释发光谱中,峰温在350℃波长为680nm处有一宽发光峰,这可能与Mn2+离子有关;波长为695nm峰温在170℃和350℃的线状光谱,叠加在680nm宽发光峰上,是Cr3+离子的发光谱线,其中可能有Mn4+离子的贡献.与纯α-Al2O3单晶的热释发光谱相比,掺入Mn杂质后,γ射线照射的三维热释发光谱中完全地抑制了波长为416nm的α-Al2O3的F心发光峰.经1017cm-2中子注量辐照和退火后,γ射线照射后测量的三维热释发光谱中,在150℃出现了波长为416和695nm的发光峰,以及在250℃波长为680和695nm的发光峰,其中695nm新发光峰的强度略超过了中子辐照前α-Al2O3:Mn在350℃波长为695nm的发光峰,说明中子辐照产生了大量浅陷阱能级和F心.然而,经1018cm-2中子注量辐照和退火后,γ射线照射后测量的三维热释发光谱中,出现了峰温150℃,190℃和250℃波长为520nm的Mn2+离子发光峰,以及300℃波长为680和695nm的Cr3+(或Mn4+)的发光峰,表明增高中子注量的辐照,产生了温度为190℃,250℃和300℃深陷阱能级和F心,并使Mn2+离子发光峰明显加强.
关键词:
α-Al2O3:Mn
三维发光谱
缺陷结构
发光机理 相似文献
17.
E. V. Konovalova O. B. Perevalova N. A. Koneva E. V. Kozlov 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(8):1062-1065
The grain boundary ensembles in Ni3Mn alloy with L12 superstructure and different manganese content were investigated. It was found that the process of atomic ordering is accompanied
by the migration of grain boundaries. The presence of oxygen atoms in solid solution and oxide particles at the grain bound-
aries hinders the formation of the long-range atomic order in the crystalline lattice and migration of grain boundaries. 相似文献
18.
In order to microscopically investigate the magnetic properties of both paramagnetic and antiferromagnetic phases in Mn3Si (T N?=?23 K), the 55Mn NMR has been carried out at temperatures between 2.2 K and 300 K. The temperature dependences of the spectrum, Knight shift (or resonance frequency shift) and spin-lattice relaxation time T 1 of 55Mn NMR have been measured. In the paramagnetic phase, only one resonance spectrum can be obtained. The observed spectrum is identified to be a signal corresponding to the Mn(II) site. In the antiferromagnetic phase, two different spectra corresponding to the Mn(I) and Mn(II) sites are found at the resonance frequencies of 145 and 6 MHz, respectively, by the zero field NMR at 4.2 K. From these results, the internal magnetic fields on the 55Mn(I) and 55Mn(II) nuclei are found to be 13.6 and 0.6 T, respectively. According to the NMR results, the helical structure in incommensurate Mn spin states is better explained compared with the transverse sinusoidal structure. 相似文献
19.
Ya. Zhydachevskii A. Suchocki M. Berkowski P. Bilski S. Warchol 《Radiation measurements》2010,45(3-6):516-518
The paper contains characterization of the YAlO3:Mn2+ thermoluminescent (TL) detectors. Namely, such TL parameters of the detectors as repeatability, thermal fading, effect of daylight exposure and dose dependence have been studied. The performed investigations confirm a high application potential of the detectors for middle- and high-dose dosimetry of ionizing radiation. 相似文献
20.
Multiplexing holograms in LiNbO3:Fe:Mn crystals 总被引:7,自引:0,他引:7
Persistent holograms are recorded with red light in lithium niobate crystals doped with manganese and iron. Different erasure mechanisms are investigated, and a recording schedule for multiplexing holograms with equal diffraction efficiencies is proposed. To test the recording schedule experimentally, we multiplex 50 plane-wave holograms with the proposed recording schedule. 相似文献