Results 151 to 160 of about 38,396 (204)
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Lattice vibrations of MgAl2O4 spinel
Journal of Physics and Chemistry of Solids, 1973Abstract Raman spectra have been measured on oriented single crystals of MgAl2O4 spinel. The fundamental frequencies are A1g = 772, Eg = 410, and T2g = 671, 492 and 311 cm−1. A Kramers-Kronig analysis of the reflectance spectrum of spinel yields the i. r. -active vibrations T1u = 670, 485, 428 and 305 cm−1.
M.P. O'Horo, A.L. Frisillo, W.B. White
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On Infrared Intensities of Spinel, MgAl2O4
Bulletin of the Chemical Society of Japan, 2005Abstract In spinel (MgAl2O4), the strongest infrared band at 485 cm−1 shows less LO–TO splitting than the medium band at 670 cm−1. This unexpected relationship is explained in terms of the vibrational coupling of these TO modes. A new manner for evaluating the LO mode is proposed.
Isao Kanesaka +2 more
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Crack-healing in spinel (MgAl2O4) ceramic
Materials Science and Engineering: A, 2015Abstract This paper reports the crack-healing behavior in spinel ceramic. Spinel nanopowder was synthesized via mechanical activation with subsequent annealing of magnesium carbonate and aluminum hydroxide. The produced nanopowder was uniaxially pressed and then sintered at 1200 °C for 1 h.
Fariborz Tavangarian, Guoqiang Li
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Low temperature synthesis of spinel (MgAl2O4)
Materials Letters, 1997Spinel (MgAl2O4) is prepared by a combined gelation-precipitation process from a mixed solution of sulphates of aluminium and magnesium. X-ray diffraction of gel samples calcined at different temperatures shows that a spinel-like phase starts forming at 600 °C and complete conversion is obtained at 1000 °C in 1 h.
Vinay Kumar Singh, Rakesh Kumar Sinha
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Cathodoluminescence of Mn2+ centers in MgAl2O4 spinels
Journal of Luminescence, 1990Abstract MgAl 2 O 4 :Mn spinels containing between 0 and 8% Mn by weight were prepared (a) by growth from an induction melt, and (b) by Mn + implantation into nonstoichiometric spinel crystals. Cathodolumenescence brightness measurements (520 nm emission band) were made as a function of Mn concentration on both (a) and (b), revealing increasing ...
R. Mlcak, A.H. Kitai
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Magnesium Aluminum Spinel (MgAl2O4)
1997Publisher Summary Magnesium aluminum spinel (MgAl2O4) is a face-centered cubic material, the prototype for the spinel structural family, which includes binary oxides, sulfides, and selenides. The space group is Fd3m, unit cell length is 0.8084 nm, and the unit cell has eight formula units.
WILLIAM J. TROPF, MICHAEL E. THOMAS
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Synthesis and characterization of MgAl2O4 spinel nanowires
Journal of Materials Chemistry, 2003MgAl2O4 spinel nanowires have been synthesized on an alumina substrate by reaction of magnesium oxide powders with graphite at 1350 °C in a flowing argon atmosphere. Transmission electron microscopy (TEM) images show that they have a diameter of 50–120 nm, and a length up to 500 micrometers.
Xingcai C. Wu +3 more
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Inversion in synthetic spinel: Fluorescence of Cr3+ ions in MgAl2O4 spinel ceramics
Journal of Luminescence, 2020Abstract The fluorescence spectra of probe Cr3+ ions in MgAl2O4 spinel ceramics have been studied. The analysis of the spectra shows that the normal non-inverse spinel phase dominates the samples. The possibility of obtaining normal spinel by the standard high-temperature ceramics synthesis is established.
S.P. Feofilov +2 more
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New synthesis methods of MgAl2O4 spinel
Journal of the European Ceramic Society, 2007Abstract The paper presents a study concerning the influence of the precursors upon the synthesis temperature, particle size and morphology of the MgAl2O4 spinel. With this view there have been used by comparison three synthesis methods: thermal conversion of the heteropolynuclear complex combination resulted from the oxidation reaction of 1,2 ...
C. Păcurariu +5 more
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An orthorhombic chromium-center in the spinel MgAl2O4
Journal of Physics and Chemistry of Solids, 1973Abstract In Cr-doped MgAl 2 O 4 most of the Cr 3+ -ions occupy normal B -sites. In addition to this axial center we report here the presence of an orthorhombic Cr 3+ -center. The ESR-spectra of this new center can be described by the spin Hamiltonian: ℋ = D [ S z 2 − 1 3 S ( S + 1 ) ] + g x β H x S x
H. Van den Boom, J.C.M. Henning
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