Results 181 to 190 of about 5,849 (219)

Structural analysis on spinel (MgAl2O4) for application in spinel-bonded castables

Ceramics International, 2009
Abstract An intimate mixture of common hydrated magnesium salt and cheaper boehmite sol had been used as a cost-effective precursor of reactive nanometric spinel (1:1) powder. It was gelled at controlled pH, temperature and time, and calcined at significantly lower temperature after soft mechanochemical treatment.
A. Banerjee, S. Das, S. Misra, S. Mukhopadhyay   +3 more
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Synthesis of dense nanocrystalline ZrO2–MgAl2O4 spinel composite

Scripta Materialia, 2005
Abstract A nanocrystalline ZrO2–spinel composite with an average grain size of smaller than 100 nm can be synthesized by high-energy ball-milling followed by spark plasma sintering. Nanocrystallization can strengthen the ZrO2–spinel composite by a factor of 2.0–2.5; the maximum flexural strength of the nanocrystalline composite reached ≈2200 MPa.
K. Morita, K. Hiraga, B.-N. Kim, H. Yoshida, Y. Sakka   +4 more
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Spectroscopic properties of Nd3+ in MgAl2O4 spinel nanocrystals

Journal of Alloys and Compounds, 2012
Abstract Nd 3+ doped MgAl 2 O 4 spinel nanocrystals have been prepared by the sol–gel method. Their size decreases from 12 to 7 nm with increasing Nd 3+ concentration from 0.1 to 5%, respectively. Some crystal field components of the Nd 3+ energy levels in MgAl 2 O 4 spinel were found from the 300 K reflectance absorption and the 77 K emission ...
P.J. Dereń, K. Maleszka-Bagińska, P. Głuchowski, M.A. Małecka   +3 more
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Interfaces in Transparent Polycrystalline MgAl2O4 Spinel

2019
Transparent ceramics have unique properties enabling applications no other materials can and magnesium aluminate spinel has been at the forefront of their development. However, the processing-property relationships of transparent spinel fabrication, in particular interfaces, which often govern densification and influence final properties, remain poorly
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Radiation-induced electrical conductivity in MgAl2O4 spinel

Journal of Nuclear Materials, 1991
Abstract The dc electrical conductivity of high purity, polycrystalline MgAl2O4 spinel of 99.5% theoretical density has been measured during irradiation by 18 MeV protons at reactor relevant ionization dose rates. The radiation-induced conductivity (RIC) at 200°C varied in a slightly sub-linear manner with dose rate. At temperatures between 250–350°C
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Electronic ionization induced atom migration in spinel MgAl2O4

Journal of Nuclear Materials, 2010
Abstract We report direct spectroscopic evidence for atom migration during the initial stage of electron irradiation in spinel MgAl2O4. Time-dependent electron energy-loss spectroscopy of the Mg and Al L23 edges shows that both Mg and Al have a tendency to occupy the octahedral interstices under electron irradiation, along with a slight expansion of ...
Nan Jiang, John C.H. Spence
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Piezo- and thermo-optic behavior of spinel (MgAl2O4)

Journal of Solid State Chemistry, 1975
Abstract The piezo- and thermo-optic properties of oxides are extremely interesting and fascinating, since in some oxides such as vitreous silica, α-quartz, etc., the refractive index increases with hydrostatic pressure, while in some others such as MgO, SrTiO 3 , α-Al 2 O 3 , etc., it decreases with pressure.
K. Vedam, J.L. Kirk, B.N.N. Achar
openaire   +1 more source

Fabrication of magnesium aluminate (MgAl2O4) spinel foams

Ceramics International, 2011
Abstract This paper reports on a novel-processing route for fabricating magnesium aluminate (MgAl 2 O 4 ) spinel (MAS) foams from aqueous suspensions containing 30–35 vol.% solids loading. A stoichiometric MAS powder formed from alumina (71.8%) and magnesia (28.2%) at 1400 °C was surface passivated against hydrolysis in an ethanol solution of H 3 PO ...
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An orthorhombic chromium-center in the spinel MgAl2O4

Journal of Physics and Chemistry of Solids, 1973
Abstract 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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Radiation-induced cation disorder in the spinel MgAl2O4

Journal of Nuclear Materials, 2006
Abstract There is some controversy in the literature concerning the nature of radiation-induced cation disorder and phase transformation in the spinel MgAl2O4. Attempts have been made to interpret the experimental data either in terms of a pure inversion involving the exchange between the Mg and Al atoms, or the disordering of the cation sublattice ...
openaire   +1 more source