Behavior of Chromium in the System MgA12O4– A12O3

Arlett, Robert H.

doi:10.1111/j.1151-2916.1962.tb11050.x

Cited by 27 publications

(4 citation statements)

References 7 publications

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“…The principal component at 6875A is the sharpest. The width of this component is considerably wider than that of natural spinel (42,43), but is similar to those reported on Verneuil (41) and Czochra]ski (11) grown stoichiometric spinel crystals. The sharp line components of Cr +3 in Czochralski spinel was not observed.…”

Section: Absorption and Emission Characteristics O]supporting

confidence: 87%

“…There are two broad absorption bands observed with peaks at 5480 and 3910A, corresponding to transition from the ground state to the 4T2 and 4T1 excited states, respectively. The absorption peaks of the spectra, as shown in Table III, are in general agreement (with slight differences in peak positions) with those reported for Cr +3 in natural (40) stoichiometric spinel and in stoichiometric spinel grown by Verneuil (41) and Czochralski (11) methods. A sample was annealed at 1000~ for 1/2 hr.…”

Section: Absorption and Emission Characteristics O]supporting

confidence: 86%

“…The emission has vibrational fine structure with peaks at 6750, 6875, 6980, 7075, d Ref. (41). and 7165A.…”

Section: Absorption and Emission Characteristics O]mentioning

confidence: 99%

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Dielectric and Optical Properties of Stoichiometric Magnesium Aluminate Spinel Single Crystals

Wang

Zanzucchi

1971

J. Electrochem. Soc.

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Stoichiometric magnesium aluminate spinel false(MgAl2O4false) single crystals grown by the flux, Czochralski, and Verneuil methods have been characterized for their dielectric and optical properties. Dielectric properties were determined from capacitance measurements in the frequency range 102–105 Hz. The dielectric constant and loss tangent of MgAl2O4 spinel crystals grown by the various methods are comparable. At 1 kc the MgAl2O4 spinel has a dielectric constant of 8.4 and a loss tangent of 10−4. Optical transmission and reflection measurements were made in the wavelength range uv to IR (0.2–40 µm). Optical characteristics of the MgAl2O4 crystals are highly dependent on the method of growth. Chromium‐doped MgAl2O4 spinel single crystals have also been grown by a flux technique. Optical emission and absorption characteristics of Cr+3 in flux‐grown MgAl2O4 spinel have been studied. The results are compared with those of Cr+3 in natural spinel and synthetic spinel crystals prepared by the Czochralski and Verneuil methods.

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Section: Absorption and Emission Characteristics O]supporting

confidence: 87%

Section: Absorption and Emission Characteristics O]supporting

confidence: 86%

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Dielectric and Optical Properties of Stoichiometric Magnesium Aluminate Spinel Single Crystals

Wang

Zanzucchi

1971

J. Electrochem. Soc.

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“…22 23 The behavior of chromium in magnesium-aluminate spinel was studied in Ref. 24. In absorption and luminescence spectra, it was revealed that excess alumina added to stoichiometric spinel creates cation vacancies.…”

Section: (4) Influence Of Impurity Ions On Defect Formation In Spinelmentioning

confidence: 99%

Structure and Electronic States of Defects in Spinel of Different Compositions MgO·nAl2O3:Me

Gritsyna

Afanasyev-Charkin

Kobyakov

et al. 1999

Journal of the American Ceramic Society

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This paper reviews the nature of defects and optical centers in magnesium aluminate spinel. The identification of absorption and luminescence bands was used to investigate the influence of UV and electron irradiation on optical center formation. Crystals examined were nominally pure MgO-nAl 2 O 3 crystals with compositions in the series n = 1.0, 1.5, 2.0, and 2.5. MgOؒAl 2 O 3 crystals doped with transition-metal ion dopants were also studied to determine the influence of impurities on the nature and concentration of lattice defects in spinel. Results strongly suggest that absorption bands at 3.78 and 4.15 eV, and luminescence bands near 5 eV, may be attributed to optical centers on antisite defects. It is also apparent that through the introduction of specific amounts of Mn and Cr ions, the concentration of optical centers (which are related to defects such as cation antisites in the spinel structure) can be considerably changed.

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