Effect of grain boundary microcracking on the light transmittance of sintered transparent MgAl2O4

Effect of Chemical Composition on the Optical Properties and Fracture Toughness of Transparent Magnesium Aluminate Spinel Ceramics

“…The absorption coefficients decrease towards higher wavelengths where impurity atoms have less electronic transitions. 24) The difference of the processing related impurity content of the present spinel ceramics, 13) however, gives rise to variations in their absorption coefficients in different spectral ranges. In the visible wavelength range, spinel III has the highest absorption coefficient at lower wavelengths, while at higher wavelengths spinel I and II show higher absorption, where the observed differences range between $0:7 and 2 cm À1 .…”

“…The starting ceramic powders were mixed by a mechanical preparation process; the details were reported elsewhere. 13) Al 2 O 3 content was changed in the powder mixture in order to obtain three different final compositions of MgOÁnAl 2 O 3 with n ¼ 1:0, 1.5 and 2.0, which will be denoted as ''spinel I,'' ''spinel II'' and ''spinel III,'' respectively, hereafter.…”

“…The dotted area between the reflection and total transmission spectra shows the amount of absorption losses that most probably resulted from the impurities in the material the presence of which was reported by the present authors for spinel ceramics fabricated with the same processing route. 13) In addition to this, multiple scattering losses, if there are any, were also included in the absorption losses, which is the portion of the emerging beam that could not be captured by the integrating sphere attachment of the spectrometer during the total transmittance measurement. The striped region between the total and in-line transmission spectra corresponds to the scattering losses in the spinel ceramic.…”

“…In this context, there have been several efforts to correlate the optical properties of spinel to the applied processing conditions such as applied sintering, hot-pressing, hot isostatic pressing or annealing parameters and the resulting microstructural features. [9][10][11][12][13] However, although magnesium aluminate spinel exists in a wide composition range because of the high solid solubility of Al 2 O 3 in MgO 14) that is expressed by the formula MgOÁnAl 2 O 3 (1 n < 3), the effect of chemical composition on the light transmittance of spinel has not been investigated thoroughly in a wide spectrum range from the visible to the IR wavelengths. The present study has focused on the chemical composition dependence of the optical properties of magnesium aluminate spinel ceramics.…”

Magnetic and optical properties of MgAl2O4-(Ni0.5Zn0.5)Fe2O4thin films prepared by pulsed laser deposition

“…The ferrite is based on the solid solution of (Ni, Zn)Fe 2 O 4 (NZF) and MgAl 2 O 4 (MA), which we label as [MA(100 − x)-NZFx]. Here, NZF is ferromagnetic and is known as a promising ferrite with high magnetization [11,12], whereas MA is paramagnetic and is transparent in the visible range [13]. Both NZF and MA have a cubic spinel structure and their lattice parameters are very similar (NZF: 0.8370 nm and MA: 0.8083 nm); therefore, these compounds are expected to form a solid solution.…”