Diluted and non-diluted ferric ions in borate glasses studied by electron paramagnetic resonance

Properties and structural features of iron doped BABAL glasses

“…Some specific features of the EPR line width and shape of Fe 3+ ions in glass matrices depend on the glass composition and the concentration of paramagnetic ions 8 . The EPR spectra of most glasses containing iron exhibit the two well known resonances at the effective g values g ef ≈ 2 and g ef ≈ 4.3 that have been considered as a signature of the presence of Fe 3+ ions in a glassy host 9 . The X-band EPR spectra (~ 9 GHz) of most oxide glasses with low Fe 3+ concentrations show a g ef = 4.3 line, and in most cases the g ef = 2 line is also present.…”

“…A low field feature (g ef ~ 9.7) is also observed in X-band EPR spectra of oxide glasses 10 . At low iron concentrations (< 1 mol%), only a sharp g ef ≈ 4.3 resonance is commonly observed 9 . As the concentration is increased, a broad line begins to grow at about g ef ≈ 2 11 .…”

Microstructural Evolution in α-Al2O3 Compacts During Laser Irradiation

“…In this case, I is proportional to the amount of PC in the specimen, i.e., to c. At higher concentration, dipole-dipole broadening, which is proportional to the impurity content, manifests itself (Berger et al, 1995;Kittel & Abrahams, 1953). By generalizing results of (Berger et al, 1995;Kittel & Abrahams, 1953) for S = 3/2, we obtain…”

“…The dependence of the EPR linewidth on the amount of -Cr 2 O 3 in -Cr x Al 2-x O 3 samples for T = 400 K (100wt % of -Cr 2 O 3 corresponds chromium concentration in the sample of 40 mol %). The solid curves is a dependence of the linewidth for a homogeneous distribution of a chromium impurity in the samples; (•) -experimental data of (Stone & Vickerman 1971); (◆) data of (de Biasi & Rodrigues 1985); (▼) data of (Wertz & Bolton 1972); (▲) data of (Kittel & Abrahams, 1953); (■) data of (Berger et al, 1995 where D is the diffusion coefficient, t is the heat treatment time (Akulova, 1986). From this expression it follows that the impurities are inhomogeneously distributed in the sample.…”

EMR study and superposition model analysis of Cr3+ and Fe3+ impurity ions in mullite powders used in aerospace industry

“…The analysis of the line positions suggests that the lines with g eff = 4.28 and g eff  2.00 may be attributed to Fe 3+ (S = 5/2) ions, because they present a typical spectrum for so-called disordered systems [12] that present a glassy host [13]. The line intensities decrease progressively showing the evolution of the relative line shapes and the intensities at g eff = 4.3 from isolated ions in local tetrahedral (and eventually octahedral) sites [13]. The line with g eff = 1.98 may be attributed to Cr 3+ (S = 3/2) ions in the slightly distorted octahedral sites [14].…”