TY - JOUR A1 - Buzaré, J.Y. A1 - Silly, G. A1 - Klein, J. A1 - Scholz, G. A1 - Stösser, R. A1 - Nofz, Marianne T1 - Electron paramagnetic resonance investigations of alpha-Al2O3 powders doped with Fe3+ ions: experiments and simulations N2 - Electron paramagnetic resonance (EPR) of Fe3+ ions in Al2O3 is studied in powder samples prepared by different routes and/or modified by thermal or mechanical treatments, with different doping levels and grain sizes. The measurements are performed in various frequency bands (S, X, K, Q and W) and with bimodal detection in X-band. Simulations of the spectra are achieved with a code designed for computing EPR powder spectra described by any spin Hamiltonian including second-, fourth-and sixth-order ZFS terms (S ? 7/2). The linewidths, intensities and lineshapes are accounted for. The lineshape is Gaussian at low Fe3+ concentration whereas it is Lorentzian for higher concentration. The linewidths are interpreted as the superimposition of three main contributions: intrinsic linewidth, dipolar broadening and broadening due to lattice imperfections. The latter is tentatively interpreted in terms of quadrupolar spin Hamiltonian parameter distributions treated using first-order perturbation theory. Whatever the sample, only the b22 spin Hamiltonian parameter is found to be distributed around a mean zero value which corresponds to rhombic distortions. Angle and bond length distributions are tentatively extracted from the b22 distributions which gives some insight into the local order around the spin probe in relation to the preparation and treatment of the samples. PY - 2002 DO - https://doi.org/10.1088/0953-8984/14/43/329 SN - 0953-8984 SN - 1361-648X VL - 14 SP - 10331 EP - 10348 PB - IOP Publ. Ltd. CY - Bristol AN - OPUS4-2261 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stösser, R. A1 - Scholz, G. A1 - Buzaré, J.-Y. A1 - Silly, G. A1 - Nofz, Marianne A1 - Schultze, Dietrich T1 - A magnetic resonance investigation of the process of corundum formation starting from sol-gel precursors PY - 2005 SN - 0002-7820 SN - 1551-2916 VL - 88 IS - 10 SP - 2913 EP - 2922 PB - Blackwell Publishing CY - Malden AN - OPUS4-11888 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -