Structural and magnetic–luminescent properties of carbon-doped aluminum oxide

Three-phase (corundum + $\delta$ phase + amorphous phase) amorphous–nanocrystalline powders of pure and carbon-doped Al$_{2}$O$_{3}$ ($x_{C}$ = 1.07–6.6 wt %) have been produced by pulsed electron beam evaporation in vacuum. The corundum hexagonal nanocrystals in the Al$_{2}$O$_{3}$–C nanopowder ($x_C$ = 1.07 wt %) had sizes about 5 nm. The carbon solubility boundary in the Al$_{2}$O$_{3}$ lattice was lower than 1.07 wt % C. The dependence of the form of the cathode-luminescence spectra and the phase compositions of the prepared Al$_{2}$O$_{3}$ and Al$_{2}$O$_{3}$–C nanopowders has been found. The absence of $R$ lines of Cr$^{3+}$ ions in photoluminescence spectra of doped nonopowders has been detected. All the nanopowders of the pure and C-doped Al$_{2}$O$_{3}$ were ferromagnets at room temperature with the maximum magnetization of $\sim$0.12 emu/g at $x_C$ = 6.6 wt %.