Preparation, characterization and temperature-dependent photoluminescence in Ca0.90Sr0.10RuO3 compound

We report the Ca0.90Sr0.10RuO3 compound synthesized by solid-state reaction method at ambient pressure using temperatures between 700 and 800◦C in air. By X-ray powder diffraction (XRD), we determine a solid solution until Ca0.85Sr0.15RuO3 compound. Scanning electron microscopy (SEM) indicates than the particle size varies between 0.422 and 1.598 µm. The resistance measurement, as a function of temperature measurement from 10 to 300 K for Ca0.90Sr0.10RuO3 compound shows a metallic behavior. Finally, photoluminescence (PL) and its temperature dependence of  Ca0.90Sr0.10RuO3  compound in the temperature range 6.7-296 K were measured. It was observed than the main broad band centered at ∼ 1.73 eV with the shoulders at ∼ 1.38 eV and ∼ 2.05 eV exists in the entire temperature range. It can be well fitted by three Gaussian curves B1, B2 and B3, centered at ∼ 1.38, ∼ 1.73 and ∼ 2.05 eV, respectively. The transitions identified as B1 and B2  are studied with temperature. The photoluminescence mechanics for Ca0.90Sr0.10RuO3  compound are presented based on the electronic structures formed by the interactions among spin, charge and lattice, in which B1 was identified with the charge transfer excitation of an electron from the lower Jahn-Teller split eg level of a Ru3+ ion to the eg level of an adjacent Ru4+ ion, B2 was assigned to the transition between the spin up and spin down eg bands separated by Hund’s coupling energy Ej , whereas B3 is attributed to the transition, determined by the crystal field energy Ec between a t2g core electron of Ru3+ to the spin up eg bands of Ru4+ by a dipole allowed charge transfer rocess.