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A new oxide NaCu3Fe2Os2O12is synthesized using high pressure and temperature conditions. The Rietveld structural analysis shows that the compound possesses both A- and B-site ordered quadruple perovskite structure in Pn3̅ symmetry. The valence states of transition metals are confirmed to be Cu2+/Fe3+/Os5.5+. The three transition metals all take part in magnetic interactions and generate strong Cu2+(↑)Fe3+(↑)Os5.5+(↓) ferrimagnetic superexchange interactions with a high Curie temperature about 380 K. Electrical transport measurements suggest its half-metallic properties. The first-principles theoretical calculations demonstrate that the compound has a spin-down conducting band and a spin-up insulating band with a wide energy gap.

This study investigates the strong photoluminescence (PL) and x-ray excited optical luminescence observed in nitrogen-functionalized two dimensional graphene nano-flakes (GNFs:N), which arise from the significantly enhanced density of states in the region of Π states and the gap between Π and Π* states. The increase in the number of the sp2 clusters in the form of pyridine-like N-C, graphite-N-like and the C=O bonding, the resonant energy transfer from the N and C atoms to the sp2 clusters was found to be responsible for the blue-shift and the enhancement of the main PL emission feature. The enhanced PL is strongly related to the induced changes of the electronic structures and bonding properties, which were revealed by the x-ray absorption near-edge structure, x-ray emission spectroscopy and resonance inelastic x-ray scattering. The study demonstrates that PL emission can be tailored through appropriate tuning of the nitrogen and oxygen contents in GNFs, and pave the way for new optoelectronic devices.