Core-shell BaMoO4@SiO2 nanospheres: Preparation, characterization, and optical properties

Core-shell BaMoO4@SiO2 nanospheres were prepared in reverse microemulsions and exhibited enhanced photoluminescence (PL) intensity as compared to that of the uncoated BaMoO4. Characterization was performed using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDX), and X-ray powder diffraction (XRD). It was found that the silica shell could increase the PL intensity, but the shell is not the thicker the better. The PL emission can be decomposed into three individual Gaussian components: two UV emissions at 308 nm and 369 nm and a visible emission at 448 nm. Such short emission wavelengths can be attributed to quantum size effect of the small BaMoO4 cores (∼16 nm).