Synthesis of (Ca, Ba) co-substituted SrMoO4 hierarchical microstructures and their composition-dependent structural and optical properties.

In this work, a series of Sr 1-x Ba x MoO 4 , Sr 1-x Ca x MoO 4 , and Sr 1-2x Ca x Ba x MoO 4 nanocrystal solid-solutions with well-defined morphologies have been prepared by a surfactant-free coprecipitation method at room temperature. X-ray diffraction, Rietveld refinement data, Fourier transform Raman, and Fourier transform infrared spectroscopies confirmed the formation of continuous-solid solutions over the entire composition range for Sr 1-x Ca x MoO 4 and Sr 1-x Ba x MoO 4. The substitution of Ca and Ba for Sr in Sr 1-2x Ca x Ba x MoO 4 leads to phase-pure powders where x ≤ 0.1. X-ray fluorescence spectroscopy confirms that the actual composition is close to the nominal stoichiometry of the samples. The molybdate powders are composed of micronic particles having diverse morphologies, including shuttle, microsphere, flower, dumbbell, and spindle. These superstructures are composed of primary particles having an average particle size of less than 60 nm. The optical band gap of Sr 1-x Ba x MoO 4 and Sr 1-x Ca x MoO 4 varies from 4.17 to 4.34 and 4.17 to 3.87 eV, respectively, with the chemical composition (x). The bandgap of Sr 1-2x Ca x Ba x MoO 4 is not significantly affected by variation of the nominal composition(x). The relatively small bandgap bowing parameter indicates good miscibility of the alloying constituents. [Display omitted] • (Ca, Sr, Ba)MoO 4 solid-solutions with diverse morphologies have been prepared by a room-temperature co-precipitation method. • Synthesis is simple, low-cost and surfanctant-free. • The band-gap energy of SrMoO 4 can be manipulated by Ca and Ba substitution. • Bandgap bowing parameter was determined. [ABSTRACT FROM AUTHOR]