Single step combustion synthesis of nanocrystalline scheelite Ba_0.5Sr_0.5MoO₄ for optical and LTCC applications: Its structural, optical and dielectric properties

The synthesis of nanocrystalline Ba_0.5Sr_0.5MoO₄ by an auto-igniting combustion technique is reported. The structural characterization done by X-ray diffraction, Fourier transform Raman spectroscopy and infrared spectroscopy reveals that the as-prepared powder itself is phase pure with tetragonal structure. The particle size determined from Transmission electron microscopy is 21 nm. The ultraviolet-visible absorption spectrum of the sample shows maximum absorption in the UV region and the optical band gap determined is 4.71 eV. The photoluminescence spectrum of Ba_0.5Sr_0.5MoO₄ shows green emission, associated with the perfect order and crystallinity of the sample. The sample is sintered at a relatively low temperature of 815 °C. Scanning electron microscopy showed that the sample achieved 95 % of its theoretical density. The dielectric constant and loss factor of the sample measured at 5 MHz is found to be 10.58 and 1.66.×10⁻³ at room temperature. The effect of change in composition of A²⁺ site of scheelite AMO₄ compounds comparative are also presented. The experimental results show that nano Ba_0.5Sr_0.5MoO₄ is an excellent luminescent material and also a promising ‘Low temperature Co-fired Ceramic’. Also it is inferred that we can fine tune both optical and dielectric properties to desired values according to our requirements by adjusting the cationic stoichiometric ratio in [AO₈] octahedron.