Complex perovskites have attracted extensive attention due to their fascinating physical properties and novel features owing to the coexistence of the ferro-/ferri-magnetic ground state and semiconducting behavior in the single material. Herein, the triple perovskite Sr 3 Co 2 WO 9 (SCWO) has been successfully synthesized for the first time in the nanocrystalline form with an average crystallite size of 23 nm using a high yield (81%) aqueous citrate sol−gel method. At room temperature, the crystal structure of Sr 3 Co 2 WO 9 is cubic, space group Fm3̅ m, with lattice parameter a = 7.9073(6) Å. The formation of SCWO triple perovskite was studied in situ by X-ray diffraction and subsequently analyzed by the Rietveld analysis. The detected hysteresis loops with nonzero remanent magnetization and rather large coercive field reveal ferrimagnetic ordering with a Curie temperature of 144 K. The measured effective magnetic moment of 3 μ B is close to the expected value for the rarely observed intermediate spin S = 1. It is found that the compound exhibits semiconducting properties with the optical band gaps equal to 3.52 eV (indirect) and 3.76 eV (direct), respectively, further confirmed by the determination of the AC conductivity, which in the measured temperature range (25−500 °C at 1 kHz) lies within the interval from 10 −5 −10 −4 Ω −1 cm −1 . The Maxwell−Wagner model is employed to describe the frequency dependent dielectric constant. The frequency-dependent AC conductivity follows the universal Jonscher power law. Since it possesses both magnetic and semiconductor properties, this material could be a promising candidate to use in devices where its semiconducting properties would be spin-controlled.

Barium titanate thin films were prepared by spin coating deposition technique of an acetic precursor sol and sintered at 750, 900 and 1050?C. Phase composition of the obtained thin films was characterized by X-ray diffraction and Raman spectroscopy. Their morphology was analysed by scanning electron microscopy and atomic force microscopy. Dielectric properties of thin films sintered at 750 and 900 ?C were characterized by LCD device, where the influence of sintering temperature on dielectric permittivity and loss tangent was inspected. It was concluded that higher sintering temperature increases grain size and amount of tetragonal phase, hence higher relative permittivity was recorded. The almost constant relative permittivity in the measured frequency (800Hz-0.5MHz) and temperature (25-200?C) ranges as well as low dielectric loss are very important for the application of BaTiO3 films in microelectronic devices. [Projekat Ministarstva nauke Republike Srbije, br. III45021]

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