Nanocrystalline scheelite SrWO_4: a low temperature co-fired ceramic optical material-synthesis and properties

摘要

Nanocrystalline strontium tungstate (SrWO_4) is synthesized through a single step modified combustion process. The X-ray diffraction, Fourier transform Raman and Infrared spectroscopy studies reveal that the as-prepared powder is single phase and possess tetragonal structure. The transmission electron microscopic investigations have shown that the particle size of the as prepared powder is in the range 18-22 nm. The optical constants are estimated from the UV-Visible studies and calculated optical band gap is 4.28 eV. The sample showed maximum transmission in the visible regions but poor transmittance in the ultraviolet region. The photoluminescence spectra recorded at different temperatures showed intense blue emission. The nanocrystalline SrWO_4 obtained by the present combustion method was sintered to 95 % density at a relatively lower temperature of 810 ℃ for 3 h. The dielectric constant (ε_r) and loss factor (tan δ) of the sintered SrWO_4 pellets at 5 MHz measured at room temperature were 9.9 and 6.29 × 10~(-3) respectively. The experimental results obtained in this work demonstrate the application of SrWO_4 as UV filters, transparent films for window layers on solar cells, anti-reflection coatings, scintillators, detectors and for low-temperature co-fired ceramic applications.