Impact of Sr2+ Doping on the Structural, Dielectric, Ferroelectric and Optical Properties of Yfeo3 Perovskite Phosphor

Abstract

The single phase Y1-xSrxFeO3 perovskite phosphors with x = 0, 0.025 and 0.050 were synthesized by using sol-gel combustion method followed by calcination at a low temperature. The structural characteristics of Y1-xSrxFeO3 perovskites have been investigated using Rietveld refinement of the X-ray diffraction data. The Rietveld refinement shows that the Y1-xSrxFeO3 perovskites crystallize into orthorhombic crystal structure with Pnma space group. The average value of crystallite size decreases with increasing concentration of Sr 2+ ion at Y-site; however, the lattice strain increases. The HRSEM images of the phosphors show that the particles size of phosphors decreases with increasing concentration of Sr2+ ion. At room-temperature, the dielectric permittivity and the electric polarization of Y1-xSrxFeO3 phosphors increase via doping of Sr2+ ions. The FTIR spectra confirm low phonon frequency of Y1-xSrxFeO3 phosphors. The optical band gap of YFeO3 decreases as the doping concentrations of Sr2+ ions were increased. The phosphor gives large numbers of absorption bands at 334, 350, 360, 388, 467 and 482 nm. The Y1-xSrxFeO3 phosphor emits blue, yellow and red emissions on excitations with 350 and 360 nm. The lifetime of excited levels of the phosphor decreases with the contents of Sr2+ ion. The CIE diagram reveals that the emitted color lie in the bluish magenta region of visible spectrum. Therefore, the Y1-xSrxFeO3 phosphors may be applicable in capacitors, display devices and solid state lighting.

Keywords: perovskite, Dielectric permittivity, Ferroelectricity, Sr2+ ion, Optical properties