Synthesis and characterization of rare-earth doped SrBi2Nb2O9 phase in lithium borate based nanocrystallized glasses

Glass composites comprising of un-doped and samarium-doped SrBi2Nb2O9 nanocrystallites are fabricated in the glass system 16.66SrO–16.66[(1−x)Bi2O3–xSm2O3]–16.66Nb2O5–50Li2B4O7 (0⩽x⩽0.5, in mol%) via the melt quenching technique. The glassy nature of the as-quenched samples is established by differential thermal analyses. Transmission electron microscopic studies reveal the presence of about 15 nm sized spherical crystallites of the fluorite-like SrBi1.9Sm0.1Nb2O9 phase in the samples heat treated at 530 °C. The formation of layered perovskite-type un-doped and samarium-doped SrBi2Nb2O9 nanocrystallites with an orthorhombic structure through the intermediate fluorite phase is confirmed by X-ray powder diffraction and micro-Raman spectroscopic studies. The influence of samarium doping on the lattice parameters, lattice distortions, and the Raman peak positions of SrBi2Nb2O9 perovskite phase is clarified. The dielectric constants of the perovskite SrBi2Nb2O9 and SrBi1.9Sm0.1Nb2O9 nanocrystals are relatively larger than those of the corresponding fluorite-like phase and the precursor glass.