Optical and ferroelectric properties of ruthenium-doped BaTiO3 nanocubes

Structural, optical, dielectric and ferroelectric properties of Ru-doped BaTi1-xRuxO3(x = 0.01, 0.03, 0.05, 0.07, 0.10) nanocubes have been investigated. The average size of nanocube obtained from Rietveld refinement is in the range 35-60 nm. The incorporation of Ru leads to a mixed tetragonal and cubic crystalline phases in doping concentration range 5-7%. Optical band gap changes from 3.2 to 2.74 eV with increase in Ru concentration. Replacement of Ti with Ru quenches band-edge emission and enhances defect emission intensity. Optical absorption and emission spectra have been interpreted in terms of oxygen vacancy. Ruthenium 4d orbital plays a crucial role to improve dielectric constant and diminish ferroelectric Curie temperature. The combined effect of Ru dopant and size gives rise to complex variation of Curie temperature.