Development of optical nonlinearity, high dielectric constant and ferromagnetic behavior in a silicate glass nanocomposite by suitable heat treatment

We have explored the development of multifunctionalities viz, optical nonlinearity, high dielectric constant and ferromagnetic behavior in a nanostructured silica based glass of 14.0Na ₂O, 26.0BaO, 26.0TiO ₂, 16.0B ₂O ₃, 17.0SiO ₂, 1.0NiO (mol%) composition. A heat treatment at 863 K for 4 h led to nonlinear refractive index and absorption coefficients at wavelength 800 nm of 0.11 × 10 ⁻¹⁹m ²/W and 1.15 × 10 ⁻³ cm/GW, respectively. A heat treatment at 1073 K for 2 h followed by 1113 K for 3 h increased the dielectric constant from 11 to 50, apparently due to the formation of nanocrystals of BaTiO ₃ within the glass medium. Glass samples reduced at 923 K for 1 h exhibited ferromagnetic behavior due to the presence of nickel nanoparticles.