Tuning the optical, electrical and magnetic properties of Ba0.5Sr0.5TixM1−xO3 (BST) nanopowders

Metal doped barium strontium titanate (BST; Ba0.5Sr0.5TixM1−xO3) nanopowders have been successfully synthesized through the oxalate precursor route based on low cost starting materials. The effect of metal ion substitution, namely Fe3+, Mn2+, Co2+ and Y3+, on the crystal structure, microstructure and optical, electrical, dielectric and magnetic properties of BST was studied. The results revealed that a crystalline single cubic BST phase was formed for pure and Mn2+, Co2+ and Y3+ ion-substituted BST samples, whereas a tetragonal BST structure was obtained for the Fe3+ substituted BST sample at an annealing temperature of 1000 °C for 2 h. Furthermore, addition of the metal ions was found to decrease the crystallite size and unit cell volume of the produced BST phase. The microstructure of the produced pure BST phase was metal ion dependent. Most BST particles appeared as a cubic like structure. The transparency of BST was found to increase with metal substitution. Meanwhile, the band gap energy was increased from 3.4 eV for pure BST to 3.8, 4.1, 4.2 and 4.3 eV as the result of substitution by Fe3+, Mn2+ and Co2+ and Y3+ ions, respectively. The DC resistivity was metal ion dependent. The highest DC resistivity (ρ = 66.60 × 105 Ω cm) was accomplished with the Mn2+ ion. Moreover, the addition of metal ions decreased the dielectric properties of the expected Mn2+ ion and increased the magnetic properties.