Influence of different materials on the microstructure and optical band gap of α-Fe2O3 nanoparticles

Composites of hematite (α-Fe2O3) nanoparticles with different materials (NiO, TiO2, MnO2 and Bi2O3) were synthesized. Effects of different materials on the microstructure and optical band gap of α-Fe2O3 nanoparticles were studied. Crystallite size and strain analysis indicated that the pure α-Fe2O3 nanoparticles were influenced by the presence of different materials in the composite sample. Crystallite size and strain estimated for all the samples followed opposite trends. However, the value of direct band gap decreased from ∼2.67 eV for the pure α-Fe2O3 nanoparticles to ∼2.5 eV for α-Fe2O3 composites with different materials. The value of indirect band gap, on the other hand, increased for all composite samples except for α-Fe2O3/Bi2O3.