Structural and magnetic properties of single-crystalline Co-doped barium titanate nanoparticles

Undoped and Co-doped BaTiO₃ nanoparticles were synthesized by a one-step sol-precipitation method. For all the samples, X-ray diffraction showed characteristic diffraction lines for BaTiO₃ without the indication of secondary phases. High-resolution transition electron microscopy images showed that BaTiO₃ nanoparticles exhibit the nature of single-crystal. Magnetometry revealed that all the Co-doped BaTiO₃ samples show paramagnetic behaviors and Co ions in BaTiO₃ are present as isolated paramagnetic centers. This is contrasted to several reported cases of ferromagnetism in Co-doped BaTiO₃.