High-temperature ferromagnetism of Ni-doped PbPdO2 nanograin films synthesized by sol-gel spin-coating method

• Published in: Ceramics international Vol. 43; no. 2; pp. 1997 - 2003
• Main Authors: Mei, C., Liu, J., Chuang, P.Y., Song, T.T., Tang, F.L., Su, H.L., Huang, J.C.A., Wu, Y.C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2017
• Subjects: High-temperature ferromagnetism; Nanograin film; Ni-doped PbPdO2; Pb vacancy; Nanograin film; Ni-doped PbPdO2; Pb vacancy; High-temperature ferromagnetism
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2016.10.167

The single-phase Ni-doped PbPdO2 films with a body-centered orthorhombic structure were synthesized by the sol-gel spin-coating method and an oxidation treatment. The films with a thickness of about 440nm were found to have a nanograin structure and large amount of Pb vacancies. The valence states of Ni and Pd ions within the Ni-doped PbPdO2 films were very close to 2+, while the Pb ions exhibited a mixed valence between 2+ and 4+. The existence of Pb vacancies and the low electronegativity of Pb2+ ion resulted in the increase of the valence of Pb ions. The analysis of the magnetic properties indicated that the magnetisms of the single-phase Ni-doped PbPdO2 nanograin films were all composed of the ferromagnetism and the paramagnetism. The ferromagnetism enhanced with the calcination temperature increasing and could be retained up to 380K. A carrier-mediated mechanism bridged to the bound magnetic polaron model based on the Pb vacancies, the doped Ni ions and the Pb ions with a valence higher than 2+ were used to explain the magnetic origin of these Ni-doped PbPdO2 nanograin films.