Effect of thulium substitution on conductivity and dielectric belongings of nanospinel cobalt ferrite


ÜNAL B., Almessiere M., Korkmaz A. D., Slimani Y., Baykal A.

Journal of Rare Earths, vol.38, no.10, pp.1103-1113, 2020 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 38 Issue: 10
  • Publication Date: 2020
  • Doi Number: 10.1016/j.jre.2019.09.011
  • Journal Name: Journal of Rare Earths
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Communication Abstracts, Compendex, INSPEC, Metadex, Civil Engineering Abstracts
  • Page Numbers: pp.1103-1113
  • Keywords: CoFe2O4, Conductivity, Dielectric properties, Rare earths, Spinel ferrites, Tm3+ substitution
  • Istanbul Gelisim University Affiliated: Yes

Abstract

The CoTmxFe2−xO4(x ≤ 0.1) NPs were synthesized sonochemically. X-ray powder diffraction patterns and TEM images of the samples prove their chemical purity and cubic structure-morphology, respectively. Some substitution ratio of thulium ions to cobalt ferrites have an important effect on the characteristic evaluation of both electrical and dielectric characteristic measured at frequencies up to 3.0 MHz between room temperature and 120 °C. Since the thulium substitution has a very strong effect on the characteristic evaluation of both electrical and dielectric properties of cobalt-ferrite samples, four substitutional ranges - none, small, medium and high were determined for the interpretation of contribution of thulium ratio to ac/dc conductivity, dielectric constant, dielectric loss and tangent loss. Conductivity increases with the incremental frequencies, in general depending on a variety of tendencies of both temperature and substitutional Tm ratios while the activation energy varies with a high dependency to the regional level of Tm substitution in Co-ferrites NPs. The Arrhenius graph appears to provide us with a single activation energy much higher than 400 meV for x = 0.02, which can be attributed to electron hopping mechanisms, apart from other substituted spinel ferrites.