Sintering behavior and electromagnetic properties of a Ni-Co ferrite/NiO biphasic ceramic

• Published in: Materials research express 2019-04, Vol.6 (7), p.76110
• Main Authors: Amarante, Mayara dos Santos, Silva Júnior, Eduardo de Oliveira, de Lima, Rodrigo Gabas Amaro, Lente, Manuel Henrique, Machado, João Paulo Barros, Migliano, Antonio Carlos da Cunha, de Brito, Vera Lúcia Othéro
• Format: Article
• Language: English
• Subjects: ceramics processing; complex magnetic permeability; complex permittivity; dilatometry; electronic materials; ferrites; sintering
• ISSN: 2053-1591; 2053-1591
• DOI: 10.1088/2053-1591/ab160b

Tailoring of the electromagnetic properties of materials is a key issue for the development of electronics. Literature has shown that NiCo ferrites have many applications in electronic devices, such as sensors, antennas, and miniaturized devices. In this work, a biphasic ferrite-based ceramic was produced by the standard ceramic method, starting from iron, nickel, and cobalt oxides as raw materials with a (Ni + Co):Fe atomic proportion of 1.3:1.7. EDS microanalysis and x-ray diffractometry of the sintered sample revealed the presence of a major fraction of ferrite phase (estimated as Ni0.8Co0.2Fe2O4) and a NiO.CoO second phase with NiO in majority. The complex magnetic permeability of the sintered biphasic sample was evaluated in frequencies between 6 MHz-13 GHz and its complex permittivity was evaluated in frequencies between 9-12 GHz. Comparing to a reference NiCo ferrite sample and to data from literature, it was verified that the presence of the NiO.CoO second phase reduced the losses of the material in GHz frequencies, maintaining the typical ′ levels of a ferrite material. The results suggest that adjustment of the oxides' proportion on the formulation step of the ferrite processing is a simple an effective way of tailoring the electromagnetic properties of the ferrite.