Structural, dielectric and electromagnetic shielding properties of Ni–Cu nanoferrite/PVP composites

• Ni–Cu nanoferrite particles were prepared using solution combustion method.
• Dielectric behavior and a.c. conductivity of the Ni–Cu nanoferrite/PVP composites were studied.
• Electrical conduction mechanism was in accordance with the electron hopping model.
• The EMI shielding effectiveness (SE) of Ni–Cu nanoferrite/PVP composites was investigated.
• Ni–Cu nanoferrite/PVP composites were demonstrated as a promising efficient material for the absorbing of electromagnetic waves.

Nickel–copper (Ni–Cu) nanoferrites were synthesized using solution combustion method. The XRD pattern of the as prepared and calcinated samples at 600 °C revealed the presence of both cubic NiFe2O4 and tetragonal CuFe2O4 phases. Frequency and temperature dependence of dielectric constant (ɛ′), dielectric loss (tan δ) and a.c. conductivity (σac) studies have been undertaken on the Ni–Cu nanoferrites blended with polyvinylpyrrolidone (PVP) in the range 100 Hz–5 MHz. Studies have shown increasing trend of ɛ′, tan δ and σac with the increase of temperature for Ni–Cu ferrite nanoparticles in the PVP matrix. Further, frequency and temperature dependence of electromagnetic interference (EMI) shielding effectiveness (SE) is studied. The SE is found to increase with the temperature and decrease with an increase in the frequency. Ni–Cu nanoferrite/PVP composites were demonstrated a promising efficient material for the absorbing of electromagnetic waves because of a large amount of dipole polarizations in the polymer backbone and the interfaces of the ferrite nanoparticles and PVP matrix.