Abstract
Diethylene glycol (DEG)-stabilized Cu-substituted Fe
3
O
4
nanoparticles (Cu
x
Fe
1−
x
Fe
2
O
4
, 0.0≤
x
≤1.0) were prepared via polyol method. DEG was used as a stabilizer and dispersant. The X-ray powder diffraction analysis confirmed the formation of cubic spinel structure for all products. The scanning electron microscopy (SEM) micrographs confirmed that all products were roughly spherical in shape with a narrow size distribution and a homogenous shape. The dielectric properties of DEG-stabilized Cu
x
Fe
1−
x
Fe
2
O
4
nanoparticles were studied as a function of composition, frequency, and temperature. The dielectric constant (
ε
′
), dielectric loss (
ε
″
), and dielectric loss tangent (tan
δ
) indicate different trends with temperature as well as with the composition. The ac and dc conductivities are temperature and frequency dependent. The maximum dc conductivity was found to be about 1.85×10
−7
S cm
−1
for
x
=0.0 at 120
∘
C. The conduction mechanism is due to electron hopping and temperature-assisted reorganization process.