Abstract
The electrical measurements and positron annihilation lifetime spectroscopy (PALS) of LaxCoFe2-xO4 (x = 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) synthesized by two different techniques (citrate-gel autocombustion and autocombustion flash techniques) were carried out. The dielectric constant (epsilon') and dielectric loss (tan delta) were reduced with La concentration at low La value samples. On contrary, La enhanced the values of epsilon' and tan delta at high La content samples. AC-resistance measurement recommended that hopping conduction prevails in the studied samples. PALS indicated that defects present at grains' boundaries and vacancy-type defects in the structure are not changed with different La3+ contents. PALS also indicated the presence of large free volume regions between grains. Finally, it is recommended that these prepared samples are preferable for use in applications like microwave devices, actuators, isolators, and phase shifters.