Impedance spectroscopy and magneto-dielectric analysis of La3+substituted Co2Z hexaferrite

Single phase Ba3Co2Fe24O41 (Co2Z) and Ba2.8La0.2Co2Fe24O41 (La-Z) were prepared by solid state ceramic method. The dielectric, impedance and electric modulus were systematically investigated as a function of temperature from 50 degrees C-250 degrees C and in the frequency range of 1 Hz-1 MHz. Frequency dependent imaginary impedance and electric modulus implies that La3+ substitution significantly affect hopping and relaxation mechanism of charge carriers. Cole-Cole plots (Z vs Z') has been fitted with suitable equivalent circuit for both Co2Z & La-Z. The obtained grain and grain boundary resistances confirmed that charge carriers experienced lower resistance in La-Z. Arrhenius plots of relaxation time (z) vs 1/T showed parallel conduction mechanism in system. Complex electric modulus spectrum distinguished the capacitive contribution of grain, grain boundary and electric effect. A very high magnetodielectric effect at low frequencies has been observed for La-Z.

Automated summary

The study found that La3+ substitution significantly affects the hopping and relaxation mechanism of charge carriers, as evidenced by frequency-dependent imaginary impedance and electric modulus. Arrhenius plots showed parallel conduction mechanism in the system. The complex electric modulus spectrum distinguished the capacitive contribution of grain, grain boundary, and electric effect.