Single phase polycrystalline samples of (Ho_(1-x)Nd_x)₂CoMnO₆ (x = 0.0 – 0.2)(HNCMO) double perovskite were prepared by using conventional solid state reaction route and their structural and dielectric properties were analyzed. These compounds are of monoclinic structure having space group P2₁/n. From the plots of XRD it is seen that the most intensed peaks are shifting towards lower Bragg angle, which reveals an increase in lattice parameters with increase in Nd doping. The grain size decreases with increase in Nd concentration which is seen from the FESEM images. The average grain size of HNCMO (x = 0.0, 0.05, 0.1, 0.2) are found to be 416μm, 347μm, 337μm, 300μm respectively. Room temperature frequency variation of real and imaginary parts of dielectric constant show a drop in their value with increase in frequency. Moreover, a dispersion in the low frequency region is observed and is attributed to the contribution of space charge polarization. At the same time, we have observed a decrease in the value of dielectric loss with Nd substitution. The frequency dependence of both real and imaginary components of impedance data show charge carriers’ relaxation across grains and grain boundaries. The complex impedance data were modelled using an equivalent circuit having constant phase element and resistance. The observed impedance data deviate from the standard Debye model.

References
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