Low temperature impedance spectroscopy evidence of phase coexistence within bulk Pr0.50Ca0.50MnO3 manganites

Impedance spectroscopy is employed to characterize the electrical microstructure of Pr0.50Ca0.50MnO3 ceramic at low temperatures. The existence of different relaxations associated with grain, grain boundaries and electrode effects are discussed. Around 40 K, high frequency (HF) and low frequency (LF) relaxations are identified using combined spectroscopic plots. With temperature variation, change in resistance values of HF and LF relaxations are associated with changes in resistivity rather than volume fraction. Activation energies of HF and LF relaxations are calculated to be 4.21 meV and 6.1 meV, respectively. To substantiate an electrode effect, different electrode materials along with dc biasing experiments are carried out.