Hydrostatic pressure influence on electric relaxation response of bismuth manganite ceramics

Electrical impedance of bismuth manganite ceramics was studied under ambient and high hydrostatic pressure. Local disorder of crystal lattice was confirmed using XRD and DSC. Two relaxation processes were discerned. One was attributed to small polarons, which showed a changeover from variable range hopping features related to Fermi glass and structural disorder to the nearest neighbor hopping behavior in higher temperature range related to uniform distribution of energy levels. Hydrostatic pressure shortened relaxation times that would be interesting for applications. The second process, which was assigned to the nearest neighbor hopping of polarons, also exhibited a changeover to glassy features in a high-temperature range.