Influence of Mn-substitution on the structure and low-temperature electrical conduction properties of PrCoO3

Rare earth cobalt perovskite oxide (LnCoO3) is one kind of complex metal oxides and has a wide variety of applications. The performance of LnCoO3 is controlled by its electrical conduction, and therefore it is essential to study the behaviour of electrical conduction in LnCoO3 and elucidate the corresponding conduction mechanism. In this work, a series of PrCo1−xMnxO3(x = 0, 0.05, 0.1, 0.15, 0.2) were prepared by sol-gel method. The structures and low-temperature electrical conduction properties of these samples were investigated using x-ray diffraction, infrared spectra and alternating current impedance spectroscopy. All samples crystallized in an orthorhombic perovskite structure. Structural refinements reveal that the lattice parameters increased, while the orthorhombility decreased with Mn substitution. Further investigation of infrared spectrum indicates that the stretching vibration bands of Co-O bonds shifted towards lower wavenumbers followed by an increase of the population of Co3+ ions with intermediate spin state. These variations led to a reduced bandwidth of eg band which could be the dominant reason for the abrupt decrease of bulk semi-conduction and the increase of activation energies for small polaron hopping conduction in PrCo1−xMnxO3.