Preparation of dense La0.67Ca0.33MnO3 ceramics by plasma activated sintering and hot-pressing

Highly dense La0.67Ca0.33MnO3 (LCMO) ceramics were prepared by plasma activated sintering (PAS) and hot-pressing (HP). The comparison of structural, magnetic, and electrical transport properties of the LCMO ceramics after PAS and HP were investigated. XRD and SEM analyses confirmed that both samples exhibited orthorhombic phase with highly dense microstructure. The differences of magnetic and electrical transport properties in PAS and HP LCMO ceramics could be attributed to the different grain sizes, which have an effect on grain boundaries, domain states, Mn-O-Mn bond angles and Mn-O bond lengths. On analyzing the fitting data with several empirical equations, the conduction mechanism of the samples was found to be electron-magnon scattering in the ferromagnetic low-temperature region and variable range hopping (VRH) in the paramagnetic high-temperature region.