Thermal stability of A-site ordered PrBaMn2O6 manganites

The crystal structure and electromagnetic properties as well as thermal stability of the A-site ordered PrBaMn2O6 manganites have been investigated. These samples have been prepared by using ‘two-steps’ synthesis mode. They have tetragonal structure with no tilt of MnO6 octahedra and show ferromagnetic metal to paramagnetic semiconductor transition. The most significant structural feature of the A-site ordered manganites is that the MnO2 sublattice is sandwiched by two types of rock-salt layers PrO and BaO. The different degree of Pr and Ba ions in the A-sublattice is revealed. The A-site ordered PrBaMn2O6 sample with maximum degree of the A-site order demonstrates ferromagnetic metallic to paramagnetic insulating transition with the Curie point ∼320 K. The A-site disordered Pr0.50Ba0.50MnO3 sample is ferromagnetic metal below TC≈140 K. The cation order in these compounds is stable in air up to 1300 °C. For the partly A-site ordered samples the magnetic and electronic phase separation is observed. The magnetotransport properties of the A-site ordered manganites treated under different conditions are discussed in terms of the superexchange interactions and A-site order degree.