Phase relationship, structural and magnetic properties of Nd-deficient Nd 0.95−x Ca x MnO 2.93±δ

Phase relationships in Nd-deficient solid solutions Nd0.95−xCaxMnO2.93±δ (x=0.00, 0.05, 0.10, 0.15, 0.20) were investigated in the temperature range T=800–1100°C in air and under reduced oxygen partial pressure (at T=1000°C). Phase diagrams in the coordinates “Temperature-calcium content” and “Po2-calcium content” were constructed. The boundaries of two-phase regions on the phase diagrams were defined.The oxidation mechanism and the stability conditions for the perovskite structure were determined.The magnetic properties of single phase samples with x=0, 0.1, 0.2 have been studied as a function of temperature and magnetic field. The observed magnetic anomalies: magnetization sign reversal and spin-reorientation transitions are compatible with the coexistence of AFM and FM phases, clusters of different nature, quasi heterogeneity (presence of clusters enriched/depleted with neodymium or manganese oxide). Quadrupole centers are considered as a source of spin inversion phenomena.