Crystal and magnetic structures of the Bi1 − x Sr x FeO3 − δ and Bi1 − x A x Fe1 − x Mn x O3 (A = Sr, Ca) solid solutions

Mn substitution-induced revival of the ferroelectric antiferromagnetic phase in Bi1−x Ca x FeO3−x/2 multiferroics

“…The crossover from a cycloidal antiferromagnetic ordering to one which is weakly ferromagnetic can be interpreted in terms of the development of oxygen vacancy-related local strain heterogeneities, which would act to suppress coupling between gradients of the magnetic order parameter in the rhombohedral Bi 1-x Ca x FeO 3-x/2 samples [38]. This interpretation is consistent with a compositional evolution of the magnetic state in the Bi 0.9 Ca 0.1 Fe 1-y Mn y O 3 system exhibiting the revival of the AFM order upon substitution that results in the elimination of anion vacancies [28,29]. Indeed, our XRD and PFM data indicate that the Mn 4?…”

“…oxidation state in perovskites (thus resulting in a marginal (d * 0.02) oxygen superstoichiometry in the Bi 1-x Ln x Fe 1-y Mn y O 3 samples obtained by quenching in air) [15,17], the observed stabilization is likely due to the Mn 4? doping-induced removal of the anion vacancies [28,29]. Indeed, the decrease of amount of the oxygen vacancies should contribute to the revival of the polar structure: when compared with the Bi 3þ 1Àx Ca 2þ…”

Structure and complex magnetic behavior of disordered perovskite (Bi0.5Sr0.5)(Fe0.5Mn0.5)O3

“…In the present case, the cooling rate at the final stage of sintering was 3u/min and when this rate changed to higher or lower value, a short range magnetic ordering is observed above T N similar to a previous report. 18 As can be seen from the figure, ZFC-FC shows a large irreversibility which might indicate a glassy state below T N . Moreover, as the field is increased, the anomalies below T N shift towards lower temperature.…”

“…A slightly better x 2 and low values of estimated error in the refined parameters were obtained for the centrosymmetric space group R3 ¯c for both the compounds which is consistent with a previous report on BSFMO. 18 The lattice parameters and the atomic positions obtained from X-ray data were used as initial parameters for the Rietveld refinement on the neutron data. The rhombohedral phase (R3 ¯c) in BSFMO persists over a wide temperature range (100 to 923 K) as confirmed from low and high temperature X-ray data (not shown).…”

Antiferromagnetic–weak ferromagnetic transition in lightly doped BiFeO3: role of structural defects

“…for Bi 3? ) [20] [21]. The corresponding defect structure is described in terms of the formation of highly strained nanorod precipitates and antiphase boundaries demonstrating a drastic deviation from the average crystal structure and chemical composition [22,23].…”