Charge disproportionation and ordering in La_1/3Sr_2/3FeO_3- 

Abstract

The perovskite La1/3Sr2/3FeO3−δ was investigated by neutron diffraction, magnetic and Mössbauer spectroscopy measurements. La1/3Sr2/3FeO3−δ undergoes magnetic ordering at T = 190–200 K accompanied by charge disproportionation. Magnetic peaks due to charge ordering are observed below 200 K. The charge ordering is gradually developed below 200 K along with a charge disproportionation, 2Fe4+ ⇒ Fe3+ + Fe5+. La1/3Sr2/3FeO3−δ shows an antiferromagnetic structure at low temperature. Magnetic moments of about 3 and 1.3 μB were obtained from the neutron diffraction data refinement for Fe3+ and Fe5+ at 15 K, respectively, which suggest that both Fe ions are in a low spin state. These values are significantly lower than those reported by Battle et al for La1/3Sr2/3FeO2.98. Mössbauer spectra indicate that full charge ordering might be reached below 20 K with no Fe4+.

Glassy magnetic phase driven by short-range charge and magnetic ordering in nanocrystalline La1/3Sr2/3FeOSabyasachi1, Patra2, Majumdar3 et al. 2012Phys. Rev. B

“…The results reveal rhombohedral crystal structure (space group: R3c) in the hexagonal setting. 18,19 The refined parameters are summarized in Table I. We note that lattice parameters of the bulk specimen are consistent with the reported results.…”

“…18,19 The unit cell of the magnetic structure is considered same as that of the crystalline structure. This includes six iron atoms at positions (0, 0, 0), (1/3, 2/3, 1/4), (2/3, 1/3, 1/3), (0, 0, 1/2), ( Although the intensity profile of nano specimen is much weaker than the bulk counterpart, a similar refinement is carried out on magnetic diffraction data of nano specimen at 3 K considering the same charge-ordering sequence.…”

“…We note that lattice parameters of the bulk specimen are consistent with the reported results. 18,19 The refined parameters for nano given in Table I show a minor structural change compared to the bulk counterpart. Unit cell volume slightly increases up to 0.12% for the nano specimen.…”

In Situ Studies on the Catalytic and Electronic Properties of Multi-Dimensional Cathode

“…On the other hand, collection of full neutron data sets allows all three determinations to be carried out simultaneously, as the refinement adjusts all of these quantities in fitting the measured data. Mössbauer spectroscopy 9 has been employed to successfully study Fe valence state in LSF, from which the fraction of Fe 3+ and Fe 4+ can also result in oxygen content. These techniques are essentially independent, which therefore can provide cross checks on the oxygen content.…”

Ultrasonic anomalies in La1/3Sr2/3Fe1−xCoxO3 perovskites

“…In La 1/3 Sr 2/3 FeO 3 [3,4], the charge ordering (CO) accompanies charge disproportionation (CD) of 2Fe 4+ → Fe 3+ + Fe 5+ and simultaneous antiferromagnetic (AFM) spin ordering. It is well known that in many CO and CD systems, the charges strongly couple with the lattice.…”