High-Pressure Synthesis of a Novel PbFeO₃

Abstract

A novel perovskite-type oxide PbFeO 3 was successfully synthesized under a pressure as high as 7GPa, and the crystal structure, oxidation state, thermal stability, magnetic and dielectric properties were investigated. PbFeO 3 possesses an orthorhombic perovskite unit cell and there is no phase transition between room temperature and 570 K. This compound decomposes into Pb 2 Fe 2 O 5 in the vicinity of 740 K in air. According to XPS, it was found that this compound includes the Pb 2+ , Pb 4+ , and Fe 3+ ions.

Valence State of Pb in Transition Metal Perovskites PbTMO3 (TM = Ti, Ni) Determined From X‐Ray Absorption Near‐Edge Spectroscopy

“…Our results indicate that the spectral weight of the pre‐edge peak in the Pb‐L 3 edge is a sensitive tool to explore Pb valence state in the bulk. In recently synthesized transition metal perovskites PbCrO 3, PbFeO 3 , and PbCoO 3, Pb ions were inferred to have the mixed Pb 2+ and Pb 4+ valence state. It is also expected that the ratio of Pb 2+ /Pb 4+ could be varied by external pressure.…”

“…Because the 6s 1 configuration (Pb 3+ ) is prohibited, Lead is called valence‐skipping (or negative‐ U ) ion, a characteristic that is also typically observed for the Bi ion, that can have either Bi 3+ (6s 2 ) or Bi 5+ (6s 0 ) valence. The application of high‐pressure synthesis in recent years has made available PbTMO 3 with TM covering almost all 3d transition metals, with TM = Ti, V, Cr, Mn, Fe, Co, and Ni and a 4d transition metal Ru in PbRuO 3 . Starting from the left end of the periodic table, PbTiO 3 is expected to have charge state Pb 2+ /Ti 4+ , while to the right end, PbNiO 3 is expected to have the Pb 4+ /Ni 2+ charge state .…”

“…Starting from the left end of the periodic table, PbTiO 3 is expected to have charge state Pb 2+ /Ti 4+ , while to the right end, PbNiO 3 is expected to have the Pb 4+ /Ni 2+ charge state . In between, for TM = Cr, Fe and Co a mixed valence state 6s 2 (Pb 2+ )/6s 0 (Pb 4+ ) has been inferred from the valence determination on the TM ions or the Pb core‐level X‐ray photoemission spectroscopy . PbMnO 3 (P4 mmm −1 ) is special with the claim of Pb 2+ Mn 4+ O 3 (6s 2 ), which requires further confirmation with spectroscopic methods.…”

Varied roles of Pb in transition-metal PbMO3perovskites (M= Ti, V, Cr, Mn, Fe, Ni, Ru)

“…Tsuchiya et al [10] have reported the synthesis of PbFeO 3 under high pressure. In comparison with other Pb M O 3 perovskites, the study of PbFeO 3 is incomplete.…”

Interplay between breathing and polar instabilities in transition metal perovskites with active A-sites

“…Following the same guideline, one would expect PbFeO 3 with orbitally inactive Fe d 5 nominal state to show a disproportionate chargedriven breathing distortion at the A-site, as in the case of PCO. Such a suggestion was indeed made [33], and PbFeO 3 was synthesized under high pressure [34], but the situation remains to be settled.…”