Design and magnetic properties of new compounds containing iron 2D building blocks of the perovskite type

Abstract

Using the concept of 2D building blocks we have looked for new compounds containing iron 2D perovskite type building blocks. In that purpose, we have tried to exchange the [Cu 2S 2] 2D building blocks found in Sr 3Fe 2Cu 2S 2O 5 by other isostructural blocks such as [Cu 2Se 2], [Ag 2S 2], [Ag 2Se 2] or [Zn 2P 2]. With a high temperature ceramic method and/or a metathesis reaction we have then succeeded to synthesize Sr 3Fe 2Cu 2Se 2O 5, Sr 3Fe 2Ag 2S 2O 5 and Sr 3Fe 2Ag 2Se 2O 5. Structure refinement from X-ray powder diffraction patterns of Sr 3Fe 2Cu 2Se 2O 5 and Sr 3Fe 2Ag 2S 2O 5 have confirmed that the structure of both compounds results from the expected alternated stacking of perovskite [Sr 3Fe 2O 5] and anti-fluorite [Cu 2Se 2] or [Ag 2S 2] 2D building blocks. Mössbauer spectroscopy measurements for Sr 3Cu 2Fe 2Se 2O 5 revealed the presence of Fe 3+ high spin within the perovskite [Sr 3Fe 2O 5] block and showed that the magnetic moments of iron are ordered at low temperature. Moreover neutron diffraction experiments have revealed an antiferromagnetic structure ( T N ≈ 490 K ) with iron magnetic moments aligned along the a axis.