Abstract
A new oxygen-deficient Ruddlesden-Popper (RP) cobaltite Sm 2BaCo2O7-δ (δ ≈ 1.0) has been synthesized and the crystal structure elucidated by Rietveld analysis of X-ray powder diffraction (XRD) data and transmission electron microscopy (TEM). The phase crystallizes in a primitive orthorhombic unit cell, with lattice parameters a = 5.4371(4) Å b = 5.4405(4) Å and c = 19.8629(6) Å, and space group Pnnm. Contrary to other oxygen-deficient cobalt RP phases, the oxygen vacancies are located in the equatorial positions of the [CoO] layers to give an intralayer structure similar to Sra2Mn 2O5, which is not usually observed for cobalt-containing materials. The Sm3+ and Ba2+ cations show a strong preference for distinct sites, with the majority of the larger Ba2+ cations situated in the perovskite block layers and Sm3+ cations predominantly in the rock salt layers. Magnetic susceptibility data demonstrate the strong antiferromagnetic (AFM) character of Sm2BaCo 2O7-δ.
| Original language | English |
|---|---|
| Pages (from-to) | 6231-6237 |
| Number of pages | 7 |
| Journal | Chemistry of Materials |
| Volume | 20 |
| Issue number | 19 |
| DOIs | |
| Publication status | Published - 14 Oct 2008 |