Cation Ordering and Electrical Properties of the Ruddlesden-Popper Gd2−2xSr1+2xCo2O7 Compounds (x = 0 and 0.10)

• Published in: Zeitschrift für anorganische und allgemeine Chemie (1950) Vol. 633; no. 11-12; pp. 1890 - 1896
• Main Authors: Sánchez-Andújar, M., Señarís-Rodríguez, M. A.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.09.2007; WILEY‐VCH Verlag
• Subjects: Cation ordering; Cobalt oxides; Electrical properties; Perovskite phases; Structure elucidation
• ISSN: 0044-2313; 1521-3749
• DOI: 10.1002/zaac.200700260

We report the structure and microstructure of the Ruddlesden‐Popper (RP) series n=2 Gd2−2xSr1+2xCo2O7 (x = 0 and 0.10). X‐ray powder diffraction, electron diffraction and HRTEM indicate that these compounds have a tetragonal structure (space group: P42/mnm) with cell parameters a ≈ 5.3749Å c ≈ 19.3591Å, in which the [CoO6] octahedra are distorted and tilted. Also, very interestingly, according to the obtained results these compounds presents A‐site cation ordering where the divalent and bigger Sr2+ cation selectively prefers the 12‐coordinated P site while the smaller and trivalent Gd3+ cation prefers the 9‐coordinated R site. From the electrical point of view these materials are semiconducting and their resistivitiy decreases upon doping. In addition, the highest doped sample presents a small magnetoresistive effect MRmax = −3.2 % under Hmax = 50 kOe at T = 55 K.