Electron spin resonance evidence for the role of copper ions in interlayer coupling in layered copper oxycarbonates

✍ Scribed by P. Ganguly; N. Shah; F.C. Matacotta

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 353 KB
• Volume: 206
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(93)90702-r

✦ Synopsis

Electron spin resonance (ESR) studies have been carded out on the layered copper oxycarbonates (alternating layers of CuO2 and CO ]-) with the nominal composition Ba3SrCu206.2CO2 and their reaction products with ammonium slats. The ESR signals typical of copper ions in square-planar geometry with a slight orthorhombic distortion presumably arise from the copper ions being incorporated in the carbonate layer. A simple grinding procedure at room temperature using (NH + ),X n-(X=F-, (NOa)-, (VO3)-, (HPO4)2-) incorporates X"-anions in the structure with the liberation of ammonia. The environment of the copper ion in the carbonate layer is thus changed without altering the structure. The ga values are most affected by this reaction showing that the filled e s orbitals are oriented in the plane of the carbonate layer. The half-filled e 8 orbitals (transforming as dx2_y2 orbitals) are oriented out of the plane. This suggests that the copper ions in the carbonate layers are probably involved in introducing magnetic coupling between the CuO2 layers.