Charge ordering and elastic anomalies in NaxCoO2

✍ Scribed by M. Saint-Paul; G. Garbarino; P. Lejay; M. Armand; M. Núñez-Regueiro

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 662 KB
• Volume: 403
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2007.09.060

✦ Synopsis

We report in-plane resistivity and elastic constant C 33 measurements on the Na 0.8 CoO 2 and Na 0.5 CoO 2 systems. An ordering transition is found at T 0 ¼ 280 K for Na 0.8 CoO 2 . The temperature dependence of the elastic constant C 33 propagating perpendicular to the CoO 2 layers is interpreted, in a phenomenological approach, as being due to the anharmonicity of atomic vibrations. The effective Gru¨neisen parameter g eff deduced directly from the temperature dependence of C 33 exhibits important changes at the charge ordering, magnetic and metal-insulator phase transitions.