کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1594570 | 1515695 | 2008 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: A sodium ordering transition above room temperature in NaxCoO2 deduced by mechanical spectrum A sodium ordering transition above room temperature in NaxCoO2 deduced by mechanical spectrum](/preview/png/1594570.png)
The mechanical spectrum of Na0.66CoO2 above room temperature was measurement using the vibrating reed method at kilohertz frequency. A novel transition was observed around 427 K as indicated by temperature-dependent internal friction and resonance frequency. The characteristic transition temperature is defined as the start of a step increase of resonance frequency with the decrease of temperature, which is concurrent with the decrease of internal friction below a plateau. At the same time, this characteristic transition temperature shifts towards lower temperatures at a lower cooling rate, or higher heating rate during its respective thermodynamic processes. This unconventional behavior seems to be explained by critical slowing down at a second-order phase transition. Furthermore, sodium ordering is expected for this phase transition.
Journal: Solid State Communications - Volume 148, Issues 3–4, October 2008, Pages 91–95