Heat capacity anomalies at incommensurate-normal transition of åkermanite solid solution (Ca, Sr)2(Mg, Co, Zn, Fe)Si2O7

✍ Scribed by K. Iishi; T. Mizota; K. Fujino; Y. Furukawa

• Book ID: 104661579
• Publisher: Springer-Verlag
• Year: 1991
• Tongue: English
• Weight: 614 KB
• Volume: 17
• Category: Article
• ISSN: 0342-1791
• DOI: 10.1007/bf00202243

✦ Synopsis

The heat capacity of gtkermanite solid solutions was measured by a small scale adiabatic calorimeter near the incommensurate-normal (I-N) transition. The heat capacity anomalies caused by the I-N transition show the 2 type characteristic behavior implying the presence of dynamical fluctuations. The heat capacity anomalies were observed over the whole range of the 5kermanite solid solutions CazMga_xCoxSizO 7 and Ca2Mgl-x-ZnxSi202. With increase of Co or Zn atoms, the transition temperature, Ti, rises linearly from ca. 83 ~ C to 220~ and to 130 ~ C, respectively. In the system Ca2CoSizOT-Ca2FeSi207 and Ca2MgSi2Ov-Ca/-FeSizO 7 electronic microscopy revealed that the temperature of the heat capacity anomaly decreases with increasing Fe content, whereas the Ti rises. This unusual behavior is ascribed to the microdomains observed in high resolution lattice images.