X-ray study of the anomalous thermal hystereses of the modulation wavevectors in Cs2HgCl4 |
| |
| Authors: | Bagautdin Bagautdinov Zachery Shaw Andrii Orlov Marat A Aliev |
| |
| Institution: | 1. Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Sayo-gun, Hyogo, Japanbagautdi@spring8.or.jp;3. Northeastern University, Boston, MA, USA;4. The National Technical University of Ukraine “KPI”, Kyiv, Ukraine;5. Institute of Physics, Dagestan Scientific Center of the Russian Academy of Sciences, Makhachkala, Russia |
| |
| Abstract: | A rich sequence of structural modulations in Cs2HgCl4 as a function of temperature was studied by means of X-ray diffraction. Accurate satellite-position measurements on the cooling and heating paths of the crystal revealed abnormal thermal hystereses for incommensurate phases and coexistences of neighboring commensurate phases. A well-defined X-ray picture of the a-axis modulated phases in the range of 221–184 K were observed on the heating path, while the c-axis modulated phases existing below 184 K were definitely detected on the cooling path. The proper conditions for a precise phase diagram of Cs2HgCl4 can be correlated with relatively defect-free transformations of a-axis modulations at heating and of c-axis modulations at cooling. The peculiarity of Cs2HgCl4 to switch modulation direction among the a- and c-axes at 184 K allows us deliberately accumulate and thus control a majority of mobile defects on the mutually perpendicular (100) or (001) planes by possessing crystal within temperature domain of a- or c-axes modulations, respectively. |
| |
| Keywords: | A2XB4-family phase transitions modulated structures global hysteresis X-ray diffraction |
|
|
