Thermal evolution of an organic ferroelectric, namely, glycinium phosphite, was probed by multi-temperature single-crystal diffraction using synchrotron radiation and also by a similar experiment with a laboratory X-ray diffractometer. Both series of measurements showed a transition from the paraelectric to the ferroelectric state at nearly the same temperature, T_c = 225 K. Temperature evolution of the unit-cell parameters and volume are drastically different for the synchrotron and laboratory data. The latter case corresponds to previous reports and shows an expected contraction of the cell on cooling. The data collected with the synchrotron beam show an abnormal nonlinear increase in volume on cooling. Structure analysis shows that this volume increase is accompanied by a suppression of scattering at high angles and an apparent increase of the anisotropic displacement parameters for all atoms; we therefore link these effects to radiation damage accumulated during consecutive data collections. The effects of radiation on the formation of the polar structure of ferroelectric glycinium phosphite is discussed together with the advantages and drawbacks of synchrotron experimentation with fine temperature sampling.

中文翻译：

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有机铁电体中的相变：亚磷酸甘氨酸盐，有和没有 X 射线辐射损伤

通过使用同步辐射的多温度单晶衍射以及实验室 X 射线衍射仪的类似实验，对有机铁电体（即亚磷酸甘氨酸盐）的热演化进行了探测。这两个系列的测量显示在几乎相同的温度下从顺电到铁电状态的转移，Ť _Ç = 225 K。同步加速器和实验室数据的晶胞参数和体积的温度演变是截然不同的。后一种情况对应于之前的报告，并显示了电池在冷却时的预期收缩。同步加速器光束收集的数据显示冷却时体积出现异常的非线性增加。结构分析表明，这种体积增加伴随着高角度散射的抑制和所有原子各向异性位移参数的明显增加；因此，我们将这些影响与连续数据收集过程中积累的辐射损伤联系起来。