【摘要】 本文叙述从室温到230℃的温度范围内,借助于高温衍射装置对磷酸二氢钾(KDP)和磷酸二氘钾(DKDP)试样进行的高温X—射线衍射研究。实验表明:KDP在上述温度内在熔化(分解)以前只有一个相转变点,其温度用T_l表示。这个相变点与失水有关。DKDP具有二个不同的相转变点,其温度分别用T_p和T_l表示。T_p是与氘键减弱相关的重建式相变。在这个温度时,晶体结构从四方转变为单斜。这个相变在热力学上为一级相变。晶体试样经历T_p相变以后在室温下放置一段时间即变成四方相。更多还原

【Abstract】 High-temperature X-ray diffraction studies in KDP and DKDP crystals from room temperature to 230℃ have been carried out by means of high temperature X-ray diffraction technique. It has been shown that there is onty one phase transition in KDP crystals before melting (decomposed). This phase transition referred to as Tl is associated with water-evaporation. But there are two different phase transitions in DKDP, which are referred to as T_p and T_l respectively. T_p is a reconstructed phase transition associated with the weakening of the deuterium bonds. At T_P temperature, the structure of the crystal changes from tetragonal to monoclinic. Thermodynamically it is a first order transition. After being kept for a period of time, the crystal samples undergone Tp transition Change back to tetragonal phase.更多还原