【摘要】 为了论证层错是硫化锌晶体中交流电致发光的一个必要条件,我们把3C-ZnS单晶体在1100℃热处理后引入了层错。同时,我们对热处理前后的结构,用劳埃背反射法和文献[8、13]推导的公式进行了分析。结果表明,沿3C-结构<111>四个等价方向都可以产生无序、孪晶和2H-结构,而且当热处理时间足够长时,结构转变趋向于一个<111>方向。这些实验结果,在有关的文献中尚未见到。更多还原

【Abstract】 Zinc sulphide has a high-temperature stable structure at T>1024℃, i.e. wurtzite (2H) and a low-temperature stable structure at T<1024℃, i. e. sphalerite (3C). Much x-ray diffraction study of 2H-3C structure transformations were reported, but the study of 3C-2H structure transformations are little. Especially, the experimental investigations about the orientations of 3C-2H transformations by Laue diffraction haven’t been seen as yet.In the present work,the stacking faults were introduced into 3C-ZnS single-crystals by heat treatment,the orientated relation of 3C-MT(micro-twin) -2H transformations was then investigated with Laue back reflection method. Specimens of ZnS single-crystals were prepared with vapour-grown method. It was found by means of x-ray diffraction that the crystallinity of the specimens is fine, and there is no stacking faults in ZnS crystals. The heat treatment condition. 1100℃,S vapour protecting the specimens, keeping crystals at high temperature 10 minutes to 5 hours, cooling the specimens in air. The x-ray condition. Cu radiation, 35kV, D = 37mm, taking Laue back reflection photographs of each specimen in fixed position before and after each heat treatment respectivly. After that, a lot of new Laue diffracted patterns which have not been reported in the literature were observed.In order to interpret these patterns, simple and suitable formulas to index Laue photographs and calculate "anomalous diffracted spots" have been derived, and the stereographic projections corresponding to some crystal planes also have been plotted. All of Laue diffracted spots and streaking in the Laue photographs were indexed and analysed.The results show that.1.For the heat treated 3C-ZnS single-crystals, the probabilities of the structure transformations along four<111>irections are equal. Therefore, the diffracted patterns of the structure transformations along four <111>irections can be observed simultaneously.On the other hand, because the crystal is not uniform, the minute difference of local temperature and the time of structure transformations are different, these made the development in the process of structure transformations along one direction, while the structure transformation along another directions are prohibited. Therefore, we have not only observed the diffracted patterns of structure transformations along four <111>irections at the same time, but also observed the patterns of transformation along one, two or three <111>irections.2.When the time of heat treatment is sufficient, the structure transformations go from four <111>irections to one <111>irection gradually. This explains that the structure transformations are produced in the heating process.3.After the heat treatments, the streaking extent of diffracted patterns in the Laue photographs show the strong disorder along one direction. In the transition of zinc sulphide 3C-2H, MT, micro-2H and the disorder layers arrange alternately and randomly, and the three structure are often produced together. On the other hand, the uniformity of the streaking extent along four <111>irections in the diffracted patterns show that the stacking faults, MT and micro-2H structure statistically distribute along four <111>irections.4.The method of Laue back reflection is an effective method to identify twin of HCP in an FCC matrix.更多还原